Search results for "competition."
showing 10 items of 1367 documents
High population density in bank voles stimulates food hoarding after breeding.
1998
The effects of conspecific density (i.e. risk of intraspecific competition) on hoarding behaviour were studied in breeding pairs of bank voles, Clethrionomys glareolus. I simulated high population density by using odours of conspecifics, to exclude the direct effects of exploitation or interference competition for food. The pairs of bank voles hoarded only at the end of their breeding season. Hoarding was not correlated with whether the voles had a litter during the experiment or their litter size, but was more likely at the high population density and for pairs with small females. This may indicate that smaller females especially make caches in the autumn, possibly to ensure better winter …
Romania: Regional Persistence in a Highly Nationalized Party System
2017
Romania has a nationalized party system whereby the effective number of parliamentary parties has gone down and the left-right dimension of political competition has become consolidated. Statewide parties manage to electorally homogenize the electorate through using a similar electoral system for regional and national elections and by holding regional elections just before national elections. However, in this chapter, we also find that regional parties are persistently present in some regions and some of them mobilize voters along an ethno-cultural dimension. These regional parties do not only have an important impact at the regional level by offering alternative policy options but they are…
La memoria democrática en las aulas de secundaria y bachillerato : balance de una experiencia didáctica
2018
Este artículo presenta los resultados de una investigación sobre la concepción y el conocimiento de la memoria democrática en las aulas de secundaria y bachillerato, mediante la confección e implementación de una propuesta didáctica sustentada sobre la historia local y la concepción del aula como un lugar de investigación. A su vez, se analizan los mecanismos de aprendizaje, las transformaciones de la percepción del alumnado y los resultados del proyecto didáctico, que permiten ofrecer, de este modo, algunas claves para el trabajo de la historia y la memoria en la enseñanza de la Guerra Civil y la represión franquista.
Stress, angst og selvtillit hos topphåndballspillere i kampsituasjon : En kartlegging av før-konkurranseangst sammenlignet med spillernes mentale tøf…
2017
Masteroppgave idrettsvitenskap ME517 - Universitetet i Agder 2017 The purpose of this study was to establish pre-competition anxiety, self-confidence and mental toughness among high level handball players before matches during the handball season. The development of pre-competition anxiety and self-confidence before the matches was compared between two different teams and compared between players scoring high and low on mental toughness. Pre-competition anxiety and self-confidence was measured using the questionnaire CSAI-2 and mental toughness was measured using the questionnaire SMTQ. The participants was 34 female handball-players, recruited from two teams playing in the Norwegian nation…
Exposing the structure of an Arctic food web
2015
15 pages; International audience; How food webs are structured has major implications for their stability and dynamics. While poorly studied to date, arctic food webs are commonly assumed to be simple in structure, with few links per species. If this is the case, then different parts of the web may be weakly connected to each other, with populations and species united by only a low number of links. We provide the first highly resolved description of trophic link structure for a large part of a high-arctic food web. For this purpose, we apply a combination of recent techniques to describing the links between three predator guilds (insectivorous birds, spiders, and lepidopteran parasitoids) a…
Evolution of male and female choice in polyandrous systems
2017
We study the evolution of male and female mating strategies and mate choice for female fecundity and male fertilization ability in a system where both sexes can mate with multiple partners, and where there is variation in individual quality (i.e. in the availability of resources individuals can allocate to matings, mate choice and production of gametes). We find that when the cost of mating differs between sexes, the sex with higher cost of mating is reluctant to accept matings and is often also choosy, while the other sex accepts all matings. With equal mating costs, the evolution of mating strategies depends on the strength of female sperm limitation, so that when sperm limitation is stro…
Reproductive conflict delays the recovery of an endangered social species
2008
1. Evolutionary theory predicts that individuals, in order to increase their relative fitness, can evolve behaviours that are detrimental for the group or population. This mismatch is particularly visible in social organisms. Despite its potential to affect the population dynamics of social animals, this principle has not yet been applied to real-life conservation. 2. Social group structure has been argued to stabilize population dynamics due to the buffering effects of nonreproducing subordinates. However, competition for breeding positions in such species can also interfere with the reproduction of breeding pairs. 3. Seychelles magpie robins, Copsychus sechellarum, live in social groups w…
Sex roles and the evolution of parental care specialization
2019
Males and females are defined by the relative size of their gametes (anisogamy), but secondary sexual dimorphism in fertilization, parental investment and mating competition is widespread and often remarkably stable over evolutionary timescales. Recent theory has clarified the causal connections between anisogamy and the most prevalent differences between the sexes, but deviations from these patterns remain poorly understood. Here, we study how sex differences in parental investment and mating competition coevolve with parental care specialization. Parental investment often consists of two or more distinct activities (e.g. provisioning and defence) and parents may care more efficiently by s…
Genetic dissimilarity between mates, but not male heterozygosity, influences divorce in schistosomes.
2008
6 pages; International audience; Background: Correlational studies strongly suggest that both genetic similarity and heterozygosity can influence female mate choice. However, the influence of each variable has usually been tested independently, although similarity and heterozygosity might be correlated. We experimentally determined the relative influence of genetic similarity and heterozygosity in divorce and re-mating in the monogamous endoparasite Schistosoma mansoni. Methodology/Principal Findings: We performed sequential infections of vertebrate hosts with controlled larval populations of parasites, where sex and individual genetic diversity and similarity were predetermined before infe…
Food availability and competition do not modulate the costs of Plasmodium infection in dominant male canaries.
2013
7 pages; International audience; Understanding the different factors that may influence parasite virulence is of fundamental interest to ecologists and evolutionary biologists. It has recently been demonstrated that parasite virulence may occur partly through manipulation of host competitive ability. Differences in competitive ability associated with the social status (dominant or subordinate) of a host may determine the extent of this competition-mediated parasite virulence. We proposed that differences between subordinate and dominant birds in the physiological costs of infection may change depending on the level of competition in social groups. We observed flocks of domestic canaries to …