Nested whole-genome duplications coincide with diversification and high morphological disparity in Brassicaceae

Angiosperms have become the dominant terrestrial plant group by
diversifying for ~145 million years into a broad range of environments.
During the course of evolution, numerous morphological innovations arose,
often preceded by whole genome duplications (WGD). The mustard family
(Brassicaceae), a successful angiosperm clade with ~4000 species, has been
diversifying into many evolutionary lineages for more than 30 million
years. Here we develop a species inventory, analyze morphological
variation, and present a maternal, plastome-based genus-level phylogeny.
We show that increased morphological disparity, despite an apparent
absence of clade-specific morphological innovations, is found in tribes
with WGDs or diversification rate shifts. Both are important processes in
Brassicaceae, resulting in an overall high net diversification rate.
Character states show frequent and independent gain and loss, and form
varying combinations. Therefore, Brassicaceae pave the way to concepts of
phylogenetic genome-wide association studies to analyze the evolution of
morphological form and function.