Inbreeding is commonly associated with a lowering of viability and birth weights—a phenomenon known as inbreeding depression. A severe inbreeding depression was encountered in a captive breeding program for Speke's gazelle. Unfortunately, the solution of simply avoiding inbreeding could not be implemented because the entire herd was descended from one import male and three import females. Because of this founder effect, it was impossible to avoid inbreeding. However, laboratory experiments with fruit flies and basic evolutionary theory indicate that animals can rapidly adapt to inbreeding by the selective elimination of the genes responsible for inbreeding depression. These experimental and theoretical results were translated into a breeding program for the Speke's gazelle. The first goal of the breeding program is a demographic goal: increase the total population size as rapidly as possible to the carrying capacity. The other goals all deal with genetic attributes of either parents or offspring: Both parents and offspring should be inbred, and both parents and offspring should have genes from as many different founding ancestors as possible. In this paper, we document that this breeding program does eliminate the inbreeding depression very rapidly, and moreover that the genetic goals of the program aid this elimination exactly as theory predicts. Furthermore, our analysis clearly shows that the gazelles suffered from an inbreeding depression rather than an outcrossing depression. We conclude that inbreeding depressions can be rapidly and effectively reduced by an appropriate breeding program, and hence an inbreeding depression does not constitute an insurmountable barrier to the long‐term maintenance of a species in which inbreeding cannot be avoided.
Computer simulation is a valuable tool in the genetic management of captive populations. It can be used to assess the extent of genetic variability in a colony, to predict the risk of future loss of variability, or to identify likely ancestral sources of traits of interest. "Gene dropping"tis a simulation procedure in which hypothetical alleles are assigned to each colon! founder, and a genotype is created for each descendant by Mendelian segregation of parental alleles. The gene dropping method is applied to analyses of four populations: (1) a colony of small South American marsupials, Monodelphis domesticu; (2) Speke's gazelles, Guzella spekei; (3) Przewalski's horses, Equus przewalskii; and (4) American Standardbred horses.
The association between man and elephant in Sri Lanka is ancient. Elephants being the largest terrestrial herbivores require relatively large areas and diversity of environments to forage. With the increase in human population density and changes in the land-use patterns, elephant habitat is being continuously reduced. As a result, much of the present day elephant range extends into and overlaps with agricultural lands resulting in conflict with man. The assessment of the human-elephant conflict was carried out from January to March 2008 through the use of a questionnaire in 100 villages selected randomly from five provinces whose combined extent is 42,559 km 2 which amounts roughly to 65% of the total land area of Sri Lanka. 65% of the respondents identified crop depredations with bull elephants, both young and old. At least 13 food items have been identified by the villagers as preferred by wild elephants in agricultural areas. Crop damage to paddy accounted for 69% of the complaints. At the same time, most of the farmers identified citrus trees as the most likely crop to be avoided by elephants. Failure to recognize the significance of the human-elephant conflict can result in a negative attitude to elephants and apathy or indifference to conservation initiatives. Although it is unlikely that the human-elephant conflict can be eliminated altogether, yet every effort must be taken to reduce it to tolerable levels.
Optimal plans to manage captive populations for propagation depend upon the goals of the program. Two basic goals have been proposed. The first and more frequent is preservation of genetic diversity in captivity for return to natural environments. The second is adapting a wild population to propagation in the captive environment. Each goal prescribes a general strategy for demographic and genetic management: a plan for return to natural environments and a plan for adaptation to the captive environment. These plans can be considered ends of a spectrum of possible management programs. Similarities and differences in the two plans are discussed. Practical contraints limit the implementation of the basic management plans.
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