A target capture approach for phylogenomic analyses at multiple
evolutionary timescales in rosewoods (Dalbergia spp.) and the
legume family (Fabaceae)
Abstract
Understanding the genetic changes associated with the evolution of
biological diversity is of fundamental interest to molecular ecologists.
The assessment of genetic variation at hundreds or thousands of unlinked
genetic loci forms a sound basis to address questions ranging from
micro- to macro-evolutionary timescales, and is now possible thanks to
advances in sequencing technology. Major difficulties are associated
with i) the lack of genomic resources for many taxa, especially from
tropical biodiversity hotspots, ii) scaling the numbers of individuals
analyzed and loci sequenced, and iii) building tools for reproducible
bioinformatic analyses of such datasets. To address these challenges, we
developed a set of target capture probes for phylogenomic studies of the
highly diverse, pantropically distributed and economically significant
rosewoods (Dalbergia spp.), explored the performance of an
overlapping probe set for target capture across the legume family
(Fabaceae), and built a general-purpose bioinformatics pipeline.
Phylogenomic analyses of Dalbergia species from Madagascar
yielded highly resolved and well supported hypotheses of evolutionary
relationships. Population genomic analyses identified differences
between closely related species and revealed the existence of a
potentially new species, suggesting that the diversity of Malagasy
Dalbergia species has been underestimated. Analyses at the family
level corroborated previous findings by the recovery of monophyletic
subfamilies and many well-known clades, as well as high levels of gene
tree discordance, especially near the root of the family. The new
genomic and bioinformatics resources will hopefully advance systematics
and ecological genetics research in legumes, and promote conservation of
the highly diverse and endangered Dalbergia rosewoods.