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Global climate change (CC) is an evolutionary challenge for natural tree populations. Scientific experts forecast an increase in temperature and a decrease in precipitation in the Argentine Patagonian Cordillera. Knowledge of the variation of adaptive traits at the seedling stage is crucial to prediction the adaptability of forest tree species. We aim to analyze genetic variation in root and shoot quantitative traits among and within natural populations of two key North Patagonian forest species, in order to evaluate their ability to deal with CC through adaptation. We established two common garden nursery trials: (1) 81 open pollinated families of Nothofagus obliqua from eight natural populations, and (2) 74 families of Nothofagus alpina from seven populations. At the end of the first growing season we measured shoot height, diameter, root length and root and stem dry biomass; we also estimated foliage biomass. In addition the root to stem ratio, specific root length and the root to shoot ratio were calculated. For both species intra-population variation was generally low, and average differentiation was moderate, with high levels of differentiation in some traits related to drought stress, indicating low adaptation capacity but also adaptation to current stressful conditions, which means it may be possible for some populations to survive CC without changing their genetic structures. Further studies are needed, including phenotypic plasticity assays, to complete the picture. [ABSTRACT FROM AUTHOR]

Patagonian forests are the southernmost temperate forests in the world, and Nothofagus pumilio is one of their most ecologically important tree species (i.e., a foundation species). It presents great adaptability and a wide distribution range, making it a suitable model for predicting the performance of trees facing global climate change. N. pumilio forests are increasingly threatened by extreme climatic events and anthropogenic activities. This study aims to identify priority conservation areas and Genetic Zones (GZs) for N. pumilio, promoting the implementation of specific practices to ensure its management and long-term preservation. Thirty-five populations (965 trees) sampled across its distribution (more than 2200 km latitudinally) were genotyped with SSRs, and geographical patterns of genetic variation were identified using Bayesian approaches. The phylogeographic patterns of the species and geomorphological history of the region were also considered. Six priority conservation areas were identified, which hold high allelic richness and/or exclusive allelic variants. Eighteen GZs were delineated based on the genetic structure of this species, and maps showing their distributional range were drawn up. Overall, this study defines management units based on genetic data for N. pumilio for the first time, which will facilitate the establishment of sustainable practices and highlight priorities for investment of conservation funding. [ABSTRACT FROM AUTHOR]

Abstract: Knowledge about current patterns of genetic structure of populations together with the evolutionary history of a species helps to understand and predict the adaptation of populations to future climate change. We assayed variation at nuclear microsatellite markers among peripheral vs. continuous populations of the temperate South American species Austrocedrus chilensis, to investigate the role of historical vs. demographical forces in shaping population genetic structure. This species occurs in continuous populations in the west and central distribution range, but becomes highly fragmented at the eastern limit, which comprised ice-free areas during Quaternary glaciations and has extreme climatic conditions at present times. Bayesian analysis methods identified two contrasting patterns of genetic structure; (I) populations from humid, mesic and peri-glacial regions formed a single deme with relatively low genetic differentiation and high admixture levels whereas (II) a highly heterogeneous genetic structure with low level of admixture was found in the steppe, towards the east and northeast limit of the distribution range. In the steppe, population fragmentation, restricted gene flow and isolation-by-distance were also inferred. In addition, several small steppe populations showed high genetic diversity and divergent gene pools, suggesting that they constitute ancient refuges from pre-Holocene glaciations with just a subgroup of them contributing significantly to post-glacial spread. These results are discussed in relation to patterns of genetic variation found for other temperate species and the contribution of the particular southern Andes topography and climate to post-glacial spread. [Copyright &y& Elsevier]