A molecular reevaluation of Bewick's wren (Thryomanes bewickii) subspecies of New Mexico, Oklahoma, and Texas



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Modern advancements in sequencing technology now allow for fine scale analyses of genetically distinct populations to test subspecific boundaries at a genetic level. Despite these advances, many avian subspecies have not undergone reevaluation since their morphologically-based designation decades ago. The Bewick's wren (Thryomanes bewickii) is a small wren species in North America currently subdivided into 15 recognized subspecies. These designations have been questioned because some specimens used in the original designations suffered from foxing or were soiled skins, necessitating reassessment. Of the described subspecies, four occur across Texas, Oklahoma, and eastern New Mexico (T. b. pulichi, T. b. cryptus, T. b. eremophilus, and T. b. sadai). Population structure among these subspecies was tested using a combination of molecular methods; screening genomic DNA for single nucleotide polymorphisms, and sequencing of the ND2 mitochondrial gene. Across New Mexico, Oklahoma, and Texas 68 individuals were captured and sampled. Analysis of population structure using the program STRUCTURE found the populations of Bewick's wrens within the study area to be a panmictic population with little genetic structuring. Construction of a haplotype network generated based on the ND2 gene suggested two distinct clusters across the study area with all birds in Oklahoma, Texas, and eastern New Mexico clustering together and birds in New Mexico west of the Rio Grande representing a second cluster.