39 research outputs found

    Living on the edge: Exploring the role of coastal refugia in the Alexander Archipelago of Alaska

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    Although islands are of long‐standing interest to biologists, only a handful of studies have investigated the role of climatic history in shaping evolutionary diversification in high‐latitude archipelagos. In this study of the Alexander Archipelago (AA) of Southeast Alaska, we address the impact of glacial cycles on geographic genetic structure for three mammals co‐distributed along the North Pacific Coast. We examined variation in mitochondrial and nuclear loci for long‐tailed voles (Microtus longicaudus), northwestern deermice (Peromyscus keeni), and dusky shrews (Sorex monticola), and then tested hypotheses derived from Species Distribution Models, reconstructions of paleoshorelines, and island area and isolation. In all three species, we identified paleoendemic clades that likely originated in coastal refugia, a finding consistent with other paleoendemic lineages identified in the region such as ermine. Although there is spatial concordance at the regional level for endemism, finer scale spatial and temporal patterns are less clearly defined. Demographic expansion across the region for these distinctive clades is also evident and highlights the dynamic history of Late Quaternary contraction and expansion that characterizes high‐latitude species

    Laws in finite strictly simple loops

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    It is shown that a finite loop with no proper nontrivial subloops has a finite basis for its laws

    Various varieties

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    On laws in linear groups

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    A Basis for the Laws of Psl(2,5)

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    Groundwater management in drought-prone areas of Africa

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    The issues pertaining to groundwaterdrought are reviewed with particular regard to the historical and present situations in Malawi, northern Ghana and the Northern Province of South Africa. These three quite different examples highlight some of the major difficulties facing respective governmentsand donor agencies, not least the shortcomingsof drought-reliefdrilling programmes,the general lack of routine monitoring and the need for longer term analysis and assessment of groundwatersystems than is currently possible. The distinct character of groundwater systems and their reaction to prevailing and changing environmentalconditions is discussed, and it is argued that essentially predictable variations in groundwater drought vulnerability are rarely planned for or acted upon. Managementissues arising are discussed and it is suggested that governments,and particularly donors, should place more emphasis on longer term, pre-droughtmitigation measures to reduce the need for costly and sometimes ineffective emergency interventions

    Appx I & IX

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    Appendix I - Specimens examined. Museum number acronyms are MSB= Museum of Southwestern Biology, UAM=University of Alaska Museum of the North, Fairbanks, HG= Gwaii Haanas National Park Reserve and Haida Heritage Site, and UWBM=University of Washington Burke Museum. GenBank numbers correspond to cyt b, and each phased allele for M. longicaudus (ETS2, FGB and Rag1), Peromyscus (FGB, IRBP and Zp3) and S. monticola (ADH2, ApoB and FGB) respectively, –= not applicable. GenBank in bold were obtained from other studies. Appendix IX - Between group net genetic divergences of cyt b among refugial and non-refugial Southeast Alaskan populations lineages of M. longicaudus, P. keeni and S. monticola. The number of base differences per site from estimation of net average between groups of sequences is shown. Standard error estimate(s) are shown above the diagonal. All ambiguous positions were removed for each sequence pair. Evolutionary analyses were conducted in MEGA5
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