The Palaeoentomological record of Cavallo island (Lavezzi archipelago, southern Corsica): 7000 years of a complex environmental history

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What is a tree in the mediterranean basin hotspot? A critical analysis

Background: Tree species represent 20% of the vascular plant species worldwide and they play a crucial role in the global functioning of the biosphere. The Mediterranean Basin is one of the 36 world biodiversity hotspots, and it is estimated that forests covered 82% of the landscape before the first human impacts, thousands of years ago. However, the spatial distribution of the Mediterranean biodiversity is still imperfectly known, and a focus on tree species constitutes a key issue for understanding forest functioning and develop conservation strategies. Methods: We provide the first comprehensive checklist of all native tree taxa (species and subspecies) present in the Mediterranean-European region (from Portugal to Cyprus). We identified some cases of woody species difficult to categorize as trees that we further called “cryptic trees”. We collected the occurrences of tree taxa by “administrative regions”, i.e. country or large island, and by biogeographical provinces. We studied the species-area relationship, and evaluated the conservation issues for threatened taxa following IUCN criteria. Results: We identified 245 tree taxa that included 210 species and 35 subspecies, belonging to 33 families and 64 genera. It included 46 endemic tree taxa (30 species and 16 subspecies), mainly distributed within a single biogeographical unit. The countries with the highest tree richness are Greece (146 taxa), Italy (133), Albania (122), Spain (155), Macedonia (116), and Croatia (110). The species-area relationship clearly discriminated the richest central-eastern (Balkans) and northern (Alpine and Cevenno-Pyrenean) biogeographical provinces, against the five western provinces in the Iberian Peninsula. We identified 44 unrecognized “cryptic trees”, representing 21% of the total trees. Among the 245 taxa identified, 19 are considered to be threatened (15 CR + EN + VU) or near threatened (4 NT) by IUCN. Conclusions: The Mediterranean-European region includes an unsuspectedly high number of tree taxa, almost 200 tree taxa more than in the central European region. This tree diversity is not distributed evenly and culminates in the central-eastern part of the Mediterranean region, whereas some large Tyrrhenian islands shelter several narrow endemic tree taxa. Few taxa are recognized as threatened in the IUCN Red list, and the vulnerability of these species is probably underestimated.French Foundation for Research on Biodiversity (FRB). Centre for Synthesis and Analysis of Biodiversity data ANR-11-LABX-006

WOODIV, a database of occurrences, functional traits, and phylogenetic data for all Euro-Mediterranean trees

Trees play a key role in the structure and function of many ecosystems worldwide. In the Mediterranean Basin, forests cover approximately 22% of the total land area hosting a large number of endemics (46 species). Despite its particularities and vulnerability, the biodiversity of Mediterranean trees is not well known at the taxonomic, spatial, functional, and genetic levels required for conservation applications. The WOODIV database fills this gap by providing reliable occurrences, four functional traits (plant height, seed mass, wood density, and specific leaf area), and sequences from three DNA-regions (rbcL, matK, and trnH-psbA), together with modelled occurrences and a phylogeny for all 210 Euro-Mediterranean tree species. We compiled, homogenized, and verified occurrence data from sparse datasets and collated them on an INSPIRE-compliant 10 × 10 km grid. We also gathered functional trait and genetic data, filling existing gaps where possible. The WOODIV database can benefit macroecological studies in the fields of conservation, biogeography, and community ecology.Labex OT-Med n ANR-11-LABX-006

Advances in genotyping microsatellite markers through sequencing and consequences of scoring methods for Ceratonia siliqua (Leguminosae)

Premise of the Study: Simple sequence repeat (SSR) or microsatellite markers have been used in a broad range of studies mostly scoring alleles on the basis of amplicon size as a proxy for the number of repeat units of an SSR motif. However, additional sources of variation within the SSR or in the flanking regions have largely remained undetected. Methods: In this study, we implemented a next-generation sequencing–based genotyping approach in a newly characterized set of 18 nuclear SSR markers for the carob tree, Ceratonia siliqua. Our aim was to evaluate the effect of three different methods of scoring molecular variation present within microsatellite markers on the genetic diversity and structure results. Results: The analysis of the sequences of 77 multilocus genotypes from four populations revealed SSR variation and additional sources of polymorphism in 87% of the loci analyzed (42 single-nucleotide polymorphisms and five insertion/deletion polymorphisms), as well as divergent paralog copies in two loci. Ignoring sequence variation under standard amplicon size genotyping resulted in incorrect identification of 69% of the alleles, with important effects on the genetic diversity and structure estimates. Discussion: Next-generation sequencing allows the detection and scoring of SSRs, single-nucleotide polymorphisms, and insertion/deletion polymorphisms to increase the resolution of population genetic studies.This research is part of the DYNAMIC project funded by the French National Research Agency (ANR‐14‐CE02‐0016). J.V. benefited from a postdoctoral fellowship funded by DYNAMIC (ANR‐14‐CE02‐0016) and a Marie Skłodowska‐Curie Individual Fellowship (704464‐YAMNOMICS‐MSCA‐IF‐EF‐ST)