Abstract Detail

The power of two: Marrying phylogeny and biogeography to reconstruct the evolutionary history of pteridophytes

Barrington, David S. [1], Driscoll, Heather [1].

Polystichum biogeographically: a history of vicariance, long-distance dispersal, and secondary contact.

A complex history of vicariance and long-distance dispersal resulting in both divergent and polyploid speciation characterizes the genus Polystichum. Strong fidelity of Polystichum species to Takhtajan’s floristic regions suggests that vicariance is a significant factor in the historical biogeography of the genus. Globally, Polystichum species-diversity is concentrated in 11 endemic centers, which differ in degree of geographic isolation. Molecular data so far collected reveal that monophyletic groups tend to occupy centers or adjacent groups of centers. For instance, all of the neotropical species sampled to date belong to a single lineage, which appears to have originated in the boreotropics and diversified into the Antilles and South America. However, a second set of distribution patterns points to an important role for long-distance dispersal at least in the recent past. The origins of Polystichum species in Hawaii, Taiwan, and western North America provide insights into the role of long-distance dispersal in speciation. In the neotropics, long-distance dispersal between island-like high-elevation habitats has led to renewed contact between lineages from different endemic centers, giving rise to hybrids and polyploid species. Spatial disparity in the source of hybrid progenitors may be a significant factor in the genetic constitution and evolutionary potential of polyploid species.

Related Links:
Barrington webpage

1 - University of Vermont, Department of Botany, Marsh Life Sciences Building, Burlington, Vermont, 05405-0086

Keywords:
Polystichum
polyploidy
biogeography
floristic regions.

Presentation Type: Symposium
Session: 34-4
Location: Ballroom 1 (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 4:00 PM
Abstract ID:815