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Atlantic Europe (atlantic + europe)
Selected AbstractsVegetation gradients in Atlantic Europe: the use of existing phytosociological data in preliminary investigations on the potential effects of climate change on British vegetationGLOBAL ECOLOGY, Issue 3 2000J. C. Duckworth Abstract 1This paper aims to demonstrate the use of available vegetation data from the phytosociological literature in preliminary analyses to generate hypotheses regarding vegetation and climate change. 2Data for over 3000 samples of calcareous grassland, mesotrophic grassland, heath and woodland vegetation were taken from the literature for a region in the west of Atlantic Europe and subjected to ordination by detrended correspondence analysis in order to identify the main gradients present. 3Climate data were obtained at a resolution of 0.5° from an existing database. The relationship between vegetation composition and climate was investigated by the correlation of the mean scores for the first two ordination axes for each 0.5° cell with the climate and location variables. 4The ordinations resulted in clear geographical gradients for calcareous grasslands, heaths and woodlands but not for mesotrophic grasslands. Significant correlations were shown between some of the vegetation gradients and the climate variables, with the strongest relationships occurring between the calcareous grassland gradients and July temperature, latitude and oceanicity. Some of the vegetation gradients were also inferred to reflect edaphic factors, management and vegetation history. 5Those gradients that were related to temperature were hypothesized to reflect the influence of a progressively warmer climate on species composition, providing a baseline for further studies on the influence of climate change on species composition. 6The validity of the literature data was assessed by the collection of an original set of field data for calcareous grasslands and the subsequent ordination of a dataset containing samples from both the literature and the field. The considerable overlap between the samples from the literature and the field suggest that literature data can be used, despite certain limitations. Such preliminary analyses, using readily available data, can thus achieve useful results, thereby saving lengthy and costly field visits. [source] Biogeography of Plagiochila (Hepaticae): natural species groups span several floristic kingdomsJOURNAL OF BIOGEOGRAPHY, Issue 7 2003Henk Groth Abstract Aim This paper presents a synthesis of our recent results regarding the biogeography of Plagiochila using a molecular approach, and documents intercontinental ranges within this largest genus of the hepatics. Methods A maximum likelihood analysis of sixty-one nrITS sequences of Plagiochila was performed and the molecular topology obtained was compared with morphological, phytochemical and geographical data. Results Our molecular data set allowed the identification of eleven Plagiochila sections, the majority of which cover at least two floristic kingdoms. Seven sections have species in Europe (sect. Arrectae, Carringtoniae, Fuscoluteae, Glaucescentes, Plagiochila, Rutilantes, Vagae). Plagiochila species from Atlantic Europe are usually close to or conspecific with neotropical taxa, whereas species widespread in Europe are closely related to Asian ones and not to those in the Neotropics. Plagiochila sect. Arrectae represents a neotropical , Atlantic European clade. The section is not closely related , as has often been suggested , to the morphologically similar sect. Zonatae from Asia and western North America. Sequence data show that the African P. integerrima and the neotropical P. subplana are members of the Asian sect. Cucullatae (sect. Ciliatae, syn. nov.), which becomes pantropical in distribution. An ITS sequence of P. boryana from Uganda confirms the Afro-American range of the primarily neotropical sect. Hylacoetes. Similarities in sporophyte morphology between the sect. Cucullatae and sect. Hylacoetes are the result of parallel evolution. Main conclusions Our results indicate that intercontinental ranges at section and species level are common in Plagiochila. Carl's (1931) subdivision of Plagiochila into sections restricted to one floristic kingdom is outdated. Biogeographical patterns in Plagiochila are not dissimilar to those of other groups of bryophytes but elucidation of the geographical ranges of the taxa requires a molecular approach. Contrary to earlier belief, most Plagiochila species from Atlantic Europe do not have close relatives in Asia but are conspecific with or closely related to species from tropical America. [source] A biogeographical analysis of the European Atlantic lowland heathlandsJOURNAL OF VEGETATION SCIENCE, Issue 5 2010Javier Loidi Abstract Questions: What is the climatic envelope of European Atlantic heathlands and the relationship between their floristic geographical variability and climatic parameters? Are the biogeographic patterns extracted from genuine heath plants comparable to those extracted from the accompanying flora? To what extent does the species composition extracted from phytosociological data support the current theory of refuge areas of heath vegetation in southern Atlantic Europe during the Pleistocene ice ages? Location: Atlantic Europe and NW Morocco. Methods: The geographical territory in which Atlantic heathlands occur was divided into 23 sectors following geographic and chorological criteria. A presence,absence table with 333 taxa was then constructed with the available phytosociological data. The taxa were classified into different groups according to their phytosociological affinity. Several types of numerical analysis were performed with this matrix and the climatic data obtained from meteorological sources. Results: Heathlands require a humid and oceanic climate and are limited by cold temperatures in the north and by summer droughts in the south. The highest floristic richness of this vegetation type is found in NW Iberia. Ordinations indicate a strong correlation between floristic composition of biogeographic sector and summer drought (Ios) and thermicity (It). Conclusions: The main climatic factors determining lowland heathland floristic distribution are thermicity and summer drought. The current optimal conditions for heath flora in NW Iberia suggest that there were southern refuges during the Pleistocene ice ages from which northward expansion has taken place. [source] Y-specific microsatellites reveal an African subfamily in taurine (Bos taurus) cattleANIMAL GENETICS, Issue 3 2010L. Pérez-Pardal Summary Five cattle Y-specific microsatellites, totalling six loci, were selected from a set of 44 markers and genotyped on 608 Bos taurus males belonging to 45 cattle populations from Europe and Africa. A total of 38 haplotypes were identified. Haplogroups (Y1 and Y2) previously defined using single nucleotide polymorphisms did not share haplotypes. Nine of the 27 Y2-haplotypes were only present in African cattle. Network and correspondence analyses showed that this African-specific subfamily clustered separately from the main Y2-subfamily and the Y1 haplotypes. Within-breed genetic variability was generally low, with most breeds (78%) showing haplotypes belonging to a single haplogroup. amova analysis showed that partitioning of genetic variation among breeds can be mainly explained by their geographical and haplogroup assignment. Between-breed genetic variability summarized via Principal Component Analysis allowed the identification of three principal components explaining 94.2% of the available information. Projection of principal components on geographical maps illustrated that cattle populations located in mainland Europe, the three European Peninsulas and Mediterranean Africa presented similar genetic variation, whereas those breeds from Atlantic Europe and British Islands (mainly carrying Y1 haplotypes) and those from Sub-Saharan Africa (belonging to Y2-haplogroup) showed genetic variation of a different origin. Our study confirmed the existence of two large Y-chromosome lineages (Y1 and Y2) in taurine cattle. However, Y-specific microsatellites increased analytical resolution and allowed at least two different Y2-haplotypic subfamilies to be distinguished, one of them restricted to the African continent. [source] | ||||||||||