Intrapopulation genomics in a model mutualist: Population structure and candidate symbiosis genes under selection in Medicago truncatula

Michael A. Grillo, Stephane De Mita, Patricia V. Burke, Kathryn L.S. Solórzano-Lowell, Katy D. Heath

Research output: Contribution to journalArticle

Abstract

Bottom-up evolutionary approaches, including geographically explicit population genomic analyses, have the power to reveal the mechanistic basis of adaptation. Here, we conduct a population genomic analysis in the model legume, Medicago truncatula, to characterize population genetic structure and identify symbiosis-related genes showing evidence of spatially variable selection. Using RAD-seq, we generated over 26,000 SNPs from 191 accessions from within three regions of the native range in Europe. Results from STRUCTURE analysis identify five distinct genetic clusters with divisions that separate east and west regions in the Mediterranean basin. Much of the genetic variation is maintained within sampling sites, and there is evidence for isolation by distance. Extensive linkage disequilibrium was identified, particularly within populations. We conducted genetic outlier analysis with FST-based genome scans and a Bayesian modeling approach (PCAdapt). There were 70 core outlier loci shared between these distinct methods with one clear candidate symbiosis related gene, DMI1. This work sets that stage for functional experiments to determine the important phenotypes that selection has acted upon and complementary efforts in rhizobium populations.

Original languageEnglish (US)
Pages (from-to)2704-2717
Number of pages14
JournalEvolution
Volume70
Issue number12
DOIs
StatePublished - Dec 1 2016

Keywords

  • Coevolution
  • DMI1
  • legume-rhizobium, Medicago
  • mutualism
  • population genomics
  • population structure

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • Agricultural and Biological Sciences(all)

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