Data from: The symmetry spectrum in a hybridising, tropical group of rhododendrons

Many diverse plant clades possess bilaterally symmetrical flowers and
specialized pollination syndromes suggesting these traits may promote
diversification. We examine the evolution of diverse floral morphologies
and the association with diversification history in a species-rich
tropical radiation of Rhododendron. We used restriction-site associated
DNA sequencing on 114 taxa from Rhododendron sect. Schistanthe to
reconstruct phylogenetic relationships, infer colonization of Southeast
Asia, and examine hybridization. We then captured and quantified floral
variation using geometric morphometric analyses which we interpret in a
phylogenetic context. We uncovered phylogenetic complexity caused by
introgression within and between clades. Morphometric analyses revealed
flower symmetry to be a morphological continuum without a clear transition
from radial to bilateral symmetry. The largest radiation of tropical
Rhododendron species is associated with an expansion into novel floral
morphological space as species diversified in New Guinea about 6 million
years ago. Our results showed that the recent radiation of tropical
Rhododendron is a consequence of hybridization, genetic isolation caused
by mountain building, and the evolution of floral novelty. Floral
variation evolved via changes to multiple components of the corolla that
are only recognized in geometric morphometrics with both front and side
views of flowers.