Biogeographic Sectors Research Articles

The Eurasian beaver range expansion reveals uneven future trends and possible conservation issues: an European assessment

The Eurasian beaver is a keystone species and landscape-capable ecosystem engineer, which went close to extinction until the 19th century. Recently, thanks to legal protection and reintroduction programs, the species has recolonized much of its past range. However, in some countries this process did not occur. Objectives. Our objective is to model the potential distribution of the Eurasian beaver for current and future conditions, on a continental scale, at river and sub-basin level. We focus on the protected areas of Italy and Portugal for possible reintroductions. Methods. The study area is Europe, with a subset focusing on Italy and Portugal. We produce species distribution models for current and future conditions using climate change scenarios and predicting changes in river flow, including topographic and human disturbance variables. We then deepen suitability-related issues within Italian and Portuguese protected areas. Results. We find that the Eurasian beaver current suitability is comparable to its known distribution, although some potentially-suitable spots occur in Italy (where there are two occurrences), while the Iberian Peninsula and the Balkan countries host scattered suitable spots. Future scenarios predict a general lowering of suitability in Central and Northern Europe. Portuguese protected areas generally host unsuitable territories, while the Italian ones have reported a tangled scenario, depending on the biogeographical sector. Conclusions. Our results may support the large-scale management of the beaver, both for countries already hosting this species and those planning a reintroduction. The framework used may be applied to other species, and for different topics, from biogeography to conservation.

Revisiting the morphological species groups of West-Palearctic Aphaenogaster ants (Hymenoptera: Formicidae) under a phylogenetic perspective: toward an evolutionary classification

The West-Palearctic region is a diversity hotspot for the ant genus Aphaenogaster. Species in this region are characterized by high morphological variation, which has led to their subdivisioninto different infrageneric groups. The very first classification in three subgenera, dated 1915, was gradually replaced by eight species-groups. To probe the evolutionary consistency of these species-groups, we sequenced 46 species from all eight species-groups and biogeographic sectors of the region, using one mitochondrial (COI) and six nuclear markers (EPICs), and interpreted the results by integrating qualitative morphology. Our results demonstrate the non-monophyly of all formerly recognized subgenera and species-groups, except for the crocea group. We use the phylogeny and morphological characters to propose a new classification of six monophyletic species-groups (crocea, gibbosa, graeca, pallida, sardoa, subterranea). The pallida, subterranea and sardoa (formerly testaceopilosa) groups attain monophyletic status by reassigning a few taxa. The gibbosa group is to be considered exclusively Western-Mediterranean until further assessments of similar Eastern species. The new graeca group is established by including former members of the splendida and subterranea groups, while the polyphyletic cecconii, obsidiana, and splendida groups are dismissed. Notably, the first is not part of the tropical Deromyrma clade as previously thought, while at least two independent clades which require further investigation are composed of species from both the cecconii and splendida groups, suggesting repeated morphological convergences based on similar ecological adaptations. Finally, A. cardenai is confirmed to be a significantly divergent lineage. In addition, three Aphaenogaster species are moved to different genera: Messor asmaae (Sharaf, 2018) comb. nov., Messor isekram (Bernard, 1977) comb. nov., and Pheidole sarae (Sharaf, 2018) comb. nov. Further studies should address the evolutionary relationships between the clades recovered in this study.

Addressing conservation measures through fine-tuned species distribution models for an Italian endangered endemic anuran

Climate and land cover changes are the two most important stressors causing the decline of amphibians’ populations worldwide. Within the Mediterranean area, one of the global biodiversity hotspots, the endemic Italian yellow-bellied toad ( Bombina pachypus ) suffered the same fate, as the decreases and local extinctions proved over time. Since the need to preserve this Apennine endemic species is evident, we take advantage of a novel approach combining climate-based ecological niche models and post-modelling GIS techniques (i.e., the weighted overlay framework) to produce finer species distribution models for B. pachypus . In doing so, we coupled climate variables with topographic-, hydrologic-, and habitat-related predictors, sharpening the potential species’ distribution at its whole range scale. Our findings show a latitudinal subdivision in predicted suitability: Central Apennines populations are expected to suffer more than the Northern ones, with considerable potential future losses of genetic diversity. On the contrary, Southern Apennines’ suitability is predicted to remain stable over time, preserving the vast diversity. When assessing the coverage that protected areas offer to the locations of suitable habitats for B. pachypus , the protected sites of the Central Apennines result in slightly less suitable conservation areas than those in the Northern and Southern Apennines. The overall protected areas coverage is currently low (∼20%) and predicted in the future to narrow towards medium suitability values, except in Southern Apennines, where an increase is inferred. In light of our spatially-explicit results, we suggest that a national-scale conservation strategy should consider different management options according to the sub-territories that our analyses highlighted. Our coupled “weighted modelling – spatialised genetic inference” approach permits us to support different conservation policies at all spatial scales, capitalising on relatively few input data. Also, in-depth spatial analyses should be performed to support effective protection strategies and management for the conservation stakeholders. • Fine-tuned SDMs deepen knowledge and strongly uphold Bombina pachypus conservation. • Changes will differently affect biogeographic sectors’ suitability for B. pachypus. • Protected areas’ policy should base on predicted local responses to future changes.

Vascular flora of the Sierra de las Nieves National Park and its surroundings (Andalusia, Spain)

The Sierra de las Nieves National Park, declared by the Spanish Government in July 2021, is part of the Serranía de Ronda (Western Baetic mountains), which is considered one of the main centres of biodiversity and endemicity of the southern Iberian Peninsula (Andalusia, Spain) and the Mediterranean Basin. The park and its surroundings have an important diversity of vascular plants, mainly due to the orographic, climatic and geological diversity of the area, which is divided into three biogeographical sectors: Rondeño sector (limestones, dolomites and clays), Bermejense sector (peridotites and serpentines) and Aljíbico sector (gneisses and micaschists). This contribution presents the first catalogue of the vascular flora of this national park and its surrounding area, with 1,387 taxa distributed in 104 families and 542 genera. An amount of 79 taxa are endemic to Andalusia and 57 are endangered: 4 are Critically Endangered (CR), 17 are Endangered (EN) and 36 are Vulnerable (VU).

Contribution to the Knowledge of Rocky Plant Communities of the Southwest Iberian Peninsula.

The rocky habitats of southern Portugal are ecosystems with extreme xericity conditions, associated with special abiotic strains. In these unstable ecological conditions, a considerable diversity of plant communities occurs. The objective of this study, carried out in the Algarve and Monchique, and the Mariánica Range biogeographical sectors, is to compare chasmo-chomophytic communities of the southwestern Iberian Peninsula, using a phytosociological approach (Braun–Blanquet methodology) and numerical analysis (hierarchical cluster analysis). From these results, two new communities were identified, Sanguisorbo rupicolae-Dianthetum crassipedis and Antirrhinetum onubensis, as a result of floristic and biogeographical differences from other associations already described within the alliances Rumici indurati-Dianthion lusitani and Calendulo lusitanicae-Antirrhinion linkiani, both included in the Phagnalo saxatilis-Rumicetea indurate class.

SERPENTINE PLANT DIVERSITY AND VEGETATION IN A MEDITERRANEAN AREA (SIERRA DE MIJAS, SOUTHERN IBERIAN PENINSULA, SPAIN)

A study of the flora and vegetation of a serpentine outcrop in the south of the Iberian Peninsula (Malaga, Spain) has been carried out. The study area is located in the Bermejense biogeographical sector (Baetic province, Mediterranean region) and shows a Mediterranean pluviseasonal-oceanic bioclimate. Most of the outcrop is altered by urban planning linked to tourism and affected by invasive alien species. Three areas remain more intact. A catalogue of vascular flora has been completed, made up of 168 taxa, including three threatened species, four obligate serpentinophytes, one preferential serpentinophyte, and one subserpentinophyte (majority of populations on serpentine). Seven taxa are South-Iberian ultramafic endemics. Silene inaperta subsp. serpentinicola is an obligate serpentinophyte and threatened endemism. Twelve alien taxa have been identified showing invasive potential, 75% of them originating from inactive dumps. The richness of serpentinophytes / area fits in the trend of the southern outcrops of the Iberian Peninsula. Four associations and one community have been identified. The serpentine perennial grassland stands out for its abundance and dominance, for which a new association is proposed ( Scorzonero boeticae-Macrochloetum tenacissimae ass. nova ). There are three habitats included within the Directive 92/43/EEC: therophytic and perennial grasslands (6220), scrubland (5330) and oleander shrublands (92D0).

Biogeographical characterisation of Egypt based on environmental features and endemic vascular plants distribution

Biogeographical studies are considered effective for investigations on macroecology and evolution, as well as for delineating patterns of endemism and identifying the key drivers influencing the historical distribution of species. Clustering techniques, based on environmental datasets and distribution of endemic species, have been largely used in biogeography and for the definition of endemic-rich regions where conservation actions should be implemented. Despite several earlier studies have dealt with the biogeographical territories in Egypt, none of them have provided a replicable method to support such regionalisation. We proposed a two-step procedure for the biogeographical regionalisation of Egypt consisting in (1) the definition of environmental clusters (based on 24 climatic, three topographic, two soil organic carbon content and pH, and four habitat heterogeneity variables) by using the k-nearest neighbours algorithm and (2) the spatial clustering of such clusters according to the distribution of 140 endemic vascular plants. The hierarchical clustering and indicator values analyses, based on the presence-absence matrix of endemic taxa in each cluster were performed to define two cut-off levels of biogeographical sectors and subsectors. A total of six sectors and nine subsectors were identified. Climatic-related variables, elevation and soil organic carbon were the most important determinants for environmental clustering of Egypt. The highest endemic richness was recorded in the Marioutico-Arishian (71 species), Sinaico-Arabian (62 species) and Nilotic (16 species) sectors, and in Sinaic (54 species), Arishian (45 species) and Marioutic (40 species) subsectors. Nonetheless, the most protected sectors were Elbanian and Suezian (62.73 and 29.05%, respectively) while the lowest sectors were Nilotic and Marioutico-Arishian (9.86 and 13.26%, respectively). The already established protected areas in Egypt are not sufficient for conserving the representation of the identified endemic rich plant sectors. This two-step procedure confirms the usefulness of environmental attributes together with the spatial distribution of endemic vascular plants to define the biogeographical units in Egypt. Our regionalisation method could be replicated for other species’ groups, with the ultimate goal of integration all species of interest in a single biogeographical system. Furthermore, the presented regionalisation will help to identify weaknesses in current protection actions and to understand biogeographical processes.

Integrating knowledge of ecological succession into invasive alien plant management: A case study from Portugal

AbstractAimsKnowledge of invasive alien plant (IAP) ecology and plant community succession (synphytosociology) is crucial for successful restoration and prevention of (re)invasions; nevertheless, these two fields are rarely combined. Our case study aims to demonstrate how they can be integrated, by analysing the variation of IAP distribution within biogeographic territories, identifying the potential native plant communities and the ecological conditions that favour (or prevent) each IAP.LocationSouthern Portugal.MethodsSeveral native plant indicators and nine selected IAPs were surveyed in 60 1‐km2 sampling plots across the four biogeographic sectors of the study area. The native plant indicators were then used to identify the vegetation series in which IAPs occurred. Ecological requirements favouring the establishment of each IAP were inferred based on expert knowledge and on the characteristics of published vegetation series and bioclimatic data.ResultsLittoral areas were more invaded, particularly those with sand dune habitats, which are highly dynamic and exposed to disturbance. The most frequent IAPs were Acacia dealbata, Arundo donax, Acacia longifolia and Opuntia ficus‐indica. Riparian vegetation series were the most invaded, especially ash woodlands and willow galleries, as well as the littoral psammophilous cork oak and maritime turbinate juniper series. The most adequate native species to recover each of these invaded communities varies, and examples are provided for each situation.ConclusionsIntegrating knowledge about IAP ecological requirements and the dynamics of native vegetation series can help practitioners select native plants that are more likely to function as efficient natural barriers to (re)invasion, predict areas more prone to invasion by IAPs and establish management priorities.

Diversidad y distribución de los endemismos de Asteraceae (Compositae) en la Flora del Ecuador

La familia Asteraceae está representada en la Flora de Ecuador por un total de 310 táxones endémicos. Están agrupadas en 4 subfamilias (Asteroideae, Barnadesioideae, Cichorioideae y Mutisioideae), 16 tribus y 89 géneros. Doscientas setenta y dos táxones (87,74%) restringen su hábitat a la región andina. Los niveles más altos de endemismos están asociados a los Andes, mayoritariamente desde el bosque andino alto hasta el páramo, y a las Islas Galápagos. Los géneros con mayor riqueza de endemismos son Mikania (26), Pentacalia (23), y Gynoxys (20). Tres géneros monotípicos son endémicos: Cyathomone, Idiopappus y Trigonopterum. Los géneros Darwiniothamnus, Kingianthus, Lecocarpus, y Scalesia también son endémicos. La diversidad de la familia se incrementa desde los 2000 m a 3000 m, alcanzando su mayor riqueza entre los 2900-3000 m, con dominancia de las plantas arbustivas (195 especies, 1 subespecie, 2 variedades) y herbáceas (97 especies). Ciento veinteseis especies tienen categoría de vulnerable, 90 están en peligro de extinción y 24 están en estado crítico de amenaza. Las temperaturas y precipitaciones medias anuales varían significativamente entre los sectores biogeográficos.

Climate change, biological invasions, and the shifting distribution of Mediterranean fishes: A large-scale survey based on local ecological knowledge.

Climate change and biological invasions are rapidly reshuffling species distribution, restructuring the biological communities of many ecosystems worldwide. Tracking these transformations in the marine environment is crucial, but our understanding of climate change effects and invasive species dynamics is often hampered by the practical challenge of surveying large geographical areas. Here, we focus on the Mediterranean Sea, a hot spot for climate change and biological invasions to investigate recent spatiotemporal changes in fish abundances and distribution. To this end, we accessed the local ecological knowledge (LEK) of small-scale and recreational fishers, reconstructing the dynamics of fish perceived as "new" or increasing in different fishing areas. Over 500 fishers across 95 locations and nine different countries were interviewed, and semiquantitative information on yearly changes in species abundance was collected. Overall, 75 species were mentioned by the respondents, mostly warm-adapted species of both native and exotic origin. Respondents belonging to the same biogeographic sectors described coherent spatial and temporal patterns, and gradients along latitudinal and longitudinal axes were revealed. This information provides a more complete understanding of the shifting distribution of Mediterranean fishes and it also demonstrates that adequately structured LEK methodology might be applied successfully beyond the local scale, across national borders and jurisdictions. Acknowledging this potential through macroregional coordination could pave the way for future large-scale aggregations of individual observations, increasing our potential for integrated monitoring and conservation planning at the regional or even global level. This might help local communities to better understand, manage, and adapt to the ongoing biotic transformations driven by climate change and biological invaders.

Changes in plant diversity patterns along dune zonation in south Atlantic European coasts

Coastal dunes are valuable and threatened habitats. They present a sea-land environmental gradient and different vegetation types are found in a very short space: embryo, mobile and fixed dunes. The aims were to study changes in taxonomic diversity and species richness along the ecological gradient and if they were followed by changes in functional or phylogenetic diversity. This study took place along a 750 km coastal stretch, belonging to four biogeographic sectors, in the southwest of France and northwest of Spain. Twelve locations were selected, where coastal dune habitats were explored. In each location and for each vegetation type four 10 × 10 m plots were sampled. In each plot abundances of vascular plants were recorded. Taxonomic, functional and phylogenetic diversity at the alpha level were measured. NMDS analysis, PERMANOVA and linear mixed effects models were used to explore differences between biogeographic sectors and habitats for species composition and each derived taxonomic, functional and phylogenetic index. We found different species composition in each vegetation type: in embryo dunes it was constant along biogeographic sectors, while it changed in mobile and fixed dunes. Taxonomic diversity, functional diversity and phylogenetic diversity indices did not show changes at biogeographic sector level despite the species difference in mobile and fixed dunes. An increase in taxonomic diversity from embryo to fixed dunes was also found, followed by an increase in functional divergence. Phylogenetic diversity decreased from embryo to fixed dunes. Therefore, in habitats more exposed to sea, wind and waves, as embryo dunes, environmental filtering selects some traits of non-related species. On more sheltered habitats such as fixed dunes, biotic interactions like competitive exclusion leads to a divergence in functionality. In conclusion, coastal dunes showed different biodiversity patterns along a sea-land gradient; despite a difference in species, functional and phylogenetic diversity remained without changes along a geographical gradient.

Diversity of lowland hay meadows and pastures in Western and Central Europe

AbstractQuestionsWhich are the main vegetation types of lowland hay meadows and pastures in Western and Central Europe? What are the main environmental gradients that drive patterns of species composition? Is it possible to classify these grasslands to phytosociological alliances that reflect management practices?LocationWestern and Central Europe (excluding the Alps and Carpathians).MethodsA database of 21 400 vegetation plots of mesic grasslands across Western and Central Europe was compiled. After geographically stratified resampling, semi‐supervised classification based on the K‐means algorithm was applied to assign a subset of plots into 32 a priori association‐level vegetation types and to search for new types within the subset of non‐assigned plots. The vegetation plots assigned into the final vegetation types were submitted to another K‐means classification to show the grouping into higher‐level vegetation types.ResultsA total of 36 associations were distinguished in the resampled subset of 8277 vegetation plots and were grouped into four large groups: (1) eutrophic and intensively managed hay meadows and permanent pastures; (2) nutrient‐rich grasslands developed from recently abandoned fields or managed under irregular practices of mowing and manuring; (3) non‐eutrophic lowland and submontane hay meadows; (4) extensively managed pastures and Atlantic grazed hay meadows. A PCoA of the associations of these four groups showed that extensively managed pastures were floristically more similar to non‐eutrophic hay meadows than to permanent intensively managed pastures, which was more obvious in the Atlantic region than in Central Europe. Species composition of the lowland hay meadows was clearly differentiated according to biogeographic sectors. Other floristic differences were related to climate, altitude, soil base status and topography.ConclusionsThis analysis challenges the traditional concept of mesic grassland alliances separating hay meadows from pastures. New classification should be based mainly on the differences in management intensity rather than in management practice. Consequently, nutrient‐poor extensive pastures, which currently are not considered in the European Habitats Directive, should receive the same conservation attention as low‐intensive hay meadows, because both types of vegetation can be equally species‐rich and do not differ substantially in floristic composition from each other.

Phytogeographic characterization of Gran Canaria Island (Canary Islands-Spain)

Studies on the flora and fauna of the Canary Islands show that this Archipelago is one of the planet’s diversity hot spots. However, an analysis of the differences in the phytogeographic characteristics of each of the islands that make up this Archipelago is lacking. This article focuses on the phytogeographic characterization of the island of Gran Canaria. This island exhibits geological and climatic characteristics resulting in a rich vascular flora, including endemic species and genera that are significantly different from the other islands of the Archipelago. These differences are verified through statistical analysis of the existing similarity between the floras of the members of the Canary Islands. This study also analyses the subdivision of Gran Canaria Island, indicating that there are three well-differentiated areas on the island itself. Finally, this study argues that these areas, themselves, should be considered biogeographic sectors.

Vegetation diversity of mesic grasslands (Arrhenatheretalia) in the Iberian Peninsula

AbstractQuestionsWhat is the diversity and main vegetation types in mesic grasslands on the Iberian Peninsula? What are the main diagnostic species of each type? What are the main environmental gradients that drive patterns of species composition? To what extent does biogeography influence community diversity?LocationIberian Peninsula (Portugal and Spain, including the French Pyrenees).MethodsFormal definitions based on the Cocktail method were used to establish a typology of mesic grasslands of the Arrhenatheretalia order. This method was applied to a stratified data set of 3485 relevés, also including other types of perennial grassland. Semi‐supervised classification based on the K‐means algorithm was used to assign almost 757 relevés into the vegetation types defined by Cocktail and to identify new ones. The types were compared by means of detrended correspondence analysis (DCA) using climate data, altitude and Ellenberg indicator values as explanatory variables.ResultsFourteen ecologically well‐defined associations were distinguished in the Arrhenatheretalia order: five in the Arrhenatherion alliance, two in Triseto‐Polygonion and seven in Cynosurion. Soil reaction, summer aridity and altitude were identified as the most important determinants of species composition. These lithological and bioclimatic gradients are related to the biogeographic diversity of the study area, which is the main driver of community diversity in Arrhenatheretalia grasslands; it is more important than the management practices expressed in the concept of alliances. The classification and ordination analyses also showed a clear differentiation in community diversity according to biogeographic sectors (eastern Cantabrian‐Atlantic, Galician‐Portuguese, Carpetan‐Leonese, Pyrenean, Orocantabrian/western Pyrenean and Oroiberian/Catalan‐Valencian). In addition, moisture and nutrient content were more important than altitude in differentiating Arrhenatherion and Triseto‐Polygonion communities in the Pyrenees.ConclusionsWe suggest a simplification of the traditional classification of the Iberian Arrhenatheretalia grasslands. For this revised classification, we propose an electronic expert system with consistent rules for assigning vegetation observations to the associations defined, and a list of the diagnostic species of each vegetation type. These results can be applied to identify and monitor the hay meadows included in Annex I of the European Habitats Directive, taking into account the biogeographic context of the indicator species.

MidMedPol: Polychaetes from midlittoral rocky shores in Greece and Italy (Mediterranean Sea).

This paper describes a dataset of polychaetes (Annelida) from 14 midlittoral rocky shore sampling sites in Greece and Italy (Mediterranean Sea). The dataset combines the outcome of four different projects studying the hard substrate midlittoral zone in the Mediterranean between 1984 and 2009. Samples were collected by scraping and collecting the organisms from a framed area. The maximal sampling depth was 1.5 m. In total, 123 polychaete species were recorded, five of which are new records for the respective biogeographic sectors of the Mediterranean. The dataset contains 788 occurrence records, fully annotated with all required metadata. These data contribute to the knowledge of a previously very understudied regional habitat, since at present, comprehensive lists of the midlittoral communities in the Mediterranean are provided through only a few, paper-based, studies. This dataset is one of the first electronic data compilations of the Mediterranean midlittoral zone communities and certainly the most comprehensive of its kind, contributing to the ongoing efforts of the Ocean Biogeographic Information System (OBIS) which aims at filling the gaps in our current knowledge of the world's oceans. It is accessible at http://ipt.vliz.be/resource.do?r=mediterraneanpolychaetaintertidal.

The rocky-reef fish assemblages of Malta and Lampedusa islands (Strait of Sicily, Mediterranean Sea): a visual census study in a changing biogeographical sector

The rising impact of invasive species and climate change on Mediterranean fish biodiversity highlight the urgency to evaluate the current status of natural assemblages. Here we investigated the rocky-reef fish of Malta and Lampedusa (Strait of Sicily, Mediterranean Sea), two islands of high biogeographical importance subjected to a different level of protection and anthropic pressure. By using underwater visual census, a total of 192 counts were performed in May–June and September–October 2007 using a hierarchical spatial design and four depth layers. Overall, 23 families and 61 different taxa were recorded. Out of them, two highly invasive species were censused (i.e.Siganus luridusandFistularia commersonii) with relatively low abundances. Native Labridae and Sparidae shape the assemblage structure of both islands, and thermophilic species such asSparisoma cretenseandThalassoma pavooccur with high densities. The fish assemblages of Malta and Lampedusa were relatively similar in species composition, richness and total abundance. Nevertheless, multivariate analysis depicted significant differences between these two islands, mainly attributable to the unevenness of Labridae. Significant differences in the size distribution of the most abundant species were detected between islands, with parallel variation across time. The pattern of spatio-temporal variability of the whole assemblage structure strongly resembled that of nekto-benthic fish, hence pointing out the relevance of this guild as an indicator species group in future monitoring activity. This study will serve as a current baseline against which future changes in the central Mediterranean fish assemblages can be assessed.

Breeding Habitat Use and Conservation Status of the Turtle DoveStreptopelia turturin Northern Spain

SUMMARY. We investigated the abundance and breeding habitat use of the turtle dove Streptopelia turtur in the Basque Country (northern Spain). Censuses employed 500 m transects, distributed across 100 km2 grid cells where the species was previously known to occur. Turtle doves were only detected in two out of four biogeographic sectors sampled. The species was found in forested habitats, riparian forests and evergreen oak patches in particular, but its abundance decreased as tree cover increased. The abundance in farmland was lower, probably as a consequence of the scarcity of adequate nest sites. The range contraction described for this population stresses its unfavourable conservation status and the need to implement action, especially in relation to its breeding habitats.

Conservation study of endemic plants in serpentine landscapes: Antirrhinum rothmaleri (Plantaginaceae), a serpentinophyte with a restricted geographic distribution

Assessing the conservation status of endemic species by monitoring population trends is one of the main aims of plant conservation studies. This article reports a detailed study of the distribution of Antirrhinum rothmaleri, a species endemic to the serpentine systems of Trás-os-Montes in NE Portugal (Lusitan-Duriensean biogeographical sector). The species' current distribution status, the size of its populations, and the threats it faces, measured according to International Union for Conservation of Nature (IUCN) 2008 Guidelines, were all assessed. The size estimates provided for the four confirmed populations were based on census data taken at the different sites. All censuses were performed by direct counting of all potentially reproductive individuals. Based on the present data, A. rothmaleri should be assigned a conservation status of “Critically Endangered” (CR). Its conservation status, according to the IUCN criteria, is mainly based on the narrow distribution, and on the area of occupancy (AOO) and extent of occurrence (EOO). The risk of extinction faced by the local populations is high due to their typically very small size. Suitable conservation strategies should be developed in order to preserve the species. The present study allowed us to characterize its distribution and population size, to collect and store ex situ the germplasm in the UIRGEMP/Banco Português de Germoplasma Vegetal, and to investigate its ecology. The conservation status of the species requires continued monitoring of the demography of its populations. Studies on the biology of the species are also needed in order to improve its management. The present results illustrate the need to protect serpentine landscapes, which contain a range of microhabitats inhabited byendemic plants.

Biogeographical patterns of algal communities in the Mediterranean Sea: Cystoseira crinita‐dominated assemblages as a case study

AbstractAim The aim of this study was to describe the composition, community structure and biogeographical variation of subtidal algal assemblages dominated by the brown alga Cystoseira crinita across the Mediterranean Sea.Location The Mediterranean coast, from Spain (1°25′ E) to Turkey (30°26′ E).Methods Data on the species composition and structure of assemblages dominated by the species C. crinita were collected from 101 sites in nine regions across the Mediterranean Sea. Multivariate and univariate statistical tools were used to investigate patterns of variation in the composition of the assemblages among sites and regions, and to compare these with previously defined biogeographical regions. Linear regressions of species richness versus longitude and versus latitude were also carried out to test previously formulated hypotheses of biodiversity gradients in the Mediterranean Sea.Results The main features characterizing C. crinita‐dominated assemblages across the Mediterranean included a similar total cover of species, a similar cover of C. crinita, and consistency in the presence of the epiphyte Haliptilon virgatum. Biogeographical variation was detected as shifts in relative abundances of species among regions, partly coinciding with previously described biogeographical sectors. A significant positive correlation was found between species richness and latitude, while no significant correlation was detected between species richness and longitude.Main conclusions The patterns of variation in community structure detected among the studied regions reflected their geographical positions quite well. However, latitude seemed to contribute more to the explanation of biological patterns of diversity than did geographical distances or boundaries, which classically have been used to delimit biogeographical sectors. Moreover, the positive correlation between species richness and latitude reinforced the idea that latitude, and possibly temperature as a related environmental factor, plays a primary role in structuring biogeographical patterns in the Mediterranean Sea. The lack of correlation between species richness and longitude contradicts the notion that there is a decrease in species richness from west to east in the Mediterranean, following the direction of species colonization from the Atlantic.

Current status and conservation of the Lusitan Duriensean Orchids (Duero Basin, NE Portugal and CW Spain)

Twenty eight orchids species and subspecies are presently recognised as indigenous in the Lusitan Duriensean biogeographical sector, which covers part of the Duero Basin of Portugal and Spain. Twenty one of these (75%) are rare or very rare in this sector and under threat from different agents. This paper provides a detailed study of their distribution and estimates of the sizes of their populations. The latter were based on our own census data, collected at the sites where the species are found. All potentially reproductive individuals were counted. The causes of rarity and the factors responsible for the regression that still affects many species are analysed; main threats are destruction of woods by human activities and overgrazing. These data may be of use to the nature conservation authorities of Portugal and Spain.