Velando A, Beamonte-Barrientos R, Torres R
Departamento de Ecoloxía e Bioloxía Animal, Universidade de Vigo, Vigo, Spain.
J Evol Biol. 2014 Aug;27(8):1582-9. doi: 10.1111/jeb.12416. Epub 2014 May 20.
In many animal species, females select a mate on the basis of the expression of secondary sexual traits. A prevalent theory suggests that male ornaments are reliable indicators of immunocompetence, because the cost of immune function prevents cheating. However, sexual signalling is a component of male reproductive effort, and an immune challenge may also alter his perceived future prospects and hence signalling effort. In this study, blue-footed booby males (Sula nebouxii) were inoculated with a diphtheria-tetanus vaccine during courtship to investigate the consequences of mounting an immune response on signalling effort. We found that, after this immune challenge, on average, males increased their signalling effort but lost more body mass compared with control males. Importantly, vaccination affected the partner's reproductive decisions: compared with control females, females paired with vaccinated males laid eggs earlier and increased clutch volume in pairs that laid early. Overall, our results suggest that blue-footed booby males invest more in sexual signals when future breeding opportunities are at risk, eliciting a greater reproductive investment by their partners. Increased signalling effort by infected individuals may contrast the idea of sexual ornaments as signals of infection status.
在许多动物物种中，雌性会根据第二性征的表现来选择配偶。一个普遍的理论认为，雄性的装饰物是免疫能力的可靠指标，因为免疫功能的成本会阻止欺骗行为。然而，性信号是雄性繁殖努力的一个组成部分，免疫挑战也可能改变它对未来前景的认知，从而改变信号传递的努力程度。在这项研究中，对处于求偶期的蓝脚鲣鸟雄性个体接种白喉-破伤风疫苗，以研究产生免疫反应对信号传递努力程度的影响。我们发现，在这种免疫挑战之后，与对照雄性相比，雄性平均增加了信号传递的努力程度，但体重下降得更多。重要的是，接种疫苗影响了配偶的繁殖决策：与对照雌性相比，与接种疫苗的雄性配对的雌性产卵更早，并且在早期产卵的配对中增加了窝卵数。总体而言，我们的结果表明，当未来的繁殖机会面临风险时，蓝脚鲣鸟雄性会在性信号上投入更多，从而促使其配偶进行更大的繁殖投入。受感染个体信号传递努力程度的增加可能与性装饰物作为感染状态信号的观点相矛盾。
