Susoy Vladislav, Herrmann Matthias, Kanzaki Natsumi, Kruger Meike, Nguyen Chau N, Rödelsperger Christian, Röseler Waltraud, Weiler Christian, Giblin-Davis Robin M, Ragsdale Erik J, Sommer Ralf J
Max Planck Institute for Developmental Biology, Department of Evolutionary Biology, Spemannstraße 37, Tübingen 72076, Germany.
Forest Pathology Laboratory, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan.
Sci Adv. 2016 Jan 15;2(1):e1501031. doi: 10.1126/sciadv.1501031. eCollection 2016 Jan.
Diversification is commonly understood to be the divergence of phenotypes accompanying that of lineages. In contrast, alternative phenotypes arising from a single genotype are almost exclusively limited to dimorphism in nature. We report a remarkable case of macroevolutionary-scale diversification without genetic divergence. Upon colonizing the island-like microecosystem of individual figs, symbiotic nematodes of the genus Pristionchus accumulated a polyphenism with up to five discrete adult morphotypes per species. By integrating laboratory and field experiments with extensive genotyping of individuals, including the analysis of 49 genomes from a single species, we show that rapid filling of potential ecological niches is possible without diversifying selection on genotypes. This uncoupling of morphological diversification and speciation in fig-associated nematodes has resulted from a remarkable expansion of discontinuous developmental plasticity.
多样化通常被理解为表型随谱系的分化。相比之下，由单一基因型产生的替代表型在自然界中几乎仅限于二态性。我们报告了一个没有遗传分化的宏观进化尺度多样化的显著案例。在定殖于单个无花果的岛状微生态系统后，Pristionchus属的共生线虫积累了一种多态性，每个物种有多达五种离散的成虫形态型。通过将实验室和野外实验与个体的广泛基因分型相结合，包括对一个物种的49个基因组进行分析，我们表明，在不对基因型进行多样化选择的情况下，快速填充潜在生态位是可能的。无花果相关线虫形态多样化与物种形成的这种解耦是由不连续发育可塑性的显著扩展导致的。
