A regra de Rensch em Brachyura: uma abordagem com habitats

Abstract

Rensch's Rule states that there is an increase in sexual size dimorphism with an increase in the average male body size in a monophyletic taxon. In addition, another factor that can define the size of a species would be the distance from the equator, as proposed by Bergmann. Brachyura crabs constitute a monophyletic group, and they occur in the most diverse environments and are subject to environmental variables, such as primary productivity. Thus, estimates of the patterns of Rensch's Rule, conventional and latitudinal approach among marine, freshwater and mangrove crab species were presented. Hypothesizing that species in environments with higher primary production have a more evident sexual dimorphism, where the sexual selection’s pressure is stronger than environments with lower productivity. Type II Regression models was used for the rule’s estimates. The results obtained showed a relatively neutral trend in relation to Rensch's Rule for freshwater and estuarine crabs, with a positive trend for marine crabs. While in relation to a latitudinal application in the dimorphism, all species showed a positive relationship between the increase in latitude with the increase in dimorphism, with greater emphasis on marine species that had a more expressive result.