Male relatedness and familiarity are required to modulate male-induced harm to females in Drosophila

Abstract

Males compete over mating and fertilization, and often harm females in the process. Inclusive fitness theory predicts that increasing relatedness within groups of males may relax competition and discourage male harm of females as males gain indirect benefits. Recent studies in Drosophila melanogaster are consistent with these predictions, and have found that within-group male relatedness increases female fitness, though others have found no effects. Importantly, these studies did not fully disentangle male genetic relatedness from larval familiarity, so the extent to which modulation of harm to females is explained by male familiarity remains unclear. Here we performed a fully factorial design, isolating the effects of male relatedness and larval familiarity on female harm. While we found no differences in male courtship or aggression, there was a significant interaction between male genetic relatedness and familiarity on female reproduction and survival. Relatedness among males increased female lifespan, reproductive lifespan and overall reproductive success, but only when males were familiar. By showing that both male relatedness and larval familiarity are required to modulate female harm, these findings reconcile previous studies, shedding light on the potential role of indirect fitness effects on sexual conflict and the mechanisms underpinning kin recognition in fly populations.

The “unguarded-X” and the genetic architecture of lifespan: Inbreeding results in a potentially maladaptive sex-specific reduction of female lifespan inDrosophila melanogaster

“…S1C). This trend fits well with recent studies reporting relatedness effects on reproductive cooperation in male Drosophila melanogaster (Carazo et al 2014;Le Page et al 2017), but it may have partially driven the sex-specific effect reported above. To provide a more robust test of the idea that inbreeding may result in a greater reduction in female than in male lifespan per se, and not due to indirect male-specific effects in the mixed sexes treatment, we ran a series of post hoc analyses.…”

“…; Le Page et al. ), but it may have partially driven the sex‐specific effect reported above. To provide a more robust test of the idea that inbreeding may result in a greater reduction in female than in male lifespan per se, and not due to indirect male‐specific effects in the mixed sexes treatment, we ran a series of post hoc analyses.…”

“…; Martin and Long ; Le Page et al. ; Lukasiewicz et al. ; Lymbery and Simmons ; but see Chippindale et al.…”

“…More surprising was our finding that, in the mixed sexes group, inbred males exhibited a trend to live longer than the other inbreeding treatments and inbreeding did not affect females as clearly as it did in other social environments. This may be due to the role of within-group relatedness in reducing male-male competition for females and/or female harm levels (Carazo et al 2014(Carazo et al , 2015Hollis et al 2015;Martin and Long 2015;Le Page et al 2017;Lukasiewicz et al 2017;Lymbery and Simmons 2017; but see Chippindale et al 2015), which at least in some cases leads to longer male lifespan (Carazo et al 2014). Similar effects on females, via reduced female harm, may explain why inbreeding affected female lifespan relatively less in the mixed than in the other social environments.…”

Kin recognition and co‐operative foraging inDrosophila melanogasterlarvae

“…Lizé, McKay, & Lewis, ; Carazo, Perry, Johnson, Pizzari, & Wigby, ; Le Page et al. but see Chippindale et al., ; Martin & Long, ). While larvae are able to recognize each other as conspecifics using vision, smell, mechanosensation and gustation ( reviewed in Dombrovski et al., ), to the best of our knowledge there has been no published evidence that larvae have the ability to distinguish kin from nonkin.…”