Gene transfer between species during interspecific hybridization is a widely accepted reality in plants but is considered a relatively rare phenomenon among animals. Here we describe a unique case of mitochondrial DNA (mtDNA) paraphyly in the skipper genus, Erynnis, that involves well-diverged allopatric species. Using molecular evidence from both mitochondrial and nuclear genomes, we found high levels of intraspecific divergence in the mitochondrial genome within E. propertius (over 4% pair-wise sequence divergence) but no such differentiation in the nuclear genome. Sequence comparisons with related Erynnis suggest that past, but recent and infrequent introgression between E. propertius and E. horatius is the most reasonable explanation for the observed pattern of mtDNA paraphyly. This example of putative introgression highlights the complexity of mtDNA evolution and suggests that similar processes could be operating in other taxa that have not been extensively sampled. Our observations reinforce the importance of involving multiple genes with different modes of inheritance in the analysis of population history of congeneric taxa.
Bibliographical noteFunding Information:
We thank Arthur M Shapiro (University of California Davis), Cheryl B Barr (Essig Museum of Entomology, University of California Berkeley) and Michael A Wall (San Diego Natural History Museum) for invaluable help with specimen procurement and/or specimen loans and donations; and Jason Dzurisin and Christian Brown for help at the lab bench. We also thank four anonymous reviewers whose comments and suggestions significantly improved the paper. This research was supported by the Office of Science (BER), US Department of Energy, grant nos. DE-FG02-05ER 64023 and DE-FG02-06ER64263, and by the California Energy Commission, CIEE award no. MEX-06-04 to JJH.
- Allopatric distribution
- Erynnis horatius
- Erynnis propertius
- Organelle capture