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Phylogeographic insights on the evolutionary breakdown of heterostyly
Author(s) -
Zhou Wei,
Barrett Spencer C. H.,
Li HaiDong,
Wu ZhiKun,
Wang XinJia,
Wang Hong,
Li DeZhu
Publication year - 2017
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14453
Subject(s) - heterostyly , biology , selfing , evolutionary biology , population , outcrossing , phylogeography , balancing selection , population genetics , primula , genetic variation , genetics , pollen , botany , phylogenetics , pollination , gene , demography , sociology
Summary The breakdown of heterostyly to homostyly is a classic system for the investigation of evolutionary transitions from outcrossing to selfing. Loss of sexual polymorphism is characterized by changes to population morph structure and floral morphology. Here, we used molecular phylogeography to investigate the geographical context for the breakdown process in Primula chungensis , a species with distylous and homostylous populations. We genotyped plants from 20 populations throughout the entire range in south‐west China using the chloroplast intergenic spacer ( trn L‐ trn F), nuclear internal transcribed spacer ( ITS ) and 10 nuclear microsatellite loci, and determined the genetic relationships among populations and the variation in floral traits associated with homostyle evolution. The marker data identified two multi‐population lineages (Tibet and Sichuan) and one single‐population lineage (Yunnan), a pattern consistent with at least two independent origins of homostyly. Evidence from flower and pollen size variation is consistent with the hypothesis that transitions to selfing have arisen by the same genetic mechanism involving recombination and/or mutation at the distyly linkage group. Nevertheless, flowers of homostylous lineages have followed divergent evolutionary trajectories following their origin, resulting in populations with both approach and reverse herkogamy. Our study illustrates a rare example of the near‐complete replacement of sexual polymorphism by floral monomorphism in a heterostylous species.