Phylogenetic analysis of coadaptation in behavior, diet, and body size in the African antelope

Several authors have suggested that African antelope (family Bovidae) exemplify coadaptation of ecological, behavioral, and morphological traits. We tested four hypotheses related to the ecology and behavior of 75 species of African antelope using both conventional statistical techniques and techniques that account for the nonindependence of species by considering their phylogenetic relationships. Specifically, we tested the hypotheses that (1) dietary selectivity is correlated negatively with body mass, (2) dietary selectivity is correlated negatively with group size, (3) gregarious species either flee or counterattack when approached by predators, but solitary and pair-living species seek cover to hide, and (4) body mass and group size are correlated positively. Each of these hypotheses was examined for the global data set (family Bovidae) and, when possible, within the two antelope subfamilies (Antilopinae and Bovinae) and within 7 of the 10 antelope tribes. The results of our conventional and phylogenetically corrected analyses supported the hypotheses that group and body size vary predictably with feeding style and that antipredator behavior varies with group size. The hypothesis that body mass and group size are correlated positively was supported by conventional statistics, but these two traits were only weakly related using a phylogenetically corrected analysis. Moreover, qualitative and quantitative comparisons within each of the eight major African antelope tribes generally gave little support for the four hypotheses tested. Thus, although our analyses at the subfamily level provided results that were consistent with prior hypotheses, our analyses at the level of tribes were equivocal. We discuss several possible explanations for these differences.