The Status of Pseudemys Gorzugi (the Rio Grande River Cooter) in Texas Rivers




Bailey, Lindley Ann

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Many turtle species are threatened by changes to their habitats, introduced species, and exploitation for human uses including food, medicines, and pets. Pseudemys gorzugi, the Rio Grande River cooter, is listed as endangered in New Mexico. In order to determine if similar conservation measures are warranted in Texas and to establish successful management strategies, it is essential to have a basic understanding of the life history and population genetics parameters of this species. The goal of this research was to construct a profile of Pseudemys gorzugi that described the evolutionary and life history of the species including details about the population density, ecology, genetic structure, and any outside factors that may be negatively impacting the population. Extensive surveys of both the historical and current distribution of this species in Texas revealed a low population density and a paucity of juveniles in the population. An examination of basking habits revealed a late afternoon peak in basking activity of the Pseudemys gorzugi population monitored during the summer of 2004. Dietary fecal analysis showed that the majority of the diet was composed of macrophytic algae. Based on genetic analysis of the mitochondrial ND4 gene, Pseudemys gorzugi appears to be monophyletic within a limited taxonomic sampling of emydids. Genetic analyses of both the mitochondrial ND4 gene and five microsatellite DNA markers indicated the population is homogeneous throughout its range. In addition, research revealed evidence of multiple threats common to extinction events in chelonian populations, including habitat degradation, the introduction of fire ants, and over-collection for the pet trade. This research provides state management authorities with essential data to determine if additional conservation efforts are necessary to protect this unique west Texas species.



pseudemys, population genetics, endangered species, Texas


Bailey, L. A. (2005). The status of Pseudemys gorzugi (the Rio Grande River cooter) in Texas rivers (Unpublished thesis). Texas State University-San Marcos, San Marcos, Texas.


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