Miles D B, Sinervo B, Anthony Frankino W
Department of Biological Sciences, Ohio University, Athens 45701, USA.
Evolution. 2000 Aug;54(4):1386-95. doi: 10.1111/j.0014-3820.2000.tb00570.x.
A reduction in the locomotor capacity of gravid females is considered to be a cost of reproduction if it leads to an increased risk of mortality. In this study, we measured the change in endurance between gravid and postgravid female side-blotched lizards (Uta stansburiana) as a test of the cost of reproduction. We also altered reproductive investment in some females by direct ovarian manipulation (yolkectomy), which decreased reproductive burden by 30%. Regardless of experimental treatment, all females had lower endurance when gravid. Endurance was 28% lower in gravid females from the yolkectomy treatment and 31% lower in the unmanipulated females relative to postoviposition females. The experimental reduction in clutch mass resulted in a 21% increase in endurance of gravid yolkectomy females relative to control females. Postovipositional endurance was significantly higher in the yolkectomized females than unmanipulated females, which suggests that the cost of reproduction carries over to postoviposition performance. Unmanipulated females exhibited a significant negative association between endurance and size-specific burden. Endurance was not correlated with clutch size or size-specific burden in the yolkectomy females. Survivorship to the second clutch was higher in the yolkectomy females. The results from a logistic regression showed the probability of survival to the second clutch was significantly and positively associated with endurance after controlling for the effects of treatment. Our analyses demonstrated that the decrement in performance associated with current reproductive investment represents a cost of reproduction expressed as diminished locomotor performance and lowered survivorship to the next clutch.
如果妊娠雌性的运动能力下降导致死亡风险增加，那么这被认为是繁殖的一种代价。在本研究中，我们测量了妊娠和产后雌性侧斑蜥蜴（Uta stansburiana）耐力的变化，以此作为对繁殖代价的一种测试。我们还通过直接的卵巢操作（切除卵黄）改变了一些雌性的生殖投入，这使生殖负担降低了30%。无论实验处理如何，所有雌性在妊娠时耐力都较低。与产后雌性相比，接受卵黄切除处理的妊娠雌性耐力低28%，未处理的雌性耐力低31%。实验性地减少窝卵数使妊娠卵黄切除雌性相对于对照雌性的耐力增加了21%。卵黄切除雌性的产后耐力显著高于未处理的雌性，这表明繁殖代价会延续到产后表现。未处理的雌性在耐力和特定大小的负担之间表现出显著的负相关。在卵黄切除雌性中，耐力与窝卵数或特定大小的负担无关。卵黄切除雌性到第二个繁殖周期的存活率更高。逻辑回归结果表明，在控制处理效应后，存活到第二个繁殖周期的概率与耐力显著正相关。我们的分析表明，与当前生殖投入相关的性能下降代表了繁殖的一种代价，表现为运动性能下降和到下一个繁殖周期的存活率降低。
