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Population genetics of self-incompatibility in a clade of relict cliff-dwelling plant species

Silva, J.L.; Brennan, A.C.; Mejías, J.A.

Population genetics of self-incompatibility in a clade of relict cliff-dwelling plant species Thumbnail


J.L. Silva

J.A. Mejías


The mating systems of species in small or fragmented populations impact upon their persistence. Small self-incompatible (SI) populations risk losing S allele diversity, responsible for the SI response, by drift thereby limiting mate availability and leading to population decline or SI system breakdown. But populations of relict and/or endemic species have resisted these demographic conditions over long periods suggesting their mating systems have adapted. To address a lack of empirical data on this topic, we studied the SI systems of three relict cliff-dwelling species of Sonchus section Pustulati (Asteraceae): S. masguindalii, S. fragilis and S. pustulatus in the western Mediterranean region. We performed controlled pollinations within and between individuals to measure index of SI (ISI) expression and identify S alleles in multiple population samples. Sonchus masguindalii and S. pustulatus showed strong SI (ISI = 0.6-1.0) compared to S. fragilis (ISI = 0.1-0.7). Just five S alleles were estimated for Spanish S. pustulatus and a moderate 11-15 S alleles for Moroccan S. pustulatus and S. fragilis, respectively. The fact that autonomous fruit set was generally improved by active self-pollination in self-compatible S. fragilis suggests that individuals with weak SI can show a wide range of outcrossing levels dependent on the degree of self or outcross pollen that pollinators bear. We conclude that frequent S allele dominance interactions that mask the incompatibility interactions of recessive S alleles leading to higher mate availability and partial breakdown of SI leading to mixed mating, both contribute to reproductive resilience in this group.


Silva, J., Brennan, A., & Mejías, J. (2016). Population genetics of self-incompatibility in a clade of relict cliff-dwelling plant species. AoB PLANTS, 8, Article plw029.

Journal Article Type Article
Acceptance Date Apr 18, 2016
Online Publication Date May 6, 2016
Publication Date May 6, 2016
Deposit Date May 12, 2016
Publicly Available Date May 12, 2016
Journal AoB PLANTS
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 8
Article Number plw029


Published Journal Article (Advance online version) (1.5 Mb)

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Copyright Statement
Advance online version This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

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