Origin and diversification of Rio Grande Sucker, Pantosteus plebeius, in the Gila River Basin

Authors: Thomas F. Turner, Megan J. Osborne, Tyler J. Pilger, David L. Propst

Year: 2013 (xlv)

Abstract

Field collections in the 1940s and 1950s revealed that Rio Grande Sucker (RGS), a native of the Rio Grande and Guzman Basins, was present west of the Continental Divide in the Upper Gila River Basin. Ichthyologists working at the time suspected that RGS had been introduced there by humans after European settlement, probably in the 20th century. However, it is also possible that the species is native to the basin. We tested alternative hypotheses of recent introduction versus earlier (e.g., Pleistocene) colonization. Populations in Sapillo Creek, and San Francisco, Mimbres and Jemez Rivers in New Mexico were genotyped at 10 DNA microsatellite loci and two mitochondrial DNA loci (ND4 and cyt-b). Analyses of gene frequencies and gene genealogies indicated that RGS colonized Sapillo Creek from the Mimbres River probably via headwater stream capture in the late Pleistocene, and subsequently colonized the San Francisco River via dispersal. RGS populations in the Gila Basin exhibited low levels of introgression with Desert Sucker (P. clarkii). Overall, our analysis indicates that RGS should be considered native to the Gila River Basin, and managed accordingly.