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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #335671
Title: Genetic variation and differentiation in parent-descendant cattle and bison populations

Author
item CRONIN, MATTHEW - University Of Alaska
item Leesburg, Vicki

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/2016
Publication Date: 10/7/2016
Publication URL: http://handle.nal.usda.gov/10113/5661742
Citation: Cronin, M.A., Leesburg, V.L. 2016. Genetic variation and differentiation in parent-descendant cattle and bison populations. Journal of Animal Science. 94:4491-4497. doi:10.2527/jas2016-0476.

Interpretive Summary: Genetic variation is important in cattle because it allows selection for fitness and performance traits. Genetic variation is also important in wildlife populations, including bison. New populations will have only part of the genetic variation in the parent population. For example, a line of cattle will have a subset of the variation that is in the breed from which it was derived. Similarly, a wildlife population introduced into vacant habitat will have a subset of the variation that is in the population from which it was derived. Reduced levels of genetic variation in the new populations can result in inbreeding depression and reduced fitness in livestock or wildlife. In contrast, crossbreeding can result in an increase of genetic variation, with associated heterosis (= hybrid vigor), in the derived population compared to the parent breeds, We analyzed genetic variation with DNA of 32 genes called microsatellites in cattle and bison populations. This included the Line 1 Herefords, derived from the Hereford breed, the CGC cattle derived from crossing Red Angus, Charolais, and Tarantaise breeds, and the RF line derived from crossing Line 1 with CGC followed by crossing the offspring back to Line 1. We also assessed three pairs of parent-descendant bison populations in which the parent population provided bison that were transplanted to unoccupied habitat: Yellowstone National Park-Henry Mountains Utah, National Bison Range-Alaska plains bison, and Wood Buffalo National Park-Alaska wood bison. Genetic variation (measured as heterozygosity and number of alleles) was less in the descendant Line 1 population than in the parent Hereford breed, as expected. The CGC crossbred population had higher variation than the parent breeds, also as expected. The RF line also had higher variation than the Line 1 and CGC parent lines. The transplanted descendant bison populations had lower variation than the parent populations, also as expected. These results demonstrate that genetic variation is reduced in derived populations, and that genetic variation can be increased with crossbreeding in cattle. This practice can also be applied to wildlife such as bison.

Technical Abstract: Genetic variation and differentiation at 32 microsatellite DNA loci is quantified for parent-descendant cattle populations and parent-descendant bison (Bison bison) populations. Heterozygosity (Ho) and numbers of alleles/locus (AR) are less in the Line 1 Hereford inbred cattle population than in the parental Hereford breed. Ho and AR are intermediate in a composite population (CGC) compared to the three parental breeds. Crossbreeding of Line 1 with CGC resulted in an F1 generation with increased Ho and AR relative to Line 1 and CGC, followed by decreasing Ho and AR in two backcross generations. Three transplanted wild bison populations had smaller Ho and AR than their respective parental populations. These data empirically demonstrate that genetic variation is reduced from founder effects or inbreeding, but can be restored with crossbreeding and gene flow.