Evolution of sexually dimorphic characters in peccaries (Mammalia, Tayassuidae)

摘要: Cladistic analysis of osteological and dental characters in a monophyletic group Miocene younger tayassuids demonstrates pattern changes the degree sexual dimorphism canine tooth diameter zygomatic arch width, phenotypic correlations between these characters. Primitively, have teeth that are sexually dimorphic discretely bimodal size, arches narrow both sexes. Many late Pliocene broad, winglike processes. In some species, processes large sexes, but others, those females much smaller than males. The presence sexes is primitive relative to condition strong dimorphism. five separate clades, become reduced size becomes as well. congruent with predictions derived from theoretical model evolution dimorphism, it further indicates emergence new correlation two previously uncorrelated characters, zygoma size. advent this coincides pronounced Although such could be explained by genetically modifying expression homologous one sex or other, an epigenetic modification equally plausible: accomplished placing originally monomorphic character under control steroid hormones. This hypothesis consistent evidence many vertebrate groups, provides testable predictions.