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Acuña-Rodríguez IS, Torres-Díaz C, Hereme R, Molina-Montenegro MA.2017. Asymmetric responses to simulated global warming by populations of Colobanthus quitensis along a latitudinal gradient. PeerJ Preprints5:e3069v1https://doi.org/10.7287/peerj.preprints.3069v1
The increase in temperature as consequence of the recent global warming has been reported to generate new ice-free areas in the Antarctic continent, propitiating the colonization and spread of plant populations. Consequently, antarctic vascular plants have been observed extending their southern distribution. But as the environmental conditions toward southern localities are progressively far apart from these species’ physiological optimum, the colonization of new sites and ecophysiological responses could be decreased. However, if processes of local adaptation are the main cause of the observed southern expansion, those populations could appear constrained to respond positively to the expected global warming. Using individuals from the southern tip of South America, the South Shetland Islands and the Antarctic Peninsula, we assess with a long term experiment (3 years) under controlled conditions if the responsiveness of Colobanthus quitensis populations to the expected global warming, is related with their different foliar traits and photoprotective mechanisms along their latitudinal gradient. In addition, we tested if the release of the stress condition by the global warming in theses cold environments increase the ecophysiological performance. For this, we describe the latitudinal pattern of net photosynthetic capacity, biomass accumulation, and number of flowers under current and future temperatures -by warming- respective to each site of origin after three growing seasons. Overall, was showed a clinal trend was found in the foliar traits and photoprotective mechanisms in the evaluated C. quitensis populations. On the other hand, an asymmetric response to warming was observed for southern populations in all ecophysiological traits evaluated, suggesting that low temperature is limiting the performance of C. quitensis populations, mainly in those from southern. Our results suggest that under a global warming scenario those plant populations that inhabiting cold zones at high latitudes could be improved in their ecophysiological performance, enhancing the size of populations or their spread.
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Summary of the results of independent one-way ANOVAs evaluating the effect of latitudinal origin (either population or temperature) on anatomical foliar traits and xanthophyll cycle pigment content of C. quitensis individuals sampled in the field. The net photosynthetic performance (measured as net photosynthesis rate) is shown under each thermal condition and population in common gardens and the ecophysiological responses to the simulated global warming expressed as the delta values between future and current individual values.
Pair-wise a posteriori comparisons (HSD Tukey test’s) between the net photosynthetic response of each population under current (t0) and future conditions estimated during three simulated growing seasons (t1:t3). Bonferroni correction was applied to all P values due to multiple comparisons.
Descriptive statistic of net photosynthesis measured (μmol CO2 m-2s-1) of each population under current (t0) and future conditions estimated during three simulated growing seasons (t1:t3). Mean, standard deviation (SD) and standard error (SE) are shown.