Abstract Detail

Phylogenomics

Karimi, Nisa [1], Stenz, Noah [1], Grover, Corrinne [2], Joseph, Gallagher [3], Jonathan, Wendel [4], Baum, David [1].

Assessing genealogical discordance within Adansonia (Malvaceae) by targeted-sequence capture.

The nine named species of baobab (Adansonia) are iconic trees of Africa, Madagascar and northwestern Australia. Adansonia digitata, a tetraploid, occurs widely in continental Africa, alongside a recently described but still questionable diploid species, A. kilima. A. gregorii is endemic to northwestern Australia, and the remaining six species are restricted to Madagascar. The Malagasy species are divided into two sections primarily based on floral morphology; Brevitubae have short, mammal-pollinated flowers and Longitubae very elongated, hawkmoth-pollinated flowers. Previous phylogenetic analyses of the genus found three distinct clades organized by geography (Africa, Australia, Madagascar), but numerous questions remain about their evolutionary history, especially the validity of A.kilima and the extent of hybridization among species in Longitubae. In order to investigate these questions, we are employing a sequence capture (hyb-seq) strategy that targets 380 coding sequences (each at least 800 base pairs) that show strong conservation between Adansonia and Gossypium. We developed a bioinformatic pipeline for assembly of the targeted exons, spanned introns, and flanking regions in the absence of a reference genome. This approach includes paralogy inference and, consequently, allows SNP-calling and haplotype phasing. Analyses of the resulting sequence data using species tree and explicit network methods supported the three geographic clades but thus far failed to resolve their relationships, presumably because of a very short internal branch. Our preliminary analysis (and other data sources) rejected distinction of A. kilima. Species tree and concatenation analysis supported non-monophyly of Longitubae, placing A. rubrostipa sister to a clade containing Brevitubae and the other three species of Longitubae. Phylogenetic network reconstructions suggested at least one hybridization edge among the Malagasy species, possibly accounting for homoplasy in floral traits. Our hyb-seq approach coupled with new methods developed for exploring discordance can be applied to resolve numerous evolutionary phenomena including incomplete lineage sorting and introgression in many non-model systems.

1 - University of Wisconsin - Madison, Department of Botany, 430 Lincoln Drive, Madison, WI, 53706, United States
2 - Iowa State University, Department of Ecology, Evolution, and Organismal Biology, Ames, IA, 50011, USA
3 - Iowa State University, Department of Ecology, Evolution, and Organismal Biology, Ames, IA, 50011, USA
4 - Iowa State University, Department Of Ecology, Evolution, And Organismal Biology, 251 Bessey Hall, Ames, IA, 50011-1020, USA

Keywords:
none specified

Presentation Type: Oral Paper
Session: 16, Phylogenomics II
Location: 202/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 8:30 AM
Number: 16003
Abstract ID:557
Candidate for Awards:None