Synthesizing existing phylogenetic data to advance phylogenetic research in Orobanchaceae

To date, no comprehensive phylogenetic analyses have been conducted in
Orobanchaceae that include both a wide generic sampling and a large
sampling of species. In addition, a lack of fossil evidence in the clade
precludes the use of primary fossil calibrations for divergence time
estimation, preventing the establishment of a comprehensive temporal
framework for use in macroevolutionary studies. Here, we use a recently
developed set of tools for synthesizing publicly available data, apply
these to reconstruct a comprehensive timetree for Orobanchaceae, and then
investigate diversification dynamics in this clade of mostly parasitic
plants using two model based methods. The assembled supermatrix included
more than 900 species, representing approximately 40% of the known species
diversity of the family, and the resulting phylogeny largely confirmed
relationships revealed in earlier studies; however, we identified ten
non-monophyletic genera that will require focused systematic attention to
resolve. Diversification rate analyses found substantial support for
character-dependent diversification, with elevated rates in hemiparasitic
clades, and evidence for a number of speciation rate changes throughout
the tree that are likely linked to other traits. Importantly, our
multi-state HiSSE analysis revealed that transitions to a parasitic
lifestyle only occur when there is a prior transition in an unobserved
precursor state.  For Orobanchaceae, our study provides a new
comprehensive framework for the clade that can serve as a stepping-stone
for future macroevolutionary studies.