Genome-wide admixture and ecological niche modelling reveal the maintenance of species boundaries despite long history of interspecific gene flow

Amanda R. De La Torre, David R. Roberts, Sally N. Aitken

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

The maintenance of species boundaries despite interspecific gene flow has been a continuous source of interest in evolutionary biology. Many hybridizing species have porous genomes with regions impermeable to introgression, conferring reproductive barriers between species. We used ecological niche modelling to study the glacial and postglacial recolonization patterns between the widely hybridizing spruce species Picea glauca and P. engelmannii in western North America. Genome-wide estimates of admixture based on a panel of 311 candidate gene single nucleotide polymorphisms (SNP) from 290 genes were used to assess levels of admixture and introgression and to identify loci putatively involved in adaptive differences or reproductive barriers between species. Our palaeoclimatic modelling suggests that these two closely related species have a long history of hybridization and introgression, dating to at least 21 000 years ago, yet species integrity is maintained by a combination of strong environmental selection and reduced current interspecific gene flow. Twenty loci showed evidence of divergent selection, including six loci that were both Fst outliers and associated with climatic gradients, and fourteen loci that were either outliers or showed associations with climate. These included genes responsible for carbohydrate metabolism, signal transduction and transcription factors.

Original languageEnglish (US)
Pages (from-to)2046-2059
Number of pages14
JournalMolecular ecology
Volume23
Issue number8
DOIs
StatePublished - 2014
Externally publishedYes

Keywords

  • admixture
  • ecological niche modelling
  • outlier loci
  • spruce

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics

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