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Dryad

Population genetics, demographic and evolutionary history of the Dudley’s lousewort, a rare redwood forest specialist (Pedicularis dudleyi)

Abstract

Pedicularis dudleyi (Dudley’s Lousewort, Orobanchaceae) is an extremely rare wildflower endemic to the redwood forests of Central California. Until recently the species was known only from three extant natural populations. However, one of those populations was recently described as a novel species (P. rigginsiae D.J. Keil) based on morphological and ecological data leaving only two populations described as P. dudleyi. While little is known about the past distribution of the species, historical records have led to speculation that the species was once more widespread and may have suffered from habitat destruction as a result of widespread logging during the early twentieth century. We utilized a combination of ddRAD SNP and Sanger sequencing data to: 1) Describe the genetic diversity and population structure of P. dudleyi; 2) Test the hypothesis that the species underwent a bottleneck corresponding with increased logging of redwood forests in the early twentieth century and; 3) Test the morphological hypothesis that P. rigginsiae is distinct from P. dudleyi. Genetic diversity statistics and analyses of genetic structure suggest that both populations of P. dudleyi are highly differentiated from each other. Demographic modeling supports a scenario where the contemporary rarity of the species is explained by a recent bottleneck. Finally, recognition of P. rigginsiae as distinct from P. dudleyi is supported, increasing the conservation priority of both species.