Browsing by Author "Gilbert, D.A."

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    Case study of a population bottleneck: Lions of the Ngorongoro crater
    (Fosbrooke, 1970) Parker, C.; Pusey, E.A; Rowley, H.; Gilbert, D.A.; Martenson, J.; O’Brien, S.J
    Lions in the Ngorongoro Crater form a small and naturally isolated population. In 1962, the Crater lions suffered an epidemic that reduced the population from 60-75 to 10 individuals. The population rapidly recovered to its former level due to successful reproduction by the surviving females. Seven males immigrated into the Crater in 1964-65, and all subsequent breeding males have been born in the Crater. Most lions in the Crater are descended from four females that survived the epidemic, and there has been considerable exchange of males between prides of common ancestry. The Crater lions show a striking lack of genetic diversity in comparison with the very large and outbred Serengeti population. There are two populations that neighbor the Crater and the Crater lions show a greater genetic affinity to the Serengeti population. Thus genetic data from the Serengeti can be used to provide estimates of the genetic compost ion of the Crater population prior to the 1962 epidemic. Computer simulations suggest that the Crater population may have already been somewhat inbred by 1962; and that the degree of heterozygosity in the breeding population has been declining since the mid- 1970's. A loss of heterozygosity is associated with increased levels of sperm abnormality in lions and there is some evidence that the reproductive performance of the Crater lions is decreasing as a result of decreasing heterozygosity.