Landwer Allan J
Department of Biology, The University of New Mexico, 87131, Albuquerque, NM, USA.
Oecologia. 1994 Dec;100(3):243-249. doi: 10.1007/BF00316951.
Life-history theory predicts that the allocation of energy to current reproduction is associated with a decrement in future fecundity, future survival, or both. I treated this notion as the "cost hypothesis", and tested the assumption that current reproduction exacts a "cost" in future survival and fecundity. Surgical manipulations of egg production were applied to natural populations of the tree lizard, Urosaurus ornatus, in south western New Mexico by yolkectomy surgery in two different years. I reduced the number of eggs produced in the first clutch during vitellogenesis by approximately 50% in yolkectomized females relative to controls. Subsequent survival, fecundity, and growth of females were followed for two or three years, depending on the cohort. Treated females in both cohorts showed significantly higher growth and survivorship throughout the experiment than in controls. After 2 years, yolkectomized females had grown an additional 2 mm (snout-vent length) compared to controls, enough for them to add on average an additional egg to their next clutch. This demonstrated a cost in terms of future fecundity through a reduction in growth and an increase in mortality in these lizards.
生活史理论预测，分配给当前繁殖的能量与未来繁殖力的下降、未来生存能力的下降或两者都有关。我将这一概念视为“成本假说”，并检验了当前繁殖在未来生存和繁殖力方面会产生“成本”这一假设。在新墨西哥州西南部，于两年中通过卵黄切除术对丽斑麻蜥（Urosaurus ornatus）的自然种群进行了产卵的手术操作。相对于对照组，我将进行卵黄切除的雌性蜥蜴在卵黄发生期第一个窝卵中产出的卵数减少了约50%。根据不同的队列，对雌性蜥蜴随后两到三年的生存、繁殖力和生长情况进行了跟踪。在整个实验过程中，两个队列中接受处理的雌性蜥蜴的生长和存活率均显著高于对照组。两年后，接受卵黄切除的雌性蜥蜴相比于对照组多生长了2毫米（吻肛长度），足以使它们在下一窝卵中平均多产一枚卵。这表明，这些蜥蜴在生长减少和死亡率增加方面付出了未来繁殖力的代价。
