School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, USA.
PLoS One. 2013;8(2):e55900. doi: 10.1371/journal.pone.0055900. Epub 2013 Feb 7.
Field assessments were conducted to examine the interplay between host plant and predation in complex agricultural mosaic on pea aphid clover and alfalfa races. In one experiment, we examined the relative fitness on clover race (CR) and alfalfa race (AR) pea aphids on broad bean, red clover and alfalfa alone. But because clover is typically grown in a more complex agricultural mosaic with alfalfa and broad bean, a second experiment was conducted to assess the fitness consequences under predation in a more complex agricultural field setting that also included potential apparent competition with AR pea aphids. In a third experiment we tested for the effect of differential host race density on the fitness of the other host race mediated by a predator effect. CR pea aphids always had fitness losses when on broad bean (had lower fitness on broad bean relative to red clover) and fitness benefits when on red clover (higher fitness on red clover relative to broad bean), whether or not in apparent competition with alfalfa race aphids on bean and alfalfa. AR suffered fitness loss on both alfalfa and bean in apparent competition with CR on clover. Therefore we can conclude that the predation rate between host races was highly asymmetrical. The complexity of the agricultural mosaic thus can influence prey selection by predators on different host plants. These may have evolutionary consequences through context dependent fitness benefits on particular host plants.
我们进行了实地评估，以研究在豌豆蚜三叶草和紫花苜蓿品种的复杂农业镶嵌体中，宿主植物和捕食之间的相互作用。在一项实验中，我们研究了在蚕豆、红三叶草和紫花苜蓿上单种情况下，三叶草品种（CR）和紫花苜蓿品种（AR）豌豆蚜的相对适合度。但是，由于三叶草通常与紫花苜蓿和蚕豆一起种植在更复杂的农业镶嵌体中，因此进行了第二项实验，以评估在更复杂的农业田间环境中，在存在捕食的情况下，适应度的后果，该环境还包括与 AR 豌豆蚜的潜在明显竞争。在第三个实验中，我们测试了由于捕食者的影响，不同宿主品种密度对另一个宿主品种适应度的影响。当 CR 豌豆蚜在蚕豆上时，无论是否与豆类和紫花苜蓿上的 AR 豌豆蚜存在明显竞争，它们的适合度总是会降低（相对于红三叶草，在蚕豆上的适合度较低），而当它们在红三叶草上时，它们的适合度会增加（相对于蚕豆，在红三叶草上的适合度较高）。AR 在与 CR 在三叶草上的明显竞争中，在紫花苜蓿和蚕豆上都遭受了适应度损失。因此，我们可以得出结论，宿主品种之间的捕食率存在高度的不对称性。农业镶嵌体的复杂性因此可以影响捕食者对不同宿主植物的猎物选择。这些可能会通过在特定宿主植物上的依赖于上下文的适应度利益产生进化后果。
