Korol, A. B. | bioRxiv Science

bioRxiv2018

Desiccation-induced changes in recombination rate and interference in fruit flies: an evidence for fitness-dependent plasticity

Meiotic recombination is evolutionarily ambiguous, giving both benefits and costs to its bearers, with the resultant depending on a variety of conditions. The existing theoretical models explain why recombination does exist while the existence of its essential features remains underexplored. Here we test whether recombination plasticity and interference plasticity are fitness dependent. We compare effects of desiccation on recombination and interference in chromosome 3 in desiccation-sensitive and desiccation-tolerant Drosophila lines. We show that in desiccation-sensitive genotypes the treatment causes significant segment-specific increase in single- and double-crossover frequencies while in desiccation-tolerant genotypes changes are less pronounced, if seen at all. These results indicate that desiccation is a recombinogenic factor, and that desiccation-induced changes in both recombination and interference are fitness dependent, with a negative-feedback pattern implying the tendency of less fitted individuals to produce more variable progeny. Such dependence may play an important role in regulation of genetic variation in population experiencing environmental challenges.

genetics↗

bioRxiv2018

Fitness-dependent recombination can be evolutionarily advantageous in diploids: a deterministic mutation-selection balance model

Recombinations omnipresence in nature is one of the most intriguing problems in evolutionary biology. The question of why recombination exhibits certain general features is no less interesting than that of why it exists at all. One such feature is recombinations fitness dependence (FD). The so far developed population-genetics models have focused on the evolution of FD recombination mainly in haploids, although the empirical evidence for this phenomenon comes mostly from diploids. Using numerical analysis of modifier models for infinite panmictic populations, we show here that FD recombination can be evolutionarily advantageous in diploids subjected to purifying selection. This advantage is associated with benefits from the differential rate of disruption of lower- vs higher-fitness genotypes, that can be manifested in systems with at least three selected loci. We also show that in systems with linked modifier, an additional contribution to the evolutionary advantage of FD recombination may come from fitness-dependence of the intensity of modifier linkage to the selected system, although the contribution of the last effect vanishes with tighter linkage within the selected system. We also show that in systems with three selected loci, FD recombination may give rise to negative crossover interference, which may be beneficial by itself. Yet, the role of such FD-induced crossover interference in the evolutionary advantage of FD recombination is minor. Remarkably, FD recombination was often favored in situations where any constant non-zero recombination was rejected, implying a relaxation of the rather strict constraints on major parameters (e.g., selection intensity and epistasis) required for the evolutionary advantage of non-zero recombination formulated by classical models.

evolutionary biology↗