Section of Animal Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden.
Evolution. 2009 Dec;63(12):3124-35. doi: 10.1111/j.1558-5646.2009.00782.x. Epub 2009 Jul 16.
In species with separate sexes, antagonistic selection on males and females (intralocus sexual conflict) can result in a gender load that can be resolved through the evolution of sexual dimorphism. We present data on intralocus sexual conflict over immune defense in a natural population of free-ranging lizards (Uta stansburiana) and discuss the resolution of this conflict. Intralocus sexual conflict arises from correlational selection between immune defense and orange throat coloration in these lizards. Males with orange throats and high antibody responses had enhanced survival, but the same trait combination reduced female fitness. This sexual antagonism persisted across the life cycle and was concordant between the juvenile and adult life stages. The opposing selective pressure on males and females is ameliorated by a negative intersexual genetic correlation (r(m,f)=-0.86) for immune defense. Throat coloration was also genetically correlated with immune defense, but the sign of this genetic correlation differed between the sexes. This resulted in sex-specific signaling of immunological condition. We also found evidence for a sex-specific maternal effect on sons with potential to additionally reduce the gender load. These results have implications for signaling evolution, genetic integration between adaptive traits, sex allocation, and mutual mate choice for indirect fitness benefits.
在具有性别分离的物种中,雄性和雌性之间的拮抗选择(种内性冲突)可能导致性别负担,可以通过性二态性的进化来解决。我们提供了关于自由放养蜥蜴(尤塔斯坦伯里亚纳)自然种群中免疫防御的种内性冲突的数据,并讨论了这一冲突的解决。在这些蜥蜴中,免疫防御和橙色喉咙颜色之间的相关选择导致了种内性冲突。具有橙色喉咙和高抗体反应的雄性具有更高的生存能力,但相同的特征组合降低了雌性的适应性。这种性拮抗作用贯穿整个生命周期,在幼体和成年阶段都一致。雄性和雌性之间的相反选择压力通过免疫防御的负两性间遗传相关性(r(m,f)=-0.86)得到缓解。喉咙颜色与免疫防御也存在遗传相关性,但这种遗传相关性在性别之间的符号不同。这导致了免疫状况的性别特异性信号。我们还发现了母亲对儿子的性别特异性母性效应的证据,这可能会进一步减轻性别负担。这些结果对信号进化、适应性特征之间的遗传整合、性分配以及间接适应利益的相互配偶选择具有重要意义。