Multiple elevational patterns of nuclear genetic variations in oak populations elucidated by grouping populations with chloroplast markers
Classical theories predict that intra-population genetic diversity will generally decline, while among-population differentiation increases towards the range margins of a species, and historical influences such as climate changes are also likely to be reflected in genetic structures. However, many studies of plant populations have found neither the theoretically expected patterns nor evidence of historical influence along elevational gradients. Hypothesising that in some cases this may have been due to conflicting patterns among lineages, we studied genetic variation in 18 Quercus crispula populations in the southern Kiso Mountains, central Japan, using nuclear and chloroplast microsatellite markers. The chloroplast marker analysis indicated that multiple lineages came from different refugia, enabling us to delimit two groups of maternal lineages. In nuclear loci analyses, by contrast, we found a roughly homogeneous structure, consisting of populations with similar genetic variations and compositions, although allelic richness decreased significantly with increasing elevation. However, this decrease was more significant in the group of southern maternal lineages. In addition, H E showed a significant correlation with altitude in this group (with a single outlier), probably reflecting past upward movements. Consequently, the discrimination of patterns in different groups helped us to decompose and understand more minutely even considerably homogeneous structures.
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Document Type: Research Article
Affiliations: Laboratory of Forest Ecosystem Studies, Department of Ecosystem Studies, Graduate School of Agricultural and Life Sciences,The University of Tokyo, Tokyo, Japan
Publication date: 2011-08-01