MORPHOLOGY, BEHAVIOR AND MACROEVOLUTION

In evolutionary biology, the mechanisms that account for the emergence of bizarre morphological discontinuities among taxa, i.e., the origin and evolution of taxa above species, are controversial. The origin of new bauplans-macroevolution-usually requires morphological or structu ral modifications coupled to behavioral changes. Here, I discuss the r ole of animal behavior in evolution at two different levels of life or ganization. At the organismal level, behavior induces the generation o f variability during ontogeny through the integration and coadaptation of structural modifications or morphological novelties. At the popula tion level, behavior leads to the fixation of variability, through the generation of new selection pressures associated to niche shifts. A g reat ecological performance (or fitness) can be expected in those indi viduals with modifications in agreement with the new explotative syste m. In this perspective, ontogeny and phylogeny can be viewed as two ca usally related events. Behavioral flexibility could be an important fa ctor attenuating the constraints imposed on phylogenetic trends by the developmental program.