Evol Ecol Res 10: 475-492 (2008) Full PDF if your library subscribes.
A mitochondrial DNA analysis of vicariant speciation in two lineages in the Drosophila mulleri subgroup
Andrew T. Beckenbach,1* William B. Heed2† and William J. Etges 3
1Department of Biological Sciences, Simon Fraser University, Burnaby, BC V5A 1S6, Canada, 2Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA and 3Program in Ecology and Evolutionary Biology, Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701, USA
Author to whom all correspondence should be addressed.
Hypothesis: Biogeography and patterns of host cactus use in two ancestral-derived species pairs of cactophilic Drosophila suggest that recent divergence and speciation in both lineages were triggered by the same ecological/geological event in North America, the northward spread of the Sonoran Desert, isolating western coastal populations from the main distribution of each ancestral species.
Organisms: Two pairs of species in the Drosophila repleta species group: D. aldrichi and D. wheeleri of the D. mulleri cluster, and D. longicornis and D. mainlandi of the D. longicornis cluster.
Analytical methods: We analysed sequences of the mitochondrial cytochrome oxidase subunit II (cox2) and NADH dehydrogenase subunit 3 (nad3) from both species pairs, as well as members of relevant outgroups, to determine whether molecular evidence is consistent with concurrent speciation in both lineages. Based on long-term collecting records, we documented patterns of host cactus use throughout the ranges of all four species.
Results: Pairwise sequence comparisons between members of each species pair showed ∼ 1% sequence difference. This difference was no greater than pairwise intraspecific comparisons within D. aldrichi consistent with recent evidence that D. aldrichi may be composed of more than one species. The interspecific differences we observed could also represent ancient polymorphisms, rather than species-specific divergences. We estimated an upper limit on the time of divergence by constructing a linearized tree based on transversion substitutions for nine species in the D. repleta species group. The results suggest that these species pairs arose no more than 0.2 million years ago, and may be much more recent.
Keywords: cactus, Drosophila mulleri subgroup, Drosophila repleta group, mtDNA, Sonoran Desert, speciation.
DOWNLOAD A FREE, FULL PDF COPY
IF you are connected using the IP of a subscribing institution (library, laboratory, etc.)
or through its VPN.
© 2008 Andrew T. Beckenbach. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.
Subscribing institutions/libraries may grant individuals the privilege of making a single copy of an EER article for non-commercial educational or non-commercial research purposes. Subscribing institutions/libraries may also use articles for non-commercial educational purposes by making any number of copies for course packs or course reserve collections. Subscribing institutions/libraries may also loan single copies of articles to non-commercial libraries for educational purposes.
All copies of abstracts and articles must preserve their copyright notice without modification.