Evolution of performance under tradeoffs

Evolutionary Trade Offs Models

The first attempt to model the evolution of the fundamental niche was that of Levins (1968). He devised a model that should seem familiar, for in structure it is very similar to the model of the evolution of co-sexuality by Charnov et al. (1976) (Chapter 5). Imagine an organism faced with two habitats, A and B, of differing frequency. Its fitness in the two habitats is defined by a trade-off, such that when its fitness in A is high, its fitness in B will be lower, and vice versa, a situation...

Evolution of the biosphere a brief history

The origin of the biosphere and of earth's ecology occurred between 3.8 and 3.5 billion years ago. Both autotrophic and heterotrophic origins have been proposed. Previously the heterotrophic use of organic molecules synthesized in the pre-biotic broth was a popular idea (see Lazcano and Miller 1999). More recently, autotrophic theories have re-emerged, for two reasons first, early cell membranes would probably have lacked sufficient permeability to transport large molecules. Second, it is now...

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...

Sexual selection in plants

This discussion of plant reproduction is convenient for the next subject sexual selection. Sexual selection was another brainchild of Darwin (1871) who realized that characters that made organisms successful at acquiring a mate might be selected for, and that this can account for some of the extraordinary exaggerated traits of organisms, such as antlers of deer and long tails and colourful plumage of pheasants. The first person to explicitly model female choice as the exaggerating process was...

The origins and maintenance of mutualism

Figures 10.3, 10.4) are those interactions in which both partners accrue increased fitness relative to individuals that do not engage in it. How might selection favour the expression of traits that help other individuals of a different species, given a prior relationship that was more nearly neutral or even antagonistic Frank (1997) has suggested that two processes act to help the spread of such traits first, an initially high level of expression on first meeting in both...

Evidence for dispersal evolution

What evidence supports these predictions It must be admitted that the theoretical richness of dispersal evolution, while matching easily that on sex ratios, is not yet supported by the same wealth of evidence. The reason is primarily the difficulty of measuring the variables sex ratios simply require counts of males and females, whereas direct measurement of dispersal rates or distances is extremely problematic. Most studies have used some sort of morphological marker for dispersal ability,...

The evolution of animal flight understanding a major transition in ecology

There is now little doubt among most biologists that birds derive from a group of theropod dinosaurs. The theropods were a bipedal carnivorous group that share many anatomical features with birds. A series of recent fossils, most notably from Liaoning province of China and described by Xu Xing and colleagues, include therapods with epidermal feather-like structures that we might collectively refer to as 'fuzz'. They were pre-adapted for flight through a fast cursorial predatory lifestyle. This...