57 research outputs found
Distribution modelling and statistical phylogeography: an integrative framework for generating and testing alternative biogeographical hypotheses
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73644/1/j.1365-2699.2007.01814.x.pd
Fission widths of hot nuclei from Langevin dynamics
Fission dynamics of excited nuclei is studied in the framework of Langevin
equation. The one body wall-and-window friction is used as the dissipative
force in the Langevin equation. In addition to the usual wall formula friction,
the chaos weighted wall formula developed earlier to account for
nonintegrability of single-particle motion within the nuclear volume is also
considered here. The fission rate calculated with the chaos weighted wall
formula is found to be faster by about a factor of two than that obtained with
the usual wall friction. The systematic dependence of fission width on
temperature and spin of the fissioning nucleus is investigated and a simple
parametric form of fission width is obtained.Comment: RevTex, 12 pages including 9 Postscript figure
Modelo agrometeorológico para estimativa da produtividade para a cultura da soja no Estado de São Paulo
Characterization of the Occurrence and Abundance of the Common Ragweed (Ambrosia artemisiifolia L.) with Regard to Assessment of Its Expansion Potential in European Russia
Stacked species distribution models and macroecological models provide congruent projections of avian species richness under climate change
Identification and dynamics of a cryptic suture zone in tropical rainforest
Suture zones, shared regions of secondary contact between long-isolated lineages, are natural laboratories for studying divergence and speciation. For tropical rainforest, the existence of suture zones and their significance for speciation has been controversial. Using comparative phylogeographic evidence, we locate a morphologically cryptic suture zone in the Australian Wet Tropics rainforest. Fourteen out of 18 contacts involve morphologically cryptic phylogeographic lineages, with mtDNA sequence divergences ranging from 2 to 15 per cent. Contact zones are significantly clustered in a suture zone located between two major Quaternary refugia. Within this area, there is a trend for secondary contacts to occur in regions with low environmental suitability relative to both adjacent refugia and, by inference, the parental lineages. The extent and form of reproductive isolation among interacting lineages varies across species, ranging from random admixture to speciation, in one case via reinforcement. Comparative phylogeographic studies, combined with environmental analysis at a fine-scale and across varying climates, can generate new insights into suture zone formation and to diversification processes in species-rich tropical rainforests. As arenas for evolutionary experimentation, suture zones merit special attention for conservation
The BioRap biodiversity assessment and planning study for Papua New Guinea
[Extract] PAPUA New Guinea (PNG) has an incredible variety of land and marine ecosystems, including many components of biodiversity that are unique in the world. PNG's land mass\ud
constitutes less than one percent of the world's land area, yet estimates suggest that the country has more than 5% of the world's biodiversity. PNG has been recognized therefore as an\ud
important region for biodiversity conservation (see Alcorn 1993; Beehler 1993 and references within). Recently, Conservation International (CI) has recognized PNG as one of the small number of critical tropical forest areas for conservation efforts. That priority reflects not just PNG's unique biodiversity but also the fact that sustainable use of PNG's natural resources has become an important issue, particularly relating to its large mineral deposits, oil and natural gas reserves, agricultural potential, and forestry production potential. CI's perspective highlights important principles of conservation priority. PNG, like the other tropical wilderness\ud
areas on its priority list, is regarded as an opportunity for effective conservation at relatively low cost, given that these wilderness regions are still largely intact and have low human population density. In our view, realizing such opportunities requires good planning. Biodiversity conservation in PNG can imply low realized opportunity costs or quite high realized\ud
opportunity costs, depending on whether biodiversity planning is used to find a balance among society's competing needs through tradeoffs. PNG is a region worthy of urgent conservation planning attention beca.use potential high net benefits for society may be needlessly foreclosed through inefficient planning that does not address conflicts among\ud
various needs of society. The risk of losing those potential net benefits is a strong argument for conservation investment in PNG
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