The effects of forest fragmentation on genetic variation in acer saccharum marsh, (Sugarmaple) populations

Abstract

To investigate the effects of forest fragmentation on genetic variation in Acer saccharum Marsh. (Aceraceae) populations, allozyme variation in eight populations in fragmented forest patches was compared to variation in eight population samples from extensive continuous forest. Contraiy to theoretical predictions, increased genetic drift and inbreeding have not led to reduced within- individual or within-population genetic variation in patch populations. Polymorphism and individual heterozygosity were slightly higher in patch than continuous forest populations. However, overall, founder effects may have resulted in the loss of six alleles in the fragmented forest system. Maintenance of genetic 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 associations for A. saccharum. Comparison of the distribution of alleles among populations, between patch and continuous forest, suggests that the higher genetic variation in patch populations may be the result of increased interpopulation gene flow. © 1993 The Genetical Society of Great Britain.