University of Kansas Publications
Museum of Natural History
Volume 9, No. 12, pp 363-384, 7 figs, in text, 1 table
February 21, 1958
Geographic Variation
in the Pocket Gopher, Thomomys bottae,
in Colorado
BY
PHILLIP M. YOUNGMAN
University of Kansas
Lawrence
1958
University of Kansas Publications,Museum of Natural History
Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
Robert W. Wilson
Volume 9, No. 12, pp. 363-384, 7 figs. in text, 1 table
Published February 21, 1958
University of Kansas
Lawrence, Kansas
PRINTED IN
THE STATE PRINTING PLANT
TOPEKA, KANSAS
1958
27-1765
Geographic Variationin the Pocket Gopher, Thomomys bottae,in Colorado
BY
PHILLIP M. YOUNGMAN
INTRODUCTION
Two species of pocket gophers of the genus Thomomys (Family Geomyidae)occur in Colorado, Thomomys bottae (see fig. 1) in the low valleys inthe south-central and southwestern parts of the state and Thomomystalpoides mainly in the mountains and high valleys.
Thomomys bottae occurs primarily in the Piñon-juniper,Ponderosa Pine, and Short Grass zones of Daubenmire (1943) but in somelocalities is found in the Douglas Fir Zone. Thomomys talpoidesoccupies primarily the Douglas Fir Zone and Engelmann Spruce-SubalpineSpruce Zone but is found also in the Piñon-juniper and ShortGrass zones in some localities.
The ranges of the two species do not overlap in the strict sense butinterdigitate in a parapatric type of distribution.
Two other pocket gophers, Geomys bursarius and Cratogeomyscastanops, also occur in Colorado—in the Upper Sonoran Life-Zone.Geomys bursarius occupies much of the Great Plains, whereasCratogeomys castanops is found only on the plains in the southeasternpart of the state.
The objectives of the study, reported on here, were to learn thegeographic distribution of Thomomys bottae in Colorado, to find meansfor recognizing the different subspecies, and to describe individual andgeographic variation.
I am indebted to Mr. Sydney Anderson and Professor E. Raymond Hall formany helpful suggestions and for their critical reading of themanuscript, to Dr. Richard S. Miller, who made the collection of many ofthe specimens possible, and to Dr. Richard M. Hansen for numeroussuggestions. I wish to express my appreciation also to the following forthe loan of specimens in their care: Alfred M. Bailey and A. A. Rogers,Colorado Museum of Natural History, Denver, Colorado; David H. Johnson,United States National Museum, Washington, D. C; Robert W. Lechleitner,Colorado State University, Fort Collins, Colorado; and Robert Z. Brown,Colorado College, Colorado Springs, Colorado.
METHODS
Adults of approximately equal age were compared in the study ofgeographic variation. Three criteria of adulthood are: (a) sutureobliterated between supraoccipital and exoccipital, (b) suture at leastpartly obliterated between basisphenoid and basioccipital, (c)supraorbital cres