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

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.

Keywords: Developmental plasticity; Pristionchus; adaptive radiation; diversification; figs; genetic isolation; nematodes; predation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Evolution
  • Ecology
  • Ficus / genetics*
  • Ficus / parasitology*
  • Genetic Speciation
  • Genome / genetics
  • Genotype
  • Nematoda / genetics*
  • Phylogeny
  • Reproductive Isolation
  • Symbiosis / genetics*