This hypothesis is based on observed divergence in somatic morphology, penis morphology, and consistent divergence for multiple genes.
The main weaknesses include different methods used to quantify sperm count; the paucity of studies that have examined TCDD effects on DSP and the ambiguous nature of those results; the absence of documented changes in testicular and spermatozoa morphology; and the divergence of effects of TCDD upon sperm counts and circulating androgen levels.
Under random fluctuation, for instance, evolved morphologies were narrowly and randomly distributed near the origin (representing the starting morphology) of the plot of the first two axes of principal component space and divergence from starting morphology rose modestly over time while the range of morphologies rose monotonically (Polly 2004:Fig. 5).
We tested the natural selection hypothesis through multivariate analyses of color-associated ecological (stable isotope ratios of carbon and nitrogen) and morphological divergence (body shape and jaw morphology) across replicate populations, coupled with a common garden experiment.
Both the Pekin duck and broiler chicken have undergone major changes in body size and leg morphology since divergence from their 'unselected' conspecifics occurred through artificial selection.
Divergence in immune system does not imply detectable divergence in morphology and may therefore be overlooked in many animal systems.
We utilized an analysis technique that directly links individual variation in morphology to feeding performance and tested whether functional divergence in morphology and food acquisition rate has occurred since the introduction, as a result of predator release.
According to this scenario, divergence in morphology and female preferences evolved under gene flow limited by the geographic barrier.
Predation has been proposed to drive evolutionary divergence in morphology and behaviour [ 32, 37- 41] and speciation in cladocerans [ 23, 25, 26, 41- 43].
Three orders of mammals include subterranean species: the rodents, the insectivores, and the marsupials, which independently display adaptive convergence and divergence, are good subjects for comparative studies in morphology, ecology, physiology, ethology, and most recently, genetics [ 1, 2].
