Evolution of 12S rRNA gene in pocket gophers (Genus: Geomys)

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Title: Evolution of 12S rRNA gene in pocket gophers (Genus: Geomys)
Author: Jolley, Ted W.
Abstract: Pocket gophers are known for their fossorial lifestyle , small isolated populations , and low fecundity . These characteristics make pocket gophers an ideal group for examining rate heterogeneity and sequence divergence in light of recent hypotheses concerning metabolic -rate and body size . To test these hypotheses , the mitochondrial 12S ribosomal (rRNA ) gene was sequenced from individuals representing 10 species of the genus Geomys . In addition , specimens of Cratogeomys castanops . Thomomvs bottae . T^ umbrinus . Dipodomvs philHpsii . and Pedetes capensis were examined as outgroups . Specifically , the goals of this study were to : (1 ) determine if heterogeneity existed in rates of sequence divergence between fossorial and nonfossorial rodents , (2 ) determine intrageneric nucleotide sequence variation at the 12S rRNA gene , and (3 ) determine if the 12S rRNA gene contains phylogenetic signal to resolve the phylogenetic relationships within Geomys . The overall levels of 12S rRNA sequence divergence observed (average 3 .5 , range 0 .6 -7 .5 ) support a low level of divergence within Geomvs . with the overall transition /transversion ratio lower than that observed in other mammalian groups . Relative rate tests did not detect significant overall levels of rate heterogeneity within and among Geomvs and outgroup taxa , nontheless certain taxa did show rate heterogeneity when compared to other members within group . The resultant 12S rRNA gene phylogenies provided strong phylogenetic signal and consistently supported several relationships within species and subspecies of Geomvs .
URI: http : / /hdl .handle .net /2346 /22637
Date: 1997-12


Evolution of 12S rRNA gene in pocket gophers (Genus: Geomys). Master's thesis, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /22637 .

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