Data from: Immune activation generates corticosterone-mediated terminal reproductive investment in a wild bird

Despite classical expectations of a trade-off between immune activity and reproduction, an emergent view suggests that individuals experiencing activation of their immune system actually increase reproductive effort and allocation to offspring as a form of terminal investment in response to reduced survival probability. However, the components and mechanisms of increased parental investment following immunostimulation are currently unknown. We hypothesize that increased glucocorticoid production following immunostimulation modulates the increase in reproductive effort that constitutes terminal investment. We activated the immune system of breeding female house wrens (Troglodytes aedon) with an immunogen and cross-fostered the eggs that they subsequently produced to separate prenatal and postnatal components of maternal investment. Cross-fostering revealed an increase in both pre- and postnatal allocation from immunostimulated females, which was confirmed by quantification of egg constituents and maternal provisioning behavior. The increase in maternal provisioning was mediated, at least in part, by increased corticosterone in these females. Offspring immune responsiveness was also enhanced through transgenerational immune priming via the egg. Thus, our results indicate that maternal immunostimulation induces transgenerational effects on offspring through both pre- and postnatal parental effects and support an important role for corticosterone in mediating parental investment.尽管经典理论认为免疫活动与繁殖存在权衡，但新兴观点指出，当个体免疫系统被激活时，其反而会增加繁殖投入与后代资源分配，以此作为终端投资（terminal investment）策略以应对自身存活概率下降的情况。然而，当前学界对于免疫刺激后母体投资增加的具体组分与调控机制仍不明晰。我们提出假说：免疫刺激后糖皮质激素（glucocorticoid）分泌增多，可调控构成终端投资的繁殖投入提升过程。我们以免疫原激活繁殖期雌性家鹪鹩（Troglodytes aedon）的免疫系统，并对其后续所产的卵进行交叉抚育，以此分离母体投资的产前与产后组分。交叉抚育实验结果显示，免疫刺激雌性的产前与产后投入均有所提升，该结论通过卵内成分定量分析与母本育幼行为观测得到了验证。此类母本育幼投入的提升，至少部分由该个体体内皮质酮（corticosterone）水平升高所介导。通过卵质实现的跨代免疫致敏（transgenerational immune priming）还可提升后代的免疫应答能力。综上，本研究结果表明，母体免疫刺激可通过产前与产后母体效应对子代产生跨代影响，同时证实皮质酮在调控母体投资过程中发挥了重要作用。