Population genomic consequences of life-history and mating system adaptation to a geothermal soil mosaic in yellow monkeyflowers

Kory M. Kolis, Colette S. Berg, Thomas C. Nelson, Lila Fishman

Research output: Contribution to journalArticlepeer-review

Abstract

Local selection can promote phenotypic divergence despite gene flow across habitat mosaics, but adaptation itself may generate substantial barriers to genetic exchange. In plants, life-history, phenology, and mating system divergence have been proposed to promote genetic differentiation in sympatry. In this study, we investigate phenotypic and genetic variation in Mimulus guttatus (yellow monkeyflowers) across a geothermal soil mosaic in Yellowstone National Park (YNP). Plants from thermal annual and nonthermal perennial habitats were heritably differentiated for life-history and mating system traits, consistent with local adaptation to the ephemeral thermal-soil growing season. However, genome-wide genetic variation primarily clustered plants by geographic region, with little variation sorting by habitat. The one exception was an extreme thermal population also isolated by a 200 m geographical gap of no intermediate habitat. Individual inbreeding coefficients (FIS) were higher (and predicted by trait variation) in annual plants and annual pairs showed greater isolation by distance at local (<1 km) scales. Finally, YNP adaptation does not reuse a widespread inversion that underlies M. guttatus life-history ecotypes range-wide, suggesting a novel genetic mechanism. Overall, this work suggests that life-history and mating system adaptation strong enough to shape individual mating patterns does not necessarily generate incipient speciation without geographical barriers.

Original languageEnglish
Pages (from-to)765-781
Number of pages17
JournalEvolution
Volume76
Issue number4
DOIs
StatePublished - Apr 2022

Keywords

  • Edaphic adaptation, Erythranthe
  • population genetic structure
  • self-pollination
  • speciation

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