Evolution of sexually dimorphic characters in peccaries (Mammalia, Tayassuidae)
| Autor: | David B. Wright |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
0106 biological sciences
0301 basic medicine Ecology Osteology Paleontology Vertebrate Biology 010603 evolutionary biology 01 natural sciences Cladistics Sexual dimorphism 03 medical and health sciences Monophyly 030104 developmental biology medicine.anatomical_structure Evolutionary biology biology.animal medicine Zygomatic arch General Agricultural and Biological Sciences Clade Ecology Evolution Behavior and Systematics Canine tooth |
| Zdroj: | Paleobiology. 19:52-70 |
| ISSN: | 1938-5331 0094-8373 |
| DOI: | 10.1017/s0094837300012318 |
| Popis: | Cladistic analysis of osteological and dental characters in a monophyletic group of Miocene and younger tayassuids demonstrates a pattern of changes in the degree of sexual dimorphism in canine tooth diameter and zygomatic arch width, and in phenotypic correlations between these characters. Primitively, tayassuids have canine teeth that are sexually dimorphic and discretely bimodal in size, and zygomatic arches that are narrow in both sexes. Many late Miocene and Pliocene tayassuids have broad, winglike zygomatic processes. In some species, these processes are large in both sexes, but in others, those of females are much smaller than those of males. The presence of large processes in both sexes is primitive relative to the condition of strong sexual dimorphism. In five separate clades, the zygomatic processes of both sexes become reduced in size, and the degree of sexual dimorphism in canine size becomes reduced as well. The pattern is congruent with predictions derived from a theoretical model of the evolution of sexual dimorphism, and it further indicates the emergence of a new phenotypic correlation between two previously uncorrelated characters, canine size and zygoma size. The advent of this new correlation coincides with the advent of pronounced sexual dimorphism in zygomatic processes. Although such a pattern could be explained by genetically modifying phenotypic expression of homologous characters in one sex or the other, an epigenetic modification of expression is equally plausible: the evolution of sexual dimorphism in homologous characters could be accomplished by placing phenotypic expression of an originally monomorphic character under the control of steroid sex hormones. This hypothesis is consistent with evidence from many vertebrate groups, and it provides testable predictions. |
| Databáze: | OpenAIRE |
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