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6 Endemic plants in Corsica (Photo courtesy of G. Paradis) (A) Anchusa crispa, (B) Helicodiceros muscivorus, (C) Morisia monanthos (See Colour Plates)
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Corsica is the fourth largest Mediterranean Island; it is c.183 km north-south, and 83 km east-west and covers 8,682 km2. It is situated in the western part of the Mediterranean Sea (6°12–7°13 East, 41°9–43° North), at about 90 km west of continental
Italy, 14 km north of Sardinia, and 170 km south-east of continental France, its metropolitan attac...
Citations
... Looking at the literature on climatic studies in Corsica, little has been carried out so far (to the authors' knowledge). There are reports that describe the climate of Corsica [25], while other authors have specifically analyzed wind and rainfall patterns on the island, as well as the river flow patterns [26][27][28]. Regarding studies on the future evolution of climate, most studies consider the impacts of climate on Corsican vegetation or examine signs of climate change by observing the flora [29][30][31]. ...
Climate and climate change can impact present and future energy production and demand. In light of this issue, this paper conducts climatological analyses focused on the following meteorological quantities: shortwave downward irradiance (SDI), precipitation (Pr), relative humidity (RH), air temperature (Ta), 10 m wind speed (v10), and diurnal temperature range (DTR) for four locations in Corsica. The climate analyses of these atmospheric variables consist of three parts: (1) analysis of the historical trends; (2) correlation analysis; and (3) analysis of climate projections for the decades to come. It is observed that climate change is causing alterations in the trends of Pr, RH, Ta, v10, and DTR. The correlation analysis reveals a positive correlation for the Ta-SDI and v10-Pr pairs (both annually and seasonally), and a negative correlation for Ta-RH (annually and in summer). For the other variable pairs, the sign of the correlations varies depending on the time period and site considered. The trends in the projections from the multi-model ensemble simulations are consistent or inconsistent with each other depending on the time period (annual or seasonal) considered. The observed historical trends suggest that medium-term planning of the Corsican electric power system should already consider ongoing climate change. The correlation analysis provides insights into the combined effect of different atmospheric variables on electrical power systems (EPSs). Climate projections suggest studying long-term planning that is a compromise among the different (but equally likely) outputs of different climate models.
Agroforestry landscapes in the Mediterranean Basin have emerged in a co-evolution between humans and nature and provide numerous ecosystem services to society. Tree crops are iconic elements of these landscapes and have frequently been managed in a sustainable way over centuries, shaping multifunctional landscapes and local people's cultural identities. However, many Mediterranean tree-crop landscapes are undergoing substantial land-use changes, threatening important ecosystem services as a result. The overarching goal of this study is to explore common and diverging patterns of land-use change across different tree crops (oaks, chestnuts, olives) and contrasting landscapes in the Mediterranean Basin over a 200-year period. Specifically, we aim to: (1) describe the dominant land-use change processes across these three crop types using three exemplary sites per crop; and (2) identify and classify the main drivers that determine these landscapes' land change histories. We find a general acceleration of landscape dynamics and identify expansion, continuity, polarisation, intensifica-tion, abandonment and renaissance as dominant processes. Although each landscape history is contextualised, we observe a general trend from multifunctional tree-crop landscapes (expansion) towards intensification or abandonment in the last 70 years. The landscapes of the southern fringe of the Mediterranean Basin show predominant trends towards intensification, while the northern landscapes evolve towards abandonment. The driving forces identified are diverse and interrelated, comprising sets of socio-cultural, political, technical, economic and natural factors. We offer some key lessons for sustainable landscape management in highlighting the undervalued potential of tree crops, the inherent complexity of landscapes, the interdependencies of drivers and the importance of economic and socio-cultural driving forces.
In the Mediterranean region, Corsica represents one of the most important hotspots of biodiversity, partly due to the high number of endemics species. This region is also one of the most affected by forest fires worldwide. The present vegetation is adapted to a wide range of disturbance regimes, but a change in fire frequency or intensity in the future may severely affect ecological resources and other socio-economical aspects. Here, we study the dynamics of vegetation–human–fire interactions for the past 12,000 years as recorded by Lake Bastani (Corsica, France). We used well-dated sedimentary records of charcoal, pollen and fungal spores to infer past fire regime, land cover and pastoral activities, respectively, and we compared our results with charcoal records from two other Corsican lakes (Nino and Creno, respectively). Our results suggest that climate and natural fires were the main factors shaping the landscape before 5000 cal. BP. Then, the extraordinary diversity of the current Corsican vegetation has been mainly promoted by human activities on the island (i.e. deforestation and pastoralism) at least from the Bronze Age (3500 cal. BP). The top of our record shows a sharp decrease in fungal remains (Sporormiella-type), usually associated with pastoral activities, which could be attributed to the land abandonment occurring since a few decades.
Background
Mediterranean islands host a disproportionately high level of biodiversity and endemisms. Growing phylogeographic evidence on island endemics has unveiled unexpectedly complex patterns of intra-island diversification, which originated at diverse spatial and temporal scales. We investigated multilocus genetic variation of the Corsican-Sardinian endemic lizard Podarcis tiliguerta with the aim of shedding more light on the evolutionary processes underlying the origin of Mediterranean island biodiversity.
Results
We analysed DNA sequences of mitochondrial (12S and nd4) and nuclear (acm4 and mc1r) gene fragments in 174 individuals of P. tiliguerta from 81 localities across the full range of the species in a geographic and genealogical framework. We found surprisingly high genetic diversity both at mitochondrial and nuclear loci. Seventeen reciprocally monophyletic allopatric mitochondrial haplogroups were sharply divided into four main mitochondrial lineages (two in Corsica and two in Sardinia) of Miocene origin. In contrast, shallow divergence and shared diversity within and between islands was observed at the nuclear loci. We evaluated alternative biogeographic and evolutionary scenarios to explain such profound discordance in spatial and phylogenetic patterning between mitochondrial and nuclear genomes. While neutral models provided unparsimonious explanations for the observed pattern, the hypothesis of environmental selection driving mitochondrial divergence in the presence of nuclear gene flow is favoured.
Conclusions
Our study on the genetic variation of P. tiliguerta reveals surprising levels of diversity underlining a complex phylogeographic pattern with a striking example of mito-nuclear discordance. These findings have profound implications, not only for the taxonomy and conservation of P. tiliguerta. Growing evidence on deep mitochondrial breaks in absence of geographic barriers and of climatic factors associated to genetic variation of Corsican-Sardinian endemics warrants additional investigation on the potential role of environmental selection driving the evolution of diversity hotspots within Mediterranean islands.
Introduction to mountain biogeography Vegetation Flora Fauna Conservation in Mediterranean mountains Conclusion References
Island populations have been extensively used as model systems in ecology, biogeography, conservation and evolutionary biology, owing to the several simplifying assumptions that they allow. Nevertheless, recent findings from intra-island phylogeographic studies are casting doubts on the generality of some of these underlying assumptions. We investigated the phylogeography, historical demography, and population genetic structure of the Corsican endemic frog, Discoglossus montalentii. In contrast with expectations based on its insular, restricted and continuous distribution, we found evidence of 3 phylogroups, whose rather ancient divergence (Early-Middle Pleistocene) was likely primed by climatic changes that occurred during the 'middle Pleistocene revolution'. Furthermore, their differentiation explained most (68%) of the overall genetic diversity that was observed. These results and the growing evidence from intra-island phylogeographies, suggest that island populations frequently may not conform to some long-standing assumptions, including long-term stability, range-wide panmixia and the correlation of effective population size to the island size. As a consequence, both for theoretical and for applied purposes, the extensive use of these assumptions in the study of island populations warrants a careful re-examination.
Islands are hotspots of biodiversity, with a disproportionately high fraction of endemic lineages, often of ancient origin. Nevertheless, intra-island phylogeographies are surprisingly scarce, leading to a scanty knowledge about the microevolutionary processes induced on island populations by Plio-Pleistocene climatic oscillations, and the manner in which these processes contributed to shape their current genetic diversity. We investigated the phylogeography, historical demography and species distribution models of the Corsican endemic newt Euproctus montanus (north-western Mediterranean). As for many island endemics, the continuous distribution of E. montanus throughout its range has hitherto been considered as evidence for a single large population, a belief that also guided the species' categorization for conservation purposes. Instead, we found a geographic mosaic of ancient evolutionary lineages, with five main clades of likely Pliocene origin (2.6-5.8 My), all but one restricted to northern Corsica. Moreover, the copresence between main lineages in the same population was limited to a single case. As also suggested by growing literature on intra-island phylogeographic variation, it seems that the extensive use of simplifying assumption on the population structure and historical demography of island populations-both in theoretical and applicative studies-should be carefully reconsidered, a claim that is well exemplified by the case presented here.
The island of Corsica is a Mediterranean hotspot of plant biodiversity characterized by a high rate of plant endemism, but
also by a lack of studies combining genetic diversity and conservation. In Corsica, the dioecious and Corso-Sardinian endemic
Mercurialis corsica Cosson (Euphorbiaceae) occurs across a wide ecological gradient, but the number of populations have decreased considerably
over the last century. The main aim of this study was to examine the patterns of genetic diversity occurring in the Corsican
populations of M. corsica, depending on their location and demographic structure. The rDNA sequences did not show the existence of any polymorphism,
whereas the cpDNA sequences revealed the divergence of the western Corsican populations. By contrast, when the AFLP markers
were examined, although significant levels of differentiation were detected between populations, no distinct geographical
patterns were observed except for the pronounced isolation of the Cap Corse genotypes. No significant correlations were found
to exist between population size and the genetic diversity indexes used. The results of this study suggest that M. corsica has undergone a complex gene flow history involving past population admixtures, followed by fragmentation processes resulting
in population differentiation but no geographical patterns of isolation. These results support the existence of three evolutive
conservation units which have to be monitored in priority to determine whether the current pattern of demographic structure
is still declining or has stabilized.
KeywordsAFLP–Chloroplast DNA–Conservation genetics–Dioecy–Insularity–Ribosomic DNA
