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
This content will become publicly available on July 23, 2024
Multiple mechanisms contribute to isolation-by-environment in the redheaded pine sawfly, Neodiprion lecontei
Abstract Isolation by environment (IBE) is a population genomic pattern that arises when ecological barriers reduce gene flow between populations. Although current evidence suggests IBE is common in nature, few studies have evaluated the underlying mechanisms that generate IBE patterns. In this study, we evaluate five proposed mechanisms of IBE (natural selection against immigrants, sexual selection against immigrants, selection against hybrids, biased dispersal, environment-based phenological differences) that may give rise to host-associated differentiation within a sympatric population of the redheaded pine sawfly, Neodiprion lecontei, a species for which IBE has previously been detected. We first characterize the three pine species used by N. lecontei at the site, finding morphological and chemical differences among the hosts that could generate divergent selection on sawfly host-use traits. Next, using morphometrics and ddRAD sequencing, we detect modest phenotypic and genetic differentiation among sawflies originating from different pines that is consistent with recent, in situ divergence. Finally, via a series of laboratory assays – including assessments of larval performance on different hosts, adult mate and host preferences, hybrid fitness, and adult eclosion timing – we find evidence that multiple mechanisms contribute to IBE in N. lecontei. Overall, our results suggest IBE can emerge quickly, possibly due to multiple mechanisms acting in concert to reduce migration between different environments.
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- NSF-PAR ID:
- 10465114
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Evolution
- Volume:
- 77
- Issue:
- 10
- ISSN:
- 0014-3820
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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