Ch. 6— Maintaining Animal Diversity Offsite • 151 



differential contribution of different individ- 

 uals to the next generation, programs that at- 

 tempt to equalize the contribution of each in- 

 dividual can greatly low^er initial rates of genetic 

 loss (21). Likew^ise, if pedigrees of available in- 

 dividuals are known, matings can be planned 

 in an attempt to equalize the contribution of 

 different lineages. This approach has been used 

 to stabilize founder contributions in a captive 

 population of Speke's gazelle (46). Thus, efforts 

 to record and publish pedigrees of individuals 

 in endangered species (such as the records of 

 ISIS) assume great importance. 



For domesticated animals, several population 

 structures and mating systems can be used in 

 conservation programs that are generally not 

 appropriate for wild animals. In many domes- 

 tic species, the large number of existing breeds 

 (30) precludes conservation of all endangered 

 breeds as pure breeds. One possibility in such 

 cases is to preserve a single breed representa- 

 tive of a group of similar breeds. A better strat- 

 egy, however, may be to amalgamate into a gene 

 pool individuals from related breeds or from 

 several breeds that excel in a certain charac- 

 teristic. 



Gene-pool populations are designed to con- 

 serve genes rather than individual breeds. Thus, 

 several breeds noted for a certain characteris- 

 tic such as heat tolerance or proliferation might 

 be interbred to provide a single large reservoir 

 of genes for this trait. Although the identity of 

 individual breeds is lost, many genes present 

 in the breeds are retained. Selection to inten- 

 sify the trait maybe appropriate, depending on 

 the potential or current economic importance 

 of the population. Maintenance of a single in- 

 terbreeding gene pool is less desirable than of 

 a subdivided population for long-term gene con- 

 servation. For domestic species, however, the 

 larger population sizes that are possible in a 

 single gene-pool population are expected to fa- 

 cilitate selection for economically important 

 characters within the population. Simmental 

 cattle representing at least five regional or na- 

 tional strains from Europe were imported into 

 North America in the 1970s, and the current 

 American Simmental population represents a 



gene pool constituted from these breeds. A 

 gene-pool population of pigs was developed in 

 the early 1970s in Nebraska and used in efforts 

 to increase ovulation rate (53). 



A program to not only maintain but also gen- 

 erate genetic diversity in domestic breeds has 

 been suggested (26). In this effort, populations 

 would be selected to generate extreme levels 

 of performance in specific traits. These popu- 

 lations could serve as reservoirs of genetic var- 

 iation and their characteristics would be well 

 known. 



Efficient maintenance of captive populations 

 requires a thorough understanding of the re- 

 productive processes of the species. Optimal 

 use of breeding stock is often facilitated by an 

 ability to manipulate and control these proc- 

 esses. In domestic animals, control of the es- 

 trous cycle and ovulation through administra- 

 tion of exogenous hormones has become 

 commonplace, greatly assisting programs of 

 controlled mating, artificial insemination, and 

 embryo transfer. In wild species, however, 

 knowledge of basic reproduction remains 

 limited. Efforts to expand knowledge in this 

 area are largely funded by the private sector 

 and are insufficient. 



Infertility is a major problem in many spe- 

 cies of zoo animals. It reduces the effective 

 breeding size of captive populations and exacer- 

 bates genetic losses. Infertility can often be 

 traced to environmental factors such as light, 

 temperature, nutrition, disease, or social influ- 

 ences. Such problems would be more easily 

 overcome if more were known about basic re- 

 productive processes in wild animals. 



General principles underlying control of re- 

 production are relatively uniform across spe- 

 cies, yet the particular hormone levels observed 

 and the release patterns of these hormones are 

 species-specific. A practical, reasonably sim- 

 ple, relatively inexpensive kit for monitoring 

 urine hormone levels has recently been devel- 

 oped (29). This test helps confirm ovulation, 

 predict optimal times for insemination, diag- 

 nose reproductive dysfunction, and detect preg- 

 nancy. Because the test is based on urine sam- 



