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Human Effects (human + effects)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Spatial, environmental and human influences on the distribution of otter (Lutra lutra) in the Spanish provinces

DIVERSITY AND DISTRIBUTIONS, Issue 3 2001
Ana Márcia Barbosa
Abstract In a previous survey of otters (Lutra lutra L. 1758) in Spain, different causes were invoked to explain the frequency of the species in each province. To find common causes of the distribution of the otter in Spain, we recorded a number of spatial, environmental and human variables in each Spanish province. We then performed a stepwise linear multiple regression of the proportion of positive sites of otter in the Spanish provinces separately on each of the three groups of variables. Geographic longitude, January air humidity, soil permeability and highway density were the variables selected. A linear regression of the proportion of otter presence on these variables explained 62.4% of the variance. We then used the selected variables in a partial regression analysis to specify which proportions of the variation are explained exclusively by spatial, environmental and human factors, and which proportions are attributable to interactions between these components. Pure environmental effects accounted for only 5.5% of the variation, while pure spatial and pure human effects explained 18% and 9.7%, respectively. Shared variation among the components totalled 29.2%, of which 10.9% was explained by the interaction between environmental and spatial factors. Human factors explained globally less variance than spatial and environmental ones, but the pure human influence was higher than the pure environmental one. We concluded that most of the variation in the proportion of occurrences of otter in Spanish provinces is spatially structured, and that environmental factors have more influence on otter presence than human ones; however, the human influence on otter distribution is less structured in space, and thus can be more disruptive. This effect of large infrastructures on wild populations must be taken into account when planning large-scale conservation policies. [source]

A review of the potential impact of dietary endocrine disrupters on the consumer

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2002
Ian Shaw
Endocrine disrupters, in particular xenoestrogens, have been implicated in a broad array of environmental effects. Their presence in food, either as natural components (e.g. phytoestrogens) or chemical contaminants (e.g. xenoestrogenic pesticides) have been implicated in a number of human effects (e.g. declining sperm count). We present calculations which ranks the importance of the different classes of dietary endocrine disrupters, and show that only phytoestrogens are likely to have a health impact. [source]

Population history in Arabidopsis halleri using multilocus analysis

MOLECULAR ECOLOGY, Issue 16 2010
ANDREW J. HEIDEL
Abstract A. halleri is a psuedometallophyte with a patchy distribution in Europe and is often spread by human activity. To determine the population history and whether this history is consistent with potential human effects, we surveyed nucleotide variation using 24 loci from 12 individuals in a large A. halleri population. The means of total and silent nucleotide variation (,W) are within the range expected for the species. The population genetic neutrality tests Tajima's D and Wall's B had significant composite results rejecting panmixia, and Approximate Bayesian Computation analysis revealed that a subdivision model better explained the variation than the standard neutral model, refugia (or admixture), bottleneck or change of population size models. A categorical regression analysis further supports the subdivision model, and under the subdivision model, the neutrality tests are no longer significant. The best support was for two source populations, a situation consistent with the mixing of two populations possibly mediated by human activity. This scenario might limit the genetic diversity and adaptive potential of the population. The non-neutral population variation described here should be considered in bioinformatic searches for adaptation. [source]

Large-scale human effects on an arid African raptor community

ANIMAL CONSERVATION, Issue 5 2010
J. D. Anadón
Abstract In the current scenario of biodiversity crisis there is a growing need for identifying causes of changes in biodiversity at large scales. Here we assess factors driving raptor community structure in the Sahel, a region suffering a wide range of environmental degradation and a vital area for European migrant birds. Using road surveys, we estimated the effects of population size, human settlement patterns (e.g. urban vs. nomadic) and land use on the raptor community, taking into account the major natural role played by productivity. Total raptor richness values were similar to those described for other steppe regions of the world, with one super-abundant migrant species, the black kite Milvus migrans; however, richness of resident raptors was strikingly lower than expected, with most large body-size African species (both eagles and vultures) absent. Raptor richness was strongly correlated with human activities in a scale-dependent fashion. At a 25 km resolution, raptor richness was driven by habitat and productivity, with a positive response to crops. At a smaller scale, human population was positively related with wintering species richness but negatively with richness of resident ones, perhaps as a consequence of non-agricultural activities such as direct harvesting and different forms of habitat degradation (e.g. overgrazing or firewood collection). Subsistence economies in systems with low natural environmental heterogeneity and with a human population over carrying capacity, such as the Sahel, may lead to exhausted biological systems even in the absence of intensive agricultural or urban land-use changes, as shown by the deeply impoverished sedentary raptor community. Our results suggest that, because habitat and productivity seem to play a relevant role in driving species richness, climate change may have a major effect on the raptor community of the Sahel. [source]