Animal breeding and conservation genetics.

Conservation genetics in an animal breeding context relates both to questions of preservation of rare and endangered breeds or populations, and to utilization with planned genetic change to improve viability, productivity, and efficiency of production. In the developed world, preservation is the primary issue, and various organizations exist which are committed to the preservation of rare and endangered breeds. In the developing world, breeds as such often are not defined or recognized, but many local populations exist that are adapted to and integrated into existing production systems. The genotypes of at least some of these populations could well also be crucial for future production systems, but many are threatened, primarily by crossbreeding with breeds introduced from the developed world. However, not all can be conserved, and priorities will have to be set for preservation, for development (breeding programs) and for evaluation for future programs. Some priorities will be set for pragmatic reasons, but the primary rational reason must be that a breed is in some way genetically unique, and makes a substantial contribution to the genetic diversity of the species. Thus, measures of genetic distance are essential to quantify the degree of genetic differentiation among populations, but such measures must be based on a large sample of loci. Although this has been emphasized many times, it still seems not to be adequately appreciated, and the effect of using a limited sample of loci is illustrated with an example from swamp buffalo populations. Comparative estimates of distances based on electrophoretic variation and direct DNA variation (both mitochondrial and genomic) are needed as a basis for future work on conservation of the global domestic animal diversity. Finally, studies of feral populations and wild relatives of domestic animals will provide a link between natural populations and domestic animal populations, and bring together these two areas, which to now have been largely separate.