– We evaluate the putative introduction of the yellowfin shiner, Notropis lutipinnis, in the Little Tennessee river basin. This species has only been noted in the Little Tennessee in the past several decades and appears to be expanding its range, even though there have been many potential historical pathways for dispersal from native drainages in Georgia, South Carolina, and North Carolina. We use a phylogeographic approach, examining sequence data from one mitochondrial and one nuclear locus, to determine the likely source of the population in the Little Tennessee. Our results suggest a complex history and cannot reject the possibility that N. lutipinnis is native to the Little Tennessee. Our data also indicate that particular drainages, including populations in the Altamaha and Flint Rivers, may be subject to local adaptation at the nuclear transferrin locus.
Seaside Sparrows (Ammodramus maritimus) along the Gulf of Mexico are currently recognized as four subspecies, including taxa in Florida (A. m. juncicola and A. m. peninsulae) and southern Texas (Ammodramus m. sennetti), plus a widespread taxon between them (A. m. fisheri). We examined population genetic structure of this “Gulf Coast” clade using microsatellite and mtDNA data. Results of Bayesian analyses (Structure, GeneLand) of microsatellite data from nine locations do not entirely align with current subspecific taxonomy. Ammodramus m. sennetti from southern Texas is significantly differentiated from all other populations, but we found evidence of an admixture zone with A. m. fisheri near Corpus Christi. The two subspecies along the northern Gulf Coast of Florida are significantly differentiated from both A. m. sennetti and A. m. fisheri, but are not distinct from each other. We found a weak signal of isolation by distance within A. m. fisheri, indicating this population is not entirely panmictic throughout its range. Although continued conservation concern is warranted for all populations along the Gulf Coast, A. m. fisheri appears to be more secure than the far smaller populations in south Texas and the northern Florida Gulf Coast. In particular, the most genetically distinct populations, those in Texas south of Corpus Christi, occupy unique habitats within a very small geographic range.
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