Abstract Detail

Biogeography

Allen, Geraldine A. [1].

Phylogeography of arctic-alpine species in western North America: is there a common pattern?

Patterns of genetic variation not only provide insight into the history of species but can inform assessments of potential responses to climate change. I assessed the phylogeographic history of five widely distributed arctic-alpine species in western North America (as inferred from plastid or nuclear sequences and/or AFLP markers) in relation to their morphological and life history traits. To further evaluate life-history differences, I compared genetic patterns in one of the widespread species (Bistorta vivipara) and two sympatric congeners of more regional distribution (B. plumosa and B. bistortoides). All five widespread species are of probable Old World origin. Estimated divergence times for three species showed that ages of North American lineages varied from 0.06-0.47 Ma to 1.1-2.2 Ma. Four species had strong genetic differentiation with locally high levels of genetic diversity, indicating persistence through the Last Glacial Maximum in North America. Of these, three (Oxyria digyna, Rhodiola integrifolia, and Silene acaulis) persisted in both northern and southern refugia (Beringia, Rocky Mountains) and one (Sibbaldia procumbens) persisted in two distinct southern refugia (Rocky Mountains, Sierra Nevada). In the remaining species (Bistorta vivipara) there was little genetic structure with low levels of genetic diversity throughout its North American range, suggesting recent colonization from elsewhere. All five species showed evidence of rapid range expansion. Recent expansion was primarily from Beringia in three species, and from the southern Rocky Mountains in one species. The two most widely distributed species had strongly contrasting genetic diversity and life-history characteristics: Oxyria digyna (high genetic diversity) is short-rhizomatous with wind-pollinated flowers and small-winged nutlets, whereas Bistorta vivipara (low genetic diversity) is a high polyploid that can spread vegetatively via bulblets. The other species are insect-pollinated, with small seeds lacking obvious dispersal adaptations. In Bistorta, the two regional species B. plumosa and B. bistortoides, which reproduce only sexually, had much higher levels of genetic variation than did B. vivipara, which differs primarily in its capacity for vegetative reproduction. The abundant bulblets of B. vivipara are much larger than seeds, readily germinating, and animal-dispersed, giving this species greater potential for spread. Colonization of arctic North America by plants has occurred by different routes and at different times. Although the species compared here have some genetic patterns and refugia in common, their distributions and current genetic structure are strongly influenced by differences in plant traits and phylogenetic history.

1 - University of Victoria, Biology, PO Box 1700, Station CSC, Victoria, BC, V8W 2Y2, Canada

Keywords:
arctic-alpine species
North America
Last Glacial Maximum.

Presentation Type: Oral Paper:Papers for Topics
Session: 72
Location: Salon 3/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 4:15 PM
Number: 72010
Abstract ID:1252
Candidate for Awards:None