129,567 research outputs found

    A modified migration model biogeography evolutionary approach for electromagnetic device multiobjective optimization

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    Inthispaper, we present anefficient androbust algorithm for multiobjective optimization of electromagnetic devices.Therecentlydeveloped biogeography-based optimization (BBO) is modified byadapting its migration model function so as to improve its convergence.The proposed Modified Migration Model biogeography-based optimization (MMMBBO) algorithm is applied into the optimal geometrical design of an electromagnetic actuator. This multiobjective optimization problem is solved by maximizing the output force as well as minimizing the total weight of the actuator. The comparison between the optimization results using BBO and MMMBBO shows the superiority of the proposed approach

    Historical biogeography of Melastomataceae

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    Melastomataceae and Memecylaceae are pantropically distributed sister groups for which an ndhF gene phylogeny for 91 species in 59 genera is here linked with Eurasian and North American fossils in a molecular clock approach to biogeographical reconstruction. Nine species from the eight next-closest families are used to root phylogenetic trees obtained under maximum likelihood criteria. Melastomataceae comprise ∼3000 species in the neotropics, ∼1000 in tropical Asia, 240 in Africa, and 225 in Madagascar in 150-166 genera, and the taxa sampled come from throughout this geographic range. Based on fossils, ranges of closest relatives, tree topology, and calibrated molecular divergences, Melastomataceae initially diversified in Paloecene/Eocene times in tropical forest north of the Tethys. Their earliest (Eocene) fossils are from northeastern North America, and during the Oligocene and Miocene melastomes occurred in North America as well as throughout Eurasia. They also entered South America, with earliest (Oligocene) South American fossils representing Merianieae. One clade (Melastomeae) reached Africa from the neotropics 14-12 million years ago and from there spread to Madagascar, India, and Indochina. Basalmost Melastomataceae (Kibessieae, Astronieae) are species-poor lineages restricted to Southeast Asia. However, a more derived Asian clade (Sonerileae/Dissochaeteae) repeatedly reached Madagascar and Africa during the Miocene and Pliocene. Contradicting earlier hypotheses, the current distribution of Melastomataceae is thus best explained by Neogene long-distance dispersal, not Gondwana fragmentation

    Biogeography and Long-Run Economic Development

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    The transition from a hunter-gather economy to agricultural production, which made possible the endogenous technological progress that ultimately led to the industrial revolution, is one of the most important events in the thousands of years of humankind’s economic development. In this paper we present theory and evidence showing that exogenous geography and initial condition biogeography exerted decisive influence on the location and timing of transitions to sedentary agriculture, to complex social organization and, eventually, to modern industrial production. Evidence from a large cross-section of countries indicates that the effects of geographic and biogeographic endowments on contemporary levels of economic development are remarkably strong.Geography biogeography and growth; Economic development; Agricultural revolution; Institutions and growth; Plants animals and growth

    Early recognition by Ball and Hooker in 1878 of plant back-colonization (boomerang) events from Macaronesia to Africa

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    Recent work in island biogeography has shown that back-colonization (‘boomerang’ events) from islands to continents have occurred more frequently than previously understoodWe report possibly the earliest inference of this pattern, by John Ball and Joseph Dalton Hooker in a book published in 1878

    Lightning Talk: Biopython (bio) Geography Module

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    For Google Summer of Code 2009/NESCENT Phyloinformatics Summer of Code 2009, I built a Geography module for Biopython. The purpose of the module is to search, download, and process biogeographical data from GBIF, much as Biopython currently accesses Genbank. Application of the tool to a historical biogeography study on bivalves will be illustrated.

As required by Google Summer of Code and Biopython, the code is open access and is released under the Biopython License:
"http://www.biopython.org/DIST/LICENSE":http://www.biopython.org/DIST/LICENSE

The module is described, and a tutorial is presented, on the Biopython wiki:
http://biopython.org/wiki/BioGeography

The page contains links to the source hosted on Github; here is the direct link:
"http://github.com/nmatzke/biopython/tree/Geography":http://github.com/nmatzke/biopython/tree/Geograph

    Biogeography of cyclamen: an application of phyloclimatic modelling

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    © The Systematics Association 2011. Cyclamen is a genus of popular garden plant, protected by Convention on International Trade in Endangered Species (CITES) legislation. Many of its species are morphologically and phenologically adapted to the seasonal climate of the Mediterranean region. Most species occur in geographic isolation and will readily hybridise with their sister species when brought together. We investigate the biogeography of Cyclamen and assess the impact of palaeogeography and palaeoclimate change on the distribution of the genus. We use techniques of phyloclimatic modelling (combining ecological niche modelling and phylogenetic character optimisation) to investigate the heritability of climatic preference and to reconstruct ancestral niches. Conventional and phyloclimatic approaches to biogeography are compared to provide an insight into the historic distribution of Cyclamen species and the potential impact of climate change on their future distribution. The predicted climate changes over the next century could see a northward shift of many species’ climatic niches to places outside their current ranges. However, such distribution changes are unlikely to occur through natural antbased dispersal, so conservation measures are likely to be required

    Phylogenetic and phenotypic divergence of an insular radiation of birds

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    Evolutionary divergence of lineages is one of the key mechanisms underpinning large scale patterns in biogeography and biodiversity. Island systems have been highly influential in shaping theories of evolutionary diversification and here I use the insular Zosteropidae of the south west Pacific to investigate the roles of ecology and biogeography in promoting evolutionary divergence. Initially I build a phylogenetic tree of the study group and use it to reveal the pattern of colonisation and diversification. My results suggest a complex history of dispersal with the observed pattern most likely a result of repeated bouts of colonisation and extinction. I then use the new phylogeny to quantify the diversification rates of the Zosteropidae. I find a very high rate of lineage divergence and suggest the most likely explanation relates to extensive niche availability in the south west Pacific. I also find evidence for an overall slowdown in diversification combined with repeated bursts of accelerated speciation, consistent with a model of taxon cycles. I do not find evidence for sympatric speciation, however. Finally I combine morphological and phylogenetic data to investigate the mode of evolution, evidence for character displacement and influence of biogeography on trait evolution. I find little support for the traditional theory of character displacement in sympatric species. I do, however, find some support for biogeographic theories. Taken together my results do not support traditional theories on the ecological and biogeographical basis of divergence, even in those cases where Zosterops have been used as exemplars. This appears to be because those theories assume rather simple patterns of colonisation and a static ecological system. Instead, my results suggest that evolutionary diversification is dominated by recurrent waves of colonisation and extinction, which, viewed at any particular moment, tend to obscure any underlying ecological rules
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