Abstract
The increase in temperature as consequence of the recent global warming has been reported to generate new ice-free areas in the Antarctic continent, facilitating 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 become progressively more departed from the species’ physiological optimum, the ecophysiological responses and survival to the expected global warming could be reduced. 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 (three 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 the latitudinal gradient. In addition, we tested if the release of the stress condition by the global warming in these cold environments increases 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 respective to each site of origin after three growing seasons. Overall, was found 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. Our results suggest that under a global warming scenario, plant populations that inhabiting cold zones at high latitudes could increase in their ecophysiological performance, enhancing the size of populations or their spread.
Highlights
We addressed the following questions: (1) Does C. quitensis show signs of clinal variation in anatomical or physiological traits along a latitudinal gradient in which environmental stress increases with latitude; and (2) Will southern populations of C. quitensis be more responsive to simulated global warming than more northern populations? To address these questions, we measured leaf anatomy and xanthophyll pigments in C. quitensis along a latitudinal gradient consisting of three locations from South America to the Antarctic Peninsula
The greatest response to experimental warming was found in individuals from the southernmost population (AP), while individuals from South America showed the lowest response to experimental warming (Fig. 2; Tables S2, S3)
Our results indicate that in the widely distributed C. quitensis, morphological and physiological traits reflect an asymmetric response associated with increasing environmental stress induced by a combination of increasingly colder, arid and photo-inhibitory conditions with latitude
Summary
The Antarctic continent is among the most stressful environments for plant life worldwide (Robinson, Wasley & Tobin, 2003; Peck, Convey & Barnes, 2006); establishment and survival is limited by conditions such as low temperatures, desiccation, wind abrasion, high radiation and low water and nutrient availability (Alberdi et al, 2002; Robinson, Wasley & Tobin, 2003; Wasley et al, 2006; Convey, 2011). Recent warming during the last five decades has produced new summer ice-free areas, which have provided suitable habitats for plant colonization (Convey et al, 2014; Cannone et al, 2016). Increases in both the size and number of C. quitensis and D. antarctica populations have been reported (e.g., Smith, 1994; Day et al, 1999; Torres-Mellado, Jaña & Casanova-Katny, 2011; Cannone et al, 2016), and southward population expansions can be projected for the century. Climate change is expected to have an overall positive impact on the growth, survival and fitness of C. quitensis (Convey, 2011; Day et al, 2009; MolinaMontenegro et al, 2012a; Torres-Díaz et al, 2016), the eco-physiological responses to the different components of climate change (e.g., warming) could differ among populations along the latitudinal gradient
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