PARENT SESSION
Contributed Oral Session 63: Plant Genetics: Population Level Implications
Tuesday, August 9, 1:30 PM - 5:00 PM, Meeting Room 519 A, Level 5, Palais des congrès de Montréal
Rapid evolution and the spread of introduced species: New insights from Spartina alterniflora invasions.
Bando, Jun*,1, 1 Department of Environmental Science and Policy, Davis, CA, 95616
ABSTRACT- Studies of invasive species have focused on ecological explanations for invader success, but evidence is accumulating of the influence of evolutionary processes on establishment and spread. Interspecific hybridization is an important stimulus for the evolution of invasiveness, and recent theory suggests that intraspecific hybridization between differentiated source populations may similarly facilitate the rapid evolution of invasive species. Until now, direct evidence for the role of intraspecific hybridization in invasions has been lacking. This study assessed the roles of genetic diversity and intraspecific hybridization in the extent of Pacific coast invasions of smooth cordgrass (Spartina alterniflora). S. alterniflora has spread widely in Willapa Bay, Washington, but is rare in Grays Harbor, Washington and San Francisco Bay, California. Microsatellite markers were used to quantify genetic diversity in native (Atlantic/Gulf coast) and invasive (Pacific) populations and to identify geographic sources of invasive populations. Native source populations were inferred from the assignment of invasive individuals to native populations by a Bayesian clustering algorithm, and by calculating genetic distances between populations. In addition, unique allele phenotypes that appeared to be diagnostic of specific native populations or geographic regions were noted. Evidence of introduction from multiple native source populations was found in all invasive populations. The degree of intraspecific hybridization in the invasive populations correlated with their differential rates of expansion. No correlation emerged between genetic diversity and the spread of invasive populations. These findings suggest that intraspecific hybridization can facilitate the rapid evolution of invasive species and influence their rates spread.
Key words: rapid, evolution, invasions, hybridization