Antagonistic pleiotropy may help population-level selection in maintaining genetic polymorphism for transmission rate in a model phytopathogenic fungus

Abstract

It has been shown theoretically that the conditions for the maintenance of polymorphism at pleiotropic loci with antagonistic effects on fitness components are rather restrictive. Here, we use a metapopulation model to investigate whether antagonistic pleiotropy could help maintain polymorphism involving common deleterious alleles in the phytopathogenic fungus Microbotryum violaceum. This fungus causes anther smut disease of the Caryophyllaceae. A previous model has shown that the sex-linked deleterious alleles can be maintained under a metapopulation structure, when intra-tetrad selfing (mating between products of the same meiosis) is high, due to founder effects and selection at the population level. Here, we add two types of pleiotropic advantages to the metapopulation model. A competitive advantage for strains carrying the sex-linked deleterious alleles did not facilitate their maintenance because competitive situations were too rare. In contrast, higher spore production did facilitate the maintenance of the deleterious alleles at low intra-tetrad mating rates and with a large advantage for spore production. These results show that antagonistic pleiotropy may promote the persistence of genetic variation, in combination with other selective forces. Heredity (2007) 98, 45-52.

Mating System of the Anther Smut Fungus Microbotryum violaceum : Selfing under Heterothallism

“…Haplo-lethal alleles could be maintained in this model only with intratetrad mating rates higher than 0.7, which is consistent with estimates between 0.43 and 0.71 based on experimental studies (41). If a spore production advantage of biased strains was added in the model, biased strains could be maintained even more easily in the metapopulation (99).…”

Multivariate selection under adverse genetic correlations: impacts of population sizes and selection strategies on gains and coancestry in forest tree breeding

“…In this circumstance, adversely correlated traits resulted in reduced genetic gain over generations; however, the reduction was mainly the result of selection inefficiency. This is in line with evolutionary theory that antagonistic pleiotropy preserves genetic variation, as in Rose's (1982) model of 'antagonistic pleiotropy' between fitness components, and also discussed by Barton and Turelli (1989), or shown experimentally in biological models (Pemberton et al 1991;Tellier et al 2007). However, as noted by Hedrick (1999), the conditions may be very specific to the sets of traits examined and the environmental context in which selection may be occurring.…”

Intragenomic conflict produces sex ratio dynamics that favor maternal sex ratio distorters

“…For example, some instances of apparent higher‐level selection can, in fact, be attributed to the accumulated action of individual selection if the pattern results from aggregate instances of differential productivity of individual organisms (Folse & Roughgarden, 2010). Claims of selection above the individual organism often focus on groups of individuals within a population; however, selection can favor entire populations that exhibit elevated productivity or survival (Tellier, Villareal, & Giraud, 2007). If groups display differential productivity irrespective of the success of their constituents, such as populations successfully colonizing daughter populations, higher‐level selection can be invoked (Damuth & Heisler, 1988; Okasha, 2006).…”

“…however, selection can favor entire populations that exhibit elevated productivity or survival (Tellier, Villareal, & Giraud, 2007). If groups display differential productivity irrespective of the success of their constituents, such as populations successfully colonizing daughter populations, higher-level selection can be invoked (Damuth & Heisler, 1988;Okasha, 2006).…”