Physiological seed dormancy increases at high altitude in Pyrenean saxifrage (Saxifraga longifolia Lapeyr.)
Cotado A, Garcia MB, Munné-Bosch S. 2020. Environmental and Experimental Botany 171. https://doi.org/10.1016/j.envexpbot.2019.103929
Seed dormancy determines population dynamics and it is an essential feature of the ecology of high-mountain plants. Although altitudinal changes in the ecological and physiological performance of Pyrenean saxifrage (Saxifraga longifolia Lapeyr.) has been investigated to some extent, nothing it still know about how seed dormancy is influenced by environmental conditions imposed by altitude in these plants. Here, we evaluated altitudinal changes in seed viability and germination, but also on the endogenous contents of phytohormones and antioxidants in Pyrenean saxifrage. We found that, despite seed germination decreased at the highest population (2100m a.s.l.) relative to the other two populations (at 570 and 1100m a.s.l.), the highest population showed the highest seed viability, thus indicating increased seed dormancy. Hormonal profiling of the seeds revealed that this dormancy was modulated physiologically, in particular by increased abscisic acid accumulation, while gibberellin contents kept constant, relative to the seeds of the other two populations. Furthermore, seed xanthophyll contents, in particular those of lutein, neoxanthin, violaxanthin and antheraxanthin increased with altitude, while those of α-tocopherol kept unaltered. We conclude that the lower temperature imposed by altitude strongly influences not only seed viability and germination, but also seed dormancy, and that changes associated to temperature differences among populations are modulated at the physiological level by increasing the accumulation of abscisic acid and xantophylls in mature seeds. Results strongly support the contention that physiological seed dormancy has evolved as a means to increase plant survival under harsh environmental conditions in Pyrenean saxifrage plants growing in their natural habitat.
The climatic change. Learning from past survivors and present outliers.
García MB, J Arroyo, J Ehrlén. 2020. Environmental and Experimental Botany 170, 10.1016/j.envexpbot.2019.103931
Global gene flow releases plants from environmental constraints on genetic diversity.
Smith, Annabel L., Trevor R. Hodkinson, Jesus Villellas, Jane A. Catford, Anna Mária Csergő, Simone P. Blomberg, Elizabeth E. Crone, Johan Ehrlén, Maria B. Garcia, et al. Proceedings of the Natural Academy of Sciences. https://doi.org/10.1073/pnas.1915848117
When plants establish outside their native range, their ability to adapt to the new environment is influenced by both demography and dispersal. However, the relative importance of these two factors is poorly understood. To quantify the influence of demography and dispersal on patterns of genetic diversity underlying adaptation, we used data from a globally distributed demographic research network comprising 35 native and 18 nonnative populations of Plantago lanceolata. Species-specific simulation experiments showed that dispersal would dilute demographic influences on genetic diversity at local scales. Populations in the native European range had strong spatial genetic structure associated with geographic distance and precipitation seasonality. In contrast, nonnative populations had weaker spatial genetic structure that was not associated with environmental gradients but with higher within-population genetic diversity. Our findings show that dispersal caused by repeated, long-distance, human-mediated introductions has allowed invasive plant populations to overcome environmental constraints on genetic diversity, even without strong demographic changes. The impact of invasive plants may, therefore, increase with repeated introductions, highlighting the need to constrain future introductions of species even if they already exist in an area.
