Departamento de Biología Marina, Universidad Católica del Norte, Centro de Estudios Avanzados en Zonas Áridas, Coquimbo, Chile.
Evol Dev. 2010 Nov-Dec;12(6):628-34. doi: 10.1111/j.1525-142X.2010.00447.x.
Two forms of the squat lobster Pleuroncodes monodon can be found along the Pacific coast of South America: a smaller pelagic and a larger benthic form that live respectively in the northern and southern areas of the geographic distribution of the species. The morphological and life history differences between the pelagic and benthic forms could be explained either by genetic differentiation or phenotypic plasticity. In the latter case it would correspond to a heterochronic phenotypic plasticity that is fixed in different environments (phenotype fixation). The aim of this study was to evaluate whether the two forms are genetically differentiated or not; and thus to infer the underlying basis-heritable or plastic-of the existence of the two forms. Based on barcoding data of mitochondrial DNA (the COI gene), we show that haplotypes from individuals of the pelagic and benthic forms comprise a single genetic unit without genetic differentiation. Moreover, the data suggest that all studied individuals share a common demographic history of recent and sudden population expansion. These results strongly suggest that the differences between the two forms are due to phenotypic plasticity.
两种美洲螯龙虾（Pleuroncodes monodon）可以在南美的太平洋海岸被发现：一种体型较小的洄游性和一种体型较大的底栖性，分别生活在该物种分布范围的北部和南部地区。洄游性和底栖性形态和生活史的差异可能是由遗传分化或表型可塑性解释的。在后一种情况下，它对应于在不同环境中固定的异时性表型可塑性（表型固定）。本研究的目的是评估这两种形式是否存在遗传分化；从而推断两种形式存在的基础——遗传或可塑性。基于线粒体 DNA（COI 基因）的条形码数据，我们表明，来自洄游性和底栖性个体的单倍型构成一个单一的遗传单元，没有遗传分化。此外，数据表明，所有研究的个体都具有最近和突然种群扩张的共同种群历史。这些结果强烈表明，这两种形式的差异是由于表型可塑性造成的。
