Ancestral variation and the potential for genetic accommodation in larval amphibians: implications for the evolution of novel feeding strategies
Ancestral variation and the potential for genetic accommodation in larval amphibians: implications for the evolution of novel feeding strategies
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DOI：
10.1111/j.1525-142x.2008.00240.x
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发表时间：
2008-05-01
影响因子：
2.9
通讯作者：
Nascone-Yoder, Nanette
中科院分区：
文献类型：
--
作者：
Ledon-Rettig, Cris C.;Pfennig, David W.;Nascone-Yoder, Nanette
很少有研究为表型可塑性在新性状进化中的作用提供经验证据。一种方法是测试祖先是否存在潜在的可塑性，这种可塑性可以通过衍生分类群的选择（通过“遗传适应”）而得到改善、增强或减弱，从而产生新的特征。在这里，我们评估了肠道可塑性是否先于并促进了一种新的进食策略在掌足蟾蜍蝌蚪中的进化。我们研究了两种衍生物种，即多重种（Spea multiplicata）和庞氏种（Sp. bombifrons），它们的蝌蚪也表达了一种新的短肠表型，以响应新的资源（anostracan虾）。与可塑性介导的性状进化的预期一致，我们发现虾诱导了一系列不是由碎屑产生的Scaphiopus表型。在物种中，这种可塑性是被抑制还是被夸大，取决于诱导的表型是否具有适应性。此外，与对虾对形态的影响相反，对虾诱导的功能可塑性很少或根本没有，这是通过肠道细胞增殖来评估的。然而，虾确实诱导了bomifrons的大量增殖，这种物种消耗最多的虾，并且最频繁地产生短肠表型。因此，如果Spea对一种新的饮食具有祖先形态可塑性，那么它们的虾诱导的短肠形态可能经历了随后的遗传调节，从而改善了其功能。因此，饮食诱导的表型可塑性可能先于甚至促进了新表型的进化。
Few studies provide empirical evidence for phenotypic plasticity's role in the evolution of novel traits. One way to do so is to test whether latent plasticity is present in an ancestor that can be refined, enhanced, or diminished by selection in derived taxa (through "genetic accommodation"), thereby producing novel traits. Here, we evaluated whether gut plasticity preceded and promoted the evolution of a novel feeding strategy in spadefoot toad tadpoles. We studied Scaphiopus couchii, whose tadpoles develop an elongate gut and consume only detritus, and two derived species, Spea multiplicata and Sp. bombifrons, whose tadpoles also express a novel, short-gut phenotype in response to a novel resource (anostracan shrimp). Consistent with the expectations of plasticity-mediated trait evolution, we found that shrimp induced a range of phenotypes in Scaphiopus that were not produced with detritus. This plasticity was either suppressed or exaggerated in Spea depending on whether the induced phenotypes were adaptive. Moreover, in contrast to its effects on morphology, shrimp induced little or no functional plasticity, as assessed by gut cell proliferation, in Scaphiopus. Shrimp did, however, induce substantial proliferation in Sp. bombifrons, the species that consumes the most shrimp and that produces the short-gut phenotype the most frequently. Thus, if Spea had ancestral morphological plasticity in response to a novel diet, their shrimp-induced short-gut morphology may have undergone subsequent genetic accommodation that improved its functionality. Hence, diet-induced phenotypic plasticity may have preceded and even promoted the evolution of a novel phenotype.