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Spatial Expansion (spatial + expansion)
Selected AbstractsSpatial expansion and population structure of the neotropical malaria vector, Anopheles darlingi (Diptera: Culicidae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009PEDRO M. PEDRO Extensive population structuring is known to occur in Anopheles darlingi, the primary malaria vector of the Neotropics. We analysed the phylogeographic structure of the species using the mitochondrial cytochrome oxidase I marker. Diversity is divided into six main population groups in South America: Colombia, central Amazonia, southern Brazil, south-eastern Brazil, and two groups in north-east Brazil. The ancestral distribution of the taxon is hypothesized to be central Amazonia, and there is evidence of expansion from this region during the late Pleistocene. The expansion was not a homogeneous front, however, with at least four subgroups being formed due to geographic barriers. As the species spread, populations became isolated from each other by the Amazon River and the coastal mountain ranges of south-eastern Brazil and the Andes. Analyses incorporating distances around these barriers suggest that the entire South American range of An. darlingi is at mutation,dispersal,drift equilibrium. Because the species is distributed throughout such a broad area, the limited dispersal across some landscape types promotes differentiation between otherwise proximate populations. Moreover, samples from the An. darlingi holotype location in Rio de Janeiro State are substantially derived from all other populations, implying that there may be additional genetic differences of epidemiological relevance. The results obtained contribute to our understanding of gene flow in this species and allow the formulation of human mosquito health protocols in light of the potential population differences in vector capacity or tolerance to control strategies. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 854,866. [source] Thermally Driven AFM for NanoenergeticsIMAGING & MICROSCOPY (ELECTRONIC), Issue 2 2009A Method to Investigate the Decomposition on the Nanoscale Abstract A fundamental understanding of the decomposition of energetic nanocompounds infiltrated in porous host matrixes requires the investigation of their behavior on a nanoscale during a thermal stress. Up to now, the decomposition of pure energetic nanomaterials has only been observed on a macroscopic scale. Thermally driven AFM revealed that the decomposition of the energetic material present in the pores of a Cr2O3 matrix induces a spatial expansion of the oxide on the nanometric scale. [source] Multi-annual spatial and numeric dynamics of the white-headed duck Oxyura leucocephala in southern Europe: seasonality, density dependence and climatic variabilityJOURNAL OF ANIMAL ECOLOGY, Issue 6 2004PABLO ALMARAZ Summary 1A statistical model is developed for the globally threatened white-headed duck during its regional expansion throughout Spain from 1980 to 2000; the model estimates the relative intrinsic, climatic and stochastic effects on population fluctuations and spatial expansion on several time-scales. Facing the current lack of knowledge on the nature and consequences of regulation for waterfowl populations, this type of study seems timely. 2A measure of population density accounting for the spatial patchiness of the population was constructed for breeding and wintering counts. No relationship was found between spatial and numeric dynamics, which suggests different mechanisms for both dynamical patterns. 3Although a lagged non-linear climatic effect during the period of chick rearing enhanced numeric brood recruitment through a cohort effect, in the short term brood production appeared to decrease with increasing population density, despite a long-term exponential numeric growth. 4Both wintering population density and rainfall during post-nuptial moult exerted a positive effect on subsequent spatial expansion during breeding, which suggest a major role for social interactions during wintering and wetlands availability on spatial dynamics. 5Altogether, the results suggest that seasonality, density-dependence and climatic forcing are all major processes in the spatio-temporal dynamics of the white-headed duck. Ignoring the relative biotic and abiotic effects and their temporal scale of interaction on population dynamics might thus yield misleading conclusions on the factors affecting the short- and long-term abundance of waterfowl populations. [source] Seasonal maturity development of Baltic cod in different spawning areas: importance of the Arkona Sea for the summer spawning stockJOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2009M. Bleil Summary We investigated the seasonal maturity development of cod in four areas of the Baltic Sea. Two different spawning peaks were identified and found to be consistent over the period 1992,2005. In the Kiel Bight and Mecklenburg Bight (ICES SD 22) a spawning peak was observed from March to April (spring spawning). In the areas of the Arkona Sea (ICES SD 24) and Bornholm Sea (ICES SD 25) the spawning peak occurred during summer. In the Bornholm Sea, the main spawning activities began in June and ended in September, with a spawning peak in June,August (summer spawning). In the Arkona Sea, which is a transition area between the Mecklenburg Bight and the central Baltic Sea, spawning began in March and lasted until July, with a spawning peak in June,July (summer spawning). Seasonal maturity development and proportions of spawning cod in June in the Arkona Sea were similar to that of the Bornholm Sea. In addition, the proportion of spawning cod in the Arkona Sea was positively correlated with the size of the spawning stock in the Bornholm Sea. Our results provide evidence of a spatial expansion of spawning activities of the summer spawning stock from the eastern Baltic Sea into the Arkona Sea. Therefore, the Arkona Sea should be considered as one of the spawning habitats of the summer spawning stock of Baltic cod. [source] | ||||||||||