EXPERIMENTAL EVOLUTION OF FEMALE TRAITS UNDER DIFFERENT LEVELS OF INTERSEXUAL CONFLICT INDROSOPHILA MELANOGASTER

Abstract

A number of studies have documented the evolution of female resistance to mate-harm in response to the alteration of intersexual conflict in the populations. However, the life-history consequence of such evolution is still a subject of debate. In this study, we subjected replicate populations of Drosophila melanogaster to different levels of sexual conflict (generated by altering the operational sex ratio) for over 45 generations. Our results suggest that females from populations experiencing higher level of intersexual conflict evolved increased resistance to mate-harm, in terms of both longevity and progeny production. Females from the populations with low conflict were significantly heavier at eclosion and were more susceptible to mate-harm in terms of progeny production under continuous exposure to the males. However, these females produced more progeny upon single mating and had significantly higher longevity in absence of any male exposure-a potential evidence of trade-offs between resistancerelated traits and other life-history traits, such as fecundity and longevity. We also report tentative evidence, suggesting an increased male cost of interacting with more resistant females. K E Y W O R D S :Aging, Drosophila melanogaster, experimental evolution, intersexual conflict, longevity, resistance to mate-harm.

Receptive females mitigate costs of sexual conflict

“…The intensity of sexual conflict has also been manipulated by altering the adult sex ratio, under the assumption that sexual conflict should increase or decrease under male‐ or female‐biased sex ratios, respectively. Females that were allowed to evolve under female‐biased sex ratio conditions suffered larger costs from male exposure than did females that were allowed to evolve under male‐biased sex ratios in D. melanogaster (Wigby & Chapman, ; Nandy et al ., ) and the flour beetle Tribolium castaneum (Michalczyk et al ., ). These studies provide evidence that the ability of females to reduce male‐induced costs has evolved due to sexual conflict.…”

Reproductive Isolation through Experimental Manipulation of Sexually Antagonistic Coevolution in Drosophila melanogaster

“…This often leads to a scenario where adaptations benefitting one sex come at the expense of the other 3–5 , bringing about a coevolutionary chase typically called sexually antagonistic coevolution (SAC) 6 . According to verbal 7, 8 and formal 9, 10 arguments, SAC can lead to a perpetual arms race between males and females of the same species.…”

“…We used two sets of allopatric populations of Drosophila melanogaster –one set (of three populations) evolving under male biased (M) operational sex ratio and the other set (of three populations) evolving under female biased (F) operational sex ratio, demonstrating high and low levels of SAC respectively 4, 5 . We tested whether reproductive isolation between allopatric populations was more prominent, if not present only, in M as compared to F regime.…”

Sexual selection affects the evolution of contact pheromones in Drosophila melanogaster populations isolated by differential sexual conflict

“…5) could be a result of ancestry. However, since M, C and F populations were established using a large population size (N e (LH st ) ~ 2250, N e (MCF) ~ 450; (Nandy et al 2013b)), a founder effect during initial establishment is unlikely to affect the MCF populations. This is also confirmed in the linear mixed modelling analysis which shows effect of replicates on the cuticular lipid profile is negligible, if any in many cases (see Table 1).…”