Assessing population genomic structure and polyploidy: a crucial step for native plant restoration

Abstract

Establishing an effective restoration program requires baseline genetic information to make sound decisions for seed increase and transfer. For many plants this information is lacking, especially among native forbs that are critical for pollinator health. Erigeron speciosus is a widespread, perennial forb occupying montane environments in the western United States and Canada. This species is important in fostering pollinator diversity. Our study examines the population genetic patterns across the species range using reduced-representation sequencing and surveys for genome duplication using flow cytometry and cytology. These genomic tools provide critical information for seed increase and seed transfer, necessary for restoration programs. Population genetic differentiation (FST) average was 0.13 and ranged from 0.05 to 0.24 among 23 collection sites. Model-based Bayesian clustering supported a model with collection sites grouped into two populations, occupying distinct geographic regions of this species range. A genetic distance-based neighbor-joining tree also supported this division. Flow cytometry of 53 samples from 17 populations had 2C values that ranged from 1.7 to 3.6 pg with a mean 2C value of 2.3 pg. Putative triploids were found in two individuals from one collection site. The spatial distribution of genetic structure supports regionally based taxonomic descriptions of two varieties: speciosus in the North and macranthus in the South. This assessment of genetic structure and genome duplication describes an effective approach in developing baseline genetic information for restoration species, especially those species that may harbor complex taxonomy and polyploidy.