Abstract Detail

Systematics Section/ASPT

Johnson, Jens [1], Soza, Valerie [1], Di Stilio, Veronica S [2].

Inferring the Origins and Mechanisms of Polyploidy in Thalictrum (Ranunculaceae).

Polyploidy can result from a whole genome duplication event within an individual (autopolyploidy) or following a hybridization event (allopolyploidy). The rates and evolutionary consequences of these two mechanisms of polyploidy are currently under debate. We are attempting to estimate the role of these two mechanisms within the genus Thalictrum (meadow-rues, Ranunculaceae) using a phylogenetic approach. Thalictrum contains numerous shifts in ploidy, from diploid (2x) in the earliest diverging species to highly polyploid (24x) in recently derived species. Current Thalictrum phylogenies are based on chloroplast DNA and nuclear ribosomal regions. These regions tend to underestimate the role of hybridization due to maternal inheritance and concerted evolution, respectively. We used a single-copy nuclear gene, MIXTA-Like 2 (MYBML2), to uncover potential hybridization signals in Thalictrum’s evolutionary history. The relationships between MIXTA-Like 2 alleles in Thalictrum species were analyzed with Bayesian and coalescent based phylogenies and network analyses. Polyploid species with non-monophyletic inheritance of MIXTA-Like 2 alleles were identified as potential allopolyploids. Divergence dating of MIXTA-Like 2 alleles was used to tease apart the role of hybridization versus incomplete lineage sorting in the potential allopolyploids. Preliminary analyses including 9 diploid species and 12 polyploid species suggest that 10 of the polyploid species are allopolypoids while 2 are autopolyploids. This research will be expanded to estimate the relative numbers of autopolyploids versus allopolyploids in the genus. In the future, this information will be applied to questions regarding the evolution and development of genes involved in flower development after whole genome duplications.

1 - University of Washington, Biology, Box 351800, Seattle, WA, 98195-1800, USA
2 - University of Washington, Biology, Box 351800, Seattle, WA, 98195, USA

Keywords:
Thalictrum
Ranunculaceae
polyploidy
hybridization 
allopolyploidy.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PSY014
Abstract ID:494
Candidate for Awards:None