Total Fitness Ebooks Catalog

The Warrior Zero Body Weight Challenge

The Warrior zero body weight challenge was created by Helder Gomes, he is a service-connected disabled veteran. He has been a victim of body slowing down and energy stripped off, he has used the techniques and now is sharing with you to assist you as well. He has also experienced the working of other programs and has testified that they were actually doing more harm than good, so if you are thinking of other programs, don't. Filled with a decade of research information, the product has been used widely by various clients and has proven to work, it can, therefore, be trusted and used. It is an operational fitness program that will get you the lean muscles and body shape you have hoped for, without signing up for expensive membership programs at the gym or using fancy types equipment. This fitness operator shows the men over forty years how to keep active and eliminate weakness. This will also teach you how to build combat-ready conditioning at any age. This secret training method is used by the most dangerous men there exists. In the program; you will find thirteen weeks of precision fitness system operator programming that is strategically designed to help you eliminate, weakness and build a stable body. And each week you are guaranteed a result that will leave you in shock! How to get through the defined exercise performance from start to finish. Continue reading...

The Warrior Zero Body Weight Challenge Summary

Rating:

4.8 stars out of 17 votes

Contents: Ebooks, Video Course
Author: Helder Gomes
Official Website: thewarriorzeroproject.com
Price: $37.00

Access Now

My The Warrior Zero Body Weight Challenge Review

Highly Recommended

Recently several visitors of websites have asked me about this book, which is being promoted quite widely across the Internet. So I bought a copy myself to figure out what all the fuss was about.

I personally recommend to buy this ebook. The quality is excellent and for this low price and 100% Money back guarantee, you have nothing to lose.

Altruism via Inclusive Fitness Kin Selection

Where b is the reproductive benefit to the recipient, c is the cost in terms of lifetime reproduction for the actor, and r is the genetic relatedness between actor and recipient (Figure 3 a). For example, selection can favor helping a sister (r 0.5) to raise her offspring when one can raise more than twice as many of her offspring (indirect fitness), than one's own (direct fitness), because this will increase the overall propagation of copies of the actor's genes. The sum of fitness effects through indirect effects and direct effects is the 'inclusive fitness effect' of a behavior (see Kin Selection). Figure 3 Four nonmutually exclusive processes that generate altruism or altruism-like behaviors. Altruists are smiling and same-color individuals are genetically related. (a) Strong altruism can be selected when individuals are genetically related (left-hand side) but not when they are unrelated (right-hand side). (b) Weak altruism (gray, left-hand side) can be selected when helping the...

Altruism via Direct Fitness

Whose writings suggest something similar. While policing and punishment can explain apparent acts of altruism, however, one still needs an explanation for how policing, which carries a personal cost, can evolve the so-called 'second-order problem'. For this, one must appeal again to some or all of the above theories inclusive fitness, group selection, and direct benefits. If a helping behavior has arisen completely through enforcement, the primary evolutionary adaptation is in the enforcer, rather than the helping individual. The helping behavior, therefore, should probably not be considered an altruistic adaptation. This objection can be overturned, however, when an altruistic action evolves through a combination of enforcement and inclusive-fitness effects, as occurs in the social insects (below). Enforcement, punishment, and policing are central to cementing the altruism in many social groups. This includes queen and worker policing in many species ofsocial insects, whereby the...

Relative Advantage Versus Partial Change in Mean Fitness

Here the connection between the proposed fundamental theorem (6.4) and Ewens's theorems will be investigated. We will do this in three steps. First, we recall the concept of partial change in mean fitness. Second, we will study the residual of average effects. Third, we will see that the notion of partial change of mean fitness contains the concepts of relative advantage. To get insight into the connection between the partial change in mean fitness and the relative advantage we have to recall the notion of partial change in mean fitness. We will follow the derivation of Ewens's version of the fundamental theorem for one locus 3 and briefly recall all points of 3 used here. Let pi denote the frequency of allele Ai ,and Pij denote the frequency and Wij the fitness (viability) of zygote Ai Aj (i, j 1, 2, , n). Ewens 3 considered Mendelian systems, thus Wij wji. The current frequency of allele Ai is where WW (P) Ei j PijWij is the mean fitness of the population. Using this notation, Ewens...

Practical approaches to parasitoid fitness

In the literature there exists a useful distinction between measures of true fitness (indicating a mutant's capacity to increase in frequency, often expressed as a reproduction ratio R0 or a per capita population growth rate) and measures of indirect fitness such as Lifetime reproductive success (fitness) Fig. 2.1 Factors determining fitness or lifetime reproductive success. fecundity, longevity, or size (Stephens & Krebs 1986). An indirect fitness measure is only accepted as a correct fitness measure if it changes monotonically with the true fitness measure. Roitberg et al. (2001) state that few biologists ever measure fitness directly. It should be noted that different measures of fitness have their impact in different parts of the foraging process (Fig. 2.1). For instance, the body size of parasitoids, although directly related to potential fitness (fecundity and, less strictly, egg load), certainly is not directly related to realized fitness. The latter kind of fitness is what...

Theoretical approach to parasitoid fitness 231 Adaptive dynamics

When we refer to 'true' fitness, what do we actually mean Different scientific domains have developed different and sometimes apparent contradictory definitions. The framework Therefore, population dynamics, including the interaction with the host population, are largely determined by the resident population. Thus, the dynamics of the mutant is essentially decoupled in the sense that mutant traits affect neither the dynamics of the resident nor those of the host. The standard approach in adaptive dynamics is that mutation occurs on a timescale that is long relative to the timescale of convergence to an ecological attractor (stable point and limit cycle). If a new (rare) mutant appears, it can either decrease or increase in numbers. This is essentially determined by the invasion fitness, that is the per capita growth rate of the new mutant in an environment consisting of only residents. If invasion fitness is negative, then the mutant eventually disappears and nothing happens. However,...

Budget effects of plant size on fitness gains

Situations in which individuals differ in the resources they have to invest, and each individual adjusts its allocation conditional on its resource status, have received the most theoretical analysis (e.g., Lloyd and Bawa 1984 Frank 1987). In this section, I focus on the budget effects of plant size in the absence of direct effects, as might be suitable for animal-pollinated plants. In this case, the same fitness gain curves apply to all size classes. Again I assume a linear female curve, and consider the three shapes for the male gain curve (Fig. 3.4), with qualitatively different outcomes. All the results can also be applied when the male fitness curve is linear, whereas the female curve is nonlinear. If male fitness decelerates with increased resource investment, selection favours a hermaphrodite that invests in both sex functions, with gradually increased emphasis on female reproduction with increasing plant size (continuous gender adjustment Fig. 3.4a and d). In Fig. 3.4a,...

Aspects affecting parasitoid fitness

The following briefly discusses a number of aspects that are pertinent to parasitoid life histories but are difficult to capture in fitness measures. The first case that we discuss is that of egg limitation. This is a conceptually simple case that nevertheless leads to unsolvable mathematical expressions. Thereafter, we discuss a number of other examples without presenting the complex mathematical expressions that should be studied to analyze them. where the first term sums fitness contributions over the cases where the parasitoid encounters fewer hosts than her egg load while the second term collects all cases where the parasitoid runs out of eggs before dying. The factor 1 - Xf 0 q(w) gives the probability of the parasitoid being egg limited. Unfortunately, for arbitrary distributions these summations are difficult to solve analytically. It is obvious that the fitness of a parasitoid in a dynamically changing patchy environment is strongly determined by how it creates and uses the...

The Impact of Host Quality on Fitness

Host quality influences three main components of parasitoid fitness survival to the adult stage, size and development time (Waage and Godfray, 1985 Godfray, 1994). Size and age are usually considered the most important measures of host quality, although other factors, such as the diet a host feeds upon, are also important. Studies with a diversity of parasitoids indicate that host size strongly influences offspring survival and adult size, and that parasitoid size is positively correlated with other measures of lifetime reproductive success, such as fecundity, mating success and longevity. The relationship between host and parasitoid size is most direct for idiobionts, such as egg or pupal parasitoids, whose hosts are closed resources that do not change in size after parasitism. For solitary species, offspring fitness will be determined primarily by host size alone, while, for gregarious species, offspring fitness will be affected by both host size and the total number of other...

Residents Have Fitness Zero

For any long-existing community, at the E generated by that community the invasion fitnesses of all composing types equal zero. This is because any type that has invasion fitness different from zero either explodes or dies out, and therefore cannot be a permanent member of the community. For community models having equilibria corresponding to nonfluctuating environments, setting the invasion fitnesses of all types equal to zero produces as many equations for E as there are types. These can be combined with the equilibrium equations derived from the mechanisms that produce the environmental condition from the population outputs to the environment. The latter output can be calculated from the population sizes times the corresponding normalized stationary h-state

When will Long Term Evolution Maximize Some Fitness Related Measure

Given the stress on fitness maximization in the literature, it is relevant to know when there do exist properties oftypes that are maximized at CSSs. This is the case if and only if'the trait values affect fitness effectively in a one-dimensional monotone manner'. The term 'effectively' here means that the specified properties only need to pertain to the range of fitness values closely surrounding the change from negative to positive. More precisely, the following results hold, with X denoting the potential resident vectors, E the realizable environments, and the R the real numbers

Two Types of Fitness Landscapes

The first publication on this topic Wright introduced two different versions of fitness landscapes which Wright himself used somewhat interchangeably, laying the ground for confusion about their exact meaning, dimensionality, and justification. Average Fitness of the Population In one interpretation, which is much more common but sometimes misleading, a fitness landscape is a surface in a multidimensional space that represents the mean fitness of the population as a function of gamete (or allele) frequencies. A population is represented as a point on the surface. This representation can be very illuminating because in some simple population genetic models, the population evolves in the direction of the local gradient in the mean fitness approaching a local 'peak' (i.e., maximum) in a fitness landscape. However, evolutionary dynamics of populations is a very complex process. In general, all relevant evolutionary factors (e.g., natural and sexual selection, random genetic drift,...

Canonical Fitness Landscapes

Fitness landscapes for real biological organisms are, in general, unknown. Only recently have direct studies of specific landscapes such as RNA and protein landscapes started to appear. However, some general features of fitness landscapes can be identified using available data, biological intuition, and mathematical reasoning. Rugged Fitness Landscapes Strong artificial selection in a specific direction usually results in a desired response, but as a consequence of the genetic changes brought about by artificial selection, different components of fitness (such as viability or fertility) significantly decrease. Moreover, after relaxing artificial selection, natural selection usually tends to return the population to its original state. These observations stimulated Wright's view of species as occupying isolated peaks in a fitness landscape. Following Wright, fitness landscapes are often imagined as 'rugged' surfaces having many local 'fitness peaks' of different height separated by...

Holey Fitness Landscapes

Cumulatively since the origin of life. There is an important consequence of this observation. Because of the redundancy in the genotype-fitness map, different genotypes are bound to have very similar (identical from any practical point of view) fitnesses. Unless there is a strongly 'nonrandom' assignment of fitnesses (say all well-fit genotypes are put together in a single 'corner' of the genotype space), a possibility exists that well-fit genotypes might form connected clusters (or networks) that might extend to some degree throughout the genotype space. If this were so, populations might evolve along these clusters by single substitutions and diverge genetically without going through any adaptive valleys. The huge dimensionality of most biologically interesting fitness landscapes brings some new properties which one does not observe in low-dimensional landscapes (e.g., in 2D or 3D geographic landscapes). In particular, multidimensional landscapes are generically characterized by the...

Kin Selection Optimizes Inclusive Fitness

Natural selection optimizes fitness (see Fitness). Understanding what kin selection optimizes was crucial to its emergence as one of the fundamental tenets of evolutionary theory. W. D. Hamilton was the first to explain this formally in terms of his theory of inclusive fitness in 1964. Hamilton pointed out that when we measure the fitness of a trait we must take into consideration the effect that trait has on the fitness of other individuals as well as the actor who performs the behavior. If a trait has a beneficial effect on carriers of the same gene, then that gene can spread by kin selection. Inclusive fitness therefore is made up of two components - direct fitness (from the production of offspring) and indirect fitness (from aiding the reproduction of relatives). Kin selection explains how a trait can spread by its effect on indirect fitness.

Measuring the Sex Difference in Fitness Variance

Most research on sexual selection and its effects on mating systems has focused either on the context in which sexual selection occurs (i.e., via male combat or female choice), or on the evolutionary outcome of sexual selection (i.e., on descriptions of sexual dimorphism or mating behavior). This research has led to fascinating results it is the same approach used by Darwin himself but unfortunately, these results do not consider either the process or the extent to which sexual selection may achieve its evolutionary effects. To understand whether and to what degree the sexes may become distinct within a species, and to understand if sexual selection could be responsible for such divergence among related species, it is necessary to measure the fitness variance for males and females within as well as among species. This method illustrates when and why sexual selection can be strong enough to overwhelm the effects of natural selection and, therefore, how it can produce the sex-specific...

Effects on Fitness and Ecological Parameters

Organisms because they may affect organismal-level fitness components. This may be translated into effects on populations, and eventually communities and ecosystems. This is illustrated in Figure 8. First, because DNA damage and mutations can lead to cell death and cancer, this may affect survival. Because DNA damage enhances the rate of cell senescence, accumulation of unrepaired damage and mutations may affect longevity and population age structure. DNA damage and mutations have their greatest deleterious effect on rapidly dividing cells. Because gonadal germ cells are rapidly dividing, they are particularly susceptible to the effects of DNA damage and mutations. Growth may also be affected because of induced cell death, interference with DNA replication, or induced delay of cell division (DNA damage induces cell cycle delay, a phenomenon that halts the cell cycle to allow time for repair before DNA replication or mitosis). Immune cells, both mature white blood cells and white blood...

General Importance of Physiological Processes for Fitness at the Community Level

Fitness is frequently defined and quantified as the number of seeds produced ('Darwinian fitness'). However, this may cause difficulties, because it is too limited a view. This is readily recognized when we consider, for example, K- and r-strategies of plants with small and high seed numbers, respectively, or clonal growth, where particular plant species may dominate entire ecosystems without any generative propagation. Germination of seeds and establishment and survival of seedlings are essential. Thus, we see that the entire complement of physiological processes contributes to fitness, for example, in addition to the capacity of photosynthesis treated above in some detail as a special case story, and similarly important functions such as dormancy of seeds with germination at the ecologically appropriate time and the physiology of development, competition, defense, and mutualism as alluded to above.

Does phyA increase fitness

The question here is not just whether phyA increases fitness of extant species, but whether it might have conferred an adaptive advantage to newly evolving angiosperms, which faced the challenge of establishing in a landscape dominated by ferns and gymnosperms. The failure of phyA null mutants of Arabidopsis to survive in the shade suggests that its functions do increase fitness (Yanovsky et al. 1995). Moreover, since phyB inhibits de-etiolation in the shade, it is reasonable to infer that evolution of a photoreceptor to counter this inhibition (assuming it was present in early-diverging angiosperms) would be advantageous in dimly lit environments. However, since the ability to initiate development in the shade would provide an adaptive advantage only if early angiosperms colonized shaded environments, it is important to understand their ecology. using mutagenesis experiments to compare phytochrome-mediated responses of wild-type Arabidopsis with those of Arabidopsis phyA null mutants...

Dual fitness consequences for ecological speciation

The contribution of ecological trait divergence to speciation depends on the success (i.e., fitness) of migrants between environments 14,35 , as well as the success of any resulting hybrids (Figure 14.1). Success in both cases depends on the ability to exploit available resources, and is evident in the survival, growth, and fecundity of individuals before reproduction, i.e., natural selection, as well as on their ability to obtain mates, i.e., sexual selection. Both natural and sexual selection can be important in isolating populations from different ecological environments. With respect to natural selection, ecological and life-history performance (e.g., in resource use, growth, survival, and fecundity) is often low for migrants between environments relative to residents 14,32,33,143 , or for hybrids in either parental environment relative to pure forms 23,33 . With respect to sexual selection, mating probabilities are often low for individuals from different environments relative to...

Floral traits and the fitness of hybrids

In addition to affecting hybrid formation, floral traits can influence hybrid fitness and thus the level of post-zygotic reproductive isolation (Fig. 18.1d-f). Floral traits play this role most directly by affecting pollen export and import by hybrids. Low pollination success of hybrids could cause either low female fitness (seed production) or low male fitness (seeds sired). David Lloyd (1980) first articulated in detail that the functional gender of individual hermaphroditic plants varies within populations, depending on their relative success as female and male parents. Male fertility is usually difficult to measure in natural plant populations, because of the large number of potential fathers for each seed (Meagher 1986), and this has rarely been attempted for natural hybrids (Melendez-Ackerman and Campbell 1998). However, continuing advances in molecular markers, such as microsatellites, and statistical analysis of male fertility (Smouse et al. 1999 Morgan and Conner 2001) make...

Direct effects of plant size on fitness gains

Plant size can affect fitness directly, so that returns from a given absolute amount of resources differ for small and large plants (Fig. 3.5). For instance, in a wind-pollinated plant, pollen released from a tall individual may disperse farther and be more successful than pollen from a short individual. Direct effects may also occur in some animal-pollinated plants, because pollinators may prefer taller plants among neighbours (Ishii 2004). With direct effects of plant size, fitness returns per unit of investment differ for small and large plants (Fig. 3.5), so that separate gain curves must be established for individuals in different size classes. If both sexes have linear gain curves (Fig. 3.5a), direct fitness effects will most probably cause an abrupt shift from male to female at a certain size (Klinkhamer et al. 1997 Cadet et al. 2004). If the slope of the male gain curve switches from increasing less steeply than the female curve to more steeply at some threshold size, large...

The number and fitness of offspring

A second key trade-off is that between the number of offspring and their individual fitness. At its simplest, this is a trade-off between the size and number of offspring, within a given total reproductive investment. That is, a reproductive allocation can be divided into fewer, larger offspring or more, smaller offspring. However, the size of an egg or seed is only an index of its likely fitness. It may be more appropriate to look for a trade-off between the number of offspring and, say, their individual survivorship or developmental rate. Sinervo (1990), though, did manipulate the size of the eggs of an iguanid lizard (Sceloporus occidentalis) by removing yolk from them after they have been produced, giving rise to healthy but smaller offspring than unmanipulated eggs. These smaller hatch-lings had a slower sprint speed (Figure 4.23c) - probably an indication of a reduced ability to avoid predators, and hence of a lower fitness. Within natural populations, this species produces...

Options sets fitness contours and a classification of habitats

4.9.1 Options sets and fitness contours Figure 4.24 (a, b) Options sets - the combinations available to an organism of, in this case, present reproduction and present growth. As explained in the text, the outer boundary of the options set is a trade-off curve (a) is convex-outwards, (b) concave-outwards. (c) Fitness contours linking combinations of present reproduction and present growth that have equal fitness in a given habitat. Hence, contours further from the origin have greater fitness. (d) The point in an options set with the greatest fitness is the one that reaches the highest fitness contour. This point, and the (optimal) value for present reproduction giving rise to it, are marked with an asterisk. (After Sibly & Calow, 1983.) Figure 4.24 (a, b) Options sets - the combinations available to an organism of, in this case, present reproduction and present growth. As explained in the text, the outer boundary of the options set is a trade-off curve (a) is convex-outwards, (b)...

Fitness

In the population are copied at different rates. A measure of a genotype's long-term success is fitness. Individuals that produce the largest number of offspring over a long period of time have the greatest fitness. Fitness is always a relative measure, since the environmental conditions often do not allow for maximum production. One should consider the fitness of an individual relative to other individuals living in the same environment. The individual that has the most surviving offspring contributes the most to the gene pool, the sum of all genes in a population. Its phenotypic features will increase in the population, indicating it has the highest relative fitness. Two components of fitness are reproductive potential and survival. It does not necessarily follow that those individuals with the greatest number of offspring automatically have the highest fitness. It is critical to know how many of the offspring survive. A species can achieve a high degree of fitness either by...

Inclusive Fitness

The concept of inclusive fitness has become the foundation of modern biology and may be one of the most important advances in evolutionary biology since Darwin introduced the theory of natural selection. If natural selection occurs at the individual level (i.e., individuals with higher reproductive success have the greatest genetic representation in future generations), how do cooperative breeding systems evolve The apparent paradox of some individuals within a population foregoing the opportunity to breed can be explained if some individuals help their close relatives reproduce. By assisting close relatives, altruists still manage to pass on their genes indirectly. This behavior can arise when the genetic relatedness between an altruist and beneficiary (r) multiplied by the fitness gain to the beneficiary (b) minus the fitness cost to the altruist (c) is greater than zero that is, (rb - c) 0.

Acylglycerols See lipid

Adaptive function A mathematical function that combines phenotypic fitness in different environments to give a measure of the overall fitness of a phenotype in a heterogeneous environment. Where organisms encounter patches of habitat of type i in direct proportion to their frequency (p), the overall fitness of a phenotype (W) is the average of its fitnesses in each habitat type weighted by their frequencies W p1W1 + p2W2 If a graph of fitness in each of two environments is plotted, the adaptive function forms a line of equal fitness whose position on the graph is determined by the relative frequencies of the two environments. The slope of the adaptive function will vary from place to place as the relative frequencies of the different types of habitat patches vary. plied to temporally varying environments, where habitat changes with time rather than space, the adaptive function is most accurately represented by a geometric mean, since fitness in this case is expressed as changes in...

Age Structure Effects in Age ClassStructured Species

Experienced by individuals in the cohort as juveniles (cohort effects), and this variation can persist throughout life and lead to differences in fitness among cohorts. This variation among cohorts can further affect many aspects of population dynamics (see the section 'Cohort effects'). Because age structure has such a strong effect on the productivity and mortality patterns of populations and can vary markedly between years within a population, even for long-lived -selected species, the annual rate of increase of populations can also vary markedly simply because of annual changes in the age structure of a population.

Four examples and a metaphor

Type 1 is more profitable than prey type 2. Consider a long period of time T in which the only thing that the forager does is look for prey items. We ask what is the best way to consume prey Since I know the answer that is coming, we will consider only two cases (but you might want to think about alternatives as you read along). Either the forager eats whatever it encounters (is said to generalize) or it only eats prey type 1, rejecting prey type 2 whenever this type is encountered (is said to specialize). Since the flow of energy to organisms is a fundamental biological consideration, we will assume that the overall rate of energy acquisition is a proxy for Darwinian fitness (i.e. a proxy for the long term number of descendants).

The Optimal Transmission Strategy

OTS involves selective adaptations that increase the probability of the free-living stages to localize themselves in what Combes et al. (1994) called 'host space' and 'host time'. As stated above, selection tends to increase the fitness of parasites by retaining genes at each step of the life cycle. Available data mostly concern cercariae. Spectacular examples are the distribution of cercariae at various depths in water (Bartoli and Combes, 1986) and cercarial shedding at various times of the circadian period (Theron, 1984). These cercarial emergence rhythms tend to limit

Early investigations on mating systems

Attributed the evolution of self-compatibility to the need for an adequate seed set under conditions where cross-pollination was insufficient for this purpose'' (Lloyd 1965, p. 128). In contrast, emphasizing selection on the regulation of recombination, Darlington, Mather, and Stebbins had proposed that because of higher homo-zygosity ''a self-fertilizing plant can become more 'closely adapted' to its immediate environment,'' even though '' self-fertilizing plants achieve an increase in immediate fitness at the expense of a decreased flexibility'' (p. 129). Lloyd found support for the reproductive-assurance hypothesis in two results a qualitative difference in pollinator abundance among large and small populations, and fertilization failure of up to 16 of flowers in populations. In contrast, he argued that the evolution of self-compatibility could not provide an immediate genetic advantage, because his comparison of germination by self- and outcrossed seeds from a largely...

Integration of pollination and mating

In addition, Lloyd was the first to refer specifically to the displacement of outcrossed seeds by self-fertilization as seed discounting. Although this negative relation is implicit in most genetic models of mating-system evolution (e.g., Nagylaki 1976), which typically assume complete fertilization, the consequences of the weakening of this tradeoff when cross-pollination is insufficient for complete fertilization had not been explored. Finally, the alternate modes of selfing that Lloyd recognized have been measured for several species (e.g., Eckert 2000 Johnson et al. 2005), their implications for the evolution of plant mating have received additional theoretical analysis (e.g., Schoen et al. 1996 Morgan and Wilson 2005 Chapter 4) and the differential consequences for maternal fitness have since been demonstrated by Herlihy and Eckert (2002).

Allee Effects at the Individual Level

The simplest definition of an Allee effect is an increasing relationship between some component of fitness (e.g., reproductive success, growth, or survival) and some measure of the number of conspecifics (e.g., group size, density) with which an individual interacts (Figure 2). As the number of interactors increases, the benefits arising from interactions level off. Ecologists expect that fitness also declines as a function of the number of interactors as a consequence of competition and other costs, again leveling off at high interaction levels. The net fitness (the product of the two curves) results in a unimodal or humped relationship between fitness and the number of interactors. Although this unimodal pattern has also been termed an Allee effect, it is the beneficial effects of interactions upon fitness that truly define Allee effects. Table 1 provides a number of examples of Allee effects exhibited by a wide range of species. This wide variety of benefits indicates that Allee...

Proximate and ultimate factors

Ecology is changing from a descriptive science into an explanatory science. There has been a shift to view most aspects of ecology from the standpoint of fitness. The new focus of ecologists is to investigate not only how organisms are adapted to their environment, but why they have a particular adaptation, which is to ask what is their adaptive value. An example may help clarify the distinction. Some planktonic copepods (cyclopoid copepods) have a diapause or resting stage in their life cycle during which they do not undergo further development. This diapause often occurs in the summer. Adult copepods reproduce in the spring. Their larvae (nauplii) and the first juvenile stages (cope-podites) develop, but the fourth copepodite stage ceases development and buries itself in the sediment to pass the summer. They reappear in late fall and complete their development. Spindler (1971) demonstrated experimentally that day length determines the onset of diapause. This explains what controls...

Theories on the evolution of sexual systems

Plants in gynodioecious and sub-dioecious populations as ''males'' (inconstant or fruiting males), even though they produce ovuliferous flowers. This decision recognized that the fitness of fruiting males in such populations results largely from contributing pollen to female plants. However, because the notion that males can produce seed is counterintuitive, Lloyd's terminology was not adopted in a recent volume on gender and sexual dimorphism in plants (Geber et al. 1999 Sakai and Weller 1999, pp. 7-8), despite many loyal adherents.

Altruism via Group Selection

(a) Enforcement + inclusive fitness colonies with a queen (b) Inclusive fitness colonies without a queen Figure 4 Worker altruism is driven by a combination of inclusive-fitness effects and enforcement in social insect colonies. (a) Altruistic self-restraint due to enforcement. In colonies where the mother queen is alive, the workers can raise either the queen's or other workers' eggs. In species where relatedness among workers is high, they tend to raise the workers' eggs because they are highly related to them, but in species where relatedness among workers is low, like the honeybee, workers 'police' each others' eggs and remove them. This reduces the benefits to worker reproduction which, alongside indirect fitness benefits, promotes reproductive self-restraint. (b) Altruistic self-restraint due to inclusive-fitness effects. If the queen dies the workers compete to lay eggs. However, when relatedness is high, many show altruistic self-restraint and do not attempt to reproduce....

Synthetic View of Altruism and Cooperation

Altruistic behaviors are a central component of many social systems. Any judgment on the extent of altruism in the natural world, however, will always depend upon definition. A requirement for conscious intention restricts altruism to creatures with sophisticated cognition, such as humans. However, the fitness-based definition of behavioral ecology reveals a wealth of additional examples, which typically arise through a combination of mechanisms. Centrally though, actions that decrease lifetime reproduction can readily evolve when there are indirect benefits that increase overall inclusive fitness. This is nowhere more obvious than in the social insects, where workers spend their entire life building, guarding, and foraging to raise a myriad of their relatives' offspring.

Animals as individuals

Distribution in nature, we should know how an individual is adapted to its environment, what types of environment it encounters, and what resources are available. An adaptation is defined as a trait that increases fitness relative to an alternative trait (Schluter 2000). When we talk about the adaptations of individuals we mean the way in which an animal fits into its environment and uses its resources. The adaptive characters that describe an individual - its physical attributes (morphology), physiology, and behavior - are determined first by the processes of natural selection and secondly by its history over evolutionary time, its phylogeny. The selection comes from the relative success of the different types in leaving progeny. The process of natural selection is the replacement of types (or morphs) that produce fewer successful offspring with those that are more successful. The more successful types are described as fitter than less successful types. Fitness is defined as the...

Gender concepts and theory

In which oi and pi are the numbers of ovules and pollen grains produced by individual i, respectively, and E is the ratio of ovules to pollen grains in the population as a whole. Therefore, pheno-typic gender considers the production of pollen and ovules (or seeds) of individual plants relative to the average ratio of expenditure in the population. Note that Lloyd (1979b, 1980b, c) originally referred to Gp as functional gender, but changed terminology in his 1984 review with K. S. Bawa to that given in eq. 1 and 2. Values of Gp can range from 0 to 1, denoting in the extremes strictly male and female plants, respectively (Fig. 1.3c). Gp has now been measured to describe gender strategies in a wide range of flowering plants (e.g., Fig. 1.3 also see Thomson and Barrett 1981 Lloyd and Bawa 1984 Wolfe and Shmida 1997 Vaughton and Ramsey 2002). However, truly functional measurement of gender based on mating success using genetic markers is still in its infancy (Elle and Meagher 2000 Morgan...

The ecomolecular synthesis

Evolution, as in rapid island radiations, may proceed at an astonishing rate. Again this fast tempo may be genomic in origin, due to heritable developmental lability for key traits (labile versus constrained development), or ecological because the environment is permissive to phenotypic extremes and may select strongly on these extremes (permissive versus difficult fitness landscapes).

The general laws of population ecology

Sutherland (1996) wrote that population ecology suffers from having no overall a priori theory from which explanations and predictions can be devised. He continued that behavioral ecology has such a theory - evolution by means of natural selection - which yields the prediction that individuals will maximize fitness. I take this to mean that the discipline loosely known as evolutionary ecology has an a priori theory. Population ecology, however, should be treated as an extension of evolutionary ecology. Therefore, we should ask ourselves under what circumstances might a characteristic such as the low fecundity of the wandering albatross (Diomedea exulans), or a phenomenon such as the population cycles known for snowshoe hares (Lepus americanus), have evolved.

Allocation strategies

The allocation of time, energy and nutrients governs many aspects of organisms' lives, including phenology, gender and sex ratio, fecundity, growth, defence, and intrinsic longevity. Indeed the life history represents a series of allocations (e.g., age at first reproduction, schedule of reproductive effort) that fundamentally determine fitness. The life history mediates the effects of all physiological, morphological, and behavioural traits on fitness (Roff 1992), so that selection on most traits depends on their influences on allocation patterns.

Water As A Constituent Of Soil

Henderson, a noted physical chemist and physiologist, published a book (The Fitness of the Environment, 1913), which was a landmark among books on biological topics. Henderson's thesis is that one substance, water, is responsible for the characteristics of life, and the biosphere as we know it. The highly bipolar nature of water, with its twin hydrogen bonds, leads to a number of intriguing characteristics (e.g., high specific heat), which have enabled life in the thin diaphanous veil of the biosphere (Lovelock, 1979, 1988) to extend and proliferate almost endlessly through the air, water, soil, and several kilometers into the earth's mantle (Whitman et al., 1998).

Establishment Rejuvenation of Botanical Diversity within Grassland Field Margins

Careful consideration should be given to the provenance of any seed or other plant propagules being introduced, as the widespread use of non-native seed can compromise the genetic diversity of any particular species or population (Price, 2003, Smith et al, 2005). In addition, some species may demonstrate the home site advantage hypothesis i.e. propagules of local origin showing enhanced fitness when compared with non-local propagules (Montalvo and Ellstrand, 2000). Hay strewing and brush harvesting of seed from species rich donor sites can be effective methods of introducing desirable propagules of native provenance to a recipient site. Although results from individual species are known to differ depending on their structural location within the sward e.g. colonisation results by lower growing species such as Lotus corniculatus (birdsfoot trefoil) and Prunella vulgaris (self-heal), tend to be greater with hay strewing compared with brush harvesting techniques. Hay strewing has the...

Allocation to competing functions

Organisms must commonly divide a limited resource among two or more functions, each of which affect fitness. As examples, Lloyd (1985) mentioned the following the production of the different kinds of structures that perform the same function in different circumstances (e.g., shade versus sun leaves), diet composition and habitat use of foraging animals, division of altruistic acts among relatives, and production of different sterile castes by social insects. To the extent that investment in these functions is drawn from a common resource pool, increased investment in one function must decrease investment in others. In this situation, natural selection favours the allocation pattern that maximizes overall fitness, rather than performance of any individual function. As Lloyd demonstrated in a series of papers, this optimal allocation pattern satisfies a specific set of characteristics. As a simple example, consider two functions, A and B (such as the production of ovules versus pollen),...

Marine Fisheries Section American Fisheries Society Special Publication

Population growth in fluctuating environments and measures of fitness from which we conclude, of course, that N(t) lN(0). If the per capita growth rate is less than 1, the population declines, if it is exactly equal to 1 the population is stable, and if it is greater than 1 the population grows. Now let us suppose that the per capita rate of growth varies, first in space and then in time. Because there is no density dependence, the per capita growth rate can also be used as a measure of fitness.

The Optimization Assumption

Behavioral ecology begins with an optimization premise. As a result of natural and cultural evolutionary processes, behavior will tend toward constrained optimization (Foley 1985). This assumption makes operational the long-standing view of anthropologists that hunter-gatherers tend to be skilled and effective in the food quest (Winterhalder 2001). Efficiency, say in capturing food energy, is important even if food is not in short supply because it affords hunter-gatherers the time and resources to engage fully in other essential or fitness-enhancing activities (Smith 1979). We state this premise as constrained optimization because we do not expect behavior to be fully optimal. Temporal lags in adaptation and compromises among conflicting adaptive goals impede this outcome. Optimization likewise must be determined within the cognitive capacities, beliefs and goals of the organism under study. We adopt the assumption of constrained optimization rather than satisficing because the...

Sizenumber compromises

Organisms often engage in processes that involve reiteration, either simultaneously (e.g., production of many pollen grains or ovules in individual flowers), or sequentially (e.g., catching prey in a series of patches during a single foraging bout). In such cases, a single pool of R resources is divided into n units of relatively equal size, s. In general, an individual's fitness is a positive function of both the number of units produced n fn(s) and their size fs(s) , so that (Lloyd 1987b). Notice that, in contrast to the allocation of resources among competing functions (eq. 3), fitness now depends on a product, rather than on a sum. Resource limitation creates an inverse relation between the number and size of units that can be produced, n R s (Fig. 1.5a), so selection cannot maximize unit size and number simultaneously. Instead, selection favours the combination of unit size and number that Figure 1.5 An example of aspects of size-number compromises. Panel (a) depicts the...

Basic Organism Needs Get Complicated

Basic vertebrate organism needs are surprisingly simple to list. Minimal resource needs include access to food, free or metabolic water, cover from predators and perhaps inclement weather, and to mates, all at variable rates that influence fitness. However, resource acquisition is complicated when resources are distributed het-erogeneously. One might get the impression from the current voluminous literature in landscape and population ecology that the complexity stemmed primarily from spatial complications. Indeed, much is promised by an understanding of the effects of spatial scale on animal population response. At one time, panmictic mixing and homogeneous landscapes were common assumptions used in population dynamics (Fisher, 1930) before the broad acceptance that habitat heterogeneity had causal effects and that appropriate scaling of our accounting metrics was essential for a more complete understanding of animal and population response (Wiens, 1989). For ecologists, scale...

Application to specific problems

Equations 4 and 6 are powerful for two reasons. First, by recognizing that allocation to competing functions and size-number compromises are recurring and pervasive themes in the lives of organisms, Lloyd provided two general solutions that illustrate the unity of biological processes. For example, this insight allowed Lloyd (1989) to analyze the seemingly unrelated topics of self-incompatibility and sterile castes in eusocial insects as facets of the same general problem. Second, eq. 4 and 6 illustrate that the optimal solutions to all allocation problems depend primarily on how fitness changes as allocation is modified (marginal fitness), rather than on the absolute fitness realized from any specific allocation pattern. Therefore, analysis of any allocation problem should focus on identifying the allocation pattern for which a small change in allocation is accompanied by exactly counterbalancing changes in marginal fitness. Given the practical difficulties of measuring fitness...

Discussion and Future Directions

Of high quality to possess the largest sexual ornaments. This can be tested directly, where there is independent evidence that different genotypes vary in fitness or in major components of fitness. For instance, if mutation load was experimentally manipulated, then one would expect groups with the most mutations to have smaller ornaments than controls reared in the same environment non-sexual trait expression would be expected to differ much less between treatments. Alternatively, one could search for genetic variation in condition dependence (e.g. David et al., 2000). In each case, the interaction between environmental and genetic variation is likely to be crucial. If ornaments show heightened condition dependence, then they are expected a priori to be greatly influenced by the environment, as condition, like other life-history traits, is likely to exhibit a large component of environmental variance (Price and Schluter, 1991 Houle, 1992). The handicap theory predicts that...

Single Species Ecotoxicity

Antibiotics generally appear to be far less toxic to invertebrates and vertebrates than to aquatic microorganisms or plants. Cladocerans may be most sensitive to tetracyclines. For the cladoceran Daphnia magna, the no observed effect concentration (NOEC) for survival during a 48 h tetracycline exposure period was 340 mgl 1 while the EC50 for reproduction was 44.8 p.gl . Cladocerans appear to be much less sensitive to erythromycin with reported acute EC50s for immobilization or mortality ranging from 200 to 400 mgl-1. In addition, a series of toxicity tests involving ciprofloxacin, levofloxacin, lomefloxacin, ofloxacin, enro-floxacin, flumequine, and clinafloxacin, all indicated very limited mortality for the cladoceran D. magna and the fathead minnow, Pimephales promelas, at concentrations as high as 10mgl In another study, the reported ciprofloxacin NOECs for D. magna and the zebrafish, Brachydanio rerio, were 60 and 100 mgl-1, respectively. For many aquatic vertebrates, such as...

Laboratory and field experiments

The classic construction of an experiment is to hold all factors constant except for one, so that the effect of the varied factor can be investigated. Such experiments are most easily carried out in the laboratory rather than in nature. Laboratory experiments with individuals or clones, a number of genetically identical organisms, are a recognized method in physiology. They are also very important to ecology since the fitness of an organism or its role in biochemical processes is dependent on its physiological condition and abilities. Most of the results referred to in Chapter 4 are derived from this type of experiment.

The evolution of heterostyly

To test whether heterostyly promotes legitimate pollination Lloyd and Webb (1992b) introduced a novel means of analyzing empirical data on the composition of pollen loads on stigmas of the floral morphs. During the preceding 20 years, many workers had sought direct evidence for the Darwinian hypothesis based on pollen-load data, with limited success (reviewed in Ganders 1979). Lloyd and Webb (1992b) reanalyzed published data for distylous Jepsonia heteranda (Ganders 1974) and tristylous Pontederia cordata (Barrett and Glover 1985) using a different method of calculation that allows pollen loads to be examined in terms of male function, as well as the more conventional female function. They used this approach because their pollen-transfer models indicated stronger selection for more proficient cross-pollination on male than on female fitness. Their empirical analysis revealed that the average proficiencies of legitimate donation and receipt were approximately twice those of the...

Concluding Remarks and Future Directions

The above examples show that, in a single ecosystem, the circulation of information that characterizes trematode cercarial transmission is highly diversified. If we try to compare this diversity with the taxonomy and phylogenetic relationships either of trematodes or of hosts, it is almost impossible to find a correlation. For instance, the response of cercariae to vibratory cues, the location of metacercariae in a particular organ, etc., have been selected in many different trematode families. Conversely, closely related species of trematodes can use different strategies and even different types of hosts. A striking example is that of Meiogymnophallus nereicola, whose cercariae settle in annelids, and Meiogymnophallus fossarum, whose cercariae settle in molluscs (Bartoli, 1972). Both are parasites of oyster-catcher definitive hosts. This suggests that natural selection has frequently modified trematode transmission strategies in the course of evolution. Obviously, using an annelid or...

Intimacy Casual to Obligate Associations

Associations between species vary from fleeting and casual to mutually obligatory and coevolved (Figure 1). At the casual end of this spectrum, associations may arise with little or no interaction, simply because species have similar environmental requirements and tolerances, a view championed by Gleason in his individualistic concept of plant associations. A variety of essentially fortuitous associations among species can enhance fitness of one or both parties. For example, among both terrestrial plants and seaweeds, toxic or otherwise herbivore-resistant species provide small-scale refuges for the germination and growth of species that would otherwise be eaten. Although both species have equal or greater fitness when living alone in appropriate environments, such associational defenses broaden the range of conditions under which the edible species can thrive, and often increase diversity in the immediate vicinity of the defended plant. Among animals, casual associations form when...

Benefits Parasitism to Mutualism

Many associations in nature are commensal, benefiting one party with little or no impact on the other. Commensalism commonly involves a larger host species and a much smaller guest species that exploits the host's organic products or structure. Examples include many animals that live on plants or corals, as well as certain microbes that associate with the human gut or skin with no appreciable effect on the host's fitness. Sessile organisms, such as trees, kelps, or corals, are referred to as foundation species when their dominance of a habitat provides physical structure and environmental conditions that support many other plant and animal species.

The Coevolutionary Arms Race

When associations produce fitness benefits and or costs to the organisms involved, their interactions will generate natural selection on one another, potentially producing evolutionary changes in one or both species. Because parasites reduce host fitness, they impose selection on the host to defend itself. In turn, parasites experience selection to overcome host defenses, which generates selection for more effective host defenses and so on. The result is often a coevolutionary arms race. Arms races also occur between predators or herbivores and their prey.

Strategic perspectives on floral biology

Natural selection of traits that affect direct or indirect interaction among individuals commonly depends on the composition of the population. In particular, the fitness consequences of traits involved in outcrossing and or competition depend on the characteristics of potential mates and competitors. Because of this frequency dependence, the selection of traits that influence mating and or competition results in the rise to prominence of a specific ''strategy'' for interaction that promotes fitness in the face of any other strategy (the evolutionary stable strategy, or ESS). In Chapter 2, Martin Morgan introduces ESS analysis of plant reproduction and compares it with quantitative-genetic approaches. The ESS approach focuses on fitness differences among alternative phenotypes, which are assumed to be genetically determined, whereas quantitative-genetic analysis of selection emphasizes the genetic variation and covariation that govern phenotypic variation and determine the...

Evolutionary theory 2 ageing and the family

More plausibly, if the group comprises close relatives that share many of the same genes, then certain traits that enhance the fitness of relatives can spread even if they lower the fitness of the carrier (a phenomenon that comes under the umbrella of 'kin selection', see Chapter 3). There is now a surge of interest to understand this 'adaptive senescence' idea from a kin perspective.64,67 For example, it has been noted that living longer can generate a larger and more persistent reservoir of disease, from which infection can spread. If individuals are distributed in family-based groups, then this may, in theory, lead to selection for reduced longevity.68

Subjective evaluation and choice behavior by nectar and pollencollecting bees

In this chapter, I focus on the decision-making process of foraging bees with the goal of better understanding their choice behavior. This decision-making process includes the evaluation of relevant information used by the bees to make decisions which result in choice. Particularly relevant to their success on each foraging trip - and ultimately their fitness - Individuals just beginning a foraging career must learn which flowers are likely to provide the most pollen or nectar, and which flowers are not profitable to visit. During this early stage, colors, shapes, and odors of flowers are associated with profits then this information is used to make decisions in the future. Foragers must decide where and when to look for food, and which food to search out, pollen or nectar. Perhaps before each takeoff from a flower, but certainly before each landing, a bee decides which flower to visit. Should it visit another flower on the same plant, or a more distant flower of the same color and...

Mutualism Experiments

Because of the influence (lifelong it seems) of John H. Vandermeer and Daniel H. Janzen, two dedicated and inspiring faculty advisors at the University of Michigan, my fieldwork on insect-plant interactions has been divided between agricultural and tropical forest ecosystems. My approach, in crop-pest-enemy and forest plant-herbivore-predator interactions, has been to assess the effects of plants, as provisioners of food for natural enemies, on the regulation of plant-feeding insects. As a tightly interacting, symbiotic association, Piper ant-plants and their in-house Pheidole bicornis predatory ants suggested a possible mutualistic interaction for regulating Piper herbivores. Food resources and shelter provided by the plant could restrict ant-foraging bouts to the host plant itself, for maximum plant protection. On the other hand, as suggested by Risch et al. (1977), the primary benefit of these ants could, instead, be the provisioning of shrubs with vital nutrients, which enhance...

Relationship and Kinship

Genetical considerations also play an important role from a totally different angle of behavioral biology. The ultimate explanation for any behavioral trait has to refer to its relevance for fitness, which means that reproductive success is the ultimate 'coinage' to measure an organism's success in life. Fitness, as understood by evolutionary biologists and behavioral ecologists, refers to the proportion of one's own genetic material, relative to the contribution of one's competitors, in the genome of the next generation. In order to improve one's fitness, an organism, specifically an animal, has two possibilities the direct way, also called improvement of direct or individual fitness, by producing as many successful offspring as possible, caring for them, etc. or the indirect way, which goes via one's kin. To understand the improvement of indirect fitness, we have to bear in mind that the coefficient of relatedness is also an expression of shared genetic material. We are all related...

Phenotypic selection on reproductive strategy

Two features of reproduction by hermaphroditic plants are particularly important for phenotypic selection floral traits influence fertility (i.e., opportunities for genetic transmission) through both female and male functions, and reproductive success through either gender generally depends on the reproductive strategies of other individuals in the population. These features are conveniently encapsulated in the following characterization of the fitness of an individual with trait value z,

Types of Adaptations Relevant to Population Dynamics

Fitness in fish and mammal populations where reproductive success is normally size based. Such alternative reproductive tactics serve to compensate, at least in part, for reduced reproductive success in early maturing individuals. Some of the best-known life-history responses to variation in feeding and predation conditions come from guppy populations in Trinidad, where greater predation rates result in compensating increases in reproductive investment (more eggs), earlier maturity, rapid juvenile growth, decreased coloration, and smaller population sizes than populations from streams with few or no predators. These changes in life history should serve to mitigate effects of predation mortality and prevent extinction, though its effect on population dynamics is unclear. Similar in its effect to that of natural predators, commercial fishing can alter life-history parameters. For instance, in Atlantic cod (Gadus morrhua) and other species, 'longevity overfishing' (preferential removal...

Phenotypic selection and evolutionary stable strategies

The consequences of eq. 1 can be examined by two approaches ESS and quantitative genetics. An ESS identifies an individual strategy, z*, that has higher fitness than any strategy z similar to z*, when z* is common. To identify the ESS, one seeks a maximum of relative fitness (eq. 1) when z z*, so that Wf Wf (z*) and Wm Wm(z*). Note again that the fitness of an individual adopting strategy z is frequency dependent, because W (z) (1 2) Wf(z) Wf + Wm(z) Wm depends on the strategy of other individuals in the population through the average fertilities. Fitness is maximized when dW(z) dz zKz- 0, or as long as the second derivative of the relative fitness function is negative. Terms of the form (1 Wf)dWf(z) dzlzKlz* describe marginal fitness returns (Lloyd 1985). At the ESS, marginal returns through female function are equal in magnitude, but opposite in sign, to marginal returns through male function. The ESS identifies strategy z* as a local maximum, but more deviant strategies (e.g., due...

The space of variation

With the advent of whole genome sequences, we now know the approximate numbers of genes in a genome, and we can more accurately guess the numbers of possible genotypes in a population. While this depends upon the level of nucleotide polymorphism and the role of non-coding regions, with ca. 30,000 genes (Arabidopsis) and 10 polymorphisms per gene (1000 base pairs per gene, 0.01 polymorphism per pair), the total number of genotypes is astronomical 23oo,ooo s 10100,000, a number far greater than the number of atoms in the universe. There must be a subset of this space of variation that populations occupy. Many genotypes would be inherently impossible because of intrinsically low fitness even if the population was infinite, the number of habitats might be small with each habitat having an optimal adapted genotype (the ecological limit concept), or alternatively, fitnesses of alleles at alternative loci may be highly dependent, placing constraints on accessibility to the ge-nomic landscape...

Phenotypic selection and inheritance of quantitative characters

Quantitative genetic techniques introduced to evolutionary biology by Lande (1976) are well-suited to empirical assessment of fitness and short-term (microevolutionary) change in trait value due to phenotypic selection and inheritance (quantitative genetic models also offer significant insight into macroevolutionary change). Central to Lande's approach is the phenotypic selection gradient, b, defined in a manner very similar to marginal gains. The selection gradient depicts the change in average trait value caused by fitness differences among phenotypes, measured in units of phenotypic standard deviations. If phenotypic selection is not too strong (see, e.g., Abrams et al. 1993 for a more complete delimitation), the selection gradient describes the slope of the relation of relative fertility to the average trait value, fitness. These multivariate phenotypic selection gradients are estimated by multivariate regression of relative fitness on trait values. Note, however, that change in...

Measuring phenotypic selection

Assessment of phenotypic selection gradients requires a reasonable measure of ''fitness''. Evolutionarily relevant fitness measures account for the change in gene frequencies from a particular stage of one generation to the comparable stage of the next generation (Charlesworth 1980). Such information is seldom available, and investigators typically measure fitness components during a portion of the lifespan. Fitness components reflect ''true'' fitness accurately if they are statistically independent of phenotypic selection acting during other periods. This independence might seem reasonable for floral traits (e.g., how can pheno-typic selection on floral characters occur other than at flowering ), but such reasoning neglects the correlation between reproductive and other life-history characters emphasized in eq. 4 (also see Chapters 7 and 8). Such associations may be responsible for the implausibly strong phenotypic selection reported by many studies, including some that considered...

Hosthabitat Selection

Variation in the sex ratio of nematodes that emerge at different times from a host cadaver has been reported. Infective juveniles of S. glaseri that disperse early from a depleted host cadaver tend to be larger and to have a more male-biased sex ratio (Lewis and Gaugler, 1994 Nguyen and Smart, 1995 Stuart et al., 1996). Stuart et al. (1996) found that there was a genetic basis to S. glaseri emergence time and that there was selection for a highly skewed early emergence in a population recently isolated from the field. Increased size is likely to be correlated with improved fitness due to increased lipid storage and longevity. However, it is not clear if larger size is correlated with being male or if infective juveniles that are formed first, and presumably developed under the best environmental conditions, disperse first. Lewis and Gaugler (1994) proposed that this phenomenon is analogous to adult males emerging before females (i.e. protandry). By dispersing first, males are more...

Specialist or generalist

Waser et al. (1996) stimulated considerable debate in the pollination literature by emphasizing that plant-pollinator interactions are typically generalized, involving many pollinator species per plant species and vice versa, rather than specialized, reciprocal mutualisms. Waser et al. supported this proposal with a review of empirical evidence and a model that considered the relation of plant fitness to visits from up to two pollinator species. Type i pollinators have abundance Ni, visitation rate per pollinator Vi, and ''effectiveness'' gi, so that the fitness of a generalist plant exploiting both pollinators is WG J2 2 1 NiVigi. The authors then asked when the fitness of a ''specialist'' plant adopting a slightly different strategy that alters, for example, pollinator effectiveness gs,i g1 + d, gs,2 g2 d exceeds that of the generalist. The fitness of the specialist plant is WS J22 1 NiVigsi and specialization is favoured (i.e. WS WG) when N1V1 N2V2. This condition leaves no scope...

The construction and composition of freshwater phytoplankton

From an ecological point of view, the ultrastructural properties of phytoplankton cells assume considerable relevance to the resource requirements of their assembly, as well as to adaptive behaviour, productivity and dynamics of populations. Thus, it is important to establish a number of empirical criteria of cell composition that impinge upon the fitness of individual plankters and the stress thresholds relative to light, temperature and nutrient availability. These include methods for assessing the biomass of phytoplankton populations and the environmental capacity to support them.

The Dynamics of Models of Natural Selection

Nevertheless, the behavior of models of selection is sensitive to the ordering of the fitnesses. In Figure 4.7, we plot the allele frequency as a function of time using the discrete-time, diploid model to gain some understanding of the effects of natural selection. These graphs appear to reveal three main types of behavior. If the heterozygotes have the highest fitness (e.g., WM 0.8, WAa 1, and Waa 0.95), natural selection tends to preserve both alleles (Figure 4.7a). Such selection is called heterozygote advantage or overdominance. In contrast, when heterozygotes have intermediate fitness (e.g., WAA 1, WAa 0.95, and Waa 0.8), natural selection increases the frequency of one allele over the other (Figure 4.7b). This form of selection is called directional selection. Finally, when heterozygotes have the lowest fitness (e.g., WAA 0.95, WAa 0.8, and Waa 1), natural selection favors different alleles depending on the initial allele frequency (Figure 4.7c). Such selection is called...

Selffertilization phenotypic selection and reproductive assurance

The evolution of self-fertilization is perhaps the most common evolutionary transition in plant reproductive biology (Stebbins 1974), and certainly the most thoroughly studied. A central focus contrasts the genetic transmission advantage of selfing with the fitness consequences of inbreeding depression (Lande and Schemske 1985), but here I focus instead on Lloyd's (1979 refined in 1992 Lloyd and Schoen 1992 Schoen and Lloyd 1992) recognition that the mechanism and timing of selfing have important consequences for the ecology and evolution of self-ing (also see Chapters 1, 4 and 10). Specifically, Lloyd noted that prior selfing is advantageous when the fitness of selfed progeny exceeds half the fraction of ovules fertilized by pollinators. The evolution of selfing in this case still depends on an inbreeding depression threshold, but the relevant threshold is always less than or equal to the threshold under competing selfing.

Simple Introductory Model

The Tangled Nature model is an individual based model of evolutionary ecology. We give a brief outline of the model here, with more details available in 10-13 . This version of the model is an attempt to address systems with many interactions between species in the simplest possible way, with detail and realism added in stages. We start with the bare model, to which we will add spatial effects and consider more realistic forms of the fitness.

Ageing and extrinsic mortality

There is another important way to discriminate between the evolutionary and non-evolutionary explanations, but the predictions from evolutionary theory are not as clear-cut as they might at first seem. All of the individual-based evolutionary theories argue that the intensity of selection to keep an organism in good health is mediated by the probability of being killed by extrinsic factors, because there is no fitness advantage in keeping an organism going for any longer than it would naturally live. Hence, if these evolutionary explanations were broadly correct, then one potential prediction might be that ageing would be slower (and longevity longer), the lower the level of extrinsic

Ecological consequences of selfing mode

Recent work integrates Lloyd's original formulations of selfing into plant population dynamic models (e.g., Morgan et al. 2005 also Vallejo-Marin and Uyenoyama 2004 Porcher and Lande 2005a) and helps to develop Lloyd's insights about phe-notypic selection and the evolution of selfing. Consider selfing caused by pollinators, either within or between flowers, which Lloyd (1979) referred to as competing selfing. This selfing mode does not provide reproductive assurance, because seed production is by assumption the same regardless of pollen receipt, and hence does not alleviate the Allee effect. In fact, in Lloyd's original (1979) analysis competing selfing provides a one-to-one trade-off of outcrossed seeds for selfed seeds (seed discounting), so that in the presence of inbreeding depression, selfed seeds have lower fitness than outcrossed seeds. In the ecological context of eq. 6, seed discounting and inbreeding depression decrease per capita population growth rates. Consequently, the...

Evidence Relating Contact with Nature to Human Health Decline in Contact with Nature in Modern Urban Society and Well

Biophilia is defined here as the inherent human inclination to affiliate with natural systems and processes, most particularly life and life-like (e.g., ecosystems) features of the nonhuman environment. The notion of biophilia advances the idea that people's physical and mental well-being remains reliant on contact with natural systems and processes. This dependency reflects the fact that humans evolved in adaptive response to the fitness and survival requirements of a largely natural and not artificial or human-constructed world. In other words, the evolutionary context for the development of the human mind and body largely was a sensory challenging and diverse natural environment with critical elements being light, sound, odor, wind, vegetation, landscape, water, animals, and more that provided much of the basis for human learning and maturation. The emergence during the past 5000 years of small-and large-scale agriculture, technology, industry, and the city represents but a small...

Time Scale of Plant Response to Environment

Physiological processes differ in their sensitivity to stress. The most meaningful physiological processes to consider are growth and reproduction, which integrate the stress effects on fine-scale physiological processes as they relate to fitness, i.e., differential survival and reproduction in a competitive environment. To understand the mechanism of plant response, however, we must consider the response of individual processes at a finer scale (e.g., the response of photosynthesis or of light-harvesting pigments to a change in light intensity). We recognize at least three distinct time scales of plant response to stress

Total population thousands

The ideal free hypothesis predicts that most individuals should be found in preferred habitats when forager population density is low, spilling over into less preferred habitats when forager density is high. This pattern has been demonstrated several times in different bird species (Fig. 5.10). One of the earliest examples was Brown's (1969) pioneering studies of great tits (Parus major) in the woodlands near Oxford, England. Brown showed that adult birds nested predominantly in woodland habitats in years with low bird abundance, expanding outwards into less attractive hedgerows only when densities were high. Krebs (1971) tested the assumption that this distribution stemmed from differences in fitness, by experimentally removing birds from woodland habitats, resulting in vacancies that were filled rapidly by former hedgerow tenants. redistributed themselves in precisely this manner (Milinski 1979). Similar results have been recorded in continuous food input experiments with numerous...

Variable pollination environments

Variable pollination environments have interesting consequences for the phenotypic selection of prior selfing (Morgan and Wilson 2005). For instance, variation in the pollination environment erodes the threshold required to maintain out-crossing, facilitating invasion of selfing variants, because the relevant fitness measure depends on variation in fitness (e.g., Gillespie 1976 Seger and Brockmann 1987). Compared with outcrossing individuals, reproduction through prior selfing reduces both the arithmetic mean (due to inbreeding depression) and variance (due to reproductive assurance) in fitness through time. The geometric mean is the appropriate fitness measure in a temporally variable environment, and it is less than or equal to the arithmetic mean, with the discrepancy increasing with the amount of variation. Thus greater variation in the pollination environment enhances the geometric mean fitness of prior selfing compared with outcrossing individuals, even while inbreeding...

Why measure annual productivity

Annual productivity or reproductive success is the number of young fledged per adult female (or adult bird or pair) per year regardless of the number of breeding attempts. In studies of population processes, it provides a measure of mean reproductive success, which can be used in simulation models of the population to estimate the population growth rate. In studies of evolutionary ecology, productivity can be assessed at the level of the individual as a component of fitness. In species in which females never lay more than one clutch of eggs per year, productivity per breeding female or pair is the same as the mean success of an individual breeding attempt and productivity per adult or pair can be calculated from this and information on the proportion of females that attempt to breed. However, most bird species make more than one breeding attempt per year, even if they only produce a replacement clutch after failure of the first clutch at the egg stage, and many species are capable of...

Evolution of Cannibalism Evaluating the Costs and Benefits

Cannibalism may evolve in situations where the benefits to the inclusive fitness of the cannibal exceed its costs. Cannibalism is beneficial as a source of energy and as a means of reducing the number of competitors. Crowding in high-density populations, with a low availability of alternative prey types, facilitates acts of cannibalism. Filial cannibalism during periods of low food availability converts an individual's reproductive investment back into somatic tissue the energy gained can then be used for survival by the parent or converted back into eggs. In Another important cost of cannibalism is the risk of a reduction in inclusive fitness if close relatives are consumed. This potential loss of fitness will depend upon the degree of genetic relatedness between cannibal and victim. All else being equal, the potential for this loss suggests that cannibalism should be directed away from related individuals. The evidence for this, however, is equivocal. We searched the literature for...

Relative Advantage and Fundamental Theorems of Natural Selection

According to the tenet of Darwinian selection, a phenotype will spread only if its fitness is greater than the mean fitness of the entire population. It is, therefore, natural to introduce the notion of relative advantage of a replicator, which is defined as the expected fitness of this replicator minus the average fitness of the entire replicator population. For the general replicator dynamics, it is shown that the relative advantage of an offspring population over its parent population is proportional to the variance in fitness. The relationship between the proposed and earlier versions of the fundamental theorem of natural selection is also discussed. Key words Fitness variance, fundamental theorem of natural selection, relative advantage, replicator dynamics.

The classic model of sex allocation for outcrossing species

Hermaphroditic plants propagate their genes through both male and female functions. Any parent's total fitness from the two sex roles is always additive (Lloyd 1984). Female fertility can be measured by the number of seeds that survive to adulthood, and male fertility by the number of sired offspring surviving to reproductive maturity. If fi, mi, and wi are the female, male, and combined fitness contributions, respectively, of individual i, then An individual's male and female fitness contributions depend on the proportions of its available resources, R, that it allocates to male and female function, ri and 1 ri, respectively. In particular, male and female fertilities are assumed to depend on their respective resource inputs according to mi bp(r R), the ''male gain curve,'' and fi f (1 fi)R , the ''female gain curve,'' respectively, where p and f convert resources into pollen and ovules (seeds). Note that the scaling factor b depends on overall sex allocation of the population and...

The Fundamental Theorem of Natural Selection Based on Relative Advantage

Assume that we have a discrete time scale. In this case, we have the following statement the relative advantage of the offspring generation over its parent generation is always positive and is proportional to the variance of the fitness of its parent population. Indeed, according to the discrete replicator dynamics (6.1), after the operation of selection, in the offspring generation the distribution of the replicator can be given by continuous-time version of the replicator dynamics (6.2) the instantaneous rate of increase in the population's relative advantage over its current state is equal to the variance of the replicators' fitnesses.4 Indeed, for a fixed z and time-dependent x, The above two arguments are obviously true for the evolutionary matrix game, the classical Fisher's selection model and the single autosomal locus model when the individual's fitness can be given by an evolutionary game-theoretical model. In the third model, the fitness of Ai allele Fi (x) j pjJ2k i...

Connection to Fishers Theorem

Continuous version of Fisher's theorem (see, e.g., 10 ). Let us consider the classical Fisher's selection model, which considers a diploid, panmictic sexual population, in which abiotic selection takes place at the zygotic level. The marginal fitness of alleles is given by Fi (x) (Ax)i, where the viability matrix A is symmetric (i.e., aij aji for all i, j)and (Ax)i denotes the ith coordinates of vector Ax. Using these notions, the average fitness of the allele population is given by xAx and the replicator dynamics (6.2) is rewritten as In this case, the average fitness is a Lyapunov function with respect to Fisher's selection model, and its derivative with respect to Fisher's selection equation (6.12) is the variance of the marginal fitness of alleles. Indeed, since the viability matrix A is symmetric, the gradient of the average fitness is grad xAx 2(( Ax)1, (Ax)2, , (Ax)n). Thus, its derivative with respect to dynamics (6.12) is

Predictions Of The Central Place Foraging Model

The central place foraging model considers the effects of travel costs on the decisions analyzed by theories of patch choice where to forage, and prey choice what resources to pursue while foraging within a patch. For a central place forager, efficiency while feeding does not necessarily translate into increased fitness success is more appropriately measured by the rate of delivery to the central place (Orians and Pearson 1979). Central place foraging therefore changes the costs and benefits of decisions foragers must make regarding which resources and patches to exploit how much to transport on each trip op

Factors Affecting Expression of Defenses

Defensive compounds may be energetically expensive to produce, and their production competes with production of other necessary compounds and tissues (e.g., Baldwin 1998, Chapin et al. 1987, Herms and Mattson 1992, Kessler and Baldwin 2002, Strauss and Murch 2004). Some, such as the complex phenolics and terpenoids, are highly resistant to degradation and cannot be catabolized to retrieve constituent energy or nutrients for other needs. Others, such as alkaloids and nonprotein amino acids, can be catabolized and the nitrogen, in particular, can be retrieved for other uses, but such catabolism involves metabolic costs that reduce net gain in energy or nutrient budgets. Few studies have addressed the fitness costs of defense. Baldwin (1998) evaluated seed production by plants treated or not treated with jasmonate, a phytohomone that induces plant defenses. Induction of defense did not significantly increase seed production of plants that came under herbivore attack but significantly...

Connection Between Partial Change and Relative Advantage

In this subsection, we will see a possible interpretation of partial change in mean fitness. For this purpose, we will see first, in Remarks 2 and 3, two important connections between the notions of relative advantage and of partial change in mean fitness. so the partial change in the mean fitness is equal to the relative advantage of the offspring zygote population over the parent zygote population. Remark 3 Let us assume Pij pip,. Then the average excess of allele Ai is, apart from the multiplication by 2, equal to the relative advantage of allele Ai over the population p. Formally, Ai is identified with the i-replicator and Fi (p) wi (p) Ej wijpj denotes the fitness of allele Ai .Using Pij pi pj and w (p) E i j wijpj we get the definition of average excess rewritten as follows Moreover, under the condition that Pij pi pj, we already know that the average effect and the average excess are equal thus, the average effect and the relative advantage are equal as well. Therefore, for the...

What is Play for A Brief Overview

As a subject matter, play challenges psychologists to discover its consequences on behavioral development, anthropologists to identify its role in the evolution of social and cognitive skills, and evolutionary biologists to search for the functions of an apparently nonfunctional behavior. Assuming that play is a functional behavior, is it also an adaptive behavior Gould and Vrba (1982) suggested that the term adaptive can be used only for a phenotypic character that promotes the fitness of the organism and performs the function for which it was selected. For the traits that produce benefits for their present role, but were not originally selected for that role, the authors suggested the term ex-aptation. In this paper, when we use the terms benefit and function of play, we refer to its possible current utility (effects) and not to its historical genesis.

Resource Acceptability

Resource acceptability represents the willingness of the insect to feed, given the probability of finding more suitable resources or in view of other tradeoffs. Most insects have relatively limited time and energy resources to spend searching for food. Hence, marginally suitable resources may become sufficiently profitable when the probability of finding more suitable resources is low, such as in diverse communities composed primarily of nonhosts. Courtney (1985, 1986) reported that oviposition by a pierid butterfly, Anthocharis car-damines, among several potential host plant species was inversely related to the suitability of those plant species for larval development and survival (Fig. 3.10). The more suitable host plant species were relatively rare and inconspicuous compared to the less suitable host species. Hence, butterfly fitness was maximized by laying eggs on the most conspicuous (apparent) plants, thereby ensuring reproduction, rather than by risking reproductive failure...

Definition of Home Range

Why do animals have home ranges Stamps (1995 41) argued that animals have home ranges because individuals learn site-specific serial motor programs, which might be envisioned as near reflex movements that take an animal along well traveled routes to safety. These movements should enhance the animal's ability to maneuver through its environment and thereby to avoid or escape predators. Stamps argued that the willingness of an animal to incur costs to remain in a familiar area implies that being familiar with that area provides a fitness benefit greater than the costs. For animals with small home ranges that live their lives as potential prey, Stamps's hypothesis makes sense. However, many animals, especially predatory mammals and birds, have home ranges too large and use specific places too seldom for site-specific serial motor programs to have an important benefit. Site-specific serial motor patterns of greatest use to a predator would have to match the escape routes of each prey...

The Evolution of Clines at Equilibrium

There are at least five forces that affect the form of a cline the genetics of the character, genetic drift, population density, the magnitude, direction and type of selection, and the magnitude and direction of gene flow. Arguably, the two most influential of these forces are selection and gene flow. At equilibrium, the width of a cline largely represents a balance between the diversifying effects of selection and the homogenizing effects of dispersal (Figure 3). When selection (s) represents the difference in fitness between genotypes at the center of the cline, and u is the standard deviation of the distance from parents to offspring along a linear gradient (which is broadly proportional to the width of the dispersal cloud around parents and is linearly related to the distance that an offspring moves on average), then the width of the cline at equilibrium is proportional to us_1 2. Thus, narrow clines in highly dispersive organisms will be maintained only when there are high levels...

Clines and Parapatric Speciation

Viable can be intrinsic (e.g., genetic incompatibilities) or extrinsic (e.g., less competitive in the environment). As a consequence of the fitness cost of hybridization, there will be strong selection for prezygotic traits that minimize cross-breeding and thereby lead to the generation of 'good' species, a process referred to as reinforcement.

Why are male and female function often displaced temporally in cosexual plants

Level of investment resources should be allocated to whichever sex function can yield higher fitness returns. This rule ensures that fitness is maximized for an individual in the face of unpredictable resources. With a linear female gain curve and a decelerating male gain curve (Fig. 3.6a), an individual should not invest in female function when absolute male investment remains below the investment threshold (Rj), for which marginal fitness returns per unit of investment are equal through male and female function. As resource availability exceeds this threshold, the plant should switch completely to invest in female function. In this case, male and female expenditures will overlap temporally very little, although they use the same resource pool. Obviously, female investment cannot be postponed completely after male allocation, because ovules must be fertilized to develop into seeds, so that the optimal allocation pattern will also depend on the reproductive stages of other individuals...

Traits invariants and theories of everything

In general we might expect certain values of a trait to be favoured rather universally. For example, it is clearly best, in a Darwinian sense, to produce many offspring, all other things being equal. Happily for those who like diversity, all other things are not equal high fecundity must come at a cost to some other trait of importance to the organism's fitness, such as offspring size. This phenomenon is known as a trade-off. The organism is thus faced with the more complex choice of finding the value of the trait that maximizes fitness in the face of trade-offs with other traits of importance. In the above example, evolution would essentially select between organisms that have large offspring but few of them, and organisms that have many but small offspring. Following this, our evolutionary model will generally make some assumptions about the nature of any trade-offs involved (a constraint), and about the consequences of each value of the trait for fitness (a currency). In general,...

Importance of Sexual Reproduction

This, though, is a 'group selectionist' interpretation. It argues that variation generated in an individual meiosis benefits the group or population to which the individual belongs. Yet current theory prefers to emphasise that selection acts on individuals (Carlile, 1987 Dawkins, 1989). A feature that is advantageous in selection must be so because of benefit to the individual itself or its immediate progeny. As noted above, an alternative interpretation of the selective value of a sexual cycle suggests that repair of damaged DNA is the crucial advantage of meiosis (Bernstein et al., 1985). It is argued that bringing together genomes from two different individuals enables DNA damage in one parental chromosome, caused by mutation or faulty replication, to be repaired by comparison and recombination with the normal chromosome provided by the other parent. Genetic fitness would be increased but only when out-crossing ensures heterozygosis. Even an incomplete sexual cycle might be of...

Sizedependent reproductive effort

The model presented above both predicts a linear relation between reproductive output and plant size (Fig. 3.7a) and is consistent with several observations about which the allometric hypothesis is either silent or only partially compatible. The model predicts that perennial plants must achieve a minimum size (Si) before reproducing, because plants smaller than S1 realize highest fitness by investing all their resources in survival, rather than reproduction. In contrast, a minimum

Discussion and conclusion

Resource allocation commonly varies with plant size in many plant species, but the factors causing such variation and the significance of these patterns to plant life histories are not appreciated fully. Also, relatively few studies have attempted to quantify and explain the within-population variation among individuals. Using a simple graphical approach to the ESS model, I have shown that if fitness returns through allocation to female function, male function, and post-breeding survival vary differentially with plant size or resource availability, plants should modify their allocation to male versus female function and to reproduction versus survival according to their size. The theory developed in this chapter predicts that the reproductive strategies of hermaphroditic plants should equalize marginal fitness returns through male and female sexual function, and adult In developing this theory, I assumed obligate outcrossing. In contrast, hermaphrodites commonly self-fertilize,...

Utility Distributions

From location data such as those shown in figure 3.2, most home range estimators produce a utility distribution describing the intensity of use of different areas by an animal. The utility distribution is a concept borrowed from economics. A function, the utility function, assigns a value (the utility, which can be some measure of importance) to each possible outcome (the outcome of a decision, such as the inclusion of a place within an animal's home range Ellner and Real 1989). If the utility distribution maps intensity of use, then it can be transformed to a probability density function that describes the probability of an animal being in any part of its home range (Calhoun and Casby 1958 Hayne 1949 Jennrich and Turner 1969 White and Garrott 1990 van Winkle 1975), as shown in figure 3.2. Utility distributions need not be probability density functions, although they usually are. A utility distribution could map the fitness an animal gains from each place in its home range, or it...

US Navy Seal Physical Fitness Training Manual

US Navy Seal Physical Fitness Training Manual

Use the same methods the American Navy Seals use to get fit and become the elite enforcers in the world today! The Navy SEAL Physical Fitness Guide has been prepared for the SEAL community with several goals in mind. Our objective is to provide you, the operator, with information to help: Enhance the physical abilities required to perform Special Operations mission-related physical tasks Promote long-term cardiovascular health and physical fitness Prevent injuries and accelerate return to duty Maintain physical readiness under deployed or embarked environments.

Get My Free Ebook