Data from: Divergent evolution and niche differentiation within the common peatmoss Sphagnum magellanicum

PREMISE OF THE STUDY: Populations with phenotypic polymorphism in discrete
characters may be good models for investigating genome evolution and
speciation. Sphagnum magellanicum Brid. is found throughout the northern
hemisphere, and despite considerable variation in morphological
characters, it is considered one of the least taxonomically controversial
peatmoss species. We have observed two main morphs of the species
associated with different microhabitats. Here we investigated the genomic
and environmental basis of this intraspecific morphological variation.
METHODS: We conducted transplant and common garden experiments to test
whether the two morphs are genetically differentiated. We then used
RAD-sequencing to quantify the genomic divergence between the morphs and
approximate Bayesian computation (ABC) to infer the most likely
demographic scenario explaining the genome-wide differentiation of the two
morphs. KEY RESULTS: We found that genomic differentiation between the two
morphs is unexpectedly high and that several of the differentiated
morphological characters have a genetic basis. Using simulation
approaches, we found support for a scenario of ancient divergence followed
by recent secondary contact. CONCLUSIONS: We show that the two morphs
represent the two main genetic clusters previously found worldwide. Our
results demonstrate that relatively minor morphological differentiation in
a presumed phenotypically plastic peatmoss may be associated with massive
divergence across the genome.