Padrões e processos na evolução do tamanho do corpo em carnívoros (Mammalia) da América do Sul

Abstract

Patterns and processes in body size evolution of south american carnivoresIn the last few years, many models have been proposed to link microevolutionary processes to macroevolutionary patterns, defined by comparative data analysis. Among these, Brownian motion and Ornstein-Uhlenbeck (O-U) processes have been used to model, respectively, genetic drift and stabilizing selection.Since these models produce different curves of pairwise variance between species against time since divergence, different profiles in phylogenetic correlograms must appear. In this paper, we analyzed variation in body weight among 17 species of South American carnivores by means of phylogenetic correlograms, constructed using Moran's I coefficients in four distance classes. Phylogeny among species was based on molecular data.The observed correlogram was then compared with 400 simulated correlograms of Brownian motion and O-U over the same phylogeny. The observed correlogram indicates a phylogenetic gradient up to 8 mya, when coefficients tend to stabilize, and autoregressive model indicates that around 74% of the interspecific variance in body size can be explained by phylogenetic inertia. This is expected by considering that body size is usually correlated with many ecological and lifehistory traits, being subjected to many constraints that can be modeled by O-U process expressing stabilizing selection.Key words: carnivores, body size, phylogeny, autocorrelation, correlograms, stabilizing selection. RESUMONos últimos anos, muitos modelos têm sido propostos a fim de ligar os processos microevolutivos aos padrões macroevolutivos. Dentre estes, o movimento Browniano e o processo Ornstein-Uhlenbeck (O-U) têm sido utilizados, respectivamente, para modelar a evolução de um caráter quantitativo sob efeito de deriva genética e seleção estabilizadora.Uma vez que esses processos produzem curvas diferentes de relação entre variância interespecífica e tempo de divergência, eles podem ser distinguidos através de correlogramas filogenéticos. Neste trabalho, padrões no tamanho do corpo de 17 espécies de Carnívora sul-americanos foram analisados através de correlogramas filogenéticos, construídos com índices I de Moran em quatro classes de distância no tempo.O correlograma observado foi comparado a 400 correlogramas obtidos através de simulações dos dois processos (movimento Browniano e O-U) sobre a filogenia das espécies analisadas (obtida

Species Richness and Evidence of Random Patterns in Assemblages of South American Titanosauria during the Late Cretaceous (Campanian–Maastrichtian)

“…Phylogenetic effects include important processes that will determine the ecologies of large numbers of species (as opposed to putative interactions between members of the assemblage in terms of the utilization of available resources), reflecting the evolutionary histories of different lineages that diverged over millions of years [72]–[73]. Body size is strictly related to phylogenetic structures in different clades, suggesting that stabilizing selection processes may have been involved in the evolution of this character – which would be expected, as body size correlates with various ecological attributes and the life histories of the species [74].…”

The high diversity and phylogenetic signal of antipredator mechanisms of the horned frog species of Proceratophrys Miranda-Ribeiro, 1920 (Amphibia: Anura: Odontophrynidae)

“…Phenotypic traits may depend upon for root of a phylogenetic tree or may converge to their tips (Paivone et al, 2010). Moreover, the evolution of these characteristics can be explained by Brownian motion, a process of random genetic drift at a constant rate of evolution and non-directional selection (Diniz-Filho and Vieira, 1998).…”