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Major Subdivisions (major + subdivision)
Selected AbstractsPhylogeography and genetic structure of northern populations of the yellow warbler (Dendroica petechia)MOLECULAR ECOLOGY, Issue 6 2000Emmanuel Milot Abstract Phylogeographic patterns of intraspecific variation can provide insights into the population-level processes responsible for speciation and yield information useful for conservation purposes. To examine phylogeography and population structure in a migratory passerine bird at both continental and regional geographical scales, we analysed 344 bp of mitochondrial DNA (mtDNA) control region sequence from 155 yellow warblers (Dendroica petechia) collected from seven locations across Canada and from Alaska. There is a major subdivision between eastern (Manitoba to Newfoundland) and western (Alaska and British Columbia) populations which appears to have developed during the recent Pleistocene. Some localities within these two regions also differ significantly in their genetic composition, suggesting further subdivision on a regional geographical scale. Eastern and western birds form distinct phylogeographic entities and the clustering of all western haplotypes with two eastern haplotypes suggests that the western haplotypes may be derived from an eastern lineage. Analyses based on coalescent models support this explanation for the origin of western haplotypes. These results are consistent with important features of Mengel's model of warbler diversification. From a conservation perspective they also suggest that individual populations of migrant birds may form demographically isolated management units on a smaller scale than previously appreciated. [source] Biogeographical patterns of endemic terrestrial Afrotropical birdsDIVERSITY AND DISTRIBUTIONS, Issue 3 2002H. M. De Klerk Abstract. Biogeographical zones are described for terrestrial bird species endemic to the Afrotropics using up-to-date distributional data and multivariate statistical techniques. This provides an objective basis for a hierarchy of subregions, provinces and districts, based on a set of rules. Results are compared to previous studies at continental and regional scales. Biogeographical zones for passerines and non-passerines are compared and found to be similar. Peaks of species richness and narrow endemism are described for the six major subdivisions (subregions) identified by the cluster analysis. Coincidence of peaks of species richness and narrow endemism is found to be low, such that areas selected to represent high species richness tallies will often fail to represent narrow endemics. Strong regionalization of Afrotropical birds indicates the need to use a biogeographical framework in conservation priority setting exercises to ensure that unique, but species-poor, avifaunas are not neglected. [source] Hydrology and water resources in monsoon Asia: a consideration of the necessity of establishing a standing research community of hydrology and water resources in the Asia Pacific regionHYDROLOGICAL PROCESSES, Issue 14 2003Katumi Musiake Abstract Hydrological and water resources issues appear very differently in different regions, and are strongly affected by geographical conditions. Hydrological knowledge and methodologies obtained in a specific region cannot necessarily be adapted to other regions. The purpose of this paper is to clarify one way to address adequately the regional characteristics of hydrology and water resources in monsoon Asia, especially the ,too much water' problems in the region. For this purpose, geomorphological factors, climatic factors and human intervention in the natural environment are taken into consideration as the three major factors governing the regional characteristics of the hydrology,water resources system. To identify geomorphological features macroscopically between the Asia Pacific region and other continental regions, the concepts ,tectonic zone' and ,stable region', which are two major subdivisions of continental masses in the world, are introduced. Also, a new climatic subdivision termed ,warm-humid' is proposed to express the abundant precipitation due to the Asian monsoon. Then, hydrological characteristics common or similar in ,warm-humid tectonic zones' in the Asia Pacific region, contrasted with those in stable regions, are enumerated together with the human intervention corresponding to these characteristics, and research targets peculiar to warm-humid tectonic zones are discussed. Finally, the establishment of a standing research community called ,Asia Pacific Association of Hydrology and Water Resources' is proposed to promote the exchange of operational knowledge and experience in water resources management, cooperative research activities, and professional education in the Asia Pacific region. Copyright © 2003 John Wiley & Sons, Ltd. [source] The HUDSEN Atlas: a three-dimensional (3D) spatial framework for studying gene expression in the developing human brainJOURNAL OF ANATOMY, Issue 4 2010Janet Kerwin Abstract We are developing a three-dimensional (3D) atlas of the human embryonic brain using anatomical landmarks and gene expression data to define major subdivisions through 12 stages of development [Carnegie Stages (CS) 12,23; approximately 26,56 days post conception (dpc)]. Virtual 3D anatomical models are generated from intact specimens using optical projection tomography (OPT). Using mapaint software, selected gene expression data, gathered using standard methods of in situ hybridization and immunohistochemistry, are mapped to a representative 3D model for each chosen Carnegie stage. In these models, anatomical domains, defined on the basis of morphological landmarks and comparative knowledge of expression patterns in vertebrates, are linked to a developmental neuroanatomic ontology. Human gene expression patterns for genes with characteristic expression in different vertebrates (e.g. PAX6, GAD65 and OLIG2) are being used to confirm and/or refine the human anatomical domain boundaries. We have also developed interpolation software that digitally generates a full domain from partial data. Currently, the 3D models and a preliminary set of anatomical domains and ontology are available on the atlas pages along with gene expression data from approximately 100 genes in the HUDSEN Human Spatial Gene Expression Database (http://www.hudsen.org). The aim is that full 3D data will be generated from expression data used to define a more detailed set of anatomical domains linked to a more advanced anatomy ontology and all of these will be available online, contributing to the long-term goal of the atlas, which is to help maximize the effective use and dissemination of data wherever it is generated. [source] | ||||||||||