Reassessing the relationship between juvenile mortality and genetic monomorphism in captive cheetahs
Publication Type: |
Journal Article |
Year of Publication: |
1996 |
Authors: |
Nadja Wielebnowski |
Publication/Journal: |
Zoo Biology |
Publisher: |
A Wiley Company, Inc., Wiley Subscription Services |
Keywords: |
felids, homozygosity, husbandry |
ISBN: |
1098-2361 |
Abstract:
Abstract 10.1002/(SICI)1098-2361(1996)15:4<353::AID-ZOO1>3.3.CO;2-O Low levels of genetic heterozygosity are commonly considered a major threat to the survival of wild and captive populations. However, intense focus on genetic issues may obscure the importance of extrinsic factors influencing species’ survival in wild and captive environments. A key example for this is the cheetah (Acinonyx jubatus), which is frequently cited as suffering from unusually high juvenile mortality and decreased fecundity in captivity due to genetic monomorphism at the species level. It has also been suggested that as a consequence of such extreme homozygosity, juvenile mortality rates of young from related vs. unrelated parents would not be expected to differ significantly. However, examination of current studbook data and breeding records of the North American captive population showed that juvenile mortality of young from related parents was significantly higher than that of young from unrelated parents, largely as a result of intrinsic causes, such as stillbirths and congenital defects, that may have a genetic basis. This indicates that in spite of the cheetah’s homozygosity, effects of further inbreeding depression may still occur in the captive population, and deleterious recessive alleles are being segregated. Furthermore, juvenile mortality has declined over time and differs significantly among facilities, even when only young from unrelated parents are considered, suggesting that differences in management practices may be largely responsible for observed changes in mortality rate. Contrary to previous reports, cheetah juvenile mortality is not unusually high when compared to other captive-bred felids. In addition, cheetahs were found to have consistently higher litter sizes and the highest average number of surviving cubs per litter when compared to other captive-bred felid species. These findings cast doubt on the significance of overall homozygosity in this species for its juvenile survival and breeding performance and emphasize the key role of management practice in promoting breeding of endangered species. © 1996 Wiley-Liss. Inc.