Search results for "ISP"
showing 10 items of 10048 documents
Emigration speed and the production of sexuals in colonies of the ant Temnothorax crassispinus under high and low levels of disturbance
2015
A nest relocation is costly for social insects, and involves hazards. Emigrations were studied in Temnothorax crassispinus ant colonies, which inhabit ephemeral nest sites, and which frequently change their nests. In a laboratory experiment, ant colonies from one group were forced to change their nest sites 10 times over a ca. 3-month period, whilst colonies from the second group were forced to adopt this practice twice (on the beginning of May, and in the second half of July). Colonies of the ant from both the groups reduced their total emigration duration. However, the duration of the transport phase remained unchanged. In the case of colonies with higher level of disturbance, there was n…
Spatial structure and β-diversity of phytoplankton in Tibetan Plateau lakes: nestedness or replacement?
2017
Spatial patterns and β-diversity of phytoplankton assemblages depend on the relative importance of species dispersal capacity and species-sorting. Variability in species composition, composed by differences in species richness (nestedness) and/or species replacement, may be caused by niche availability and environmental selection. A field survey was carried out in Tibetan plateau on 38 lakes. Tibetan plateau lakes, located at high elevation, are harsh ecosystems characterized by low temperatures, low available nutrients, high UV amount, and strong salinity gradients. Only well-adapted species can survive in these environments. We therefore hypothesized that environmental filtering was the m…
Interactions between environmental variability and immigration rate control patterns of species diversity
2006
Abstract Theories focussing on local competition processes predict that species diversity is maximised with high-frequency environmental variability or alternatively with intermediate frequencies. The models coupling regional processes to local explanations of diversity patterns predict that the immigration rate from a regional species pool can strongly increase diversity. However, the interaction between local and regional processes in temporally fluctuating environment has received little attention. We explored in a simulation study how the patterns of species diversity are affected by the frequency spectrum of stochastic environmental variations and density independent immigration rate i…
From individual dispersal to species ranges: perspectives for a changing world.
2006
Dispersal is often risky to the individual, yet the long-term survival of populations depends on having a sufficient number of individuals that move, find each other, and locate suitable breeding habitats. This tension has consequences that rarely meet our conservation or management goals. This is particularly true in changing environments, which makes the study of dispersal urgently topical in a world plagued with habitat loss, climate change, and species introductions. Despite the difficulty of tracking mobile individuals over potentially vast ranges, recent research has revealed a multitude of ways in which dispersal evolution can either constrain, or accelerate, species' responses to en…
Ecological correlates of distribution change and range shift in butterflies
2011
1. In order to be effective custodians of biodiversity, one must understand what ecological characteristics predispose species to population decline, range contraction, and, eventually, to extinction. 2. The present paper analyses distribution change (area of occupancy) and range shift (extent and direction) of the threatened and non-threatened butterfly species in Finland, and identifies species-specific ecological characteristics promoting changes in distribution and range. 3. Overall, the range of butterflies has shifted along the climatic isotherms, suggesting that climate change has influenced species’ ranges. Interestingly, though, threatened species have moved very little and not to …
On the tolerance of charophytes to high-nitrate concentrations
2017
Currently a debate exists about whether the reduced growth of macrophytes with increased nitrogen loading in shallow ecosystems is determined by ecological or physiological factors. To discover whe...
Testing the usefulness of habitat corridors in mitigating the negative effects of fragmentation: the soil faunal community as a model system
2004
Abstract The corridor hypothesis predicts that habitat corridors should attenuate the negative effects of fragmentation on populations or communities by enhancing the dispersal of organisms between the habitat fragments (the ‘rescue effect’). In the present 12-month mesocosm experiment, this hypothesis was tested using the soil micro- and mesofaunal community in humus patches—either connected or unconnected with humus corridors to each other—as a model system. Of particular interest was to explore whether faunal groups with differing life strategies (e.g. in trophic position and dispersal capacity) would differ in their responses to the corridors. The results showed that enchytraeid worms w…
Colonisation of newly established habitats by soil decomposer organisms: the effect of habitat corridors in relation to colonisation distance and hab…
2005
Abstract The aim of the present 2.5-year-long field experiment was to explore the ability of various members of the detrital food web to colonise newly established habitat patches in field conditions, either in the presence or absence of habitat corridors. Patch size and distance to the “mainland” (colonisation source) were manipulated to explore the scale dependency of the corridor effects. Sterilised humus patches, embedded in mineral soil regarded as uninhabitable (or non-preferred) matrix for the soil organisms, functioned as newly established habitats. Intact forest soil served as the source of colonisers. Three kinds of patches were established: large ones situated at relatively long …
Onset of natal dispersal in Peregrine Falcon from Mediterranean islands (Italy)
2018
Abstract Basic information on natal dispersal of Peregrine Falcons is virtually lacking in Europe, despite increased attention on this species, and the sensitivity of this stage in the Peregrines’ life history. In this study, we collected satellite telemetry data during the onset of natal dispersal of 19 Peregrine Falcons tagged in Sicily and the Aeolian archipelago (Italy). We divided the onset of dispersal into the following 3 periods: post-fledging dependence period (PFDP), wandering, and wintering. PFDP lasted on average 47±16 days, during which young peregrines moved very little (0.167 km), and explored small areas (0.226 km2) far from the nest cliff, and showed no sex differences. The…
Emergence, dispersal, and mate finding via a substrate-borne sex pheromone in the parasitoidMetaphycus luteolus
2013
Metaphycus luteolus Timberlake (Hymenoptera: Encyrtidae) is a facultatively gregarious parasitoid of soft scale insects. We conducted behavioral experiments to better understand the mating structure of this species. Emergence of male and female offspring is synchronized, beginning at the onset of photoperiod. Both sexes are able to disperse, although dispersal of males from natal patches appears to take longer than dispersal of females. We demonstrated the presence of a female-produced contact pheromone using open arena bioassays and motion tracking software, testing residues deposited by walking females, and extracts of females. Males responded to the females' chemical footprints' and to a…