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. 2006 Nov;98(5):1025-34.
doi: 10.1093/aob/mcl182. Epub 2006 Sep 1.

Genetic Structure of Galitzkya Macrocarpa and G. Potaninii, Two Closely Related Endemics of Central Asian Mountain Ranges

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Genetic Structure of Galitzkya Macrocarpa and G. Potaninii, Two Closely Related Endemics of Central Asian Mountain Ranges

K Wesche et al. Ann Bot. .
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Abstract

BACKGROUND AND AIMS Habitats in mountains are often isolated. Plants growing in these sites face severe dispersal limitations, but also difficulties for recruitment. The focus was laid on the magnitude of genetic differences among populations but also on the size of potentially occurring clones.

Methods: RAPD fingerprints were obtained from 23 populations in southern Mongolia. Sampling covered the entire distribution range of Galitzkya macrocarpa; samples of G. potaninii represented only the Mongolian part of its mainly northern Chinese range.

Key results: The Mongolian endemic G. macrocarpa showed moderately strong population differentiation (Phi ST = 0.251), and limited evidence for isolation by distance. Local genetic diversity was not positively correlated to habitat size, and not reduced in peripheral populations. Clonal growth is possible, but most plants originate from sexual reproduction. In contrast, populations of G. potaninii were highly differentiated (Phi ST = 0.550); and the most remote outposts had reduced genetic diversity. In these areas, isolation is expected to date back to glacial times.

Conclusions: Effects of natural fragmentation differ among species. Both are rare, but G. macrocarpa appears to be able to maintain genetic diversity over its range. Clonal growth is an option in its mixed reproduction strategy and allows survival under harsh conditions. In contrast, genetic structure in G. potaninii gives reason for concern, and further studies on population dynamics are needed.

Figures

F<sc>ig</sc>. 1
Fig. 1
Position of sampling localities in southern Mongolia. Numbers of ranges refer to Table 1; the question mark indicates the site Edrengiyn Nuruu, where both species had previously been recorded (Grubov, 2001) but were not found in this study. Dotted lines demarcate the nature reserves (Great Gobi ‘A’ and ‘B’ Special Protected Areas, Gobi Gurvan Saykhan National Park) in the region.
F<sc>ig</sc>. 2
Fig. 2
Principal co-ordinate analysis of RAPD data for G. macrocarpa and G. potaninii (based on square-root transformed Sörensen similarity; explained variance axis 1 = 43·7 %; axis 2 = 7·9 %; axis 3 = 3·4 %).
F<sc>ig</sc>. 3
Fig. 3
Principal co-ordinate analysis of RAPD data for G. macrocarpa (all 138 available samples; PCA based on square-root transformed Sörensen Similarity; explained variance axis 1 = 8·6 %; axis 2 = 6·1 %; axis 3 = 5·2 %).
F<sc>ig</sc>. 4
Fig. 4
Scatterplot indicating the relationship between geographic and genetic distance among populations.
F<sc>ig</sc>. 5
Fig. 5
Small-scale distribution of shoots of G. macrocarpa. Dots indicate individual shoots, shading corresponds to its number of inflorescences. Outlined areas include shoots with an identical marker phenotype.

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