Condition-dependent sex: who does it, when and why?

Abstract

One contribution of 15 to a theme issue 'Weird sex: the underappreciated diversity of sexual reproduction'. We review the phenomenon of condition-dependent sex-where individuals' condition affects the likelihood that they will reproduce sexually rather than asexually. In recent years, condition-dependent sex has been studied both theoretically and empirically. Empirical results in microbes, fungi and plants support the theoretical prediction that negative condition-dependent sex, in which individuals in poor condition are more likely to reproduce sexually, can be evolutionarily advantageous under a wide range of settings. Here, we review the evidence for condition-dependent sex and its potential implications for the long-term survival and adaptability of populations. We conclude by asking why condition-dependent sex is not more commonly observed, and by considering generalizations of condition-dependent sex that might apply even for obligate sexuals.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.

The evolutionary advantage of fitness‐dependent recombination in diploids: A deterministic mutation–selection balance model

“…Thus, the “recombination‐supporting potential” of FD recombination, first demonstrated by Gessler and Xu () for haploids, can be extended also to diploids. Notably, the same pattern was revealed for the rate of sex, which is also long known to exhibit fitness dependence (see for review: Ram & Hadany, ). Specifically, FD sex was shown to be favored over asexual reproduction even if any constant nonzero rate of sex was disfavored (Mostowy & Engelstädter, ).…”

Host-microbiome coevolution promotes cooperation in a rock-paper-scissor dynamic

“…Interesting host-microbes dynamics can arise when the cooperative behavior is applied only under certain circumstances, e.g. when the hosts are under stress, similarly to other stress-induced behaviors [72][73][74][75]. It would also be 15 interesting to examine the evolution of the rates of microbe horizontal and vertical transmission, in the context of microbe-induced cooperation.…”

The role of recombination in evolutionary adaptation of Escherichia coli to a novel nutrient

“…By changing allelic associations, recombination can aid selection, either helping to bring two beneficial alleles into the same genome (Hill & Robertson, 1966;Felsenstein, 1974), or removing deleterious alleles from an otherwise well-adapted genome (Muller, 1964). Conversely, recombination can also have detrimental effects on adaptive evolution, breaking apart beneficial allele combinations and thus reducing fitness (Agrawal et al, 2005;Ram & Hadany, 2016). Whether recombination has a net beneficial or detrimental effect depends on many genetic factors, including epistasis (Kouyos et al, 2007), population size, mutation rate, recombination rate and environmental changes (Bretscher et al, 2004;Nagaraja et al, 2016;Whitlock et al, 2016).…”

“…Whether recombination has a net beneficial or detrimental effect depends on many genetic factors, including epistasis (Kouyos et al, 2007), population size, mutation rate, recombination rate and environmental changes (Bretscher et al, 2004;Nagaraja et al, 2016;Whitlock et al, 2016). Organisms may also modulate their recombination rate, increasing recombination in novel, stressful environments so as to bring together beneficial alleles, and decreasing it in well-adapted lineages to preserve combinations of beneficial alleles (Hadany & Beker, 2003;Agrawal et al, 2005;Griffiths & Bonser, 2013;Ram & Hadany, 2016). The contradictory predictions of theoretical studies about the benefits or detriments of recombination make it challenging to explain the high prevalence of sex and recombination in nature (Otto & Lenormand, 2002;Lehtonen et al, 2012;Baltrus, 2013).…”