Active selection for large guppies, Poecilia reticulata, by the pike cichlid, Crenicichla saxatilis
Active selection for large guppies, Poecilia reticulata, by the pike cichlid, Crenicichla saxatilis
复制标题
DOI：
10.1111/j.0030-1299.2004.12938.x
复制
发表时间：
2004-06-01
期刊：
影响因子：
3.4
通讯作者：
Persson, A
中科院分区：
文献类型：
--
作者：
Johansson, J;Turesson, H;Persson, A
尺寸选择性捕食被认为是孔雀鱼生活史性状形成的重要进化动力之一。生活在环尾梭子鱼（Crenicichlasaxatilis）存在下的种群较小，成熟较早，将更多的能量分配给后代，并且比没有Crenicichla的地方的孔雀鱼获得更多和更小的年轻。我们调查如果Crenicichlasaxatilis是一个大小选择性的捕食者，如果选择性是一个积极的选择的结果，如果最佳的猎物大小可以解释根据最佳觅食模型。在单猎物实验中，我们量化了捕食者的前捕获成本（时间），捕获成功，和捕获后的成本（时间）为四个不同的猎物大小跨越10至40毫米的总长度。为了了解捕食者在选择时考虑了猎物循环的哪些组成部分，我们用6种不同的模型预测了猎物的价值和最佳猎物大小，这些模型包括一个或多个猎物循环组成部分。在这两种情况下，Crenicichlasaxatilis都积极地选择最大的孔雀鱼。三个猎物价值函数，包括处理时间（捕获后的成本）没有准确地预测猎物的选择。相反，考虑到捕获前成本（方法和攻击时间）的猎物价值函数能够正确地预测最大的孔雀鱼大小的选择，这表明捕获前的成本可能比捕获后的成本更重要的猎物选择在Crenicichlasaxatilis。这项研究证实，Crenicichlasaxatilis是一个大小选择性的捕食者选择大孔雀鱼，而早期的证据表明，选择性的大型猎物在Crenicichla慈鲷已经弱和模棱两可。我们的研究结果加强的可能性，大小选择性捕食是在生活史进化的孔雀鱼的机制。
Size-selective predation has been proposed to be one important evolutionary force shaping life-history traits in guppies (Poecilia reticulata). Populations living in the presence of the ring-tailed pike cichlid (Crenicichlasaxatilis) are smaller, mature earlier, allocate more energy to offspring and get more and smaller young than guppies in localities without Crenicichla. We investigated if Crenicichlasaxatilis is a size-selective predator, if the selectivity is a result of active choice and if the optimal prey size can be explained according to an optimal foraging model. In single-prey experiments we quantified the predators' pre-capture costs (time), capture success, and post-capture costs (time) for four different prey sizes spanning from 10 to 40 mm total length. To see which of the components of the prey cycle the predator takes into account for its choice, we then predicted prey values and optimal prey size with 6 different models that included one or more of the prey cycle components.In two multiple prey experiments, the cichlids were given the choice of the two and four different prey sizes simultaneously. Crenicichlasaxatilis actively selected the largest guppies in both cases. The three prey-value functions that included handling time (post-capture cost) did not accurately predict the prey choice. Instead the prey-value functions that took into account pre-capture cost (approach and attack time) were able to correctly predict the choice of the largest guppy size, suggesting that pre-capture costs may be more important than post-capture costs for prey choice in Crenicichlasaxatilis. The study confirms that Crenicichlasaxatilis is a size-selective predator selecting large guppies, while earlier evidence for selectivity for large prey in Crenicichla cichlids has been weak and equivocal. Our result strengthen the possibility that size-selective predation is a mechanism in life-history evolution in guppies.