Changes in selection pressure can facilitate hybridization during biological invasion in a Cuban lizard

Dan G. Bock, Simon Baeckens, Jessica N. Pita-Aquino, Zachary A. Chejanovski, Sozos N. Michaelides, Pavitra Muralidhar, Oriol Lapiedra, Sungdae Park, Douglas B. Menke, Anthony J. Geneva, Jonathan B. Losos, Jason J. Kolbe

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Hybridization is among the evolutionary mechanisms most frequently hypothesized to drive the success of invasive species, in part because hybrids are common in invasive populations. One explanation for this pattern is that biological invasions coincide with a change in selection pressures that limit hybridization in the native range. To investigate this possibility, we studied the introduction of the brown anole (Anolis sagrei) in the southeastern United States. We find that native populations are highly genetically structured. In contrast, all invasive populations show evidence of hybridization among native-range lineages. Temporal sampling in the invasive range spanning 15 y showed that invasive genetic structure has stabilized, indicating that large-scale contemporary gene flow is limited among invasive populations and that hybrid ancestry is maintained. Additionally, our results are consistent with hybrid persistence in invasive populations resulting from changes in natural selection that occurred during invasion. Specifically, we identify a large-effect X chromosome locus associated with variation in limb length, a well-known adaptive trait in anoles, and show that this locus is often under selection in the native range, but rarely so in the invasive range. Moreover, we find that the effect size of alleles at this locus on limb length is much reduced in hybrids among divergent lineages, consistent with epistatic interactions. Thus, in the native range, epistasis manifested in hybrids can strengthen extrinsic postmating isolation. Together, our findings show how a change in natural selection can contribute to an increase in hybridization in invasive populations.

Original languageEnglish
Article numbere2108638118
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number42
StatePublished - Oct 19 2021


  • Anolis
  • Hybridization
  • Invasive species
  • Natural selection
  • Sex chromosome


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