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'Reproductive behavior in male African elephants (Loxodonta africana) and the role of musth: A genetic and experimental analysis by Julie Ann Hollister-Smith
Description:
Musth in male elephants has been recognized for hundreds of years in the Asian elephant and for at least twenty-five years in the African elephant, yet there is still a tremendous amount that remains poorly understood about this distinctive condition. Male elephants are atypical among mammals in continuing to grow in height and weight as adults, affecting musth duration and dominance rank. Additionally, because musth occurs asynchronously among males, individuals repeatedly rotate into and out of high rank in the population throughout their lifespan, also exceptional compared to other male mammals. Although these two features, indeterminate growth and lifelong repeated rank changes are unusual for mammals; male reproductive patterns are nonetheless expected to conform to existing models of mating systems and sexual selection theory. Thus far, however, no genetic parentage assessment in a wild elephant population had allowed evaluation of the hypothesis that musth males have higher reproductive success. I conducted the first successful genetic paternity analysis of a wild African elephant population to examine the relationship between musth and male reproductive success. I then determined how male state, in musth or out of musth, and two associated mating behaviors, mate guarding and mating, reflected genetic parentage. Finally, I carried out an experiment conducted within the captive African elephant population in North America to examine the potential chemical signaling role of urine dribbling exhibited by males when they are in musth. I concluded that age, size and musth all interact to affect a male's iv reproductive success and that males in musth sired a disproportionately large proportion of offspring in the wild. Male mating behaviors are relatively weak predictors however, for specific calf conceptions because estrous females switch male partners more often than previously believed. I also conclude that males are able to detect musth state in urine as indicated by their ability to differentiate between musth and non-musth urine samples using their vomeronasal or secondary olfactory system. Thus, chemosensory signals in urine may provide a possible mechanism by which males can avoid potentially injurious interactions with highly aggressive musth males, thereby extending their lifespan and greatly affecting their reproductive success.


  

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