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

Fine-scale genetic structures in an endangered perennial Primula sieboldii under different site conditions.

Ishihama, Fumiko^*,1, Ueno, Saneyoshi², Tsumura, Yoshihiko², Washitani, Izumi³, ¹ National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan² Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan³ University of Tokyo, Bunkyo, Tokyo, Japan

ABSTRACT- In plant populations, limited gene flow tends to generate marked genetic structures. While direct observation of rare long-distance dispersal is difficult, we can infer it by measuring genetic structures. Primula sieboldii is a clonally growing, bumblebee-pollinated heterostylous perennial. Its seeds are dispersed mainly by gravity in the close vicinity of maternal plants. However, its seeds and physiologically-independent ramets can be dispersed relatively long distances by water and/or with the movement of soil in occasions of various scales of flooding or land slide. Site conditions such as presence-absence of water flow and slope are thought to influence the frequencies of these types of dispersals. To evaluate the effect of these conditions, we compared fine-scale genetic structures and distribution of ramets of the same genets among populations in the following three types of site locations: flats with or without water flow, and slope without water flow. Genetic structures were analyzed on genet-basis by pairwise kinship coefficients estimated from genotypes at nine microsatellite loci. Directionality of genetic structure in relation to slope and water flow aspect was also analyzed. Marked genetic structures (kinship higher than 0.05 within 3 m) were observed in populations without water flow irrespective of flat or slope, while it was weak (kinship higher than 0.05 only within 1 m) in populations with water flow. Genetic structures tended to be relatively weak on the direction of water flow. Because genet-based genetic structure is thought to mainly reflect pollen and seed dispersals, this result suggest major contribution of water flow to seed dispersal. On the other hand, maximum distances between ramets of the same genets were remarkably long in slope populations (longer than 2 m in 24.2% genets) in comparison to flat populations with water flow (longer than 2m only in 1.7% genets), suggesting particular contribution of mudslide to ramet dispersal.

Key words: genetic structure, water flow, slope, gene flow