Selfish Genes and Plant Speciation

Abstract

A key to understand the process of speciation is to uncover the genetic basis of hybrid incompatibilities. Selfish genetic elements (SGEs), DNA sequences that can spread in a population despite being associated with a fitness cost to the individual organism, make up the largest component in many plant genomes, but their role in the genetics of speciation has long been controversial. However, the realization that many organisms have evolved a variety of suppressor mechanisms that reduce the deleterious effects of SGEs has spurred renewed interest in their importance for speciation. The relationship between SGEs and their suppressors often results in strong selection on at least two interacting loci and this arms race therefore creates a situation where SGEs may give rise to hybrid dysgenesis due to Bateson–Dobzhansky–Muller incompatibilities (BDMIs). Here, I argue that examples of SGEs underlying BDMIs may be particularly common among plants compared to other taxa and that a focus on loci involved in genetic conflicts may be especially useful for workers interested in the genetics of plant speciation. I first discuss why the frequent mating system shifts and hybridization events in plants make for a specifically dynamic relationship between SGEs and plant host genomes. I then review some recent empirical observations consistent with SGE-induced speciation in plants. Lastly, I suggest some future directions to test fully the utility of this perspective.