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History, geography and host use shape genomewide patterns of genetic variation in the redheaded pine sawfly ( Neodiprion lecontei )
Author(s) -
Bagley Robin K.,
Sousa Vitor C.,
Niemiller Matthew L.,
Linnen Catherine R.
Publication year - 2017
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.13972
Subject(s) - biology , sawfly , biological dispersal , population , genetic divergence , host (biology) , evolutionary biology , ecology , range (aeronautics) , genetic diversity , genetic variation , isolation by distance , genetic structure , genetics , hymenoptera , materials science , demography , sociology , gene , composite material
Divergent host use has long been suspected to drive population differentiation and speciation in plant‐feeding insects. Evaluating the contribution of divergent host use to genetic differentiation can be difficult, however, as dispersal limitation and population structure may also influence patterns of genetic variation. In this study, we use double‐digest restriction‐associated DNA (dd RAD ) sequencing to test the hypothesis that divergent host use contributes to genetic differentiation among populations of the redheaded pine sawfly ( Neodiprion lecontei ), a widespread pest that uses multiple Pinus hosts throughout its range in eastern North America. Because this species has a broad range and specializes on host plants known to have migrated extensively during the Pleistocene, we first assess overall genetic structure using model‐based and model‐free clustering methods and identify three geographically distinct genetic clusters. Next, using a composite‐likelihood approach based on the site frequency spectrum and a novel strategy for maximizing the utility of linked RAD markers, we infer the population topology and date divergence to the Pleistocene. Based on existing knowledge of Pinus refugia, estimated demographic parameters and patterns of diversity among sawfly populations, we propose a Pleistocene divergence scenario for N. lecontei . Finally, using Mantel and partial Mantel tests, we identify a significant relationship between genetic distance and geography in all clusters, and between genetic distance and host use in two of three clusters. Overall, our results indicate that Pleistocene isolation, dispersal limitation and ecological divergence all contribute to genomewide differentiation in this species and support the hypothesis that host use is a common driver of population divergence in host‐specialized insects.