11 research outputs found

    Geographical variation of gene diversity of Pinus pinaster Ait. in the Iberian Peninsula

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    International audienceThe geographical variation of 25 native populations of maritime pine (Pinus pinaster Ait.) was studied using ten allozymes encoded by 16 loci. A phylogenetic tree based on Nei’s unbiased genetic distance and a Mantel’s randomization test were made. Geostatistical analysis was used for describing in more detail spatial patterns of gene frequencies. The phylogenetic analysis found a clear clustering in northwestern populations and a complex pattern, with two differentiated groups, in the southeastern and eastern regions. Clinal trends of variation and fine-scale spatial structure were detected by geostatistical analysis. Directional clinal variation was found from south to north and, though to a lesser extend, from east to west. This pattern was stronger when populations were separated by more than 250 km. The long-distance founder events during postglacial spread and the orientation of the main mountain ranges are proposed to be the main causes of the geographical structure of this species

    Population genetic structure in a Mediterranean pine (Pinus pinaster Ait.): a comparison of allozyme markers and quantitative traits

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    International audienceF-statistics were employed to analyse quantitative and allozyme variation among 19 native populations of maritime pine (Pinus pinaster Ait.). Fourteen polymorphic allozyme loci were used to provide an empirical basis for constructing a null hypothesis to test natural selection as a determinant of quantitative evolution in stem form, total height growth and survival at 30 years old. Hidden biases, that may result in a difference between quantitative (Q(ST)) and allozyme (F(ST)) differentiation which are not because of the action of natural selection, were avoided by comparing pairs of populations using linear models. All quantitative traits showed higher differentiation than allozymes. The highest divergence was found in stem form, whereas divergences in total height and survival were significantly lower. Differential adaptation to regional and local patterns of precipitation, temperature and soil type seem to be the best explanation of the different structure found in quantitative traits and allozyme loci. Possible bias in the estimation of Q(ST) due to the level of quantitative within-population diversity and the role of adaptation of maritime pine after the last glaciation to highly diverse ecological conditions are discussed with special reference to the actual geographical structure of gene diversity in the species' native range
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