Data for: Natural variation reveals functional and genetic integration of a polyphenism

Integration and modularity can have a profound impact on the function and
evolution of environmentally responsive traits, especially when they
result in discrete, alternative forms—that is, developmental polyphenism.
An unresolved issue for understanding this impact is the degree to which
the genetic architectures of the individual components of a plastic trait
permit independent versus coordinated evolution. The association of trait
variation with genomic variation can provide a test of whether the same
loci influence different components of the same integrated phenotype. An
example of a coordinated, plastic trait is in the shark-tooth nematode
Pristionchus pacificus, which develops into either a bacterial-feeding or
a predatory adult morph, depending on its perception of local food
availability. Moreover, this polyphenism, when measured as morph induction
in response to a common set of cues, differs across natural isolates of
the species. By creating recombinant inbred lines (RILs) from natural
isolates that have diverged in their morph-induction bias, followed by
quantitative trait locus analysis, we tested whether and to what extent
component traits of this resource polyphenism are linked. We found that
RILs with more frequent induction of the predatory morph also produced Eu
individuals that were more effective predators. We also found that these
two traits are associated with the same major-effect locus, suggesting
that their causal genes are physically linked, if not the same, and are
therefore likely to experience coordinated selection. In contrast, we
found that morphological variation was not linked to these two traits and
that such variation within each morph was even independent of variation in
the other. Our findings show that the same coordinated plastic trait
exhibits a blend of genetic correlation and independence, whose balance
shapes the trait’s evolutionary potential