Search results for "ecological"
showing 10 items of 1263 documents
Metazoan parasite communities and diet of the velvet belly lantern shark Etmopterus spinax (Squaliformes: Etmopteridae): a comparison of two deep-sea…
2014
By combining an examination of stomach contents yielding a snapshot of the most recent trophic niche and the structure of parasite communities reflecting a long-term feeding niche, this study aimed at gaining more comprehensive information on the role of the small-sized deep-water velvet belly lantern shark Etmopterus spinax in the local food webs of the Galicia Bank and the canyon and valley system of the Aviles Canyon, which have been both proposed for inclusion in the Natura 2000 network of protected areas. As far as is known, this study provides the first comparative parasite infracommunity data for a deep-sea shark species. Component parasite communities in E. spinax were relatively ri…
Niche segregation of coexisting Arctic charr (Salvelinus alpinus) and brown trout (Salmo trutta) constrains food web coupling in subarctic lakes
2012
SUMMARY 1. Generalist fish species are recognised as important couplers of benthic and pelagic food-web compartments in lakes. However, interspecific niche segregation and individual specialisation may limit the potential for generalistic feeding behaviour. 2. We studied summer habitat use, stomach contents and stable isotopic compositions of the generalist feeder Arctic charr coexisting with its common resource competitor brown trout in five subarctic lakes in northern Norway to reveal population-level and individual-level niche plasticity. 3. Charr and trout showed partial niche segregation in all five lakes. Charr used all habitat types and a wide variety of invertebrate prey including z…
Will the invasive western conifer seed bug Leptoglossus occidentalis Heidemann (Hemiptera: Heteroptera: Coreidae) seize all of Europe?
2008
In our day, thanks to high-speed transport systems, people are moving living species (intentionally or not) across ecosystems and countless borders. As we know, most introduced species usually do not survive, because they find neither a tolerable environment nor an available ecological niche. Sometimes, successful establishment may also require multiple introductions (Balcom 2004).
Diurnal habitat suitability for a Mediterranean steppeland bird, identified by Ecological Niche Factor Analysis
2011
Context The negative effects of agricultural intensification and policies, use of pesticides, fertilisers and mechanised harvesting on several populations of pseudo-steppe birds have increasingly required more detailed and effective habitat suitability models. Distribution models of farmland species are prone to incur recordings of false absence data. Ecological Niche Factor Analysis (ENFA) allows identification of environmental predictors of species distribution by using presence data only. Aims We quantified the diurnal habitat preferences and niche width of one steppe species, the stone curlew (Burhinus oedicnemus), with unfavourable conservations status in a Mediterranean area and recl…
Factors affecting the distribution of recent lacustrine ostracoda from the Caicedo de Yuso-Arreo Lake (Western Ebro Basin, Spain)
2005
Recent Ostracoda assemblages of the Caicedo de Yuso Lake have been described as representative of palustrine/lacustrine environments in Iberian temperate lakes. This study considers the changes in assemblages at a fixed station during two consecutive annual cycles, as well as their distribution in summer and winter profiles of the lake. Total sample-assemblages have been quantified as species diversities, measured by the Shannon-Wiener index H (S). The trends of this index are compared to physical parameters (temperature, conductivity, dissolved oxygen, CO2) of the bottom waters of this lake. The Ostracoda assemblages (8100 adults and juvenile living specimens, belonging to 20 species) are …
Ontogenetic Habitat Selection by Hadwenius pontoporiae (Digenea: Campulidae) in the Intestine of Franciscanas (Cetacea)
1997
The linear habitat selection of 4 sequential maturity stages (1, 2, 3, and 4) of the trematode Hadwenius pontoporiae in the intestines of 26 South American dolphins Pontoporia blanvillei was investigated. The franciscana is a suitable host for H. pontoporiae because all 26 hosts were infected, the infrapopulations being composed mostly of gravid (stage 4) worms. Most trematodes were found in the first third of the intestine. The niches of the maturity stages decreased from stage 1 to 4. Gravid worms favored the most anterior part of the duodenum, whereas stages 1, 2, and 3 occurred more posteriorly in every host. The distributions of the maturity stages showed a narrow site fidelity and wer…
Sexual segregation of Echinorhynchus borealis von Linstow, 1901 (Acanthocephala) in the gut of burbot (Lota lota Linnaeus)
2015
Helminths often occupy defined niches in the gut of their definitive hosts. In the dioecious acanthocephalans, adult males and females usually have similar gut distributions, but sexual site segregation has been reported in at least some species. We studied the intestinal distribution of the acanthocephalan Echinorhynchus borealis von Linstow, 1901 (syn. of E. cinctulus Porta, 1905) in its definitive host, burbot (Lota lota Linnaeus). Over 80% of female worms were found in the pyloric caeca, whereas the majority of males were in the anterior two-thirds of the intestine. This difference was relatively consistent between individual fish hosts. Worms from different parts of the gut did not dif…
How picky can you be? Temporal variations in trophic niches of co-occurring suspension-feeding species
2014
Abstract Suspension-feeders largely dominate faunal communities on rocky shores and compete for food using different feeding strategies. We used stable isotopes to assess the individual specialization within common suspension-feeder populations and to evaluate both inter-specific and intra-specific differences in food source exploitation. Trophic niches were characterized by metrics calculated in a space formed by mixing model outputs. Honeycomb worms ( Sabellaria alveolata ), blue mussels ( Mytilus edulis ) and barnacles ( Chthamalus montagui ), as well as three organic matter sources (benthic microalgae, phytoplankton and green macroalgae) were surveyed over a year using stable isotopic c…
Population changes in Czech passerines are predicted by their life-history and ecological traits
2010
A species’ susceptibility to environmental change might be predicted by its ecological and life-history traits. However, the effects of such traits on long-term bird population trends have not yet been assessed using a comprehensive set of explanatory variables. Moreover, the extent to which phylogeny affects patterns in the interspecific variability of population changes is unclear. Our study focuses on the interspecific variability in long-term population trends and annual population fluctuations of 68 passerine species in the Czech Republic, assessing the effects of eight life-history and five ecological traits. Ordination of life-history traits of 68 species revealed a life-history grad…
'Niche Selection' and the evolution of a complex behavior in a changing environment--a simulation.
2000
One of the key problems in theoretical biology is the identification of the mechanisms underlying the evolution of complexity. This paper suggests that some difficulties in current models could be avoided by taking account of “niche selection” as proposed by Waddington [21] and subsequent authors [2]. Computer simulations, in which an evolving population of artificial organisms “selects” the niche(s) that maximize their fitness, are compared with a Control Model in which “Niche Selection” is absent. In the simulations the Niche Selection Model consistently produced a greater number of “fit” organisms than the Control Model; although the Niche Selection Model tended, in general, to produce o…