Date of Award
Master of Science (MS)
Jerry R. Choate
Systematic relationships among six chromosomal races of Geomys bursarius on the Central Great Plains were assessed using morphometric and electrophoretic methods. Gross cranial morphology was inadequate as a discriminator among most races and separated populations into only two geographic subsets (larger eastern gophers and smaller western gophers). Multivariate statistics of cranial morphology were useful in separating chromosomal races into four geographic regions (Northern Great Plains, Southern Great Plains, Central Great Plains, and Central Lowlands). Based on 20 presumptive loci (9 monomorphic, 11 polymorphic), the pattern of genetic differentiation was similar to that suggested in the morphometric analyses. The mean within-race genetic identities (Nei’s identity values) for chromosomal races ranged from 0.899 to 0.971. Genetic similarity values indicated that race A. a reference sample of G. knoxjonesi, exhibited the greatest overall divergence form other chromosomal races. The average value of genetic similarity among races was 0.791 (0.705-0.910), excluding race A. Although some adjacent races appeared similar morphometrically, the relatively high levels of genetic divergence among them (at least one fixed difference) compared with high within-race similarity suggest that chromosomal races represent independently evolving gene pools. However, introgression between races occurs at zones of contact. Based on these data, chromosomal races are interpreted as consistent with at least seven previously named subspecies of Geomys bursarius.
Copyright 1989 Forrest Wayne Davis
Davis, Forrest Wayne, "Taxonomic Significance of Chromosomal Races of Geomys Bursarius on the Central Great Plains" (1989). Master's Theses. 2101.