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The Southwestern Historical Quarterly, Volume 79, July 1975 - April, 1976 (open access)

The Southwestern Historical Quarterly, Volume 79, July 1975 - April, 1976

The Texas State Historical Association Quarterly Report includes "Papers read at the meetings of the Association, and such other contributions as may be accepted by the Committee" (volume 1, number 1). These include historical sketches, biographical material, personal accounts, and other research. Index is located at the end of the volume starting on page 493.
Date: 1975/1976
Creator: Texas State Historical Association
Object Type: Journal/Magazine/Newsletter
System: The Portal to Texas History
Genic Differentiation and Evolution in the Ground Squirrel Subgenus Ictidomys (Spermophilus) (open access)

Genic Differentiation and Evolution in the Ground Squirrel Subgenus Ictidomys (Spermophilus)

The genetic structure of 26 natural populations of three species (S. tridecemlineatus, S. mexicanus, and S. spilosoma) of the Ictidomys subgenus of ground squirrels was analyzed using chromosomal and electrophoretic techniques. Chromosomal variation was not observed in S. mexicanus, and only slight karyotypic variation was found in the other two species. Chromosomal evidence indicated hybridization between S. tridecemlineatus and S. mexicanus, placing these species within the classical definition of semispecies. Analysis of electrophoretic variation at 29 genetic loci indicated close genetic relationships between these species. Evolution in Ictidomys appears to be linked with Pleistocene events, and speciation appears to have occurred within the last 155,000 years.
Date: December 1975
Creator: Cothran, E. Gus, 1951-
Object Type: Thesis or Dissertation
System: The UNT Digital Library