Abstract Detail

The flora of Madagascar: uncovering mechanisms for diversification

Karimi, Nisa [1], Grover, Corrinne [2], Gallagher, Joseph [3], Wendel, Jonathan [4], Baum, David [5].

Geographic variation and floral evolution of Madagascar’s endemic baobabs (Adansonia, Malvaceae).

Using species tree and explicit network methods we aim to clarify the genealogical history and trait evolution of the six traditionally recognized species of baobab (Adansonia) that are endemic to Madagascar. The six species are divided into two sections based primarily on floral morphology and previous molecular analyses. Brevitubae comprises two species with short, white primarily mammal-pollinated flowers, whereas the four species of Section Longitubae have elongated, hawkmoth-pollinated flowers with yellow to red floral organs. While Section Brevitubae is well supported as monophyletic, recent phylogenetic analyses have contradicted the monophyly of Longitubae. Species of Longitubae occur in regional or even local sympatry and introgressive hybridization has been suggested, raising questions of species limits and patterns of gene flow within and between species. We aimed to use genome-scale data for accessions representing the full geographic ranges of each putative species, and including a few individuals that have been interpreted to be possible hybrids, to investigate these questions. Using a targeted sequence capture approach, we have obtained alignments for hundreds of nuclear loci and have also assembled almost complete plastomes. To explore causes of conflict between nuclear genes and between these and the plastid genome we estimate the optimal population tree and test whether additional sources of genealogical discordance (e.g., introgression) need to be invoked. Explicit networks, which incorporate both incomplete lineage sorting and introgression, are estimated allowing us to test prior hypotheses and evaluate the role of geographic proximity in gene flow. Our study models new methods that can be used to explore discordance in many non-model systems and illustrates the capacity for phylogenomic methods to shed light on species delimitation and phylogeographic problems.

1 - University Of Wisconsin - Madison, Department Of Botany, 430 Lincoln Drive, Madison, WI, 53706, United States
2 - Iowa State University, 251 Bessey Hall, Ames, IA, 50011, USA
3 - University Of Massachusetts, Biology Dept, 221 Morrill Science Center III, Amherst, MA, 01003, United States
4 - Iowa State Univ, Department Of Ecology, Evolution, And Organismal Biology, 251 Bessey Hall, Ames, IA, 50011, United States
5 - University Of Wisconsin, Department Of Botany, Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, United States

Keywords:
none specified

Presentation Type: Colloquium Presentations
Session: C08, The flora of Madagascar: uncovering mechanisms for diversification
Location: 101/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 4:15 PM
Number: C08011
Abstract ID:457
Candidate for Awards:None