Contrasting patterns of nuclear microsatellite genetic structure of Fraxinus mandshurica var. japonica between northern and southern populations in Japan
Article first published online: 2 MAR 2010
© 2010 Blackwell Publishing Ltd
Journal of Biogeography
Volume 37, Issue 6, pages 1131–1143, June 2010
How to Cite
Hu, L.-J., Uchiyama, K., Saito, Y. and Ide, Y. (2010), Contrasting patterns of nuclear microsatellite genetic structure of Fraxinus mandshurica var. japonica between northern and southern populations in Japan. Journal of Biogeography, 37: 1131–1143. doi: 10.1111/j.1365-2699.2010.02275.x
- Issue published online: 13 MAY 2010
- Article first published online: 2 MAR 2010
- Cold-adapted trees;
- cryptic northern refugia;
- Fraxinus mandshurica;
- nuclear microsatellites;
- post-glacial history
Aim The aim of this study is to detect extant patterns of population genetic structure of Fraxinus mandshurica var. japonica in Japan, and to provide insights into the post-glacial history of this species during the Holocene.
Location Hokkaido and Honshu islands, Japan (including the Oshima and Shimokita peninsulas).
Methods We examined nine polymorphic nuclear microsatellite loci to assess genetic variation within and among 15 populations across almost the entire range of the species in Japan. Extant patterns of geographical structure were analysed using Bayesian clustering, Monmonier’s algorithm, analysis of molecular variance, Mantel tests and principal coordinates analysis. Recent bottlenecks within populations and regional genetic variation were also assessed.
Results Northern populations (Hokkaido Island and the Shimokita Peninsula) formed a single homogeneous deme, maintaining the highest level of allelic diversity on the Oshima Peninsula. By contrast, southern populations (Honshu Island) demonstrated strong substructure on both coasts. Specifically, populations on the Pacific side of Honshu exhibited significant bottlenecks and erosion of allelic diversity but preserved distinct subclusters diverging from widespread subclusters on the Japan Sea side of this island.
Main conclusions Genetic evidence and life history traits suggest that F. mandshurica occupied cryptic northern refugia on the Oshima Peninsula during the Last Glacial Maximum, which is reflected in the species’ extant northern distribution. Strong geographical structure in southern populations, in agreement with fossil pollen records, suggests geographical isolation by mountain ranges running north–south along Honshu. Given that this tree species is cold-adapted and found in riparian habitats, populations on the Pacific side of Honshu probably contracted into higher-elevation swamps during warm post-glacial periods, leading to a reduction of effective population sizes and rare allelic richness.