Neodiprion Rohwer (Hymenoptera: Diprionidae) is a Holarctic genus of conifer-feeding sawflies with a remarkable amount of inter- and intraspecific diversity in host use, behavior, and development. This variation is thought to play a central role in Neodiprion diversification, but speciation hypotheses remain untested due to a lack of a robust phylogenetic estimate. Here, we utilize sequence data from three nuclear genes (CAD, ANL43, EF1α) to obtain a phylogenetic estimate for the genus. These analyses suggest that: (1) North American and Eurasian Neodiprion are monophyletic sister clades, (2) the sertifer group is paraphyletic with respect to the monophyletic lecontei group, and (3) on at least two occasions, dispersal from eastern to western North America proceeded via southern host bridges. Based on these results and host biogeography, we revise a previous scenario for the evolution of Neodiprion and suggest maximum ages for the genus and for the lecontei group (25 My and 14 My, respectively). In addition, because a previous study reported rampant mitochondrial introgression in the lecontei group, we assess its prevalence in the sertifer group. Analysis of three mitochondrial genes (COI, tRNA-leucine, and COII) reveals that mito-nuclear discordance is prevalent in the sertifer group, and patterns of species monophyly are consistent with those expected under frequent mitochondrial introgression. As was the case for lecontei group species, we find that introgression appears to be most pronounced between species that occasionally share hosts, suggesting that divergent host use is an important barrier to gene flow in Neodiprion. Finally, we suggest that the lack of phylogenetic resolution and prevalence of species non-monophyly in the non-Pinus feeding Neodiprion may result from the rapid divergence (possibly with gene flow) of these species following their entry into a novel adaptive zone.
|Number of pages||18|
|Journal||Molecular Phylogenetics and Evolution|
|State||Published - Jul 2008|
Bibliographical noteFunding Information:
We are grateful to the following individuals for providing specimens included in this study: B. Fitzgibbon, R. Garbutt, J. Hodge, W. Ingram, S. Li, K. Nystrom, J. Rousselet, G. Sanchez-Martinez, S. Munson, L. Pederson, D. Schultz, M. Schultz, G. Turston, D. Whittwer, and E. Wittenmuth. We also thank the following individuals for advice, logistical support, or assistance in the field: C. Asaro, M. Breon, S. Codella, D. Conser, E. Czerwinski, A. Eglitis, W. Ingram, M. Linnen, A. Lynch, B. Mayfield, K. Raffa, D. Smith, L. Thompson, T. Tigner, M. Wagner, and many kind foresters and entomologists. We would especially like to thank D. Smith for his assistance with identifications. In addition, A. Thornton provided lab assistance, and B. Jennings provided advice and assistance during the development of the anonymous nuclear locus. We also thank two anonymous reviewers for their constructive comments and suggestions. Funding for this research was provided by a Graduate Research Fellowship and a Dissertation Improvement Grant (DEB-0308815) from the National Science Foundation, a Science to Achieve Results Graduate Fellowship from the Environmental Protection Agency, the Putnam Expeditionary Fund at the Museum of Comparative Zoology, the Theodore Roosevelt Memorial Fund at the American Museum of Natural History, and the Department of Organismic and Evolutionary Biology at Harvard University.
- Conifer sawflies
- Host use
- Hypothesis testing
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Molecular Biology