My dissertation combines molecular and behavioral data to examine the evolutionaryecology of the family Hyaenidae. More specifically, I focus on the evolution of adaptive geneticvariation in hyenas, the influence of this variation on fitness, and the genetic and ecologicalcauses and consequences of behavior. My dissertation consists of four chapters following theintroductory chapter. The first of these research chapters, Chapter 2, characterizes thediversity of three genes located within the major histocompatibility complex (MHC), and arecritical to the adaptive immune system. In addition to offering the first characterization ofthese loci in spotted (Crocuta crocuta) and striped (Hyaenidae hyaenidae) hyenas, this chapterdescribes the evolutionary history of alleles at each locus and documents the presence ofpositive selection acting to increase diversity at two out of three loci. The results of theseanalyses are consistent with the hypothesis that some shared selection pressure, rather thandiffering degrees of sociality, is the predominant force shaping MHC variation within the familyHyaenidae. Chapter 3 documents correlations between MHC variation and individual measuresof fitness in spotted hyenas, and suggest the importance of specific MHC alleles to longevityand immune system function. Chapter 4 investigates whether captive female spotted hyenasexhibit differences in their behavioral responses to odors originating from unknown males thatvary in degree of MHC similarity to the female. I found a significant correlation betweenaverage pairwise relatedness and time spent sniffing, such that females spent significantlylonger times investigating odors from males that were more closely related to them and frommales that were MHC-dissimilar to them. These data suggest that genetic variation mayinfluence hyena behavior, and that female spotted hyenas prefer the odor of males thatcontain dissimilar genotypes from them at functional (i.e. MHC) loci. Chapter Five presentsneutral microsatellite marker data from two populations of striped hyenas and examines howspace use and genetic relatedness are influenced by local population ecology. These datasuggest differences in the relationship between relatedness and space use between these twopopulations. Further, I show that the area occupied by the population inhabiting Shompole,Kenya has more than triple the ungulate (i.e. prey) density than does the area inhabited by theLaikipia, Kenya, population, whereas both populations exhibit the same hyena density. Femalehome range sizes in Shompole were significantly smaller in Shompole than in Laikipia,suggesting that the ecological differences in prey availability influence the amount of areaneeded by females to meet their food requirements.My dissertation utilizes both neutral and adaptive molecular marker data, incombination with behavioral data, as tools to address questions pertaining to the evolutionaryecology of hyenas. The results of my analyses demonstrate positive selection acting to increasevariation at functional loci, and show that this variation may indeed be integral to individualfitness in spotted hyenas. Further, I show that genetic variation may influence behavior inhyenas by affecting odor preference, and that hyenas may alter their space use patterns inresponse to local ecology. Overall, my dissertation offers molecular, behavioral, and ecologicaldata rarely available for large mammalian (non-model) species and contributes to the body ofknowledge regarding extant members of the family Hyaenidae.
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