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Article Reference Changes in the distribution of carabid beetles in Belgium revisited: Have we halted the diversity loss?
Located in Library / RBINS Staff Publications
Article Reference Ant biodiversity conservation in Belgian calcareous grasslands: active management is vital
Located in Library / RBINS Staff Publications
Article Reference Acceptance of two native myrmecophilous species, Platyarthrus hoffmannseggii (Isopoda : Oniscidea) and Cyphoderus albinus (Collembola : Cyphoderidae) by the introduced invasive garden ant Lasius neglectus (Hymenoptera : Formicidae) in Belgium
Located in Library / RBINS Staff Publications
Article Reference Loss of genetic diversity and increased genetic structuring in response to forest area reduction in a ground dwelling insect: a case study of the flightless carabid beetle Carabus problematicus (Coleoptera: Carabidae)
Located in Library / RBINS Staff Publications
Article Reference Local extinction processes rather than edge effects affect ground beetle assemblages from fragmented and urbanized old beech forests
Local extinction of specialist species due to fragmentation is one of the major causes of biodiversity loss. Increased extinction rates in smaller fragments are expected to result from both smaller local population sizes, which increase the effect of environmental or demographic stochasticity, and increased edge effects. However, the relative effect sizes of these two factors are still poorly investigated. We attempt to disentangle these effects on ground beetle communities of temperate broadleaved woodland fragments situated in one of the most urbanized regions in Belgium. Assemblages were sampled along transects that extended from 30 m outside to 100 m inside both small and large historic forest fragments. Although species assemblages within the forest were highly distinct compared to those sampled outside the forest, species turnover along these transects was less pronounced within forest fragments indicating only weak edge effects. The magnitude of edge effects did not differ significantly between large and small fragments. However, larger differences in species composition were observed with respect to fragment size, wherein highly specialized species persisted only in the largest fragment. In sum, increased local extinction processes in smaller fragments, which led to a strong reduction of specialized and wingless forest species, appeared to be the most important factor that drives changes in species composition in this historic and fragmented woodland complex.
Located in Library / RBINS Staff Publications
Article Reference Ideal Free distribution of fixed dispersal phenotypes in a wing dimorphic beetle in heterogeneous landscapes
According to the ideal free distribution (IFD) theory, individuals that are able to perceive the quality of different patches in a landscape and disperse freely are expected to redistribute themselves proportionally to the carrying capacities of heterogeneous patches. Here, we argue that when dispersal is unconditional and genetically fixed, a coalition of sedentary and dispersing phenotypes can attain an IFD under spatio-temporally uncorrelated variation in fitness. This not only leads to a stable polymorphism of both dispersal phenotypes, but also implies that the number of dispersing individuals should on average be equal among patches and determined by the carrying capacity of the smallest local populations in the landscape. Differences in carrying capacity among patches are thus only reflected by changes in the number of sedentary individuals. Individual-based simulations show that this mechanism can be generalized over a wide range of spatio-temporal conditions and dispersal strategies. Moreover, these expectations are in strong agreement with empirical data on the density of both dispersal phenotypes of the wing dimorphic ground beetle Pterostichus vernalis within and among ten different landscapes. Hence, for the first time, these results demonstrate that this mechanism serves as a plausible alternative to the competition-colonization model to explain the spatial distribution of fixed dispersal phenotypes in heterogeneous landscapes. Understanding of the frequency distributions of individuals expressing discrete dispersal morphs moreover improves our predictive and management capabilities for a broad range of species, for which we currently typically rely on using mean dispersal rates.
Located in Library / RBINS Staff Publications
Article Reference Human-Induced Expanded Distribution of Anopheles plumbeus, Experimental Vector of West Nile Virus and a Potential Vector of Human Malaria in Belgium
For the majority of native species, human-created habitats provide a hostile environment that prevents their colonization. However, if the conditions encountered in this novel environment are part of the fundamental niche of a particular species, these low competitive environments may allow strong population expansion of even rare and stenotopic species. If these species are potentially harmful to humans, such anthropogenic habitat alterations may impose strong risks for human health. Here, we report on a recent and severe outbreak of the viciously biting and day-active mosquito Anopheles plumbeus Stephens, 1828, that is caused by a habitat shift toward human-created habitats. Although historic data indicate that the species was previously reported to be rare in Belgium and confined to natural forest habitats, more recent data indicate a strong population expansion all over Belgium and severe nuisance at a local scale. We show that these outbreaks can be explained by a recent larval habitat shift of this species from tree-holes in forests to large manure collecting pits of abandoned and uncleaned pig stables. Further surveys of the colonization and detection of other potential larval breeding places of this mosquito in this artificial environment are of particular importance for human health because the species is known as a experimental vector of West Nile virus and a potential vector of human malaria.
Located in Library / RBINS Staff Publications
Article Reference Effects of sublethal abiotic stressors on population growth and genetic diversity of Pellioditis marina (Nematoda) from the Westerschelde estuary
Understanding the effects of anthropogenic pollutants at the ecosystem level requires a proper understanding of the toxicological effects at the population level. Species living in estuaries resist highly fluctuating conditions, and are often exposed to sublethal concentrations of pollutants coming from industrial and domestic wastes. In the Westerschelde estuary, the most upstream sampled population of the nematode Pellioditis marina is genetically less diverse than elsewhere. It experiences lower salinities and higher Cd concentrations than more downstream populations in the estuary. In the present study, we investigate whether these environmental conditions may explain the lower genetic diversity in the most upstream location. To this end we followed the development of genetically diverse P marina populations under experimental conditions during 14 days. Genetic diversity was assessed in the F1, F2 and F5 generation by screening mitochondrial cytochrome oxidase c subunit 1 variation with the single-strand conformation polymorphism method (SSCP) and nucleotide sequencing. Our results show that sublethal Cd concentrations reduce population development of P. marina at suboptimal salinities, and that low salinity conditions induce responses at the genetic level. Nevertheless, the genetic effects were not persistent over generations, which emphasize the need for longer multigenerational experiments. (c) 2007 Elsevier B.V. All rights reserved.
Located in Library / RBINS Staff Publications
Article Reference Does behavioural isolation prevent interspecific mating within a parallel ecotypic wolf spider radiation from the Galapagos?
Located in Library / RBINS Staff Publications
Article Reference Direct and indirect effects of metal stress on physiology and life history variation in field populations of a lycosid spider
1. Under stress, life history theory predicts reduced growth rates and adult sizes, reduced reproductive allocation, production of larger offspring and postponed reproduction. Both direct and indirect effects of metals can explain these trends, mainly linked to energetic constraints. Metallothionein-like proteins (MTLP's) are believed to be an important defense mechanism against the adverse effects of metals and other stressors. 2. We tested these predictions comparing six field populations of the wolf spider Pardosa saltans, three of which were on sites that are historically polluted with heavy metals. 3. As expected for life histories evolving under energetic constraints, adult size and condition correlated negatively and egg mass positively with Cd concentrations for a subset of four populations. In the population that showed the highest cadmium and zinc body burdens, reproductive output and allocation were lowest and reproduction was postponed. 4. Contrary to our expectation, for all six study populations MTLP concentrations did not increase in exposed populations, indicating that this defense mechanism cannot explain the observed variation in life histories. 5. We conclude that indirect and synergistic effects of metal pollution may be more important than physiological defense mechanisms in shaping life history traits in field populations. (C) 2011 Elsevier Inc. All rights reserved.
Located in Library / RBINS Staff Publications