Plant populations growing along elevational gradients have been found to show inconsistent patterns in the distribution of genetic variation. Molecular markers used to study these patterns are usually targeting neutral processes, but may also be affected by selection. In this study, the effects of elevation and successional stage on genetic diversity of a dominant tree species were investigated controlling for neutrality of the microsatellite loci used. Diversity and differentiation among 24 populations of Castanopsis eyrei from different elevations (251-920m) and successional stages were analysed by eight microsatellite loci. One of the loci (Ccu97H18) deviated from a neutral model of differentiation among populations probably due to hitchhiking with an unknown locus under divergent selection. The analysis showed that C. eyrei populations had a high level of genetic diversity within populations (AR = 7.6, HE = 0.82). Genetic variation increased with elevation for both the putatively selected locus Ccu97H18 and the neutral loci. At locus Ccu97H18 one allele was dominant at low elevations, which was replaced at higher elevations by an increasing number of other alleles. The level of genetic differentiation at neutral loci was similar to that of other Fagaceae species (FST = 0.032, F'ST = 0.15). Population differentiation followed a model of isolation by distance ,however, strongly significant isolation by elevation was found, both for all and the neutral loci and he putatively selected locus Ccu97H18..These patterns indicate higher gene flow among similar altitudinal levels than across different altitudinal levels. The study underlines the importance to check the selective neutrality of marker loci in analyses of population structure.

we sampled 24 sites, including 20 CSP sites and additional 4 sites. 12 to 49 individuals (mean = 24) per sites were collected. Genomic DNA was extracted from leaf samples using the DNeasy Plant minikit (QIAGEN). Eight highly polymorphic microsatellite loci were used for genotyping (Ueno et al., 2000, 2003). Fragment analysis was performed on an ABI PRISM 3130 with GS600-LIZ (Applied Biosystems) as internal size standard and using GeneMapper v.3.7 software for genotyping.We used Micro-Checker 2.2.3 (Van Oosterhout et al. 2004), FDIST (Beaumont and Nichols, 1996), Fstat v. 2.9.3.2 (Goudet 2001) to analyse the data.

The Gutianshan National Nature Reserve (NNR) is located in the western part of Zhejiang Province (29º8'18" – 29º17'29" N, 118º2'14" – 118º11'12" E, Fig. 1). The Gutianshan NNR has an area of approximately 81 km2 and was initially established as a National Forest Reserve in 1975 and became a National Nature Reserve in 2001. The NNR comprises a large portion of broad-leaved forests of advanced successional stages (Hu & Yu 2008), which have not been managed since the beginning of the 1990ies, as well as young successional stages and conifer plantations, mainly of Cunninghamia lanceolata and Pinus massoniana. --- The vegetation is composed of different types of subtropical evergreen and mixed broad-leaved forests (Yu et al. 2001). Most of the stands are secondary forests, evidenced by maximum tree ages of 180 years, by agricultural terraces in almost all plots and by the presence of charcoal in almost all soil profiles. Around the Gutianshan NRR extensive deforestation has occurred during the Great Leap Forward in the 1950s, as in most parts of Southeast China. However, due to prevailing steep slopes, the Gutianshan area was only marginally usable for agricultural activities, and thus an exceptionally intact forest cover has been preserved. --- The climate at Gutianshan NNR is warm and temperate with a short dry season in November and December and with warm summers (Fig. 2). The climatic conditions are characteristic for the subtropics with an annual average temperature of 15.1°C, January minimum temperatures of -6.8°C, July maximum temperatures of 38.1°C and an accumulated temperature sum (≥ 5°C) of 5221.5 degree days.

Most of the data were collected in 2008, while some additional data were also collected in 2009.

Castanopsis eyrei

This data can be used to assess the within species diversity of Castanopsis eyrei.