Molecular, morphological, and biogeographic resolution of cryptic taxa in the Greenside Darter Etheostoma blennioidescomplex
DNA sequencing has led to the resolution of many cryptic taxa, which are especially prevalent in the North American darter fishes (Family Percidae). The Greenside Darter Etheostoma blennioidescommonly occurs in the lower Great Lakes region, where two putative subspecies, the eastern “Allegheny” type E. b. blennioidesand the western “Prairie” type E. b. pholidotum, overlap. The objective of this study was to test the systematic identity and genetic divergence distinguishing the two subspecies in areas of sympatry and allopatry in comparison to other subspecies and close relatives. DNA sequences from the mtDNA cytochrome bgene and control region and the nuclear S7 intron 1 comprising a total of 1,497 bp were compared from 294 individuals across 18 locations, including the Lake Erie basin and the Allegheny, Meramec, Obey, Ohio, Rockcastle, Susquehanna, and Wabash River systems. Results showed pronounced divergences among taxa ( ? ST= 0.92 – 0.97; p-distance = 0.025 – 0.039) presently designated as E. b. blennioides, E. b. newmanii, and E. b. pholidotum, as well as identification of a fourth clade in the Meramec River. Most traditional morphological characters were significantly different ( P= 0.0001) in distinguishing between E. b. blennioidesand E. b. pholidotum, including scale counts and degree of ventral squamation. However, the range of variation within these characters overlapped, obscuring accurate assignment of individuals to the taxa. The four significantly divergent taxa of the Greenside Darter complex should be evaluated further for potential elevation to species status.
School:University of Toledo
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:biogeography control region cryptic species cytochrome b etheostoma blennioides pholidotum greenside darter nuclear s7 intron 1
Date of Publication:01/01/2007