XVI International Botanical Congess

Sixty-two individuals of the freshwater red alga, Batrachospermum helminthosum, were collected from ~ 50 m stream reach in order to examine within stream genetic variation. Individuals appeared to be congregated into three distinct areas with few thalli between each site. A relatively new molecular marker technique, inter-simple sequence repeats (ISSR), was employed. One primer yielded 23 distinct bands among individuals with 5-12 bands per individual. Preliminary linkage analysis showed distinct groupings among certain groups of physically close individuals. However, other individuals that were in very close proximity were genetically distinct. The implications of this analysis to the study of dispersal by freshwater red algae and processes governing population structure will be discussed.