Abstract Detail

Population Genetics/Genomics

Faske, Trevor [1], Agneray, Alison [2], Richardson, Bryce [3], Leger, Elizabeth [4], Parchman, Thomas [5].

Determinants of mixed-ploidal variation and hybridization in big sagebrush (Artemisia tridentata) across the landscape.

Polyploidy has figured prominently in the diversification of plants, and is known to shape phenotypes such as environmental tolerance, growth rate, flower shape, and phytochemistry, all of which can have extended ecological consequences. Big sagebrush (Artemisia tridentata) is an iconic and foundational shrub species of western North America, where it dominates arid shrublands from northern Mexico to southern Canada. Our study focuses on three subspecies of A. tridentata – basin (A. t. tridentata), mountain (A. t. vaseyana), and Wyoming (A. t. wyomingensis) – that exhibit variation in phenology, seedling performance, phytochemistry, and adaptation to climatic variation. While multiple instances of autopolyploidization likely drove ploidal variation within A. t. tridentata and A. t. vaseyana, there is evidence that A. t. wyomingensis is an allotetraploid hybrid of diploid A. t. tridentata and A. t. vaseyana populations. Given its outsized importance as a foundational species, there is substantial interest in understanding landscape genetic variation within and among the subspecies and across ploidal levels and how this relates to historic and current patterns of environmental variation.
Here we aim to quantify the evolutionary history of the subspecies, the origins of polyploidy, as well as the genetic signature and environmental drivers of local adaptation by generating a range-wide landscape genomic perspective on patterns of differentiation. We analyzed reduced representation sequencing data (ddRADseq; ~23,500 loci, 709 individuals, 59 populations, 2x and 4x ploidal levels) with methods that incorporate genotype uncertainty and account for ploidal variation across populations. Initial results confirm the expectation that A. t. wyomingensis is likely a tetraploid hybrid of A. t. tridentata and A. t. vaseyana origin. Further, we expect to show the spatial structuring of subspecies/polyploidization is predicted by environmental variation and has multiple origins across the range. This newfound understanding of spatial genetic variation and its association with environmental variation should play a substantial role in supporting seed choice for the restoration of sagebrush-steppe systems and incorporating mixed-ploidal variation to landscape genomic studies overall.

1 - University Of Nevada, Reno, Biology (0314), 1664 N. Virginia Street, Reno, NV, 89557, United States
2 - Bureau of Land Management, Nevada State Office, Reno, NV, USA
3 - USDA Forest Service, Rocky Mountain Research Station, Moscow, ID, USA
4 - University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV, 89557, United States
5 - University Of Nevada Reno, Biology, 1664 North Virginia Street, Reno, NV, 89557, United States

Keywords:
landscape genomics
polyploidy
hybridization.

Presentation Type: Oral Paper
Number: PGG3003
Abstract ID:601
Candidate for Awards:Margaret Menzel Award