HOW FLUCTUATING COMPETITION AND PHENOTYPIC PLASTICITY MEDIATE SPECIES DIVERGENCE
HOW FLUCTUATING COMPETITION AND PHENOTYPIC PLASTICITY MEDIATE SPECIES DIVERGENCE
复制标题
波动的竞争和表型可塑性如何调节物种分化
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
P. Murphy
中科院分区：
文献类型：
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作者：
D. Pfennig;P. Murphy
摘要将资源竞争与物种分化联系起来的因果证据很少。在这项研究中，我们结合实地观察和实验，询问是否性格位移的程度反映了两个密切相关的铲足蟾蜍（Spea bombifrons和S。multiplicata）。这两个物种的蝌蚪发展成一个小脑袋杂食性的变体，主要是在碎屑饲料，或大头食肉性变体，专门和其表型是由仙虾。以前，我们发现S。multiplicata是仙女虾的劣势竞争者，与S. bombifrons.比较了四个关键营养性状的差异。multiplicata在自然池塘中的频率S. bombifrons变化。我们发现S. multiplicata变得越来越像杂食动物的相对丰富的S。bombifrons增加。此外，在控制的实验室群体中，S。multiplicata变得越来越像杂食动物，S.当我们增加其他物种的相对丰度时，熊蜂变得越来越像食肉动物。表型可塑性有助于调解这种分歧：S。multiplicata变得越来越不可能吃虾和发展成为食肉动物在S。bombifrons，一种以虾为食的上级捕食者。然而，分歧也反映了渠道性状的差异：当在普通条件下饲养时，S。当纳塔尔池的海拔降低时，繁殖蝌蚪越来越不可能产生食肉动物。据推测，这种模式反映了对低海拔池塘中食肉动物的选择，因为S。随着海拔的降低，bombifrons变得越来越常见。局部遗传适应S.熊蜂的颗粒非常细，几公里外的种群之间的食肉动物产量存在差异。我们的研究结果表明，字符位移的程度可能反映了相互作用的物种之间的竞争强度，表型可塑性和精细尺度的遗传分化可以介导这种反应。此外，这些结果提供了因果关系的证据连接资源竞争物种分化。
Abstract Causal evidence linking resource competition to species divergence is scarce. In this study, we coupled field observations with experiments to ask if the degree of character displacement reflects the intensity of competition between two closely related spadefoot toads (Spea bombifrons and S. multiplicata). Tadpoles of both species develop into either a small-headed omnivorous morph, which feeds mostly on detritus, or a large-headed carnivorous morph, which specializes on and whose phenotype is induced by fairy shrimp. Previously, we found that S. multiplicata are inferior competitors for fairy shrimp and are less likely to develop into carnivores in sympatry with S. bombifrons. We compared four key trophic characters in S. multiplicata across natural ponds where the frequency of S. bombifrons varied. We found that S. multiplicata became increasingly more omnivore-like as the relative abundance of S. bombifrons increased. Moreover, in controlled laboratory populations, S. multiplicata became increasingly more omnivore-like and S. bombifrons became increasingly more carnivore-like as we increased the relative abundance of the other species. Phenotypic plasticity helped mediate this divergence: S. multiplicata became increasingly less likely to eat shrimp and develop into carnivores in the presence of S. bombifrons, a superior predator on shrimp. However, divergence also reflected differences in canalized traits: When reared under common conditions, S. multiplicata tadpoles became increasingly less likely to produce carnivores as their natal pond decreased in elevation. Presumably, this pattern reflected selection against carnivores in lower-elevation ponds, because S. bombifrons became increasingly more common with decreasing elevation. Local genetic adaptation to the presence of S. bombifrons was remarkably fine grained, with differences in carnivore production detected between populations a few kilometers apart. Our results suggest that the degree of character displacement potentially reflects the intensity of competition between interacting species and that both phenotypic plasticity and fine-scale genetic differentiation can mediate this response. Moreover, these results provide causal evidence linking resource competition to species divergence.