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Adaptive capacity to climate change in the long-lived endemic cushion plant species Lyallia kerguelensis from the sub-Antarctic Kerguelen Islands

Abstract : The adaptive capacity of plants to climate change is defined as the ability of a species or population to cope with new environmental conditions and persist in surviving and reproducing. The Kerguelen Islands, in the sub-Antarctic region, harbour the long-lived endemic species, Lyallia kerguelensis Hook.f. (Montiaceae). The plant's distribution is restricted to the Island fellfields, regarded as a form of tundra ecosystem of rock with cold climate and strong winds. The plant might seem ill-equipped to face drastic climate change. Its strict endemism, relatively scarce distribution, cushion form and the occurrence of necrosis led to questioning its adaptive capacity. We hypothesized that the pool of variability (of morphology, transcriptome and soil rhizomicrobiome) of L. kerguelensis across contrasted environments might provide insights into its adaptation to harsh environments and its possible response to rapid climate change. In addition, we used data from long-term monitoring of the fate of populations and their morphological dynamics. L. kerguelensis’ morphology reveals allometry and responses to soil water content and wind intensity. Its transcriptome is region-specific with differential expression of genes related to abiotic or biotic stress responses. The microbiome of the Kerguelen Islands’ fellfield soils is specific and varies in relation to the soil nutrient content, and the rhizomicrobiome shows a similar variation while its composition is under the influence of the plant. Necrosis might be drought stress damages strongly related to fast drying and warming climate and might be worsened by salt stress and a shift in rhizomicrobiome composition. Finally, L. kerguelensis growth is very slow and population-specific and its life span is estimated at least several decades. Under current climate change trends in the Kerguelen Islands, L. kerguelensis may have the capacity to cope and change to adjust to environmental variation to a certain extent.
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Lorène Marchand. Adaptive capacity to climate change in the long-lived endemic cushion plant species Lyallia kerguelensis from the sub-Antarctic Kerguelen Islands. Vegetal Biology. Université Rennes 1, 2021. English. ⟨NNT : 2021REN1B049⟩. ⟨tel-03628579⟩

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