Data from: Rio Grande sucker Pantosteus plebeius is native to the Gila River Basin

In the late 1940s, Rio Grande Sucker Pantosteus plebeius was reported in
tributaries of the Gila River in the Colorado Basin and presumed to be
introduced because of its absence in mid-19th century surveys. We assayed
genetic variation at 10 microsatellite loci and two mtDNA genes (cyt b and
ND4) to test the hypothesis of human-mediated introduction into the Gila
within the last century. Phylogeographic analysis indicated that Gila
River populations shared recent common ancestry with populations in the
Mimbres River. Using approximate Bayesian computation (ABC), we rejected
the hypothesis that Rio Grande Sucker was introduced to the upper Gila
River within the last century. Rather, we hypothesize an older (~4000
years before present) headwater capture event that facilitated transfer of
fishes from the Mimbres to Sapillo Creek in the Gila Basin. From there,
suckers dispersed to the San Francisco River and became established in
upland stream habitats. Rio Grande Sucker exhibits low levels (<
10%) of introgression with Desert Sucker but maintains species cohesion in
the Gila Basin. We conclude that Rio Grande Sucker is native to the Gila
Basin, and that these populations harbor unique diversity that could play
an important role in species conservation. More generally, rigorous
testing for human mediated translocation is a difficult analytical
problem, but a definitive means to do so is essential to fully understand
the biogeography of freshwater fishes of the American Southwest.