Errol Véla

Range-wide phylogeography of Juniperus thurifera L., a presumptive keystone species of western Mediterranean vegetation during cold stages of the Pleistocene.

We investigate the range-wide population structure and phylogeography of thuriferous juniper (Juniperus thurifera L.), a species with a highly disjunct distribution in the western Mediterranean. We genotyped a total of 327 individuals from 20 populations using amplified fragment length polymorphisms (AFLP). Different analyses such as principal co-ordinate analysis (PCoA), nonmetric multidimensional scaling of F(ST) distances among populations, unweighted pair group method with arithmetic mean (UPGMA), and Bayesian clustering revealed that the Strait of Gibraltar acted as an efficient barrier against gene flow between the Moroccan and European populations for a very long time, and consequently support that the Moroccan populations should be recognised as a distinct subspecies (J. thurifera L. subsp. africana (Maire) Romo and Boratyńsky). The Algerian population was genetically more closely related to the European than to the Moroccan ones, probably due to dispersal events from Europe to Algeria. With respect to the mainland European populations, our data are not conclusive to reject any of the two following hypotheses: (1) the Iberian Peninsula was subdivided into different gene pools, and was the source for the colonisation of the Pyrenees and the Alps; and (2) the pattern we see today is partly the result of immigration into the Iberian Peninsula, e.g. from the Alps. Finally, the Corsican population was closely related genetically to two northern Iberian populations most probably due to relatively recent long-distance dispersal.

BASECO: a floristic and ecological database of Mediterranean French flora

The French Mediterranean zone is one of the richest of the country, with 3200 species and many endemics. Because of its interest as a synthetic tool to store and manage data, an ecological Mediterranean flora database was created. Built around five tables, BASECO allows several queries about the botanical and ecological characteristics of about 1800 plants. The database was implemented in Access, which is a relational database management system. Each species is identified by a code and is characterised by several qualitative traits relating to morphology, reproduction, life forms and biogeographical distribution, including several modalities. Each trait is informed from one or two pre-defined reference botanical handbooks as much as possible. There are many different possible uses of this database, even at a huge scale, allowing to reveal patterns hard to detect with the taxonomic approach alone.

Temporal speciation pattern in the western Mediterranean genus Tudorella P. Fischer, 1885 (Gastropoda, Pomatiidae) supports the Tyrrhenian vicariance hypothesis.

The land snail genus Tudorella shows a peculiar disjunct distribution around the western Mediterranean coasts. Despite high phenotypic plasticity, only two species with a disputed number of subspecific taxa are currently recognised. We delimited the species with mitochondrial (COI & 16S) and nuclear (ITS-1) markers based on the unified species concept and suggested that there are eight species in the genus, two of them currently undescribed. Applying Bayesian phylogenetic model selection, we tested four different biogeographic hypotheses that could be causal for the current distribution pattern of extant Tudorella species. A scenario involving vicariance events resulting from the repeated splits of the Tyrrhenian plate with subsequent dispersal events over land bridges during the Pliocene received greatest support in the data.

Phylogeography of North African Atlas cedar (Cedrus atlantica, Pinaceae): Combined molecular and fossil data reveal a complex Quaternary history

Northwest Africa is a major hotspot of plant biodiversity, but very little is known about the Quaternary range dynamics of plant species in this region. Here we investigate the range-wide population structure and phylogeography of Atlas cedar (Cedrus atlantica), an emblematic forest tree endemic to Morocco and Algeria. We genotyped 261 individuals from 11 populations using AFLP markers. Data were analyzed using both conventional F(ST)-based techniques and Bayesian clustering. Overall population differentiation was high (F(ST) = 0.25). Two major groups of populations were identified, one distributed through the Rif and Middle Atlas mountains in Morocco and the other through the Algerian Tell Atlas and Aurès mountains as well as the Middle Atlas. Combined molecular and fossil data indicate that C. atlantica survived the Last Glacial Maximum in at least three disjunct refugia along the coast of the Mediterranean Sea, whereas the Middle Atlas, today the core of the species range, has been colonized relatively recently (<10000 yr BP). The colonization history of individual populations has left clear imprints in their present-day diversity, which may vary greatly even between nearby stands. Our study illustrates how integrating different data sources and analytical approaches can help elucidate complex range dynamics that would otherwise remain undeciphered.

Recurrent fires and environment shape the vegetation in Quercus suber L. woodlands and maquis.

The effects of fire recurrence on vegetation patterns in Quercus suber L. and Erica-Cistus communities in Mediterranean fire-prone ecosystems of south-eastern France were examined on stands belonging to 5 fire classes, corresponding to different numbers of fires (from 0 to 4) and time intervals between fires since 1959. A common pool of species was identified among the plots, which was typical of both open and closed maquis. Fire recurrence reduced the abundance of trees and herbs, whereas it increased the abundance of small shrubs. Richness differed significantly between the most contrasting classes of fire recurrence, with maximal values found in control plots and minimal values in plots that had burned recurrently and recently. Equitability indices did not vary significantly, in contrast to Shannons diversity index which mostly correlated with richness. Forest ecosystems that have burnt once or twice in the last 50 years were resilient; that is to say they recovered a biomass and composition similar to that of the pre-fire state. However, after more than 3-4 fires, shrubland communities displayed lower species richness and diversity indices than unburned plots. The time since the last fire and the number of fires were the most explanatory fire variables, governing the structure of post-fire plant communities. However, environmental factors, such as slope or exposure, also made a significant contribution. Higher rates of fire recurrence can affect the persistence or expansion of shrublands in the future, as observed in other Mediterranean areas.

Phylogeography of SW Mediterranean firs: Different European origins for the North African Abies species

The current distribution of Western Mediterranean Abies species is a result of complex geodynamic processes and climatic oscillations that occurred in the past. Abies sect. Piceaster offers a good study model to explore how geo-climatic oscillations might have influenced its expansion and diversification on both sides of the W Mediterranean basin. We investigated the genetic variation within and among nine populations from five Abies species by molecular markers with high and low mutation rates and contrasting inheritance (AFLP and cpSSR). Analyses revealed the opening of the Strait of Gibraltar as an effective barrier against gene flow between the Southern Iberian (A. pinsapo) and North African (A. marocana and A. tazaotana) firs. The A. pinsapo populations in Spain and likewise those of the A. marocana - A. tazaotana population complex were not differentiated, and no evidence was found to distinguish A. tazaotana at the species level. Diversification of Abies across North Africa could occur by way of at least two vicariant events from Europe, in the west, giving rise to the A. marocana - A. tazaotana complex, and in the east, giving A. numidica. Secondary contacts among species from Abies sect. Piceaster (A. pinsapo and A. numidica), and with A. alba (Abies sect. Abies) are also indicated. However, there is a closer relationship between the Algerian fir (A. numidica) and the North Mediterranean widespread A. alba, than with the Moroccan firs (A. marocana and A. tazaotana) or the Southern Iberian (A. pinsapo). We also discuss the distribution range of these taxa in its paleogeological and paleoclimatic context, and propose that part of the modern geography of the South-Western Mediterranean firs might be traced back to the Tertiary.

Factors Underlying the Narrow Distribution of the Mediterranean Annual Plant Arenaria provincialis (Caryophyllaceae)

The factors responsible for the patterns of niche differentiation and narrow endemism have rarely been investigated in annual Mediterranean plants. This topic was addressed here by performing comparative studies on realized niches, regional occupancy, global biogeographical distribution and seed traits of a set of Arenaria (Caryophyllaceae) species inhabiting southern Provence (SE France), focusing in particular on Arenaria provincialis, a narrow endemic restricted to the hills and modest calcareous mountains around the city of Marseille. Field studies were carried out from 2008 to 2009 at 624 sites in the limestone mountains where Arenaria species are likely to occur. The Arenaria species occurring in southern Provence vary greatly in their patterns of regional occupancy and their biogeographical distribution. Multivariate analysis of the realized niche showed that they have some similar limiting environmental factors in common, but they do not all occupy the same habitats. Studies on the fruits and seeds showed that the endemic A. provincialis has a larger seed than its congeners and a capsule that remains closed and falls from the plant at maturity. This well-differentiated diaspore specific to A. provincialis may be responsible for the limited dispersal capacity of this species. Phylogenetic analyses showed that A. provincialis is not closely related to the other taxa inhabiting southern Provence, but rather to Arenaria occurring in highland areas in the south of France. The restricted pattern of distribution of A. provincialis is probably due to the past isolation event from which it originated and to its limited dispersal capacity, rather than resulting from its ecological niche range.

Ecological magnitude and fine scale dynamics of the mediterranean narrow endemic therophyte, Arenaria provincialis (Caryophyllaceae)

Abstract In the context of plant species rarity in mediterranean ecosystems, this study aims to precise the autoecology of the local annual endemic plant, Arenaria provincialis (Caryophyllaceae), by quantifying habitat and vegetation characteristics, and demographic parameters. Its populations are surprisingly scattered along a wide altitudinal and topological range, but over small geographical distances. This implies an important habitat differentiation from the thermophilous dry coast to the colder supra—mediterranean summits in open limestone rocky habitats such as steep screes, ledges, cracks or crests. Among the 163 plant species identified in presence of A. provincialis within 100 m2 area, 92% belong to the stress Grime pole, highlighting the stressful conditions within the different habitats caused by drought, strong wind, and high thermic contrasts. Demographical surveys reveal strong spatial and temporal fluctuations.

Eastward colonization of the Mediterranean Basin by two geographically structured clades: The case of Odontites Ludw. (Orobanchaceae).

The biogeography of Mediterranean groups is very heterogeneous, because of the complex geologic and climatic history of the region. Our goal was to reconstruct the spatio-temporal history of the genus Odontites. In particular, we aimed to infer its area of origin and colonization routes, investigate its timing of diversification, and examine possible correlations with major environmental events. Based on sequencing of three chloroplast markers (psbA-trnH, trnL-trnF and trnC-ycf6), we reconstructed phylogenetic relationships among species. We performed molecular dating analyses (based on a large-scale rbcL dataset), ancestral areas reconstructions, and interpreted the observed patterns in the light of the complex geologic and climatic histories of the region. Our results suggested that Bartsiella and Bornmuellerantha should be reintegrated into Odontites s.l. The genus originated in the Iberian Peninsula ca. 18.9Ma and diverged into two main clades 16.2Ma, but species diversification was most intense <5-6Ma. The two clades showed a clear geographic pattern: one clade originated in the Iberian Peninsula and Morocco, and extended its range to Eastern North Africa and the central Mediterranean Basin; the other clade originated in Europe and Western Asia, and mostly diversified within this ancestral area. The eastward colonization of the Mediterranean Basin contrasts with many other plant groups. Nevertheless, the burst of diversification in the Plio-Pleistocene agrees with what has been reported for other groups, and is concomitant with the end of the Messinian Salinity Crisis, onset of the Mediterranean climate and Quaternary glaciations. The link between phylogeny and geography suggests limited dispersal, and most dispersal events may have occurred overland rather than overseas.

Waiting for integrative taxonomy: Morphospecies as an operational proxy for the radiative and reticulate genus Ophrys L. (Orchidaceae)?

Recently published botanical floras provided an opportunity to develop operational systems for identifying in the field in France of species of the difficult genus Ophrys. Its specific and infra-specific taxonomy is extremely complex because of conflicting points of view and/or insufficient knowledge about specific biological features. In order to produce an identification key based on observable morphological criteria we developed a pragmatic taxonomy suitable for non-expert botanists, which includes “morphospecies” that are unambiguously identifiable based on a number of unique or a combination of diagnostic criteria and “subspecies” that are sets of populations sharing the same geographical and ecological adaptations but not distinctly differing morphologically. The taxonomic scheme reviewed here for the section Pseudophrys is well correlated with the floral chemical signatures of all the French taxa. This intermediate position, between splitters (mainly orchidologists) and lumpers (mainly geneticists), will hopefully enable us to revise the taxonomy of this genus at the Euro- Mediterranean level.