Abstract
During 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 or directional selection and stabilizing selection. These models produce different curves of pairwise variance between species against time since divergence, in such a way that different profiles appear in phylogenetic correlograms. We analyzed variation in body length among 19 species of South American owls, by means of phylogenetic correlograms constructed using Moran's I coefficient in four distance classes. Phylogeny among species was based on DNA hybridization. The observed correlogram was then compared with 500 correlograms obtained by simulations of Brownian motion and O-U over the same phylogeny, using discriminant analysis. The observed correlogram indicates a phylogenetic gradient up to 45 mya, when coefficients tend to stabilize, and it is similar to the correlograms produced by the O-U process. This is expected when we consider that body size of organisms is correlated with many ecological and life-history traits and subjected to many constraints that can be modeled by the O-U process, which has been used to describe evolution under stabilizing selection.
Highlights
In the last few years, considerable attention has been given to the analysis of quantitative trait evolution, especially in terms of linking microevolutionary processes to macroevolutionary patterns, evaluated using comparative data (Felsenstein, 1988; Martins, 1994; Hansen and Martins, 1996)
The comparison of the phylogenetic correlogram of body length for the South American owls with correlograms obtained by simulations of two stochastic processes suggests that the data are better explained by an OU process, which have been used to model effects of stabilizing selection (Felsenstein, 1988; Martins, 1994; Hansen and Martins, 1996)
Pure statistical stochastic processes such as Brownian motion and O-U process are not expected to model in detail all genetic factors responsible for phenotypic variation in a complex trait such as body size, they can give a first indication of the general evolutionary patterns and processes involved at very large time scales (Martins, 1994)
Summary
In the last few years, considerable attention has been given to the analysis of quantitative trait evolution, especially in terms of linking microevolutionary processes (selection, drift, mutation) to macroevolutionary patterns, evaluated using comparative data (Felsenstein, 1988; Martins, 1994; Hansen and Martins, 1996). The first is Brownian motion, that has often been used to describe evolution by random genetic drift (Felsenstein, 1985, 1988; Lynch, 1990; Martins, 1994). In this model, change in mean phenotype occurs at a constant rate and is non-directional. The linear relationship of Vb to t generated by Brownian motion is expected under other genetic models, including constant directional selection ( B would be larger than expected by drift alone) and directional selection in fluctuating environments with a quick phenotypic response (Hansen and Martins, 1996)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
