Abstract
Research Highlights: We detected the longitudinal gradients of genetic diversity parameters, such as the number of alleles, effective number of alleles, heterozygosity, and inbreeding coefficient, and found that these might be attributable to climatic conditions, such as temperature and snow depth. Background and Objectives: Genetic diversity among local populations of a plant species at its distributional margin has long been of interest in ecological genetics. Populations at the distribution center grow well in favorable conditions, but those at the range margins are exposed to unfavorable environments, and the environmental conditions at establishment sites might reflect the genetic diversity of local populations. This is known as the central-marginal hypothesis in which marginal populations show lower genetic variation and higher differentiation than in central populations. In addition, genetic variation in a local population is influenced by phylogenetic constraints and the population history of selection under environmental constraints. In this study, we investigated this hypothesis in relation to Abies sachalinensis, a major conifer species in Hokkaido. Materials and Methods: A total of 1189 trees from 25 natural populations were analyzed using 19 EST-SSR loci. Results: The eastern populations, namely, those in the species distribution center, showed greater genetic diversity than did the western peripheral populations. Another important finding is that the southwestern marginal populations were genetically differentiated from the other populations. Conclusions: These differences might be due to genetic drift in the small and isolated populations at the range margin. Therefore, our results indicated that the central-marginal hypothesis held true for the southernmost A. sachalinensis populations in Hokkaido.
Highlights
The spatial distribution of genetic variation provides essential information for conservation programs and management of forest tree species [1]
These differences might be due to genetic drift in the small and isolated populations at the range margin
Our results indicated that the central-marginal hypothesis held true for the southernmost A. sachalinensis populations in Hokkaido
Summary
The spatial distribution of genetic variation provides essential information for conservation programs and management of forest tree species [1]. Long-lived plant species are sessile organisms and their survival is attributed to their adaptation to the local environment. Such adaptation processes inevitably involve genetic changes in local populations [9]. Genetic variation in a local population is influenced by phylogenetic constraints and the population history of selection under environmental constraints. Useful for inferring the genetic structure of local populations They are useful for inferring adaptability to similar environments according to similarities in genetic characteristics, as geographic genetic variations reflect the results of selection and adaptation to the local environment [10]
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