Deep Phylogeographic Structure and Environmental Differentiation in the Carnivorous Plant Sarracenia alata

Abstract

We collected ~29 kb of sequence data using Roche 454 pyrosequencing in order to estimate the timing and pattern of diversification in the carnivorous pitcher plant Sarracenia alata. Utilizing modified protocols for reduced representation library construction, we generated sequence data from 86 individuals across 10 populations from throughout the range of the species. We identified 76 high-quality and high-coverage loci (containing over 500 SNPs) using the bioinformatics pipeline PRGmatic. Results from a Bayesian clustering analysis indicate that populations are highly structured, and are similar in pattern to the topology of a population tree estimated using *BEAST. The pattern of diversification within Sarracenia alata implies that riverine barriers are the primary factor promoting population diversification, with divergence across the Mississippi River occurring more than 60,000 generations before present. Further, significant patterns of niche divergence and the identification of several outlier loci suggest that selection may contribute to population divergence. Our results demonstrate the feasibility of using next-generation sequencing to investigate intraspecific genetic variation in nonmodel species.