Fish Ecology and Conservation Physiology Laboratory, Ottawa-Carleton Institute of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada.
Gen Comp Endocrinol. 2011 Jan 15;170(2):215-21. doi: 10.1016/j.ygcen.2010.11.004. Epub 2010 Nov 11.
We investigated whether circulating glucocorticoids and androgens are correlated with reproductive investment in smallmouth bass (Micropterus dolomieu), a teleost fish with sole paternal care. Circulating cortisol and androgens prior to and 25 min following a standardized 3 min emersion stressor were quantified for non-reproductive and parental fish across the parental care period. To experimentally investigate the influence of reproductive investment on endocrine parameters, we manipulated brood size (reduced, enlarged, sham-treated, or unmanipulated) 24h prior to sampling parental fish. We predicted that fish guarding offspring would exhibit increased androgens and baseline cortisol levels, and an attenuated cortisol response to the stressor when compared with non-reproductive individuals. We further predicted that these effects would scale with reproductive investment. As predicted, parental care-providing fish exhibited lower post-stress plasma cortisol concentrations than non-reproductive fish. This difference was strongest early during parental care. However, no differences in baseline or post-stress cortisol concentrations were detected among parents guarding offspring with varying brood sizes. There was, however, a trend for parental fish to exhibit an increased cortisol response following brood manipulation, regardless of the direction of change in brood size, a response that likely reflected disturbance. No differences were found in baseline cortisol concentrations. Circulating androgens were found to be highest during early parental care, and no differences were found among parents guarding manipulated broods. Collectively, these findings demonstrate that the endocrine stress response is affected by reproductive status, but the response in this model species does not appear to be scaled according to reproductive investment as predicted by life-history theory.
我们研究了循环中的糖皮质激素和雄激素是否与小口黑鲈（Micropterus dolomieu）的生殖投资有关，小口黑鲈是一种具有单一雄性亲代照顾的硬骨鱼。在亲代照顾期间，我们针对非繁殖和有亲代照顾的鱼，在经历了 3 分钟的标准浸水应激源之前和之后 25 分钟，量化了循环中的皮质醇和雄激素。为了实验性地研究生殖投资对内分泌参数的影响，我们在取样亲代鱼之前 24 小时操纵了产卵量（减少、增加、假处理或未处理）。我们预测，与非繁殖个体相比，照顾后代的鱼会表现出更高的雄激素和基础皮质醇水平，并且对压力源的皮质醇反应减弱。我们进一步预测，这些影响将与生殖投资成正比。正如所预测的那样，有亲代照顾的鱼表现出的应激后血浆皮质醇浓度低于非繁殖的鱼。这种差异在亲代照顾的早期最为强烈。然而，在具有不同产卵量的后代的亲鱼中，没有检测到基础或应激后皮质醇浓度的差异。然而，无论产卵量的变化方向如何，亲鱼表现出皮质醇反应增加的趋势，这种反应可能反映了干扰。在基础皮质醇浓度方面没有差异。循环中的雄激素在早期亲代照顾期间最高，在照顾操纵过产卵量的亲鱼中没有发现差异。总的来说，这些发现表明，内分泌应激反应受到生殖状态的影响，但在这个模式物种中，反应似乎没有按照生活史理论预测的那样根据生殖投资进行调整。
