Abstract

Increasing our understanding of how evolutionary processes drive the genomic landscape of variation is fundamental to a better understanding of the genomic consequences of speciation. However, genome-wide patterns of within- and between- species variation have not been fully investigated in most forest tree species despite their global ecological and economic importance. Here, we use whole-genome resequencing data from four Populus species spanning the speciation continuum to reconstruct their demographic histories and investigate patterns of diversity and divergence within and between species. Using Populus trichocarpa as an outgroup species, we further infer the genealogical relationships and estimate the extent of ancient introgression among the three aspen species (Populus tremula, Populus davidiana and Populus tremuloides) throughout the genome. Our results show substantial variation in these patterns along the genomes with this variation being strongly predicted by local recombination rates and the density of functional elements. This implies that the interaction between recurrent selection and intrinsic genomic features has dramatically sculpted the genomic landscape over long periods of time. In addition, our findings provide evidence that, apart from background selection, recent positive selection and long-term balancing selection have also been crucial components in shaping patterns of genome-wide variation during the speciation process.

Keywords

ancient introgression; incomplete lineage sorting; linked selection; phylogenetic relationship; Populus; recombination

Published in

Molecular Ecology
2020, Volume: 29, number: 6, pages: 1120-1136
Publisher: WILEY

SLU Authors

• Ingvarsson, Pär

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Ecology
Evolutionary Biology


Publication identifier

DOI: https://doi.org/10.1111/mec.15388

Permanent link to this page (URI)

https://res.slu.se/id/publ/105215