THE EFFECTS OF FOREST FRAGMENTATION ON GENETIC-VARIATION IN ACER-SACCHARUM MARSH (SUGAR MAPLE) POPULATIONS

To investigate the effects of forest fragmentation on genetic variatio n in Acer saccharum Marsh. (Aceraceae) populations, allozyme variation in eight populations in fragmented forest patches was compared to var iation in eight population samples from extensive continuous forest. C ontrary to theoretical predictions, increased genetic drift and inbree ding have not led to reduced within-individual or within-population ge netic variation in patch populations. Polymorphism and individual hete rozygosity were slightly higher in patch than continuous forest popula tions. However, overall. founder effects may have resulted in the loss of six alleles in the fragmented forest system. Maintenance of geneti c variation in patch populations may be because of the limited number of generations since fragmentation occurred, or because populations in patches have not been reduced below the size of normal breeding assoc iations for A. saccharum. Comparison of the distribution of alleles am ong populations, between patch and continuous forest, suggests that th e higher genetic variation in patch populations may be the result of i ncreased interpopulation gene flow.