Report
Population structure in the roundtail chub (Gila robusta complex) of the Gila River basin as determined by microsatellites
Abstract
Ten microsatellite loci were characterized for 33 populations from the Gila robusta complex of the lower Colorado River basin to quantify the distribution of genetic variation within and among samples of G. intermedia, G. nigra, and G. robusta. Different populations exhibited different levels of variation, with the headwater species intermedia tending to possess fewer alleles than the other two forms. Patterns of variation were consistent with significant structure that supported independent evolution of most samples; however, the mainstem species robusta exhibited smaller FSTs, indicating greater connectedness among regions relative to the other taxa. Assignment testing also indicated that individuals from most localities are distinct and populations are evolving independently, and hierarchical analysis indicated that geography plays an important role in patterns of distinctiveness. While these markers did not identify any species-specific variants they are generally consistent with continued recognition of each as a taxonomic entity. Placement of some populations seemed to conflict with morphological assignment, and these should be re-examined to insure proper identification. Likewise, variation is consistent with multiple hybrid origins of nigra, making it important that the potential influence of introgressive hybridization be considered as management plans are developed for conserving this complex. The significance of isolation and local processes in shaping each of these populations highlights the importance of maintaining each independently to preserve unique genetic variation and maximum evolutionary potential. As programs are initiated to replace extirpated populations or establish new ones, it is important that species and geography are considered when identifying sources for translocation.
Full Citation
Dowling, T.E., P.C. Marsh, C.D. Anderson, M.S. Rosenberg, and A.T. Kelsen (2008) Population structure in the roundtail chub (Gila robusta complex) of the Gila River basin as determined by microsatellites. Arizona Game and Fish Department: Phoenix, AZ.
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6 citations as of 2024-02-19