There Goes the Neighborhood: Complex Interactions Between Squirrels, Crossbills and Conifers

有人认为，群落中物种之间相互作用的复杂性限制了成对共同进化的潜力。然而，很少有研究测试了其他物种的相互作用如何影响特定物种对之间的共同进化的特定假设。红松鼠和红十字雀争夺松树种子。研究者将通过检查黑松的种子和球果形态特征来测试红松鼠是否阻碍了红十字杉和松树之间的共同进化相互作用，在其中一个或两个竞争者存在（或不存在）的情况下。这项研究将通过确定间接相互作用的进化意义来扩展复杂物种相互作用的研究。其次，它将区分为什么成对共同进化可能不常见的几种潜在解释。第三，它将区分不同的共同进化假说。本研究将有助于了解不同种子捕食者对重要商业松物种黑松地理变异的影响，并有助于阐明不同种子捕食者对松树进化和多样性的重要性。其次，它将为理解为什么群落中物种的缺失会导致这些群落中剩余物种的快速进化变化提供基础。这意味着，引进以前不存在的物种可能导致引进物种的增加，以至于它们成为害虫，可能导致当地独特物种的灭绝，并可能导致以前独特群落的同质化。

It has been argued that the complexity of interactions among species in communities limits the potential for pair-wise coevolution. There are, however, few studies that have tested specific hypotheses of how other species' interactions influence coevolution between particular species pairs. Red squirrels and red crossbills compete for pine seeds. The investigator will test whether the red squirrels impede the coevolutionary interaction between red crossbills and pines by examining characteristics of seed and cone morphology of lodgepole pine where one or both competitors are present (or absent). This research will extend studies of complex species interactions by determining the evolutionary significance of indirect interactions. Second, it will distinguish among several potential explanations for why pair-wise coevolution may be uncommon. Third, it will distinguish between alternative hypotheses of coevolution. This study will provide an understanding of the impact of various seed predators on geographic variation in an important commercial pine species, lodgepole pine, and will help elucidate the importance of different seed predators on pine evolution and diversity. Second, it will provide the basis for understanding why the absence of species from communities can lead to rapid evolutionary change in the remaining species in these communities. The implications are that introductions of formerly absent species may result in increases of the introduced species to the point where they become pests, may lead to local extinctions of unique species, and may result in the homogenization of formerly unique communities.