Population Genetic Structure of Two Forest Grasses with Contrasting Life Forms, Arundinella setosa and Garnotia tenella in Thailand

Abstract

Plastid microsatellite DNA markers and Nei’s (1978) unbiased genetic distance, the unweightedpair-group method of analysis and principal components analysis were employed to assess the intra- and interpopulation genetic variations of two forest grasses with contrasting breeding systems. Seven haplotypes and 4 groups from 11 populations of Arundinella setosa, and 11 haplotypes and 4 groups from 8 populations of Garnotia tenella, were defi ned. The high value of genetic diversity within the populations suggested that they consist of multiple genets and indicates nonclonality in individuals of clonally spreading A. setosa. For the annual G. tenella, it suggested that the populations are not fi xed for a plastid DNA type and that seed-mediated genefl ow is occurring. The haplotype distributions refl ect patterns of plant dispersal via seed. The low population genetic differentiations among populations (GST: Arundinella = 0.049; Garnotia = 0.155) suggested that the most variation in haplotypes is distributed within populations. The high value of genetic diversity but low gene fl ow estimates of both grasses, found in Northern Thailand, could be affected by topographical barriers and habitat fragmentation but no obvious correlations of biogeographical distribution were found that were consistent with previously defi ned Thai fl oristic regions. However, groupings in the analyses provided weak evidence for a general east-west divide.