TY - JOUR A1 - Walz, Yvonne A1 - Wegmann, Martin A1 - Dech, Stefan A1 - Vounastou, Penelope A1 - Poda, Jean-Noel A1 - N'Goran, Eliézer K. A1 - Raso, Giovanna A1 - Utzinger, Jürg T1 - Modeling and Validation of Environmental Suitability for Schistosomiasis Transmission Using Remote Sensing JF - PLoS Neglected Tropical Diseases N2 - Background Schistosomiasis is the most widespread water-based disease in sub-Saharan Africa. Transmission is governed by the spatial distribution of specific freshwater snails that act as intermediate hosts and human water contact patterns. Remote sensing data have been utilized for spatially explicit risk profiling of schistosomiasis. We investigated the potential of remote sensing to characterize habitat conditions of parasite and intermediate host snails and discuss the relevance for public health. Methodology We employed high-resolution remote sensing data, environmental field measurements, and ecological data to model environmental suitability for schistosomiasis-related parasite and snail species. The model was developed for Burkina Faso using a habitat suitability index (HSI). The plausibility of remote sensing habitat variables was validated using field measurements. The established model was transferred to different ecological settings in Côte d’Ivoire and validated against readily available survey data from school-aged children. Principal Findings Environmental suitability for schistosomiasis transmission was spatially delineated and quantified by seven habitat variables derived from remote sensing data. The strengths and weaknesses highlighted by the plausibility analysis showed that temporal dynamic water and vegetation measures were particularly useful to model parasite and snail habitat suitability, whereas the measurement of water surface temperature and topographic variables did not perform appropriately. The transferability of the model showed significant relations between the HSI and infection prevalence in study sites of Côte d’Ivoire. Conclusions/Significance A predictive map of environmental suitability for schistosomiasis transmission can support measures to gain and sustain control. This is particularly relevant as emphasis is shifting from morbidity control to interrupting transmission. Further validation of our mechanistic model needs to be complemented by field data of parasite- and snail-related fitness. Our model provides a useful tool to monitor the development of new hotspots of potential schistosomiasis transmission based on regularly updated remote sensing data. KW - schistosomiasis KW - Burkina Faso KW - remote sensing KW - surface water KW - habitats KW - agricultural irrigation KW - rivers KW - snails Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-125845 VL - 9 IS - 11 ER - TY - JOUR A1 - Lakovic, Milica A1 - Poethke, Hans-Joachim A1 - Hovestadt, Thomas T1 - Dispersal timing: Emigration of insects living in patchy environments JF - PLoS One N2 - Dispersal is a life-history trait affecting dynamics and persistence of populations; it evolves under various known selective pressures. Theoretical studies on dispersal typically assume 'natal dispersal', where individuals emigrate right after birth. But emigration may also occur during a later moment within a reproductive season ('breeding dispersal'). For example, some female butterflies first deposit eggs in their natal patch before migrating to other site(s) to continue egg-laying there. How breeding compared to natal dispersal influences the evolution of dispersal has not been explored. To close this gap we used an individual-based simulation approach to analyze (i) the evolution of timing of breeding dispersal in annual organisms, (ii) its influence on dispersal (compared to natal dispersal). Furthermore, we tested (iii) its performance in direct evolutionary contest with individuals following a natal dispersal strategy. Our results show that evolution should typically result in lower dispersal under breeding dispersal, especially when costs of dispersal are low and population size is small. By distributing offspring evenly across two patches, breeding dispersal allows reducing direct sibling competition in the next generation whereas natal dispersal can only reduce trans-generational kin competition by producing highly dispersive offspring in each generation. The added benefit of breeding dispersal is most prominent in patches with small population sizes. Finally, the evolutionary contests show that a breeding dispersal strategy would universally out-compete natal dispersal. KW - animal migration KW - statistical disperison KW - organismal evolution KW - animal sexual behavior KW - habitats KW - insects KW - carrying capacity KW - moths and butterflies Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-126466 VL - 10 IS - 7 ER - TY - JOUR A1 - Hovestadt, Thomas A1 - Poethke, Hans J. A1 - Messner, Stefan T1 - Variability in dispersal distances generates typical successional patterns: a simple simulation model N2 - More recently, it became clear that conclusions drawn from traditional ecological theory may be altered substantially if the spatial dimension of species interactions is considered explicitly. Regardless of the details of these models, spatially explicit simulations of ecological processes have nearly universally shown that spatial or spatio-temporal patterns in species distributions can emerge even from homogeneous starting conditions; limited dispersal is one of the key factors responsible for the development of such aggregated and patchy distributions (cf., Pacala 1986, Holmes et al. 1994, Molofsky 1994, Tilman 1994, Bascompte and Sole 1995, 1997, 1998, Jeltsch et al. 1999). In line with these ideas, we wish to draw attention to the fact that in heterogeneous landscapes differences in characteristic dispersal distances between species are a sufficient precondition for the emergence of a successional pattern. We will use a simple, spatially explicit simulation program to demonstrate the validity of this statement. We will also show that the speed of the successional progress depends on scale and heterogeneity in the distribution of suitable habitat. KW - community KW - competition KW - environments KW - habitats KW - life-history Y1 - 2000 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-48178 ER - TY - JOUR A1 - Hopfenmueller, Sebastian A1 - Steffan-Dewenter, Ingolf A1 - Holzschuh, Andrea T1 - Trait-Specific Responses of Wild Bee Communities to Landscape Composition, Configuration and Local Factors N2 - Land-use intensification and loss of semi-natural habitats have induced a severe decline of bee diversity in agricultural landscapes. Semi-natural habitats like calcareous grasslands are among the most important bee habitats in central Europe, but they are threatened by decreasing habitat area and quality, and by homogenization of the surrounding landscape affecting both landscape composition and configuration. In this study we tested the importance of habitat area, quality and connectivity as well as landscape composition and configuration on wild bees in calcareous grasslands. We made detailed trait-specific analyses as bees with different traits might differ in their response to the tested factors. Species richness and abundance of wild bees were surveyed on 23 calcareous grassland patches in Southern Germany with independent gradients in local and landscape factors. Total wild bee richness was positively affected by complex landscape configuration, large habitat area and high habitat quality (i.e. steep slopes). Cuckoo bee richness was positively affected by complex landscape configuration and large habitat area whereas habitat specialists were only affected by the local factors habitat area and habitat quality. Small social generalists were positively influenced by habitat area whereas large social generalists (bumblebees) were positively affected by landscape composition (high percentage of semi-natural habitats). Our results emphasize a strong dependence of habitat specialists on local habitat characteristics, whereas cuckoo bees and bumblebees are more likely affected by the surrounding landscape. We conclude that a combination of large high-quality patches and heterogeneous landscapes maintains high bee species richness and communities with diverse trait composition. Such diverse communities might stabilize pollination services provided to crops and wild plants on local and landscape scales. KW - habitats KW - bees KW - grasslands KW - species diversity KW - biodiversity KW - pollination KW - flowers KW - foraging Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-112872 ER -