Present address: Department of Zoology, Oklahoma State University, 430 Life Sciences West, Stillwater, OK 74078, U.S.A.
History repeated: recent and historical mitochondrial introgression between the current darter Etheostoma uniporum and rainbow darter Etheostoma caeruleum (Teleostei: Percidae)
Article first published online: 31 JAN 2008
2008 The Fisheries Society of the British Isles
Journal of Fish Biology
Volume 72, Issue 2, pages 418–434, February 2008
How to Cite
Ray, J. M., Lang, N. J., Wood, R. M. and Mayden, R. L. (2008), History repeated: recent and historical mitochondrial introgression between the current darter Etheostoma uniporum and rainbow darter Etheostoma caeruleum (Teleostei: Percidae). Journal of Fish Biology, 72: 418–434. doi: 10.1111/j.1095-8649.2007.01732.x
- Issue published online: 31 JAN 2008
- Article first published online: 31 JAN 2008
- (Received 6 July 2007, Accepted 10 October 2007)
- mitochondrial DNA replacement;
Incongruence between recognized taxonomy and phylogenetic relationships between two species from a diverse clade (Percidae: Etheostomatinae) of stream fishes was found in a mitochondrial (mt) DNA gene tree. Two darters in subgenus Oligocephalus, Etheostoma uniporum current darter and Etheostoma caeruleum rainbow darter were sampled throughout their sympatric distribution in the Ozark Highlands of the central United States. Sequences from cytochrome (cyt) b and the first intron of the nuclear marker S7 were analysed separately using maximum parsimony and Bayesian methods. Cyt b recovered both species as polyphyletic; E. uniporum haplotypes were interspersed within E. caeruleum. However, both species were monophyletic and non-sister taxa based on S7. The cyt b gene tree pattern is caused by introgressive hybridization resulting in the mtDNA replacement of E. uniporum haplotypes by those of E. caeruleum. Some E. uniporum haplotypes are shared with geographically proximate E. caeruleum, and this is consistent with recent hybridization, while other E. uniporum haplotypes indicate historical sorting of introgressed lineages. The mechanism of introgression is likely asymmetric sneaking behaviour by male E. uniporum, a mating tactic observed in related species. MtDNA replacement may have occurred in E. uniporum due to drift fixation in a historically small female effective population. Additional evidence for darter hybridization will likely be discovered in future molecular genetic surveys of the nearly 200 species in eastern North America.