EVOLUTIONARY DIVERGENCE IN DIRECTIONS OF HIGH PHENOTYPIC VARIANCE IN THE OSTRACODE GENUS POSEIDONAMICUS

摘要: Trait variation and covariation are understood to influence the response of populations natural selection on generational time scales, but their role, if any, in shaping long-term macroevolutionary divergence is still unclear. The present study uses rich fossil record ostracode genus Poseidonamicus reconstruct great detail evolutionary history a set landmark-based morphometric characters. This reconstruction included two kinds inferences: ancestor–descendant transitions among repeatedly sampled at same location between lineages measured as independent contrasts phylogeny. reconstructed was then used test changes were concentrated directions (traits or combinations traits) with high phenotypic variance. Two different statistics association evolution tested null hypothesis that occur random respect trait variability. first these similarity change axis maximum variance, second degree which variation. Randomization tests indicated both inferences (ancestor–descendant phylogenetic contrasts) occurred preferentially variance (and close maximal variation), suggesting within-population can structure divergence. effect decayed after few million years, least for one metric, never disappeared completely. These results consistent Schluter's genetic constraints model trajectories adaptive landscapes deflected by within traits.