Macrogeographic patterns of genetic differentiation in the pocket gopher Thomomys umbrinus

Publication Type:Journal Article
Year of Publication:1987
Authors:M. S. Hafner, Hafner, J. C., Patton, J. L., Smith, M. F.
Journal:Systematic Zoology
Volume:36
Issue:1
Pagination:18 - 34
Date Published:1987
Abstract:

Electromorphic and chromosomal variation is analyzed in 26 populations of Tho- momys umbrinus sampled from throughout the range of the species. Interpopulation levels of genic differentiation are extreme, generally exceeding values measured between conspecific populations of most animals or plants. Two principal groups of T. umbrinus are recognized based on chromosomal evidence, one with 2n = 76 chromosomes and the other with 2n = 78. Further, the 2n = 78 group (but not the 2n = 76 group) is bisected into geographic subgroups with respect to chromosome morphology and heterochromatin position. The kind and degree of chromosomal differentiation observed suggests that the three groups may be reproductively incompatible. Allozymic evidence corroborates the above groupings, and an analysis of patterns of allele sharing suggests the absence of gene flow among the groups. A cladistic analysis of electro- morphic data indicates that the two 2n = 78 groups may be independently derived from the 2n = 76 lineage. The combined evidence supports the hypothesis that T. umbrinus is actually a composite of at least three biological species and confirms the observation that speciation in the genus Thomomys is unrelated to the level of genic differentiation between populations. [Evolu- tionary genetics; geographic variation; evolutionary concordance; pocket gophers; cladistic anal- ysis; paraphyly; speciation.]

URL:http://www.jstor.org/stable/2413305?seq=1#page_scan_tab_contents
DOI:10.2307/2413305
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