PARENT SESSION
Poster Session 36: Genetics / Population Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Neutral genetic diversity in small populations of a commercially valuable plant, American ginseng.

Anderson, M Rebecca^*,1, Loew, Sabine¹, ¹ Behavior, Ecology, Evolution and Systematics Section, Normal, IL, USA

ABSTRACT- American ginseng, Panax quinquefolius L., is a commercially valuable herbaceous species of rich forest habitat in eastern North America. Small isolated wild populations are heavily impacted by harvest for export, primarily to Asian markets. In general, small populations of species exhibit lower genetic diversity than larger ones, which may reduce their evolutionary capability to adapt to environmental change. We tested the hypothesis that genetic variation is positively correlated with population size. Neutral genetic diversity was assessed using electrophoretic allozyme variation in individuals selected from seven Illinois and one Wisconsin American ginseng populations that vary in size from eight to several hundred individuals. Allozyme variation detected by cellulose acetate gel membrane electrophoresis revealed very little differentiation between populations (F_ST = 0.216, CI 0.046 to 0.339), and a high degree of apparent genetic relatedness (F_IS = 0.984, 95% CI 0.895 to 1.0). The two smallest populations, n=8 and 22, demonstrated the lowest expected heterozygosity He (0.068 and 0.051, respectively) and the largest two populations, n>150 and >500, had the highest He, 0.129 and 0.203, respectively. The overall mean He was 0.102 and the observed heterozygosity Ho was 0.106. In order to further investigate the underlying explanation for this extremely low level of allozyme diversity, we have expanded our genetic analysis to include Amplified Fragment Length Polymorphisms (AFLP), a more variable molecular marker than can be used to generate DNA fingerprint and population diversity data. We have successfully implemented the initial analyses of AFLP fragment profiles.

Key words: Panax quinquefolius, genetic diversity, population size, AFLP