PARENT SESSION
Oral Session #67: Metapopulations, fragmented landscapes, and patch dynamics. Presiding: C. Kraft.
Thursday, August 9, 2001. 1:00 PM to 4:30 PM. Hall of Ideas F.

Landscape history and the genetic structure of forest plant populations.

Vellend, Mark¹, ¹

ABSTRACT- Widespread abandonment of agricultural land in temperate Europe and eastern North America has created a mosaic of forest "islands" that vary in their size and age. Seeds of herbaceous forest understory plants are generally dispersed short distances, and their colonization of post-agricultural forests is thus dispersal limited. Metapopulation-genetic theory predicts that dispersal-limited colonization should result in reduced genetic variation within populations in secondary vs. primary forest stands. I assayed variation at five allozyme loci in populations of Trillium grandiflorum (a long-lived, ant-dispersed forest herb) in three primary and three secondary forest stands in central New York, USA. Allelic richness was reduced in secondary vs. primary stands, though mean heterozygosity did not differ between stand types. Populations in secondary stands were genetically more similar to nearby populations in primary stands than to more distant populations in primary stands. These results provide the first evidence for genetic consequences of post-agricultural forest recovery in eastern North America, and provide further evidence for localized dispersal of forest understory plants in fragmented landscapes.

KEY WORDS: colonization genetics, dispersal, forest herbs, forest history