Nature 329, 328 - 331 (24 September 1987); doi:10.1038/329328a0

Reproductive and genetic consequences of founding isolated lion populations

D. E. Wildt, M. Bush, K. L. Goodrowe, C. Packer^*, A. E. Pusey^*, J. L. Brown^†, P. Joslin^‡ & S. J. O'Brien^§

National Zoological Park, Smithsonian Institution, Washington, District of Columbia 20008, USA
^*Department of Ecology and Behavioral Biology, University of Minnesota, Minneapolis, Minnesota 55455, USA
^†Department of Obstetrics and Gynecology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA
^‡Chicago Zoological Park, Brookfield, Illinois 60513, USA
^§Section of Genetics, Laboratory of Viral Carcinogenesis, National Cancer Institute, Frederick, Maryland 21701, USA

Species survival is critically dependent on reproductive performance, a complex physiological process under rigorous genetic control. Classical studies of inbreeding in laboratory animals and livestock have shown that increased homozygosity can adversely affect spermatogenesis, ovulation and perinatal mortality and morbidity^1–3. For wild populations, the consequences of inbreeding depression have not been examined intensively, although our recent studies of the African cheetah revealed a striking degree of genetic uniformity^4,5 combined with an extremely high incidence of structurally abnormal spermatozoa (>70%) in captive⁶ as well as free-ranging⁷ males. In this study, we report definitive evidence that the reproductive function of free-ranging mammals can be impaired as a result of demographic contraction followed by inbreeding. In an examination of three distinct lion populations (two from the Serengeti ecosystem in East Africa and a third descended from lions in the Gir Forest of western India), a direct correlation was observed between genetic variability and two physiological traits, incidence of abnormal sperm and circulating testosterone, a critical hormone for spermatogenesis.

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