The Mediterranean region - a hotspot for plant biogeographic research

Transnational conservation to anticipate future plant shifts in Europe

To meet the COP15 biodiversity framework in the European Union (EU), one target is to protect 30% of its land by 2030 through a resilient transnational conservation network. The European Alps are a key hub of this network hosting some of the most extensive natural areas and biodiversity hotspots in Europe. Here we assess the robustness of the current European reserve network to safeguard the European Alps' flora by 2080 using semi-mechanistic simulations. We first highlight that the current network needs strong readjustments as it does not capture biodiversity patterns as well as our conservation simulations. Overall, we predict a strong shift in conservation need through time along latitudes, and from lower to higher elevations as plants migrate upslope and shrink their distribution. While increasing species, trait and evolutionary diversity, migration could also threaten 70% of the resident flora. In the face of global changes, the future European reserve network will need to ensure strong elevation and latitudinal connections to complementarily protect multifaceted biodiversity beyond national borders.

Nested singletons in molecular trees: Utility of adding morphological and geographical data from digitized herbarium specimens to test taxon concepts at species level in the case of Casearia (Salicaceae)

Using the genus Casearia, we assessed the status of nested singletons: individual specimens corresponding to accepted species but in molecular trees appearing nested within clades of closely related species. Normally, such cases would be left undecided, while on the other hand, timely taxonomic decisions are required. We argue that morphological, chorological, and ecological data can be informative to illuminate patterns of speciation. Their use can provide a first step in testing taxon concepts at species level. We focused on five cases of nested singletons in trees of the genus Casearia. We employed PCA and cluster analysis to assess phenotypic differentiation. Using geocoordinates, we calculated niche space differentiation based on 19 bioclim variables, by means of PCA and niche equivalency and similarity tests and generated dot maps. We found that the singletons were morphologically distinctive in two of the five cases (Casearia selloana and C. manausensis), relatively distinctive in two other cases (C. zizyphoides and C. mariquitensis), and partially overlapping in the last case (C. grandiflora). For two cases (C. mariquitensis and C. selloana), ecological niche space was broadly overlapping, in two cases it was found broadly nested (C. grandiflora and C. zizyphoides), and in one case narrowly nested (C. manausensis), but in no case niche differentiation was observed. Niche overlap, similarity and equivalency showed corresponding patterns. Given these data, one would interpret C. selloana and C. manausensis as presumably well-distinguished taxa, their narrow distribution ranges suggesting recently emerging lineages. The other three cases are not clearcut. Morphological data would suggest particularly C. grandiflora conspecific with C. arborea, but differences in the distribution are intriguing. Our approach would reject the notion of potential synonymy based on nested phylogenetic placement for at least two of the five cases. The other case also shows no complete lack of differentiation which would support synonymy.

Genome-wide footprints in the carob tree (Ceratonia siliqua) unveil a new domestication pattern of a fruit tree in the Mediterranean

Intense research efforts over the last two decades have renewed our understanding of plant phylogeography and domestication in the Mediterranean basin. Here we aim to investigate the evolutionary history and the origin of domestication of the carob tree (Ceratonia siliqua), which has been cultivated for millennia for food and fodder. We used >1000 microsatellite genotypes to delimit seven carob evolutionary units (CEUs). We investigated genome‐wide diversity and evolutionary patterns of the CEUs with 3557 single nucleotide polymorphisms generated by restriction‐site associated DNA sequencing (RADseq). To address the complex wild vs. cultivated status of sampled trees, we classified 56 sampled populations across the Mediterranean basin as wild, seminatural or cultivated. Nuclear and cytoplasmic loci were identified from RADseq data and separated for analyses. Phylogenetic analyses of these genomic‐wide data allowed us to resolve west‐to‐east expansions from a single long‐term refugium probably located in the foothills of the High Atlas Mountains near the Atlantic coast. Our findings support multiple origins of domestication with a low impact on the genetic diversity at range‐wide level. The carob was mostly domesticated from locally selected wild genotypes and scattered long‐distance westward dispersals of domesticated varieties by humans, concomitant with major historical migrations by Romans, Greeks and Arabs. Ex situ efforts to preserve carob genetic resources should prioritize accessions from both western and eastern populations, with emphasis on the most differentiated CEUs situated in southwest Morocco, south Spain and eastern Mediterranean. Our study highlights the relevance of wild and seminatural habitats in the conservation of genetic resources for cultivated trees.

Pollination in Agroecosystems: A Review of the Conceptual Framework with a View to Sound Monitoring

The pollination ecology in agroecosystems tackles a landscape in which plants and pollinators need to adjust, or be adjusted, to human intervention. A valid, widely applied approach is to regard pollination as a link between specific plants and their pollinators. However, recent evidence has added landscape features for a wider ecological perspective. Are we going in the right direction? Are existing methods providing pollinator monitoring tools suitable for understanding agroecosystems? In Italy, we needed to address these questions to respond to government pressure to implement pollinator monitoring in agroecosystems. We therefore surveyed the literature, grouped methods and findings, and evaluated approaches. We selected studies that may contain directions and tools directly linked to pollinators and agroecosystems. Our analysis revealed four main paths that must come together at some point: (i) the research question perspective, (ii) the advances of landscape analysis, (iii) the role of vegetation, and (iv) the gaps in our knowledge of pollinators taxonomy and behavior. An important conclusion is that the pollinator scale is alarmingly disregarded. Debate continues about what features to include in pollinator monitoring and the appropriate level of detail: we suggest that the pollinator scale should be the main driver.

Phylogeny and historical biogeography analysis support Caucasian and Mediterranean centres of origin of key holoparasitic Orobancheae (Orobanchaceae) lineages

The extensive diversity of the tribe Orobancheae, the most species-rich lineage of holoparasitic Orobanchaceae, is concentrated in the Caucasus and Mediterranean regions of the Old World. This extant diversity has inspired hypotheses that these regions are also centres of origin of its key lineages, however the ability to test hypotheses has been limited by a lack of sampling and phylogenetic information about the species, especially in the Caucasus region. First, we assessed the phylogenetic relationships of several poorly known, problematic, or newly described species and host-races of four genera of Orobancheae occurring in the Caucasus region-Cistanche, Phelypaea, Phelipanche and Orobanche-using nuclear ribosomal (ITS) and plastid (trnL-trnF) sequence data. Then we applied a probablistic dispersal-extinction-cladogenesis model of historical biogeography across a more inclusive clade of holoparasites, to explicitly test hypotheses of Orobancheae diversification and historical biogeography shifts. In sum, we sampled 548 sequences (including 196 newly generated) from 13 genera, 140 species, and 175 taxa across 44 countries. We find that the Western Asia (particularly the Caucasus) and the Mediterranean are the centre of origin for large clades of holoparasitic Orobancheae within the last 6 million years. In the Caucasus, the centres of diversity are composed both of long-branch taxa and shallow, recently diversified clades, while Orobancheae diversity in the Mediterranean appears to represent mainly recent diversification.

Distribution of plant mycorrhizal traits along an elevational gradient does not fully mirror the latitudinal gradient

The influence of mycorrhizal symbiosis on ecosystem processes depends on the mycorrhizal type and status of plants. Early research hypothesized that the proportion of arbuscular mycorrhizal (AM) species decreases and of ectomycorrhizal (ECM) and ericoid mycorrhizal (ERM) species increases along increasing elevations and latitudes. However, there is very scarce information about this pattern along elevation gradients. We aimed to test this hypothesis and to describe the trends in plant mycorrhizal status by examining the Pyrenean mountain range (from 400 to 3400 m asl). The distribution of plant mycorrhizal types: AM, ECM, ERM, and non-mycorrhizal (NM) and status (obligately, OM, or facultatively, FM mycorrhizal plants, FM) were identified based on the Pyrenean Floristic Atlas and analyzed for climatic and edaphic drivers. The proportion of AM plants decreased slightly with elevation, while ECM species peaked at 1000 m asl. The proportion of ERM and NM plant species rose with increasing elevation. The proportion of FM species increased, and OM species decreased with increasing elevation. The change of AM and ECM species, and OM and FM species, along the elevational gradient, corresponds broadly to changes along the latitudinal gradient, driven by a combination of climatic and edaphic factors. Differently, the elevational occurrence of NM plant species is mainly driven only by climatic factors (low temperature) and that of ERM species by only edaphic factors (low pH). Large-scale macroecological studies (≥ 50 km grid cell) well reflect the effects of climate on the distribution of plant mycorrhizal traits, but local data (≤ 1 km grid cell) are needed to understand the effects of soil conditions and land use.

Geo-Climatic Changes and Apomixis as Major Drivers of Diversification in the Mediterranean Sea Lavenders (Limonium Mill.)

The Mediterranean realm, comprising the Mediterranean and Macaronesian regions, has long been recognized as one of the world's biodiversity hotspots, owing to its remarkable species richness and endemism. Several hypotheses on biotic and abiotic drivers of species diversification in the region have been often proposed but rarely tested in an explicit phylogenetic framework. Here, we investigate the impact of both species-intrinsic and -extrinsic factors on diversification in the species-rich, cosmopolitan Limonium, an angiosperm genus with center of diversity in the Mediterranean. First, we infer and time-calibrate the largest Limonium phylogeny to date. We then estimate ancestral ranges and diversification dynamics at both global and regional scales. At the global scale, we test whether the identified shifts in diversification rates are linked to specific geological and/or climatic events in the Mediterranean area and/or asexual reproduction (apomixis). Our results support a late Paleogene origin in the proto-Mediterranean area for Limonium, followed by extensive in situ diversification in the Mediterranean region during the late Miocene, Pliocene, and Pleistocene. We found significant increases of diversification rates in the "Mediterranean lineage" associated with the Messinian Salinity Crisis, onset of Mediterranean climate, Plio-Pleistocene sea-level fluctuations, and apomixis. Additionally, the Euro-Mediterranean area acted as the major source of species dispersals to the surrounding areas. At the regional scale, we infer the biogeographic origins of insular endemics in the oceanic archipelagos of Macaronesia, and test whether woodiness in the Canarian Nobiles clade is a derived trait linked to insular life and a biotic driver of diversification. We find that Limonium species diversity on the Canary Islands and Cape Verde archipelagos is the product of multiple colonization events followed by in situ diversification, and that woodiness of the Canarian endemics is indeed a derived trait but is not associated with a significant shift to higher diversification rates. Our study expands knowledge on how the interaction between abiotic and biotic drivers shape the uneven distribution of species diversity across taxonomic and geographical scales.

Biogeography of the xerophytic genus Anabasis L. (Chenopodiaceae)

AIM

Using the extremophile genus Anabasis, which includes c. 28 succulent, xerophytic C4 species, and is widely distributed in arid regions of Northern Africa, Arabia, and Asia, we investigate biogeographical relationships between the Irano-Turanian floristic region (ITfr) and its neighboring regions. We test whether the spread of arid and semi-arid biomes in Eurasia coincides with the biogeography of this drought-adapted genus, and whether the ITfr acted as source area of floristic elements for adjacent regions.

LOCATION

Deserts and semi-deserts of Northern Africa, Mediterranean, Arabia, West and Central Asia.

METHODS

Four cpDNA markers (rpL16 intron, atpB-rbcL, trnQ-rps16, and ndhF-rpL32 spacers) were sequenced for 58 accessions representing 21 Anabasis species. Phylogenetic relationships and divergence times were inferred using maximum likelihood and a time-calibrated Bayesian approach. To document the extant distribution of Anabasis, material from 23 herbaria was surveyed resulting in 441 well-documented collections used for the coding of eight floristic regions. Using this coded data, ancestral range was estimated using "BioGeoBEARS" under the DEC model.

RESULTS

Anabasis originated during the Late Miocene and the ancestral range was probably widespread and disjunct between Western Mediterranean and the Irano-Turanian regions. Diversification started with two divergence events at the Miocene/Pliocene boundary (5.1 and 4.5 mya) leading to Asian clade I with ITfr origin which is sister to a slightly younger Asian clade II, which originated in the Western ITfr, and a Mediterranean/North African clade with an origin in the Western Mediterranean.

MAIN CONCLUSIONS

Anabasis did not follow aridification and continuously expanded its distribution area, in fact its probably wide ancestral distribution area seems to have been fragmented during the very Late Miocene and the remnant lineages then expanded into neighboring arid regions. This genus supports the role of the ITfr as source area for xerophytic elements in the Mediterranean and Central Asia.

Modelization of the Current and Future Habitat Suitability of Rhododendron ferrugineum Using Potential Snow Accumulation

Mountain areas are particularly sensitive to climate change. Species distribution models predict important extinctions in these areas whose magnitude will depend on a number of different factors. Here we examine the possible impact of climate change on the Rhododendron ferrugineum (alpenrose) niche in Andorra (Pyrenees). This species currently occupies 14.6 km2 of this country and relies on the protection afforded by snow cover in winter. We used high-resolution climatic data, potential snow accumulation and a combined forecasting method to obtain the realized niche model of this species. Subsequently, we used data from the high-resolution Scampei project climate change projection for the A2, A1B and B1 scenarios to model its future realized niche model. The modelization performed well when predicting the species's distribution, which improved when we considered the potential snow accumulation, the most important variable influencing its distribution. We thus obtained a potential extent of about 70.7 km(2) or 15.1% of the country. We observed an elevation lag distribution between the current and potential distribution of the species, probably due to its slow colonization rate and the small-scale survey of seedlings. Under the three climatic scenarios, the realized niche model of the species will be reduced by 37.9-70.1 km(2) by the end of the century and it will become confined to what are today screes and rocky hillside habitats. The particular effects of climate change on seedling establishment, as well as on the species' plasticity and sensitivity in the event of a reduction of the snow cover, could worsen these predictions.

Biogeography of Mediterranean Hotspot Biodiversity: Re-Evaluating the 'Tertiary Relict' Hypothesis of Macaronesian Laurel Forests

The Macaronesian laurel forests (MLF) are dominated by trees with a laurophyll habit comparable to evergreen humid forests which were scattered across Europe and the Mediterranean in the Paleogene and Neogene. Therefore, MLF are traditionally regarded as an old, 'Tertiary relict' vegetation type. Here we address the question if key taxa of the MLF are relictual. We evaluated the relict hypothesis consulting fossil data and analyses based on molecular phylogenies of 18 representative species. For molecular dating we used the program BEAST, for ancestral trait reconstructions BayesTraits and Lagrange to infer ancestral areas. Our molecular dating showed that the origins of four species date back to the Upper Miocene while 14 originated in the Plio-Pleistocene. This coincides with the decline of fossil laurophyllous elements in Europe since the middle Miocene. Ancestral trait and area reconstructions indicate that MLF evolved partly from pre-adapted taxa from the Mediterranean, Macaronesia and the tropics. According to the fossil record laurophyllous taxa existed in Macaronesia since the Plio- and Pleistocene. MLF are composed of species with a heterogeneous origin. The taxa dated to the Pleistocene are likely not 'Tertiary relicts'. Some species may be interpreted as relictual. In this case, the establishment of most species in the Plio-Pleistocene suggests that there was a massive species turnover before this time. Alternatively, MLF were largely newly assembled through global recruitment rather than surviving as relicts of a once more widespread vegetation. This process may have possibly been triggered by the intensification of the trade winds at the end of the Pliocene as indicated by proxy data.

Understanding the formation of Mediterranean-African-Asian disjunctions: evidence for Miocene climate-driven vicariance and recent long-distance dispersal in the Tertiary relict Smilax aspera (Smilacaceae)

Tethyan plant disjunctions, including Mediterranean-African-Asian disjunctions, are thought to be vicariant, but their temporal origin and underlying causes remain largely unknown. To address this issue, we reconstructed the evolutionary history of Smilax aspera, a hypothesized component of the European Tertiary laurel forest flora. Thirty-eight populations and herbarium specimens representing 57 locations across the species range were sequenced at seven plastid regions and the nuclear ribosomal internal transcribed spacer region. Time-calibrated phylogenetic and phylogeographic inferences were used to trace ancestral areas and biogeographical events. The deep intraspecific split between Mediterranean and African-Asian lineages is attributable to range fragmentation of a southern Tethyan ancestor, as colder and more arid climates developed shortly after the mid-Miocene. In the Mediterranean, climate-induced vicariance has shaped regional population structure since the Late Miocene/Early Pliocene. At around the same time, East African and South Asian lineages split by vicariance, with one shared haplotype reflecting long-distance dispersal. Our results support the idea that geographic range formation and divergence of Tertiary relict species are more or less gradual (mostly vicariant) processes over long time spans, rather than point events in history. They also highlight the importance of the Mediterranean Basin as a centre of intraspecific divergence for Tertiary relict plants.

Diversification of Scrophularia (Scrophulariaceae) in the Western Mediterranean and Macaronesia--phylogenetic relationships, reticulate evolution and biogeographic patterns

The flora of the Mediterranean region and Macaronesia is characterized by high levels of species diversity and endemism. We examined phylogenetic relationships of Scrophularia within one of its secondary centers of diversity located in the Iberian Peninsula and adjacent Macaronesia. In total, 65 ingroup accessions from 45 species, representing an almost complete sampling of the region, were analyzed using sequences from the internal transcribed spacer region (ITS) and the plastid trnQ-rps16 intergenic spacer. Phylogenetic relationships were inferred using Bayesian inference, maximum likelihood and statistical parsimony networking. Incongruence between datasets was assessed with statistical tests and displayed by split networks. Biogeographic inferences incorporating information from both markers (despite low resolution in some parts of the trees) and all incongruent taxa were accomplished with a novel combination of methods, using trees generated with the taxon duplication approach as input for Bayesian binary MCMC (BBM) analysis as implemented in RASP. Nuclear and chloroplast markers support a clade which comprises the majority of Iberian and Macaronesian species and consists of three subclades. Analyses of the substantial incongruence observed among markers indicate reticulate evolution and suggest that Scrophularia species diversity in this region is largely attributable to hybridization; a combination of both polyploidy and dysploidy in the karyotypic evolution of Western Mediterranean Scrophularia taxa is proposed. Our results provide support for an ancient hybridization event between two widespread lineages, which resulted in an allopolyploid ancestor of the Iberian - Macaronesian group with 2n=58 chromosomes. The ancestor then diverged into the three main lineages present in the Iberian Peninsula, Northern Africa and Macaronesia today. Subsequent interspecific hybridizations at different ploidy levels additionally generated new species. Presumably, hybridization and diversification within the genus in the Western Mediterranean have not been restricted to one particular event, but occurred repeatedly. It can be assumed that the topographical complexity found in the Iberian Peninsula has promoted diversification and hybrid speciation processes in Scrophularia, and that isolation in glacial refugia has preserved recent and ancient lineages. For the Macaronesian taxa, biogeographic analyses support several origins, by colonizations from at least four distinct lineages.

Contrasting biogeographic and diversification patterns in two Mediterranean-type ecosystems

The five Mediterranean regions of the world comprise almost 50,000 plant species (ca 20% of the known vascular plants) despite accounting for less than 5% of the world's land surface. The ecology and evolutionary history of two of these regions, the Cape Floristic Region and the Mediterranean Basin, have been extensively investigated, but there have been few studies aimed at understanding the historical relationships between them. Here, we examine the biogeographic and diversification processes that shaped the evolution of plant diversity in the Cape and the Mediterranean Basin using a large plastid data set for the geophyte family Hyacinthaceae (comprising ca. 25% of the total diversity of the group), a group found mainly throughout Africa and Eurasia. Hyacinthaceae is a predominant group in the Cape and the Mediterranean Basin both in terms of number of species and their morphological and ecological variability. Using state-of-the-art methods in biogeography and diversification, we found that the Old World members of the family originated in sub-Saharan Africa at the Paleocene-Eocene boundary and that the two Mediterranean regions both have high diversification rates, but contrasting biogeographic histories. While the Cape diversity has been greatly influenced by its relationship with sub-Saharan Africa throughout the history of the family, the Mediterranean Basin had no connection with the latter after the onset of the Mediterranean climate in the region and the aridification of the Sahara. The Mediterranean Basin subsequently contributed significantly to the diversity of neighbouring areas, especially Northern Europe and the Middle East, whereas the Cape can be seen as a biogeographical cul-de-sac, with only a few dispersals toward sub-Saharan Africa. The understanding of the evolutionary history of these two important repositories of biodiversity would benefit from the application of the framework developed here to other groups of plants present in the two regions.

Morphological versus molecular markers to describe variability in Juniperus excelsa subsp. excelsa (Cupressaceae)

BACKGROUND AND AIMS

Juniperus excelsa M.-Bieb. is a major forest element in the mountains of the eastern part of Mediterranean and sub-Mediterranean regions. This study comprises the first morphological investigation covering a large part of the geographical range of J. excelsa and aims to verify the congruency between the morphological results and molecular results of a previous study.

METHODOLOGY

We studied 14 populations sampled from Greece, Cyprus, Ukraine, Turkey and Lebanon, 11 of which have previously been investigated using molecular markers. Three hundred and ninety-four individuals of J. excelsa were examined using nine biometric features characterizing cones, seeds and shoots, and eight derived ratios. Statistical analyses were conducted in order to evaluate the intra- and inter-population morphological variability.

PRINCIPAL RESULTS

The level of intra-population variability observed did not show any geographical trends. The total variation mostly depended on the ratios of cone diameter/seed width and seed width/seed length. The discrimination analysis, the Ward agglomeration method and barrier analysis results showed a separation of the sampled populations into three main clusters. These results confirmed, in part, the geographical differentiation revealed by molecular markers with a lower level of differentiation and a less clear geographical pattern. The most differentiated populations using both markers corresponded to old, isolated populations in the high altitudes of Lebanon (>2000 m). Moreover, a separation of the northern Turkish population from the southern Turkish populations was observed using both markers.

CONCLUSIONS

Morphological variation together with genetic and biogeographic studies make an effective tool for detecting relict plant populations and also populations subjected to more intensive selection.

Patterns of genetic variability and habitat occupancy in Crepis triasii (Asteraceae) at different spatial scales: insights on evolutionary processes leading to diversification in continental islands

BACKGROUND AND AIMS

Archipelagos are unique systems for studying evolutionary processes promoting diversification and speciation. The islands of the Mediterranean basin are major areas of plant richness, including a high proportion of narrow endemics. Many endemic plants are currently found in rocky habitats, showing varying patterns of habitat occupancy at different spatial scales throughout their range. The aim of the present study was to understand the impact of varying patterns of population distribution on genetic diversity and structure to shed light on demographic and evolutionary processes leading to population diversification in Crepis triasii, an endemic plant from the eastern Balearic Islands.

METHODS

Using allozyme and chloroplast markers, we related patterns of genetic structure and diversity to those of habitat occupancy at a regional (between islands and among populations within islands) and landscape (population size and connectivity) scale.

KEY RESULTS

Genetic diversity was highly structured both at the regional and at the landscape level, and was positively correlated with population connectivity in the landscape. Populations located in small isolated mountains and coastal areas, with restricted patterns of regional occupancy, were genetically less diverse and much more differentiated. In addition, more isolated populations had stronger fine-scale genetic structure than well-connected ones. Changes in habitat availability and quality arising from marine transgressions during the Quaternary, as well as progressive fragmentation associated with the aridification of the climate since the last glaciation, are the most plausible factors leading to the observed patterns of genetic diversity and structure.

CONCLUSIONS

Our results emphasize the importance of gene flow in preventing genetic erosion and maintaining the evolutionary potential of populations. They also agree with recent studies highlighting the importance of restricted gene flow and genetic drift as drivers of plant evolution in Mediterranean continental islands.

Historical isolation versus recent long-distance connections between Europe and Africa in bifid toadflaxes (Linaria sect. Versicolores)

BACKGROUND

Due to its complex, dynamic and well-known paleogeography, the Mediterranean region provides an ideal framework to study the colonization history of plant lineages. The genus Linaria has its diversity centre in the Mediterranean region, both in Europe and Africa. The last land connection between both continental plates occurred during the Messinian Salinity Crisis, in the late Miocene (5.96 to 5.33 Ma).

METHODOLOGY/PRINCIPAL FINDINGS

We analyzed the colonization history of Linaria sect. Versicolores (bifid toadflaxes), which includes c. 22 species distributed across the Mediterranean, including Europe and Africa. Two cpDNA regions (rpl32-trnL(UAG) and trnK-matK) were sequenced from 66 samples of Linaria. We conducted phylogenetic, dating, biogeographic and phylogeographic analyses to reconstruct colonization patterns in space and time. Four major clades were found: two of them exclusively contain Iberian samples, while the other two include northern African samples together with some European samples. The bifid toadflaxes have been split in African and European clades since the late Miocene, and most lineage and speciation differentiation occurred during the Pliocene and Quaternary. We have strongly inferred four events of post-Messinian colonization following long-distance dispersal from northern Africa to the Iberian Peninsula, Sicily and Greece.

CONCLUSIONS/SIGNIFICANCE

The current distribution of Linaria sect. Versicolores lineages is explained by both ancient isolation between African and European populations and recent events of long-distance dispersal over sea barriers. This result provides new evidence for the biogeographic complexity of the Mediterranean region.

Conservation genetics of the endangered Iberian steppe plant Ferula loscosii (Apiaceae)

Ferula loscosii (Lange) Willk (Apiaceae) is a threatened endemic species native to the Iberian Peninsula. The plant has a narrow and disjunct distribution in three regions, NE, C and SE Spain. Genetic variability within and among 11 populations from its natural distribution was assessed using allozymes. Intermediate levels of genetic diversity were detected in F. loscosii (P(99%) = 36.83; H(E) = 0.125; H(T) = 0.152). However, the highest genetic diversity (58%) corresponded to the threatened populations from SE and C Spain (H(T) = 0.169) rather than the more abundant and larger populations from NE Spain (Ebro valley) (H(T) = 0.122). Low to moderate levels of genetic structure were found among regional ranges (G(ST) = 0.134), and several statistical spatial correlation analyses corroborated substantial genetic differentiation among the three main regional ranges. However, no significant genetic differentiation was found among the NE Spain populations, except for a northernmost population that is geographically isolated. Outcrossing mating and other biological traits of the species could account for the maintenance of the present values of genetic diversity within populations. The existence of an ancestral late Tertiary wider distribution of the species in SE and C Spain, followed by the maintenance of different Quaternary refugia in these warmer areas, together with a more recent and rapid post-glacial expansion towards NE Spain, are arguments that could explain the low genetic variability and structure found in the Ebro valley and the higher levels of diversity in the southern Iberian populations.

Phylogeography of the rare Balkan endemic Martino's vole, Dinaromys bogdanovi, reveals strong differentiation within the western Balkan Peninsula

The spatial genetic structure of Martino's vole, a rare palaeoendemic species of the western Balkans, was investigated using DNA isolated from archived museum samples. The study was based on partial sequencing (555 bp) of the mitochondrial cytochrome b gene for 63 specimens from 20 different localities throughout the species' range. Three highly divergent allopatric phylogenetic lineages (Northwestern, Central and Southeastern) were recognized among 47 haplotypes, suggesting three independent glacial differentiation centres within the western Balkans. The Northwestern lineage, which showed the highest divergence from all other samples (mean sequence divergence of 6.64% +/- 1.10), comprised samples collected from northwest of the Neretva River in Croatia, western Bosnia and Herzegovina. The Central and Southeastern lineages were separated by an average sequence divergence of 2.95% +/- 0.66 and were geographically divided by the Drim River (the Kosovo Basin in Serbia). Overall, haplotype diversity decreased from the Northwestern lineage to the Central and subsequently the Southeastern lineage, in a geographical pattern consistent with a stepping stone colonization. The observed distribution indicates a gradual southerly expansion with subsequent allopatry across the Neretva River and Drim River approximately 1 and 0.3 million years ago, respectively. Such a scenario is concordant with palaeontological evidence. Several highly divergent sublineages within the Northwestern and Central lineages showed no significant geographical structuring, suggesting secondary contact of allopatrically evolved lineages. We hypothesize that the topographical complexity of the Balkans promoted allopatry and isolation on a small geographical scale during interglacial periods, with secondary contact during glacial maxima. Furthermore, the three main lineages should be regarded as evolutionary significant units with important implications for conservation. Ecological data show that the Northwestern lineage in particular fulfils all criteria for a highly endangered, evolutionarily significant unit.

Genetic diversity and spatial correlation patterns unravel the biogeographical history of the European sweet vernal grasses (Anthoxanthum L., Poaceae)

Different processes have contributed to shaping the present distribution of the European biotas. Up to three different tertiary- to quaternary-time-scale evolutionary scenarios have been proposed to interpret the divergence and genetic structuring of plant species in Europe. In the present study, the Amplified Fragment Length Polymorphisms technique has been used to unravel the species and regional phylogeography of the European sweet vernal grasses (Anthoxanthum L. Poaceae). Forty-six populations belonging to all seven European species of Anthoxanthum and covering a broad geographical and ecological range were selected. Different phylogeography and population genetics diversity and structure estimates indicated a clear divergence of old Messinian Mediterranean lineages, followed by a pre-Pliocene split between Mediterranean annuals and Eurosiberian perennials and a more recent Pleistocene differentiation of Arctic-Alpine, Atlantic and Submediterranean diploid to polyploid landraces. Regional and population correlation tests between geographical and genetic distances allowed to postulate distinct pre- and post-glacial colonization pathways across Europe for the taxa of this widespread genus.