Svensson Erik I, Friberg Magne
Section for Animal Ecology, Ecology Building, Lund University, Lund, Sweden.
Am Nat. 2007 Jul;170(1):101-12. doi: 10.1086/518181. Epub 2007 May 21.
Although predation is thought to affect species divergence, the effects of predator-mediated natural selection on species divergence and in nonadaptive radiations have seldom been studied. Wing melanization in Calopteryx damselflies has important functions in sexual selection and interspecific interactions and in species recognition. The genus Calopteryx and other damselfly genera have also been put forward as examples of radiations driven by sexual selection. We show that avian predation strongly affects natural selection on wing morphology and male wing melanization in two congeneric and sympatric species of this genus (Calopteryx splendens and Calopteryx virgo). Predation risk was almost three times higher for C. virgo, which has an exaggerated degree of wing melanization, than it was for the less exaggerated, sympatric congener C. splendens. Selective predation on the exaggerated species C. virgo favored a reduction and redistribution of the wing melanin patch. There was evidence for nonlinear selection involving wing patch size, wing patch darkness, and wing length and width in C. splendens but weaker nonlinear selection on the same trait combinations in C. virgo. Selective predation could interfere with species divergence by sexual selection and may thus indirectly affect male interspecific interactions, reproductive isolation, and species coexistence in this genus.
虽然捕食被认为会影响物种分化，但捕食者介导的自然选择对物种分化以及非适应性辐射的影响却鲜有研究。豆娘（Calopteryx）翅膀的黑化在性选择、种间相互作用以及物种识别中具有重要作用。Calopteryx属以及其他豆娘属也被作为性选择驱动辐射的例子提出。我们发现，鸟类捕食对该属（华丽豆娘Calopteryx splendens和纯洁豆娘Calopteryx virgo）两个同属且同域分布的物种的翅膀形态和雄性翅膀黑化的自然选择有强烈影响。翅膀黑化程度较高的纯洁豆娘面临的捕食风险几乎是黑化程度较低的同域近缘种华丽豆娘的三倍。对黑化程度较高的纯洁豆娘的选择性捕食有利于翅膀黑色素斑块的减少和重新分布。有证据表明，华丽豆娘存在涉及翅膀斑块大小、翅膀斑块颜色深浅以及翅膀长宽的非线性选择，但纯洁豆娘对相同性状组合的非线性选择较弱。选择性捕食可能会干扰性选择导致的物种分化，从而可能间接影响该属中雄性种间相互作用、生殖隔离以及物种共存。
