Microsatellite markers help to assess genetic diversity among Opuntia ficus indica cultivated genotypes and their relation with related species

Opuntia spp. belong to the Cactaceae family and are native to Central America. The most economically important species is O. ficus indica, cultivated both for fruits and cladodes. The genus includes other important edible species (from diploid to octoploid) that occur worldwide as either wild or cultivated species in many arid or semiarid areas (e.g., the Mediterranean region). Several accessions are cultivated in different growing regions, but little is known about their ancestries and levels of genetic diversity. The aim of this study was to investigate the level of intraspecific genetic diversity among O. ficus indica cultivated varieties and some related species. Specifically, six highly polymorphic simple sequence repeats (SSR) and two expressed sequence tag (EST)-SSR loci were investigated in 62 wild and cultivated genotypes belonging to 16 Opuntia species. The clusters identified by the distance and model-based analyses clearly separated the wild opuntias from the cultivated ones. However, the O. ficus indica accessions did not cluster separately from other arborescent cactus pear species, such as O. amyclaea, O. megacantha, O. streptacantha, O. fusicaulis, and O. albicarpa, indicating that their current taxonomical classifications do not fit with their genetic variability. In general, the genotypes cultivated in Mexico showed high levels of diversity, whereas most of the spineless accessions collected in other countries had a very narrow genetic base. This study increases our knowledge of the variability among some of the most diffused Opuntia cultivated accessions. This study also points to the inconsistencies of previous taxonomical genotype assignments that were based solely on morphological characteristics.     

Centennial olive trees as a reservoir of genetic diversity

Background and Aims

Genetic characterization and phylogenetic analysis of the oldest trees could be a powerful tool both for germplasm collection and for understanding the earliest origins of clonally propagated fruit crops. The olive tree (Olea europaea L.) is a suitable model to study the origin of cultivars due to its long lifespan, resulting in the existence of both centennial and millennial trees across the Mediterranean Basin.

Methods

The genetic identity and diversity as well as the phylogenetic relationships among the oldest wild and cultivated olives of southern Spain were evaluated by analysing simple sequence repeat markers. Samples from both the canopy and the roots of each tree were analysed to distinguish which trees were self-rooted and which were grafted. The ancient olives were also put into chronological order to infer the antiquity of traditional olive cultivars.

Key Results

Only 9·6 % out of 104 a priori cultivated ancient genotypes matched current olive cultivars. The percentage of unidentified genotypes was higher among the oldest olives, which could be because they belong to ancient unknown cultivars or because of possible intra-cultivar variability. Comparing the observed patterns of genetic variation made it possible to distinguish which trees were grafted onto putative wild olives.

Conclusions

This study of ancient olives has been fruitful both for germplasm collection and for enlarging our knowledge about olive domestication. The findings suggest that grafting pre-existing wild olives with olive cultivars was linked to the beginnings of olive growing. Additionally, the low number of genotypes identified in current cultivars points out that the ancient olives from southern Spain constitute a priceless reservoir of genetic diversity.     

On the Genetic Affinity of Individual Tree Biomass Allometry in Poplar Short Rotation Coppice

Woody biomass is one of our main resources available to enhance the bio-economy, but its production varies considerably depending on the species, the environment and crop management. The variability associated with these crops complicates the estimation of biomass through prediction models. The specificity of environment or genotype level limits the application of many of the models, which are often developed for use at local geographical levels. Although generalizations involve some loss of accuracy, the inclusion of a wide range of data for a wide range of environments and genotypes can improve model applicability. A total of 11,265 data from short-rotation, high-density poplar plantations (from 22 sites in Spain, covering 29 genotypes belonging to 7 different taxonomic groups) were used to develop biomass prediction models under Mediterranean conditions and to test whether similarities in individual tree biomass allometry occur within the taxonomic group level. A general model and both taxonomic group- and genotype-level models were fitted using weighted nonlinear regression. The simplified model, in which only the basal diameter is included, presented the best model performance, explaining 87% of the variability. The allometric similarities among different genotypes were evaluated in order to explore the relationship between the most frequently used poplar genotypes in the Mediterranean area, and although certain groups were identified, it was not possible to relate these similarities among different genotypes to their taxonomic group affinity. This was also confirmed by comparing the performance of the general models with the taxonomic group-level models when predicting at the genotype level. Although estimates made using the general models are relatively precise, the use of genotype-level models is recommended for more accurate predictions.     

Origin of the invasive Arundo donax (Poaceae): a trans-Asian expedition in herbaria

Background and Aims

The hypothesis of an ancient introduction, i.e. archaeophyte origin, is one of the most challenging questions in phylogeography. Arundo donax (Poaceae) is currently considered to be one of the worst invasive species globally, but it has also been widely utilzed by man across Eurasia for millennia. Despite a lack of phylogenetic data, recent literature has often speculated on its introduction to the Mediterranean region.

Methods

This study tests the hypothesis of its ancient introduction from Asia to the Mediterranean by using plastid DNA sequencing and morphometric analysis on 127 herbarium specimens collected across sub-tropical Eurasia. In addition, a bioclimatic species distribution model calibrated on 1221 Mediterranean localities was used to identify similar ecological niches in Asia.

Key Results

Despite analysis of several plastid DNA hypervariable sites and the identification of 13 haplotypes, A. donax was represented by a single haplotype from the Mediterranean to the Middle East. This haplotype is shared with invasive samples worldwide, and its nearest phylogenetic relatives are located in the Middle East. Morphometric data characterized this invasive clone by a robust morphotype distinguishable from all other Asian samples. The ecological niche modelling designated the southern Caspian Sea, southern Iran and the Indus Valley as the most suitable regions of origin in Asia for the invasive clone of A. donax.

Conclusions

Using an integrative approach, an ancient dispersion of this robust, polyploid and non-fruiting clone is hypothesized from the Middle East to the west, leading to its invasion throughout the Mediterranean Basin.     

Assessing the drought tolerance variability in Mediterranean alfalfa (Medicago sativa L.) genotypes under arid conditions

This work investigated the variability in drought tolerance under arid conditions of Mediterranean alfalfa genotypes with the overall aim to assess the main criteria that are associated with the relative tolerance and to discover the most tolerant ecotypes. For this, 16 alfalfa genotypes originating from seven countries of the Mediterranean basin were tested in an experimental station in south of Tunisia. The trial was conducted under two irrigation treatments. The first was normally irrigated by providing an amount of water corresponding to the potential evapotranspiration of the crop, and in the second with water deficit which was applied by stopping the irrigation during 8 weeks in summer. A significant decrease was observed under water deficit for biomass production, leaf stem ratio and water use efficiency. The sensitive index, in stress treatment, varies between 13.8% and 46.2% for dry yield. Results showed that some genotypes exhibited high-forage yield potential even in the presence of stress, mainly Amerist, Sardi10 and Siriver. Proline accumulation in leaves was greater in water-stressed plants, while the K⁺ osmo-regulatory role was not definite. High biomass production, accumulation of proline and constancy of K⁺ in leaves are the most important criteria for tolerant alfalfa.     

Analysis of genetic diversity among medicinal therapist <Emphasis Type="Italic">Trigonella foenum</Emphasis>-<Emphasis Type="Italic">graecum</Emphasis> L. genotypes through RAPD and SSR markers

Trigonella is recognized as a medicinal therapist throughout the globe due to its multifaceted rare medicinal properties. It is indigenous from Iran to Northern India but has gained global acceptance towards cultivation and consumption for its yellow-to-amber colored seed which substantially contributes to food, pharmaceutical, nutraceutical and cosmetic industry. Genetic diversity serves as an excellent tool for developing improved crop varieties with breeder preferred traits. Unfortunately, very little information available on variability existing in commercial Trigonella genotypes considerably impedes the crop improvement. In this study, ninety Trigonella genotypes belonging to most productive North Indian states were subjected to multilocus genotyping using RAPD (49) and SSR (13) primers and detected an average of 55.60 and 50.16% polymorphism, respectively. The percentage polymorphism range (RAPD, 16.7–90.90; SSR, 33.30–66.66) average band informativeness (RAPD, 0.182–0.85; SSR, 0.21–0.91) and resolving power (RAPD, 0.95–9.984; SSR, 1.68–7.28) obtained revealed the wide range of diversity prevailing among these genotypes. Hierarchical clustering of genotypes in nine different clusters showed Trigonella’s genetic variability has wide genetic distribution across different agro-climatic zones. No consistency was observed while grouping Trigonella varieties based on eco-geographical region. Eventually, knowledge of these genetic differences significantly contributes in designing intra-specific crosses with potential interest to spice breeding programs. To the best of our knowledge, this is the first report of genetic diversity using SSR molecular markers in Trigonella foenum-graecum L.     

Multiple origins of the western European house mouse in the Aeolian Archipelago: clues from mtDNA and chromosomes

The expansion of Mus musculus domesticus from its origin has been studied in detail. The colonization routes and times depended on its commensal habits which favoured a rapid and recent dispersal, making it difficult to unravel the expansion pattern. The situation is still obscure in the central Mediterranean area. Mitochondrial D-loop was sequenced for 65 mice from the Aeolian Archipelago and the sixteen haplotypes identified were compared with the 528 available mouse haplotypes. The central Mediterranean phylogeography, the demographic history of the Aeolian mice and the relationships between mtDNA and karyotypes was investigate. Five lineages are present, belonging to five of the haplogroups previously described for the Mediterranean basin, and most individuals fall within the European haplogroups. The Archipelago was subjected to multiple colonizations and chromosomal and molecular data agree in indicating Sicily and Italy as possible sources of colonization in recent times. Nevertheless, the signatures of earlier colonizations might have been lost through extinction and admixing of mice due to human movements. Drastic events during the entire colonization process have led to the present-day random distribution of haplotypes. Furthermore, Salina emerges as an ancestral condition and no relation between karyotype composition and haplotype variability was highlighted.     

Structure of genetic diversity in <Emphasis Type="Italic">Olea europaea</Emphasis> L. cultivars from central Italy

The olive is considered one of the most important fruit crops of the Mediterranean basin where it shows a wide range of variability, with about 2,000 cultivars. Italy, with about 500 cultivars, plays a fundamental role. The ability to discriminate olive cultivars and estimate genetic variability are important factors in better management of genetic resources and in helping to understand how genetic diversity is partitioned among cultivars. The two main objectives of the present investigation were to evaluate the identity of cultivars grown in Abruzzo region, central Italy, and to study their genetic structure. We applied amplified fragment length polymorphism (AFLP) methodology on 84 genotypes belonging to the most relevant and oldest varieties cultivated in Abruzzo and on six unknown genotypes. The information content of data was evaluated using the Marker Ratio index and the Polymorphic Index Content. Moreover, STRUCTURE software was used to investigate the genetic population structure. The analysis enabled us to clearly distinguish eight cultivars within seven clusters. Additionally, one cluster was found to have various minor cultivars and showed a relatively high level of diversity. The partitioning of genetic diversity showed that the largest amount of molecular variance was within groups. Our data suggest that both sexual and clonal propagation have played an important role in the evolution of olive cultivars. In our hypothesis, some ancestral population spread in central Italy with a relevant role of seed propagation, followed by a selection of superior clones from which more traditional varieties originated. In a few cases, hybridization should be taken into consideration to explain the diffusion of recently developed cultivars.     

Cardoon as a Sustainable Crop for Biomass and Bioactive Compounds Production

Cardoon is a multi‐purpose and versatile Mediterranean crop, adapted to climate change, with a wide spectrum of potential applications due its added value as a rich source of fibers, oils and bioactive compounds. The Cynara species are a component of the Mediterranean diet and have been used as food and medicine since ancient times. The important role of cardoon in human nutrition, as a functional food, is due to its high content of nutraceutical and bioactive compounds such as oligofructose inulin, caffeoylquinic acids, flavonoids, anthocyanins, sesquiterpenes lactones, triterpenes, fatty acids and aspartic proteases. The present review highlights the characteristics and functions of cardoon biomass which permits the development of innovative products in food and nutrition, pharmaceutics and cosmetics, plant protection and biocides, oils and energy, lignocellulose materials, and healthcare industries following the actual trends of a circular economy.     

Genetic characterisation of traditional chestnut varieties in Italy using microsatellites (simple sequence repeats) markers

European chestnut (Castanea sativa) is an important multipurpose tree that has been cultivated for wood and fruit in the Mediterranean basin since ancient times. Cultivation of traditional chestnut varieties has a long tradition in Italy, where cultivars have been selected over centuries as a function of the best nut traits. In this study, 94 grafted chestnuts corresponding to 26 representative cultivars from Italy were evaluated by seven simple sequence repeat (SSR) markers to establish whether they corresponded to varieties in the narrow sense. The results allowed 20 genotypes to be identified that corresponded to the same number of clones. In total, 52 alleles were identified, eight of which were exclusive. Cases of homonymies and synonymies were detected. Moreover, our results highlighted a considerable genetic uniformity among ‘Marrone-type’ cultivars and, on the contrary, a high genetic diversity among the evaluated cultivars demonstrating that this is a valuable germplasm and an important genetic resource to be preserved.     

Genetic diversity and parentage of Tunisian wild and cultivated grapevines (Vitis vinifera L.) as revealed by single nucleotide polymorphism (SNP) markers

Based on 261 single nucleotide polymorphism (SNP) markers, we analyzed 57 grapevine genotypes, consisting of 29 wild grapevines (Vitis vinifera subsp. sylvestris) prospected from the northwest part of Tunisia and 28 cultivated accessions (V. vinifera subsp. vinifera) maintained in the repository of the Arid Land Institute of Medenine (Tunisia). Pair-wise multilocus comparison with the ICVV SNP database allowed the identification of 13 cultivated genotypes, including ten synonymous groups with known Mediterranean or international varieties, three cases of color sports, and two misnomers. Genotypic analysis showed a high level of genetic diversity for both wild and cultivated groups. Multivariate and structure analyses clearly differentiated wild from cultivated grapevines and showed high average posterior probabilities of assignment to their group of origin. The clustering results largely supported the perceived classification and reflect that most of the present Tunisian cultivated varieties do not derive directly from the local wild populations but could correspond to materials introduced from different locations during historical times. Parentage analysis allowed the determination of the genetic origin of four Tunisian cultivars, “Garai”, “Jerbi” (from Kerkennah), “Mahdoui”, and “Reine de Vignes faux”, and showed that “Heptakilo” and “Planta Fina”, two old and widely distributed varieties in the Mediterranean basin, had an important role in the origin of Tunisian grapevines. The present study demonstrates the efficacy of SNP makers for germplasm characterization and genetic studies in grapevine.     

Genetic variability among Pinus pinea L. provenances for survival and growth traits in Portugal

Pinus pinea L. (Mediterranean stone pine) is an important forest species not only for its economically relevant kernel production, but also for environmental protection. The detection of genetic variability is an essential issue for Mediterranean forest species for conservation and improvement programs. Based on data collected for several years at three field sites from a P. pinea L. provenance trial established in Portugal in 1993, the present study aimed to evaluate the genetic variability of the adaptive traits of P. pinea L. and to identify a group of provenances with high performance for growth traits to be used in future plantings. Several mixed models were fitted to survival and growth trait data to estimate provenance and provenance × site interaction variability. The empirical best linear unbiased predictors of provenance genotypic effects were used to select a superior group of provenances. The provenance genetic variability of P. pinea L. was successfully detected for survival and height of different planting ages and also for diameter at breast height at age 13 years after planting. For growth traits, the most successful methods used for evaluating provenance genetic variability were based on the linear mixed spatial models. When multi-environmental analysis was performed, provenance × site interaction variability was detected for survival, but not for height at age 6 years. The existence of provenance variability in P. pinea L. permitted the identification of a seed lot composed of a mixture of the best provenances for height and diameter.     

Genetic and leaf-trait variability of Vinca minor at ancient and recent localities in Central Europe

In Central Europe, Vinca minor has been planted for centuries as an ornamental, medicinal and ritual plant. We asked how variability in genetic and leaf traits of V. minor at ancient localities differs from that at recently established localities sampled mainly in the Czech Republic. Using selected ISSR primers, we obtained two clusters that correspond well with locality history. In the recent cluster, we identified a certain degree of genetic variability, whereas the ancient cluster exhibited none. We recorded significant differences in leaf shape between the clusters. Genotypes with narrow leaves were more characteristic of recent localities. Although the ancient cluster showed no variability in ISSR primers, it did show variability in leaf traits, indicating that some of the morphologically expressed genetic variability cannot be detected using ISSR primers. All samples were diploids (2n = 46), with an identical relative DNA content. Samples from ancient localities, such as deserted medieval settlements and castles, probably descended from a single or a few related clones. This supports the hypothesis concerning the allochthonous character of V. minor in the Czech Republic.     

High Genetic Diversity Detected in Olives beyond the Boundaries of the Mediterranean Sea

Background

Olive trees (Olea europaea subsp. europaea var. europaea) naturally grow in areas spanning the Mediterranean basin and towards the East, including the Middle East. In the Iranian plateau, the presence of olives has been documented since very ancient times, though the early history of the crop in this area is shrouded in uncertainty.

Methods

The varieties presently cultivated in Iran and trees of an unknown cultivation status, surviving under extreme climate and soil conditions, were sampled from different provinces and compared with a set of Mediterranean cultivars. All samples were analyzed using SSR and chloroplast markers to establish the relationships between Iranian olives and Mediterranean varieties, to shed light on the origins of Iranian olives and to verify their contribution to the development of the current global olive variation.

Results

Iranian cultivars and ecotypes, when analyzed using SSR markers, clustered separately from Mediterranean cultivars and showed a high number of private alleles, on the contrary, they shared the same single chlorotype with the most widespread varieties cultivated in the Mediterranean.

Conclusion

We hypothesized that Iranian and Mediterranean olive trees may have had a common origin from a unique center in the Near East region, possibly including the western Iranian area. The present pattern of variation may have derived from different environmental conditions, distinct levels and selection criteria, and divergent breeding opportunities found by Mediterranean and Iranian olives.These unexpected findings emphasize the importance of studying the Iranian olive germplasm as a promising but endangered source of variation.     

Introgression in peripheral populations and colonization shape the genetic structure of the coastal shrub Armeria pungens

The coastal shrub Armeria pungens has a disjunct Atlantic-Mediterranean distribution. The historic range expansion underlying this distribution was investigated using the nuclear internal transcribed spacer region, three plastid regions (namely trnL-F, trnS-fM and matK) and morphometric data. A highly diverse ancestral lineage was identified in southwest Portugal. More recently, two areas have been colonized: (1) Corsica and Sardinia, where disjunct Mediterranean populations have been established as a result of the long-distance dispersal of Portuguese genotypes, and (2) the southern part of the Atlantic range, Gulf of Cadiz, where a distinct lineage showing no genetic differentiation among populations occurs. Genetic consequences of colonization seem to have been more severe in the Gulf of Cadiz than in Corsica-Sardinia. Although significant genetic divergence is associated with low plastid diversity in the Gulf of Cadiz, in Corsica-Sardinia, the loss of plastid haplotypes was not accompanied by divergence from disjunct Portuguese source populations. In addition, in its northernmost and southernmost populations, A. pungens exhibited evidence for ancient or ongoing introgression from sympatric congeners. Introgression might have created novel genotypes able to expand beyond the latitudinal margins of the species or, alternatively, these genotypes may be the result of surfing of alleles from other species in demographic equilibrium into peripheral populations of A. pungens. Our results highlight the evolutionary significance of genetic drift following the colonization of new areas and the key role of introgression in range expansion.     

Genetic relationships and population structure of local olive tree accessions from Northeastern Spain revealed by SSR markers

The olive (Olea europaea L. subsp. europaea) is an old traditional crop which was domesticated from the wild at various locations around the Mediterranean basin, resulting in a vast number of accessions worldwide. This is the case of the northeast part of Spain (Aragon), where 163 genotypes were prospected and characterised. The majority of these genotypes (90 %) seem to be autochthonous accessions of this area and the rest are synonyms of accessions from other areas of Spain. In this study, 11 nuclear SSR markers were used to discriminate between the accessions and to understand the genetic relationship among them. All primers produced a successful amplification giving a total of 176 fragments in the genotypes studied, with an average of 16 alleles per SSR, ranging from 5 (DCA13) to 24 (DCA11). Allele size ranged from 120 bp at locus UDO99 to 284 bp at locus DCA15. The dendrogram generated using the variability observed classified most of the genotypes according to their geographical origin (Huesca, Teruel and Zaragoza provinces), confirming the particular evolution of different olive ecotypes. Structure software was used to investigate the genetic population structure among olive accessions, showing that the maximum rate of change in the log probability of the data occurred at K = 2. In addition, the SSR markers have consequently shown their usefulness for cultivar identification in olive, for establishing the genetic closeness among its accessions, and for establishing genealogical relationships.     

Steady-state assemblages in a Mediterranean hypertrophic reservoir. The role of Microcystis ecomorphological variability in maintaining an apparent equilibrium

Lake Arancio is a hypertrophic Mediterranean man-made lake, located on the southern coast of Sicily. Its artificial origin and the climate make it a very dynamic environment, strongly characterised by very wide water-level fluctuations. These vertical water movements interfere with the thermal stability of the water body often causing the breaking of the thermocline in mid-summer. In addition, the summer level-decrease influences the nutrient dynamics and modifies the z_mix/z_eu ratio. All these modifications were observed to support a high environmental variability, which was reflected by the richness of its phytoplankton composition and by its dynamics. Nevertheless, an investigation carried out from March 2001 to March 2002 showed that the assemblage was strongly dominated by a few species, one by one. In particular, two different Microcystis morphotypes dominated the assemblage from mid-April till the beginning of October. The prolonged dominance of these `species' should suggest that a steady state condition took place in Lake Arancio during spring and summer 2001. This is in contrast with previous investigations, which showed high diversity values especially occurring in the period of strong environmental instability when the continuous dewatering caused the breaking of the thermocline in the middle of summer. Nevertheless, this dominant species showed a very wide morphological variability and alternated among `more S', `S', and `R' (sensu Reynolds) ecotypes. The ever-changing morphological features suggest a different ecological behaviour of the species involved. They seem to confirm that the environmental variability of Mediterranean reservoirs sustains high diversity values, even though this diversity has to be sought in the amplitude of morphological plasticity of one or a few species, rather than in the coexistence of a variety of species.     

The introduction of Citrus to Italy, with reference to the identification problems of seed remains

While some consensus exists about the roles of southwestern China and northeastern India in the origin and diversification of the genus Citrus, the scarcity of its archaeological remains, as well as some methodological limits in unequivocally identifying taxa, do not facilitate reconstruction of the tempo and mode of spread of the genus towards other areas, notably the Mediterranean. Recent discoveries of archaeobotanical macro-remains (seeds and fruits) and pollen records from some important Italian sites in the Vesuvius area and Rome can be used to shed new light on this history. However, due to their morphological variability and the changes derived from the preservation processes, Citrus seeds appear difficult to recognise. In this paper, we present criteria to facilitate their precise identification, based on the observation of the morphology of modern seeds, and most of all the seed-coat patterns. The reference material consisted of “archaic” varieties of C. medica L. (citron), C. × limon (L.) Burm. f. (lemon) and seeds of C. × aurantium L. (bitter or Seville orange), C. × aurantiifolia (Christm.) Swingle (lime) and C. reticulata Blanco (tangerine, mandarin orange). Considering the fact that the general morphology of seeds, especially when mineralised, can confuse the identification of Citrus with Maloideae types, we also add criteria for the recognition of Cydonia oblonga Mill. (quince), Malus domestica Borkh. (apple), Pyrus communis L. (pear), Sorbus aria (L.) Crantz (whitebeam) and S. domestica L. (service tree). The observation of the keels and cell patterns was mostly useful to identify new material from Pompeii and Rome dating from the 3rd/2nd century b.c. and the Augustan period around the beginning of the Common (Christian) Era as C. medica L. (citron) and C. cf. × limon (L.) Burm. f. (possible lemon). The classical Greek and Latin sources helped us to understand the use and status of citrus fruits in the ancient world and, in combination with all available archaeobotanical remains compiled in this paper, have allowed us to discuss the spread of Citrus from its regions of origin to the eastern Mediterranean and then within the Mediterranean.     

Genetic differentiation and secondary contact zone in the seagrass Cymodocea nodosa across the Mediterranean–Atlantic transition region

Aim A central question in evolutionary ecology is the nature of environmental barriers that can limit gene flow and induce population genetic divergence, a first step towards speciation. Here we study the geographical barrier constituted by the transition zone between the Atlantic Ocean and the Mediterranean Sea, using as our model Cymodocea nodosa, a seagrass distributed throughout the Mediterranean and in the Atlantic, from central Portugal to Mauritania. We also test predictions about the genetic footprints of Pleistocene glaciations. Location The Atlantic–Mediterranean transition region and adjacent areas in the Atlantic (Mauritania to south‐west Portugal) and the Mediterranean. Methods We used eight microsatellite markers to compare 20 seagrass meadows in the Atlantic and 27 meadows in the Mediterranean, focusing on the transition between these basins. Results Populations from these two regions form coherent groups containing several unique, high‐frequency alleles for the Atlantic and for the Mediterranean, with some admixture west of the Almeria–Oran Front (Portugal, south‐west Spain and Morocco). These are populations where only one or a few genotypes were found, for all but Cadiz, but remarkably still show the footprint of a contact zone. This extremely low genotypic richness at the Atlantic northern edge contrasts with the high values (low clonality) at the Atlantic southern edge and in most of the Mediterranean. The most divergent populations are those at the higher temperature range limits: the southernmost Atlantic populations and the easternmost Mediterranean, both potential footprints of vicariance. Main conclusions A biogeographical transition region occurs close to the Almeria–Oran front. A secondary contact zone in Atlantic Iberia and Morocco results from two distinct dispersal sources: the Mediterranean and southernmost Atlantic populations, possibly during warmer interglacial or post‐glacial periods. The presence of high‐frequency diagnostic alleles in present‐day disjunct populations from the southernmost Atlantic region indicates that their separation from all remaining populations is ancient, and suggests an old, stable rear edge.     

The impacts of the Messinian Salinity Crisis on the biogeography of three Mediterranean sandfly (Diptera: Psychodidae) species

The desiccation of the Mediterranean Basin at the end of the Miocene was a milestone in the evolution of the Mediterranean sandfly fauna. This severe environmental change should have notably influenced their paleobiogeography as well as paleoecology and might have triggered the rapid speciation of the ancestors of the extant European sandfly species. The aim of this study was to explore how the Messinian Salinity Crisis could influence the distribution and migration routes of the ancient Mediterranean sandfly species. The unknown ecological requirements of this ancient species were replaced by the distribution-limiting climatic values of three species of extant European phlebotomine sandflies which represent the three ecological types of European sandfly fauna. The former potential occurrence patterns were determined by Climate Envelope Modelling Method. As a climate model for the Messinian Period in the Mediterranean Basin, the modified mid-Pliocene warm period model was used. The thermal surplus of the desiccated seafloor was reconstructed based on the atmospheric lapse rate. It was found that the extraordinary hot climate of the Mediterranean abyssal plain did not allow the direct cross-migration of the ancient sandfly species anywhere between Europe and North Africa neither through Gibraltar nor the Strait of Sicily. While Phlebotomus neglectus and Phlebotomus papatasi could colonize the Adriatic Plain, Phlebotomus ariasi could not. The results indicate that the Messinian played an important role in the speciation rather than migration of the ancestors of present-day Mediterranean sandflies.