Abstract Detail

Phylogenomics

Chanderbali, Andre [1], Berger, Brent [2], Howarth, Dianella [3], Soltis, Douglas [4], Soltis, Pamela S. [5].

Grappling with gamma--a new look at an old WGD event.

Whole-genome duplication (WGD, polyploidy) is a rich source of genetic raw material for evolutionary change and a key feature of flowering plant evolution. Indeed, all extant flowering plants share an ancient polyploid event that predates their evolutionary origin, and multiple independent WGDs are evident in younger lineages. The largest extant clade of flowering plants, the core eudicots, with ~75% of all angiosperm species, exhibits a triplicate genome structure suggestive of ancient hexaploidy resulting from two WGDs – termed “gamma” – that occurred in close succession. The phylogenetic placement of “gamma” is of particular interest because “gamma” may be directly related to changes in floral morphology and other innovations associated with the unparalleled evolutionary success of the core eudicots. Efforts to pinpoint the precise positions of the two WGDs contributing to “gamma” have narrowed the possibilities to a broad evolutionary window spanning much of the phylogenetic grade of basal eudicots immediately preceding the core eudicot clade, but has otherwise remained uncertain. Here we show that the “gamma” WGDs may have occurred along two consecutive stem lineages spanning the lattermost stages of the transition from basal to core eudicots. Our phylogenomic analyses suggest that ~50% of the ancient duplicate genes (paleologs) that originated during eudicot diversification were duplicated along the branch that immediately subtends all core eudicots (i.e., Gunnerales and Pentapetalae), while the remaining ~50% were duplicated earlier, most likely along the branch leading to a clade comprising two basal eudicot lineages (Buxales and Trochodendrales) and all core eudicots. This earlier WGD, potentially the first of the two contributing to “gamma,” however, is not as well supported as the later (pre-core eudicot) WGD and could have conceivably occurred after the divergence of Buxales and Trochodendrales. Nevertheless, our results provide significant phylogenetic support for placing the “gamma” event near, and possibly across, the two lattermost stem lineages subtending the origin of core eudicots.

1 - University Of Florida, 357 DICKINSON HALL MUSEUM ROAD & NEWELL DRIVE, P.O. BOX 117800, Gainesville, FL, 32611, USA
2 - St. John's University, Biological Sciences, 8000 Utopia Parkway, Queens, NY, 11439, USA
3 - St. John's University, Department Of Ecology & Evolutionary Biology, St. Albert Hall Rm 257, 8000 Utopia Pkwy, Jamiaca, NY, 11439, USA
4 - University of Florida, Dept. of Biology, 1659 Museum Road, Gainesville, Florida, 32611, United States
5 - University of Florida, Florida Museum of Natural History, 1659 Museum Rd., Gainesville , FL, 32611, USA

Keywords:
angiosperms
gamma
WGD
phylogenomics.

Presentation Type: Oral Paper
Session: 38, Phylogenomics III
Location: 204/Savannah International Trade and Convention Center
Date: Wednesday, August 3rd, 2016
Time: 9:15 AM
Number: 38006
Abstract ID:757
Candidate for Awards:None