Divergent artificial selection for female reproductive investment has a sexually concordant effect on male reproductive success

Abstract

Depending on the genetic architecture of male and female fitness, sex‐specific selection can have negative, positive, or neutral consequences for the opposite sex. Theory predicts that conflict between male and female function may drive the breakdown of intrasexual genetic correlations, allowing sexual dimorphism in sexually antagonistic traits. Reproductive traits are the epitome of this, showing highly differentiated proximate functions between the sexes. Here we use divergent artificial selection lines for female reproductive investment to test how female‐specific selection on a sex‐limited trait affects male reproductive success in a precocial bird, the Japanese quail (Coturnix japonica). We demonstrate that selection for increased egg investment in females positively affects male reproductive success both in competitive and non‐competitive mating situations. This increased reproductive success was linked to a relatively larger left testis in males originating from lines selected for high female reproductive investment. Given that female quail have functional gonads only on their left side, this correlated response indicates that selection has acted on the shared developmental basis of male and female gonads. Our study thereby provides evidence for a positive genetic correlation between key reproductive traits in males and females despite a high degree of sexual dimorphism, and suggests that, in this system, selection on reproductive function is sexually concordant.

Selection for Divergent Reproductive Investment Affects Neuron Size and Foliation in the Cerebellum

“…Why we found a significant difference between the 2 selection lines in males is also unexpected, particularly when one considers that maternal egg investment was selected to create the divergent lines [Pick et al, 2016a]. However, previous work in this system demonstrated correlated responses of selection for female reproductive investment on male reproductive performance, as well as changes in testes morphology in males from the divergent lines [Pick et al, 2017]. Differences in Purkinje cell size and cerebellar folding in males could thus be a direct consequence of different reproductive strategies (i.e., plastic resource allocation) and/or reflect (sex-specific) genetic correlations between reproductive performance and cerebellar morphology.…”

“…In addition to differences in egg mass, the H-line females have larger reproductive organs than L-line females [Pick et al, 2016b] and H-line quail tend to be larger [Pick et al, 2016b, c] with higher offspring survivorship than L-line quail [Pick et al, 2016c]. Further, H-line males experience higher reproductive success than L-males, which is associated with higher testis asymmetry in H-line males [Pick et al, 2017].…”

Intergenerational Costs of Oxidative Stress: Reduced Fitness in Daughters of Mothers That Experienced High Levels of Oxidative Damage during Reproduction

“…when six months old; to the nearest 1g). We focused on daughters because males show a low variation in reproductive performance (Pick et al 2017).…”

Increased male-induced harm in response to female-limited selection: interactive effects between intra- and interlocus sexual conflict?

“…pleiotropic effects of loci linked to female reproductive function on IRSC). We have previously shown that female-limited selection on reproductive investment has correlated effects on male reproductive success, with males from lines selected for high female reproductive investment (H-line) siring more offspring than males from lines selected for low female reproductive investment (L-line) [ 21 ]. This pattern was observed in both a competitive mating situation (i.e.…”

“…including male–male competition and female mate choice) and a non-competitive mating situation (i.e. excluding male–male competition and female mate choice) [ 21 ], suggesting that the male reproductive advantage was ejaculate-mediated, rather than caused by increased dominance or attractiveness [ 21 ]. We predict that if increased female reproductive investment is genetically linked to increased male-induced harm (i.e.…”