No. 1030

Title:

Demographic-genetic studies of a clonal plant Convallaria keiskei: spatial structure and growth pattern of ramets and genets

Author(s):

Araki K (Hokkaido University), Shimatani K (The Institute of Statistical Mathematics), Ohara M (Hokkaido University)

Key words:

AIC, microsatellite, normal distribution model, pair correlation function, population dynamics, reproduction

Abstract:

We investigated the population structure and dynamics at ramet and genet level in a clonal herb Convallaria keiskei for three years in northern Japan, by field monitoring of genetically identified individual shoots. During the census, 274 and 149 ramets were mapped in two 1 m × 2 m plots, and 83 and 94 ramets in two 2 m × 2 m quadrats. Thirty-eight genotypes were detected from 580 samples using microsatellite markers. Each plot included five to eighteen genets, indicating that most ramets were of the predominant genet(s) found in the plots. Flowering frequencies varying in years and plots with the interesting characteristic that a different ramet formed an inflorescence every year even if shoots had foliated for years. A considerable number of clonal offspring appeared in all plots, implying their significant contribution in maintaining genets and thus population dynamics. Seedlings were also observed every year, which suggested the evidence of sexual recruitment. The size-class structure of each genet showed a bell-shaped pattern, which may be associated with sustained clonal recruitment size. Furthermore, comparing the optimized structures applied by normal distribution models suggested the differentiation between genets and their growth patterns. Spatial distribution analyses by the pair correlation function demonstrated a complicated pattern of clustering and regularity of ramets in a genet, of which the regularity pattern effectively corresponded to the linearly elongating clonal growth form of this species. On the other hand, the spatial pattern between genets exhibited a tendency that ramets of different genets were presented close to each other. Our demographic genetic studies would therefore be an efficient approach to keep precise track of the spatio-temporal dynamics of both ramets and genets. This approach reveals various characteristics of different clones and indicates the quantitative and qualitative contribution of two reproductive modes.