Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, USA.
J Evol Biol. 2010 Oct;23(10):2104-2111. doi: 10.1111/j.1420-9101.2010.02070.x.
Animals vary greatly in their tendency to consume large meals. Yet, whether or how meal size influences fitness in wild populations is infrequently considered. Using a predator exclusion, mark-recapture experiment, we estimated selection on the amount of food accepted during an ad libitum feeding bout (hereafter termed 'satiation threshold') in the wolf spider Schizocosa ocreata. Individually marked, size-matched females of known satiation threshold were assigned to predator exclusion and predator inclusion treatments and tracked for a 40-day period. We also estimated the narrow-sense heritability of satiation threshold using dam-on-female-offspring regression. In the absence of predation, high satiation threshold was positively associated with larger and faster egg case production. However, these selective advantages were lost when predators were present. We estimated the heritability of satiation threshold to be 0.56. Taken together, our results suggest that satiation threshold can respond to selection and begets a life history trade-off in this system: high satiation threshold individuals tend to produce larger egg cases but also suffer increased susceptibility to predation.
动物在进食大餐的倾向方面存在很大差异。然而，食物摄入量是否以及如何影响野生种群的适应性却很少被考虑。本研究采用捕食者排除、标记-重捕实验，估计了在自由取食过程中接受食物量（以下称为“饱食阈值”）的选择压力，该研究以狼蛛 Schizocosa ocreata 为研究对象。我们将具有已知饱食阈值的个体标记、大小匹配的雌性狼蛛分配到捕食者排除和捕食者包含处理组，并进行了 40 天的跟踪。我们还使用母代-雌性-后代回归估计了饱食阈值的狭义遗传力。在没有捕食者的情况下，高饱食阈值与更大和更快的卵袋产生呈正相关。然而，当捕食者存在时，这些选择优势就消失了。我们估计饱食阈值的遗传力为 0.56。总的来说，我们的结果表明，饱食阈值可以对选择做出反应，并在这个系统中产生一个生活史权衡：高饱食阈值的个体往往产生更大的卵袋，但也更容易受到捕食的影响。
