Research ArticleGENETICS

Large-scale diversification without genetic isolation in nematode symbionts of figs

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Science Advances  15 Jan 2016:
Vol. 2, no. 1, e1501031
DOI: 10.1126/sciadv.1501031

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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.

  • Developmental plasticity
  • Pristionchus
  • figs
  • genetic isolation
  • adaptive radiation
  • diversification
  • nematodes
  • predation

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