Antagonistic pleiotropy can maintain fitness variation in annual plants

Abstract

Antagonistic pleiotropy (AP) is a genetic trade-off between different fitness components. In annual plants, a trade-off between days to flower (DTF) and reproductive capacity often determines how many individuals survive to flower in a short growing season, and also influences the seed set of survivors. We develop a model of viability and fecundity selection informed by many experiments on the yellow monkeyflower, Mimulus guttatus, but applicable to many annual species. A viability/fecundity trade-off maintains stable polymorphism under surprisingly general conditions. We also introduce both spatial heterogeneity and temporal stochasticity in environmental parameters. Neither is necessary for polymorphism, but spatial heterogeneity allows polymorphism while also generating the often observed non-negative correlations in fitness components.

Evolutionary rate variation among genes involved in galactomannan biosynthesis in Coffea canephora

“…Frequency of positive selection and selective constraints are most likely factors to account for evolutionary variation among gene copies in a metabolic pathway (Braverman, Hamilton, & Johnson, 2016;Gaut, Yang, Takuno, & Eguiarte, 2011;Yang et al, 2009). High ratio of synonymous (silent) to nonsynonymous (replacement) variation among and within gene copies observed in this study demonstrates a significant rate of evolutionary heterogeneity in GM pathway genes, which is consistent with high degree of endogenous heterogeneity reported in several cell wall storage polysaccharides (Gruppen, Kormelink, & Voragen, 1993;Toole et al, 2012).…”

“…In addition, previous studies reveal that high gene expression is correlated to their fitness and significant role in survival (Blanc & Wolfe, ; Popescu, Borza, Bielawski, & Lee, ). Fitness genes exhibit strong codon bias due to intense purifying selection for translation efficiency and their expression levels are usually higher (Blanc & Wolfe, ; Brown & Kelly, ; Lavin, Herendeen, & Wojciechowski, ). More recently, expression of core GM pathway genes, including Cc‐UG4E and Cc‐MGT , was reported to be positively correlated with the amount of stored cell wall storage polysaccharides (Joët et al, ).…”

Balancing selection via life-history trade-offs maintains an inversion polymorphism in a seaweed fly

“…Antagonistic pleiotropy has long been considered as a minor contributor to balancing selection because theoretical studies predicted it enables persistent polymorphism only for a limited range of parameters (20)(21)(22). Nevertheless, recent models suggest that the role of antagonistic pleiotropy has been underestimated (23)(24)(25)(26). Indeed, these new models show that several factors, realistic in natural populations, can promote polymorphism persistence.…”

“…when the level of dominance varies between fitness components (26,27)), sex-specific selection (i.e. selection strength on each fitness component differs between sexes (23)) and spatially and temporally varying selection (24,25).…”

“…Interestingly, horn size was also under sex-specific selection and involved traitspecific dominance, two factors predicted to contribute to the maintenance of genetic variation. Similarly, in the yellow monkeyflower (Mimulus guttatus) variability in flower size is related to antagonistic pleiotropy due to a trade-off between viability and fecundity, with the persistence of the polymorphism being further enhanced by spatial and temporal environmental heterogeneity (24,28,29). However, direct empirical evidence of antagonistic pleiotropy enabling long-term polymorphism remains scarce, in part because the different components of fitness are rarely estimated separately.…”