Population genetic structure of a colony of German Shepherd and Labrador Retriever dog guides

J.B. Cole1, D.E. Franke1, and E.A. Leighton2

1Department of Animal Science, Louisiana State University, Baton Rouge, LA 70803

2The Seeing Eye, Inc., Morristown, NJ


Pedigree analysis was used to describe changes in genetic diversity in a colony of dog guides. German Shepherds (GS) and Labrador Retrievers (LR) were evaluated. Parameters estimated included average coefficients of relationship to the breed, average coefficients of inbreeding, effective founder number, effective ancestor number, founder genome equivalents, and effective population size. There were rapid increases in average pairwise relationship in both breeds, although the average was approximately one-third higher in the GS population than in the LR population. A similar trend was observed for average inbreeding. Both measures showed a steady increase for several generations and levelled off thereafter. In the current generation, relationship and inbreeding for all animals averaged 25.3% and 26.2% in GS and 15.5% and 22.0% in LR, respectively. Effective founder number initially decreased in GS until generation 3, and then increased steadily. There was a constant increase in effective founder number in LR after founding. Final values were 35.5 and 20.2 in GS and LR, respectively. A similar pattern, with current values of 23.6 and 16.9, was seen for effective ancestor number as well. This is probably due to the fact that this is a small populationwhich received new genetic material by migration distinctly different populations. Founder genome equivalents were initially higher in the GS but decreased over time in both breeds to 5.6 and 5.3 in GS and LR, respectively. Changes have been effected in the genetic management of the breeding colony to slow, and eventually reverse, the trends towards increased relationships and inbreeding. Effective population sizes are not expected to change significantly in the near- to medium-term. Use of a more diverse portfolio of sires and dams, as well as the introduction of germplasm from outside of the current breeding colony, will help insure the continued health of this population.

(Key words: population structure, dog guides, genetic diversity)