Search results for " Competition"

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…

Temporal and dietary niche is context‐dependent in tropical ants

2020

A New, Ecologically Self-Significant Metric of Species-Abundance Unevenness, Reliably Highlighting the Intensity of Interspecific Competition

2021

A wide series of commonly used metrics of abundance-evenness (or -unevenness) have been proposed to characterize synthetically the distributions of species-abundances, accounting for the hierarchic-like organization of species within natural communities. Among them, most – if not all–have been relevantly criticized on their serious limitations regarding both their “descriptive” and their “interpretative” capacities. From the descriptive point of view, many authors have already repeatedly emphasized the formal non-independenceof conventional (un-)evenness metrics with respect to species-richness, leading, in particular, to unacceptable bias when comparing communities differing by their speci…

Nested assemblages resulting from host size variation: the case of endoparasite communities in fish hosts

2001

Nested species subsets are a common pattern in many types of communities found in insular or fragmented habitats. Nestedness occurs in some communities of ectoparasites of fish, as does the exact opposite departure from random assembly, anti-nestedness. Here, we looked for nested and anti-nested patterns in the species composition of communities of internal parasites of 23 fish populations from two localities in Finland. We also compared various community parameters of nested and anti-nested assemblages of parasites, and determined whether nestedness may result simply from a size-related accumulation of parasite species by feeding fish hosts. Nested parasite communities were characterised b…

Genecological and isozyme studies in Senecio vernalis Waldst. & Kit. and S. vulgaris L. var. vulgaris (Asteraceae) from Central Europe and Israel

1995

Summary Genecological evidence and evidence obtained from an isozyme survey suggest a considerable amount of intraspecific differentiation in Senecio vernalis . Plants of this species from Israel were found to differ strikingly from those of C European (German) origin in most of the traits investigated, e.g., in the possession of pronounced seed dormancy, which seems to be governed by a single gene, a shorter life cycle, lack of rosette growth correlated with stem elongation prior to budding, a larger number of smaller capitula with fewer (disc) florets, and an ephemeral habit with plants only flowering soon after the first winter rains. Both accessions achieved a similar reproductive poten…

Direct interference or indirect exploitation? An experimental study of fitness costs of interspecific competition in voles

2002

Studies on competing mammalian species in the past have focused mainly on the competitive exclusion of one species from the preferred habitat of the other. Investigations on effects of competition and coexistence on individual fitness are rare. In this study we were able to measure effects of interspecific competition on major fitness components, using a system with two vole species in asymmetric competition. Survival, reproduction and space use of bank vole Clethrionomys glareolus females were monitored in 32 enclosed populations over four replicates of eight parallel run enclosures. Into half of the enclosures we introduced an additional number of field voles Microtus agrestis, a dominant…

Paternity, copulation disturbance and female choice in lekking black grouse

1996

Female copulation behaviour in the black grouse, Tetrao tetrix, was studied by detailed observations of individually marked birds together with DNA fingerprinting analyses for paternity assessment. For each breeding occasion females typically mated only once with one male, and did not mate outside the lek arena. They re-mated with the same or another male usually only if the initial copulation was disturbed and was probably unsuccessful in sperm transfer. The willingness of females to copulate only once with one male suggests that multiple mating with several males incurs a cost that more than outweighs any possible fertility or sperm competition benefits. Attempts by neighbouring males to …

Marketisation of Universities and Legal Education in Poland: The Balance 25 Years After the Transformation

2016

This paper is dedicated to the issue of the marketisation of universities and legal education 25 years after the systemic transformation of 1989 where, in public discourse, communist ideology had been replaced by a neo-liberal one. The process of marketisation is perceived as a way to deal with externalities’ where activities in areas traditionally regarded to be of a non-economic nature are being transformed to operate according to market-oriented model (with competitive market, pursuit for profit, economic efficiency, and cost reduction). The mentioned process has encroached into the sphere of higher education where there is observable departure from Humboldt’s model of university and a s…

Geovisualizing the sail-to-steam transition through vessel movement data

2017

International audience; Technological transitions in the maritime and port industries go along with increased transport and economic efficiency, resulting in faster movements and longer travelled distances. Yet, such transformations may also enhance disparities between winners and loosers, should they be ports or shipping companies. This research focuses on the particular case of the transition from sail to steam over the period 1890-1925, which witnesses the rapid replacement of sailing vessels, the latter concentrating 65% of the world fleet in 1890 but only 3.5% in 1925. It applies a variety of measures to compare how these two layers overlap in the network (at links and ports) and what …

Rethinking Community Quality of Life in Latin American Countries

2017

The community is a totality which is meaningful to the people that form part of it. In this sense community is more than a geographic concentration; it is a concept that implies the inclusion of diversities and their being allowed to share within it. It is related to social support, intersubjective, participation, consensus, common beliefs, and a joint effort which aims at a major objective: intense and extensive relationships. Quality of life is a multidimensional concept (Bramston 2002) and comprises objective and subjective components (Cummins and Cahill 2000). Quality of life in the community is a specificity of quality of life in general, and community well-being is also a predictor of…