Cichlid Care Guidelines

Cichlid Fish Secrets

There is an amazing, brand new ebook called Cichlid Fish Secrets. It covers everything you could possibly need to know about keeping healthy, happy cichlids, and breeding them as well. Here is just a preview of what you'll learn in this book: What size tank you should have when keeping cichlids. What filter you should use in your tank. How to properly cycle your aquarium. How to properly manage pH levels. The water temperature you need to maintain. The correct way to perform a water change. How to clean the glass of your fish tank. How to be an expert water tester. The Best rocks and wood you Need to be using. The right ways to prepare your rocks & wood for your tank. The only way to have live plants in an African Cichlid tank. How to choose the right cichlids. What to feed your cichlids & how often to feed them. The expert ways to breed your cichlids. How to diagnose, treat, and cure the most dangerous fish diseases.

Cichlid Fish Secrets Summary


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Author: Mike Logan
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The author presents a well detailed summery of the major headings. As a professional in this field, I must say that the points shared in this manual are precise.

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Haplochromine Cichlids of Lake Victoria

The haplochromine cichlid fish of Lake Victoria demonstrate both the exuberance of species radiation and the tragedy of mass extinction, the first to occur during historical times. These tiny, colorful fish, which constituted 80 percent of the fish biomass in Lake Victoria prior to 1978, now account for less than 2 percent (Kaufman, 1992). This decline has been caused by a combination of human influences. The cichlids are a very large and diverse family of freshwater, perchlike fish characterized by certain anatomical features (such as having a single nostril on either side of the snout, and an interrupted lateral line system) and the high degree of parental care devoted to their offspring (Keenleyside, 1991). Cichlids are native to Africa, the Middle East, Madagascar, Sri Lanka, the southern coast of India, and Central and South America. Cichlids have also been accidentally or intentionally introduced in many other parts of the world, often with disastrous effects on the native fish...

Cichlids and evolutionary ecology

The cichlid story illustrates many of the broader features of evolutionary ecology, the science that involves both ecological and evolutionary knowledge. Evolutionary biology is the field concerned with understanding how biological lineages change through time (anagenesis), split (cladogenesis), and ultimately go extinct. Ecology is concerned with the interaction of organisms with their environment. The organisms can be considered at various levels of a hierarchy, comprising the individual, the population (groups of individuals of the same species), and the community (groups of interacting populations from different species). Communities in turn comprise the biotic component of ecosystems, which also include their interactions with the abiotic world. Ecology asks how individuals behave in different environments,what determines population size, and the properties of communities and ecosystems, such as their diversity. Knowing all this, why do ecology and evolution interact and how do...

Benefits Parasitism to Mutualism

Parasites include not only microbes and intestinal worms but also plant-feeding insects, which are estimated to make up more than half of all animal species. The most familiar parasites associate closely and permanently with their hosts, and are strongly modified to this end. But others have a less intimate association. Among the more bizarre such parasites are certain cichlid fish of the African Great Lakes that feed solely on the scales or eyes of other fish, which they obtain by surreptitiously attacking and sucking from the living victim.

Spottednecked otter Lutra maculicollis Fig 226

Rubondo is a forest-covered island in Lake Victoria, little affected by people. One early morning, quietly from my canoe, I paddled along with a group of four spotted-necked otters fishing along the shore, a group I had been watching frequently for the past few weeks. Dense masses of branches extended into the murky water, and the otters were in and out of the tangles, coming up for quick gulps of air between long, agitated dives. They were working separately, each one frequently catching small fishes, cichlids only few centimetres long, chomping quickly and continuing again with foraging. After almost half an hour of this, the otters swam out into more open water, now bunched closely together, and crossed the large bay to the other side, where they climbed out on to the rocks, well away from the crocodiles along the shore.

Total population thousands

Redistributed themselves in precisely this manner (Milinski 1979). Similar results have been recorded in continuous food input experiments with numerous other species, including mallard ducks (Harper 1982), cichlid fish (Godin and Keenleyside 1984), and starlings (Inman 1990). Measurements in the field have been less supportive. However, animals in preferred habitats generally obtain higher rates of food intake than those relegated to poorer habitats (Sutherland 1996). Researchers frequently find that individuals vary in the quantity of food that they acquire, with more dominant or larger individuals securing more of the food delivered than lower-ranking individuals. This hierarchy suggests that although animals are capable of adjusting their behavior in predictable ways to accommodate the presence of other competitors for scarce resources, differences in dominance status tend to maintain differences in fitness (Sutherland 1996).

Sympathy for sympatry

We have briefly reviewed several classic cases of suggested sympatric speciation, ranging from incipient host-based speciation in the apple maggot fly to cichlid speciation in the small crater lakes of Cameroon. In many of these cases, ranging from palms on Lord Howe Island to sticklebacks in British Columbia, we see that speciation may have arisen largely as a by-product of ecological differences. We have also touched upon mathematical and computer models that indicate that the selection for specialization, such as feeding on different food resources, coupled with assortative mating, or even assortative mating based on arbitrary traits, can, under some conditions, be expected to generate reproductive isolation among co-occurring groups. There now seems little doubt, even among the sceptics, that sympatric speciation can and does happen. Indeed, in Ernst Mayr's final book he noted Sympatric speciation is attractive as a subject in part because one has to work slightly harder to...

The food of giant otters

This species is a fish eater, with very little else in its diet, although Nicole Duplaix (1980) found crab remains in some spraints. In the different study areas, most of the food is made up by only a few species of fish, selected from an astonishingly numerous fish fauna. Duplaix mentions that near her Surinam study area 'in 1912, Eigenmann collected 70 to 90 species in one haul of a seine net. . . , and another 60 species in a small creek a few hours later' (Duplaix 1980, p 516). Nevertheless, her giant otters captured only 11 species most of these were trahiras or wolf fish (the characoid Hoplias malabaricus), a fairly large, slow, aggressive predator that lies still in shallow waters, between leaves and branches, and is easy to catch. Other favourites were the similarly slow siluroids or catfish, and perch-like fishes, especially cichlids. In other parts of its geographical range, for example Guyana (Laidler 1984) and Brazilian Amazonia (Rosas et al....

Reticulate evolution and fish peacock bass

The peacock bass (genus Cichla) belongs not to the bass clade, but rather is a member of the New World cichlid assemblage. Belonging as it does to the freshwater tropics, it forms a part of the greatest diversity of freshwater fishes in the world (Willis et al. 2007). Significantly, a portion of the South American tropical freshwater fishes has originated in the context of introgres-sion between diverging lineages (Moritz et al. 2000). Peacock bass are so-named because of their brightly colored exterior. The attractive appearance of the species belonging to this genus, along with their size and behavior (i.e., aggressiveness when caught on a hook), has resulted in sportsmen and

Dispersal and colonization

Cichlid fishes are a particularly good example in the large East African lakes. Although it is less than 1 million years old, Lake Victoria alone had about 200 species of these haplochromine fish before many of them almost went extinct due to stocking of the lake with the predatory Nile perch (Lates nilotica) (Goldschmidt 1996). There has been a debate over whether these fishes all evolved in this one lake or in separate localities. Recent molecular studies using mitochondrial DNA have shown that this species flock is probably monophyletic. Some Lake Victoria species are morphologically very similar to species in Lake Tanganyika and Lake Malawi, but genetically they are more closely related to other species in Lake Victoria that look very different from the morphologically similar foreign species (Meyer et al. 1990).

Prey availability for American otters

Little is known also about the habits and populations of otter prey in South America. There are large numbers of species of fish as an example, in the Rio Negro in the Brazilian Pantanal, giant and neotropical otters were selecting from 260 species (H. Waldeman, personal communication). The species preferred by otters are again the slow bottomfeeders, whereas the multitude of more pelagic or open-water species are left alone. Typically preferred prey of giant otters, the trahiras or wolf-fish Hoplias spp., are sluggish ambush hunters, lying quietly in wait in cover (Rosas etal. 1999) they, as well as several cichlids, inhabit parts of water bodies with many submerged branches and litter banks, where otters may surprise them. The many different catfish (Siluridae), popular prey for all otters, are also slow-moving bottom fishes, whereas the piranhas, sometimes taken by giant otters, concentrate in the open, deeper parts of ox-bows.

Prey availability in Asia and Africa

The large East African lakes are renowned for their species richness in fish for instance, in Lake Victoria about 300 species of cichlids have been reported (Barel et al. 1985) as well as various catfish, lungfish and others. Lake Malawi contains well over 500 different cichlids (Albertson et al. 1999). In these lakes otters such as the spotted-necked take many cichlids (Kruuk and Goudswaard 1990), catching them in crevices and between branches of overhanging trees, or they catch catfish on the bottom. Not surprisingly, there are no data as yet on fish biomass and availability. I noted, however, that in Lake Victoria in 1989 these otters took fewer small cichlids (Haplochromis spp.) than in previous studies (Procter 1963), after populations of these cichlids had been sharply reduced by the introduction of predatory Nile perch Lates niloticus, and by overfishing (Barel etal. 1985 Harrison etal. 1989).

Evolutionary Novelty and Innovation

It has often been argued that the differences in morphology seen in the Cambrian explosion seem more 'fundamental' than the differences in body shape and color seen in recent adaptive radiations because of a retrospective fallacy, that is, we define certain characters as more fundamental simply because they are older. While this may be true for certain characters (e.g., traits that define higher taxa in some groups vary intraspecifi-cally in others), it is hard to escape from the view that the presence or absence of a coelom, body segments, and limbs reflect greater and more fundamental differences in genetics, development, and ecology than the shape of a finch's beak or a cichlid's teeth. Therefore, evolutionists are left with the very real question of why certain periods in the history of life are characterized by major novelties in morphology and modes of life.

Adaptive or nonadaptive differentiation

A second area of evidence comes from examining hybridization events. If differences between species are adaptive, hybrids should be less fit than their parents in the native habitat, but this difference should disappear in the lab. Genetic mechanisms reducing hybrid fitness, however, should be apparent even in the lab. In fact, many groups produce highly viable and fertile laboratory hybrids, including Drosophila, Darwin's finches, East African cichlids, Hawaiian silverswords, and fishes from post-glacial lakes mentioned above. A final source of evidence comes from measuring the rate of evolution across populations or species as compared to the null hypothesis of neutral evolution through mutation and drift. Studies by Orr (1998) showed that of eight loci affecting male genital structure in the sister species D. simulans and D. mauritiana, all eight indicated evolution by selection. Studies on the genetic variation in quantitative traits among populations also indicate divergent...

Chrysophrys taurina See Porgies

Cichlidae (I) A very speciose family in fresh and brackish waters of Africa and South America, derived from marine ancestors, and related to the 'wrasses and 'parrotfishes. The cichlids share with the 'damselfishes the feature of having only one nostril on each side Some cichlid species, notably among the lepi-dophages ('scale-eaters) display a strong 'asymmetry in the orientation oftheir mouth, which may be bent left or right, thus facilitating lateral attacks (Barlow 2000, p. 36). The only member of the Family Cichlidae sampled by CD is Cichlasoma facetum (Jenyns, 1842), formerly Chromis facetus, from 'Maldonado, Uruguay (Fish, pp. 104-5 Above, greenish black the sides paler slightly iridescent). Cichlidae (II) CD discussed cichlids at length, as they provided neat examples for 'sexual selection. Thus In many of the Chromidae, for instance in Geophagus, and especially in Cichla, the males, as I hear from Professor Agassiz,21 have a conspicuous protuberance on the forehead, which is...

Setting the Stage for Speciation

For animals, various processes may lead to rapid speciation. Polyploidy is less common in animals but occurs in many molluscs, crustaceans, insects, fish, amphibians, and a few higher vertebrates. Many of the poly-ploid forms do not reproduce sexually, so forms different in chromosome number are essentially reproductively isolated. For animals, however, spe-ciation results more often by divergent natural selection. Allopatric and, possibly, sympatric speciation have apparently resulted in the recent origin of hundreds of species of cichlid fishes in East African lakes such as Lake Malawi (Owen et al. 1990) and Lake Victoria (Seehausen and Van Alp hen 1999). The Lake Victoria basin is inferred to have completely dried out in the Late Pleistocene, so the endemic species of cichlids have apparently arisen within the past 12,000 yr (Johnson et al. 1996).The precise mechanisms involved in these remarkable radiations are still somewhat unclear but may include disruptive sexual selection, as...

Behavioral Indicators and Behavioral Titrations

A similar experiment studied guppies (Poecilia reticulata) foraging in the presence of predaceous cichlids (Cichlasoma sp.) and gouramids (Trichogaster leeri) (Abrahams and Dill 1989). The study was based on the idea that foragers should distribute themselves according to an ideal free distribution (see box 10.1). The experiment offered guppies a choice between two patches differing in danger (one side of the aquarium contained a predator). Most guppies avoided the dangerous side in favor of the safe side, leaving those fish willing to take the risk with higher feeding rates. The resource supply rate in the dangerous habitat was then increased to the level required to equalize the number ofguppies on each side.

Reproductive allocation and its timing

Reproductive Allocation

Since relatively high CR habitats should favor low reproductive allocations, maturity (the onset of sexual reproduction) should be relatively delayed in such habitats but should occur at a relatively large size (in deferring maturity at any given time, an organism is making a reproductive allocation of zero). These ideas are supported by a study of guppies, Poecilia reticulata, a small fish species in Trinidad (Table 4.6). The same work also provides support for the patterns of reproductive allocation discussed above, and for patterns of variation in offspring size, discussed in Section 4.11. The guppies live in small streams that can be divided into two contrasting types. In one, their main predator is a cichlid fish, Crenicichla alta, which eats mostly large, sexually mature guppies. In the other, the main predator is a killifish, Rivulus hartii, which prefers small, juvenile guppies. The Crenicichla sites

The Arrangement of Indoor Aquariums

Vallisneria, and Anacharis are among the best choices. Mosses do well in tanks with killifishes and are useful in spawning the fish. Cichlids require robust and broad-leaved plants with firm leaves (such as Echinodorus and some varieties of Vallisneila) the roots of these plants should be protected by stones around the base of the stem so they cannot be dug out by the fish. These and other factors greatly limit the number of really satisfactory plants for each specialized aquarium, and the number is further reduced if the aquar-ist wishes to keep South American fish with South American plants, African fish with African plants, etc.

Splitting in sympatry

If speciation by geographic isolation was never in doubt then the same cannot be said of sympatric speciation (Chapter 1),speciation in the absence of geographic isolation. Until very recently, there were no clear-cut empirical cases Ernst Mayr in his 1963 book systematically attacked the best-known potential examples of the time, including the East African cichlids mentioned in Chapter 1, and another example discussed below, the apple maggot fly, as being just as (if not more) consistent with speciation in allopatry. The early theoretical work also suggested rather restrictive conditions for sympatric speciation (e.g. Maynard Smith 1966). In general, models found two problematic areas. First, it was difficult to explain assortative mating. Many models assumed strong linkage, or pleiotropy of the mating system to an ecological trait under selection, but in general pleiotropy is expected to be weak. Second, ecological differentiation is normally required to prevent competitive...

Simulated lakes and simulated radiations

However, the model appears not to be the last word in cichlid speciation. Species in the model form from brown fish gradually splitting into slightly less brown ones. In fact, individual species in nature often display a male red blue colour polymorphism, suggesting that speciation and colour change are much more instantaneous. Thus, the model is in some respects only a rough cartoon of some of the actual processes. In addition, there is a second type of colour polymorphism within some species in which females vary in colour and are associated with a rather interesting genetical system (Seehausen and van Alphen 1999 Seehausen etal. 1999). Something different must be going on in those. Fig. 1.5 A cichlid, Paralabidochromis chilotes, from Lake Victoria (length 15 cm). Blotchy morphs like these are, in most populations, female, and include sex reversed males that may play a role in speciation by sex ratio selection. Photo courtesy of Ole Seehausen. Fig. 1.5 A cichlid, Paralabidochromis...

Alternative mechanisms

Fig. 1.2 The diversity of jaw morphology of Lake Victoria cichlids. Clockwise from top left they eat, snails, fish, fish larvae, algae on rocks, invertebrates on rocks, insect larvae. What additional mechanisms might be important Can speciation, for example, occur without geographic isolation There are two problems that need to be overcome. First, there has to be ecological divergence the two incipient species have to occupy different niches to prevent them from competing and allow stable coexistence. Second, there has to be reproductive divergence, so that interbreeding does not occur. Getting these events to occur without geographic isolation is a conceptual challenge that has long occupied evolutionary biologists. In the 1990s, this question was bothering cichlid enthusiast, Ole Seehausen. Ole's hunch was that species could diverge in situ into reproductively isolated populations by assortative mating based on male coloration. Over time, mate selection by different females for...

Extinction and Extirpation due to Predation and Herbivory

Endemic fauna of more than 500 species of cichlid fish (Seehausen et al. 1997b). Direct and indirect effects of the Nile perch have contributed to the loss of many of these species. During the 1980s, about 200 of these species disappeared, apparently due to predation by Nile perch. These species lived mostly in the offshore and deep waters.The lake has experienced severe eutrophication due to accelerated nutrient inputs and predation by Nile perch on herbivorous and detritus-feeding fish. Massive growths of another alien, the water hyacinth (Eichhornia crassipes), have also changed the ecology of the shallower waters.These and other factors have contributed to further loss of species from the littoral zone. In turn, eutrophication, increased turbidity, and reduced visibility appear to interfere with color vision of many cichlids (Seehausen et al. 1997a).The result is reduced sexual selection, incorrect mate choice, and breakdown of reproductive isolation, leading to loss of species...

Where two fields meet

A teacher of mine once simplified his complex family history by saying that he, like all of us, originated from Olduvai Gorge in Tanzania (the 'cradle of mankind'). Tropical Africa has been a cauldron of diversity not only for our own species. It is, to take one example, surprisingly fishy. The Great Lakes of East Africa (Figure 1.1), and surrounding rivers, contain a whopping 1500 species in just one fish family, the cichlids, familiar to freshwater aquarium enthusiasts. This makes cichlids the most species-rich family of vertebrates, beating such diverse and familiar groups as songbirds and mice. They are so diverse that many still await proper scientific description, and many more are doubtless completely undiscovered. Lakes Victoria and Malawi each contain about 500 species, and about 250 species are found in Lake Tanganyika. Diversity of this sort is what makes our planet such an interesting place, and of course, we have to find out what caused it. The cichlid species of the East...

The interaction of questions in evolutionary ecology

In the last chapter, we saw that understanding macroecological patterns is sometimes helped by an understanding of life history evolution. For example, one macroecological pattern, the body size frequency distribution, involves variation in a life history trait. Macroevolutionary forces, such as rates of speciation and extinction, also affect many of these patterns, such as why there are more species in the tropics. Macroevolutionary patterns are also sometimes the result of major ecological or evolutionary transitions, such as the evolution of sex or flight. They are often explicable by reference to speciation and extinction theory, such as in the haplochromine cichlids of Lake Victoria. Extinction is often the result of variation in life histories, such as fecundity, ecological specialization, with specialists being more extinction prone, or co-evolutionary forces, such that invasive species can cause extinction of species that they have not co-evolved with. The theory of extinction...

Setting Priorities for Biodiversity Conservation

Cichlids and mullets, then we would direct our conservation efforts toward the rivers of Madagascar. Science 269 347-350 Raup, D. M. 1991. Extinction Bad Genes or Bad Luck New York W. W. Norton Redford, K. H., and B. D. Richter. 1999. Conservation of Biodiversity in a World of Use. Conservation Biology 13, no. 6 1246-1256 Regan, H. M., et al. 2001. The Currency and Tempo of Extinction. American Naturalist 157 1-10 Samways, M. J., et al. 1995. Inventorying and Monitoring Characterization of Biodiversity. In Global Biodiversity Assessment, edited by V. H. Heywood and R. T. Watson, pp. 475-514. Cambridge Cambridge University Press Sechrest, W., et al. 2002. Hotspots and the Conservation of Evolutionary History. Proceedings of the National Academy of Sciences 99, no. 4 2067-2071 Seehausen, O. 2002. Patterns in Fish Radiation Are Compatible with Pleistocene Desiccation of Lake Victoria and 14,600 Year History for Its Cichlid Species Flock. Proc. R. Soc. Lond. (Biological Sciences)...

Distribution of Two Species across a 1Hectare Qrid

Some regions may be the home of a burst of phylogenetic (or evolutionary) diversity, producing many closely related species. Various authors (for example, Seehausen, 2002) use as an example Lake Victoria, which has 500 to 1,000 closely related species of cichlids that evolved rapidly, perhaps within the last 14,600 years. Such areas are interesting not just because of their species richness but also because of our interest in understanding what conditions led to such a high rate of speciation. However, there are other reasons for using phylogenetic diversity as a surrogate. Stiassny (1997) explains that some regions may be very low in species richness but are the home to the basal (primitive) members of some groups of species. For example, Madagascar has very few species of cichlids, but those that are present appear to


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 producing a large number of offspring or by providing offspring with special care. Carp, for example, lay millions of tiny eggs that they cannot later care for. Sticklebacks, however, have only a few large eggs that they lay in a nest guarded by the male. During the critical phase of development, mouth-breeding cichlids provide cover and protection for their young in the mouth of the parent, but they can only host a few offspring. All three fish species achieve fitness in different ways.


Greatest products - a radiation of some 200-400 species of endemic cichlid fishes. These fish, often separated by mating habits based on female color preference, were threatened by hybridization among species induced by low light under weed mats, where color-based visual-recognition mating systems could not be sustained.

Fatal fighting

Although fatal fights between conspecifics have been reported from a wide variety of animal species, there are relatively few species in which a high proportion of individuals die as a result of combat with conspecifics (Enquist and Leimar, 1990). Game theory has also played a large role in the theoretical exploration of animal conflicts (Maynard Smith and Price, 1973 Maynard Smith, 1982) and a range of different asymmetries between contestants are predicted to be used to settle disputes without recourse to fatal fights. In many contest situations, individuals do assess each other and rare fatal fights can be attributed largely to the failure in assessment, i.e. they occur when two individuals are actually extremely similar with respect to the key variables. Assessment may involve an impressive stereotyped and escalated series of postures, as in the red deer Cervus elaphus (Clutton-Brock et al., 1982) and in the cichlid fish Nannacara anomala (Jakobsson et al., 1979), such that one...


The extremely high levels of genetic diversity in populations of the outcrossing monkey flower Mimulus guttatus have been attributed to long-term introgression of genes from the selfing congeneric M. nasutus into M. guttatus (Sweigart and Willis, 2003). Another example of this phenomenon has been found in populations of Darwin's ground finches (genus Geospiza), which experience regular bottlenecks often caused by environmental extremes such as drought or excessive rainfall. Despite these bottlenecks, populations show little evidence of depleted genetic diversity, and this seems to be at least attributable partly to ongoing hyridization among all six species (Freeland and Boag, 1999). The generation of genetic diversity following hybridization has been cited as one reason for the rapid evolutionary change that has led to adaptive radiation after species invade new environments, two examples of this being Darwin's finches on the Galapagos archipelago and African cichlid fish in Lake...

African otter diets

On Rubondo, a beautiful forested, uninhabited island in Lake Victoria, I had the opportunity to study two of the three otter species that occur south of the Sahara the spotted-necked and the Cape clawless (Kruuk and Goudswaard 1990). Spotted-necked otters were everywhere along the coasts, active by day, and it was quite easy to watch them feed, and to collect and analyse their spraints. The murky waters of Lake Victoria are host to a large number of fish species, mostly small cichlids (Haplochromidae), locally called furu-furu. Most of the prey of the spotted-neckeds were furu-furu of 3-6 cm long (size calculated from the size of fish eye lenses in the spraints), but they also took many of the, much larger, introduced tilapia Oreochromis niloticus, up to 30 cm long, and the catfishes Bagrus sp. and Clarias sp., as well as the occasional crab Potamon niloticus.

Social breeding

In some species, helpers may assist breeding adults to raise their young, and this creates a system that is known as social breeding. There are several categories of social breeding, the most developed of which is found in eusocial species. These are characterized by a division of labour that results in numerous workers assisting relatively few reproductive nest mates to raise their offspring. In most cases these workers will never reproduce themselves, often because they are sterile. Most eusocial species are insects, including termites, ants and some species of wasps, bees, aphids and thrips. Eusociality in other orders is very rare, with two notable exceptions being the snapping shrimp (Synalpheus regalis) and several species of naked mole rat (Heterocephalus glaber and Cryptomys spp.). Less stringent forms of sociality involve helpers that may reproduce in later years, and can be found in diverse taxa including about 3 per cent of bird species (e.g. the white-throated magpie-jay,...

Adaptive Radiations

In other words, adaptive radiations reflect adaptive evolution and speciation on fitness landscapes that are intrinsically coarser grained than those typically encountered by most evolving lineages. However, while such a perspective accounts for the types of adaptive radiations typically discussed in the literature (e.g., differences in trophic modes and coloration in African lake cichlids, beak morphology in finches on the Galapagos, etc.), it still leaves unanswered the other aspect of evolutionary radiations seen in the early fossil record - the origin of truly novel morphologies.


Praw and Grant (1999), for example, investigated the costs and benefits to convict cichlid fish (Archocentrus nigrofasciatus) of defending food patches of different sizes. As patch size increased, the amount of food eaten by a patch defender increased (the benefit Figure 5.29a), but the frequency of chasing intruders (the cost Figure 5.29b) also increased. Evolution should favor an intermediate patch (territory) size at which the trade-off between costs and benefits is optimized, and indeed, the growth rate of defenders was greatest in intermediate-sized patches (Figure 5.29c). Figure 5.29 Optimal territory size in the convict cichlid fish, Archocentrus nigrofasciatus. (a) As patch (territory) size increased, the amount of food eaten by a territory defender (standardized z score) increased but leveled off at the largest sizes (solid line, linear regression r2 0.27, P 0.002 dashed line, quadratic regression r2 0.33, P 0.003). (b) As patch (territory) size increased, the chase rate of...