A phylogeny of Antirrhinum reveals parallel evolution of alpine morphology

• Parallel evolution of similar morphologies in closely related lineages
provides insight into the repeatability and predictability of evolution.
In the genus Antirrhinum (snapdragons), as in other plants, a suite of
morphological characters are associated with adaptation to alpine
environments. • We test for parallel trait evolution in Antirrhinum by
investigating phylogenetic relationships using Restriction-site associated
DNA (RAD) sequencing. We then associate phenotypic information to our
phylogeny to reconstruct patterns of morphological evolution and relate
this to evidence for hybridization between emergent lineages. •
Phylogenetic analyses show that the alpine character syndrome is present
in multiple groups, suggesting that Antirrhinum has repeatedly colonised
alpine habitats. Dispersal to novel environments happened in the presence
of intraspecific and interspecific gene flow. • We find support for a
model of parallel evolution in Antirrhinum. Hybridisation in natural
populations, and a complex genetic architecture underlying the alpine
morphology syndrome, support an important role of natural selection in
maintaining species divergence in the face of gene flow.