title: Using targeted enrichment of nuclear genes to increase phylogenetic resolution in the neotropical rain forest genus Inga (Leguminosae: Mimosoideae).
abstract: Evolutionary radiations are prominent and pervasive across many plant lineages in diverse geographical and ecological settings; in neotropical rainforests there is growing evidence suggesting that a significant fraction of species richness is the result of recent radiations. Understanding the evolutionary trajectories and mechanisms underlying these radiations demands much greater phylogenetic resolution than is currently available for these groups. The neotropical tree genus Inga (Leguminosae) is a good example, with ~300 extant species and a crown age of 2-10 MY, yet over 6 kb of plastid and nuclear DNA sequence data gives only poor phylogenetic resolution among species. Here we explore the use of larger-scale nuclear gene data obtained though targeted enrichment to increase phylogenetic resolution within Inga. Transcriptome data from three Inga species were used to select 264 nuclear loci for targeted enrichment and sequencing. Following quality control to remove probable paralogs from these sequence data, the final dataset comprised 259,313 bases from 194 loci for 24 accessions representing 22 Inga species and an outgroup (Zygia). Bayesian phylogenies reconstructed using either all loci concatenated or a gene-tree/species-tree approach yielded highly resolved phylogenies. We used coalescent approaches to show that the same targeted enrichment data also have significant power to discriminate among alternative within-species population histories within the widespread species I. umbellifera. In either application, targeted enrichment simplifies the informatics challenge of identifying orthologous loci associated with de novo genome sequencing. We conclude that targeted enrichment provides the large volumes of phylogenetically-informative sequence data required to resolve relationships within recent plant species radiations, both at the species level and for within-species phylogeographic studies.
authors.affiliation: Ashworth Labs, Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh Edinburgh, UK ; Royal Botanic Garden Edinburgh Edinburgh, UK.
authors.forename: James A
authors.initials: JA
authors.lastname: Nicholls
authors.affiliation: Royal Botanic Garden Edinburgh Edinburgh, UK.
authors.forename: R Toby
authors.initials: RT
authors.lastname: Pennington
authors.affiliation: Institute of Systematic Botany, University of Zurich Zürich, Switzerland.
authors.forename: Erik J M
authors.initials: EJ
authors.lastname: Koenen
authors.affiliation: Institute of Systematic Botany, University of Zurich Zürich, Switzerland.
authors.forename: Colin E
authors.initials: CE
authors.lastname: Hughes
authors.affiliation: Ashworth Labs, Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh Edinburgh, UK.
authors.forename: Jack
authors.initials: J
authors.lastname: Hearn
authors.affiliation: Ashworth Labs, Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh Edinburgh, UK.
authors.forename: Lynsey
authors.initials: L
authors.lastname: Bunnefeld
authors.affiliation: School of Geosciences, University of Edinburgh Edinburgh, UK.
authors.forename: Kyle G
authors.initials: KG
authors.lastname: Dexter
authors.affiliation: Ashworth Labs, Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh Edinburgh, UK.
authors.forename: Graham N
authors.initials: GN
authors.lastname: Stone
authors.affiliation: Royal Botanic Garden Edinburgh Edinburgh, UK ; Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh Edinburgh, UK.
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Kidner
keywords: Inga; hybrid capture; next-generation sequencing; phylogenomics; population genomics; radiation; targeted enrichment