Investigating the Influence a Matrilineal Social Structure has on Mitochondrial Fixation and Genetic Diversity Within the Spotted Hyena, Crocuta Crocuta

Abstract

Spotted hyenas, Crocuta crocuta, live in social groups, or clans, characterized by a matrilineal hierarchy wherein the female is dominant over the male. Clans are based on female philopatry where juvenile hyenas acquire their social ranks based upon the ranks of their mothers. Females remain within their natal clan, and males typically disperse from their natal clan between 24-62 months of age to join new clans. Because the highest-ranking female and her offspring leave more surviving progeny for future generations, other lineages within the clan eventually go extinct. Field data indicates that within a period of 4-5 generations all members of the clan can be traced to a single dominant female. This analysis used modem molecular genetic techniques to examine the hypothesis that this social system, if stable over a long period, would lead to purified mitochondrial DNA (mtDNA), or 'mtDNA signature', within a clan and a definite distinction among clans. Distinctive mtDNA signatures would allow for confirmation of natal clan affiliation and facilitate pedigree analyses, ultimately resulting in a better understanding of mating and social behaviors. This study examined 1400 base pairs of mitochondrial genes and an additional 1847 base pairs of nuclear genes to assess a distinctive mtDNA signature and compare genetic diversity in 243 spotted hyenas. Although nine clans were represented in the data set no clan distinctions were found only regional differences were observed. Furthermore, data indicates that the spotted hyena sequence haplotypes are shared with Pleistocene haplotypes and extant spotted hyenas exhibited a low level of mitochondrial and nuclear variation. These Pleistocene relics are all that remains of what was once a larger, more diverse species. Extant spotted hyenas are the survivors of the last glaciation and the haplotypes exhibited today are those haplotypes that existed thousands of years ago.