Search results for "COMPETITION"
showing 10 items of 1409 documents
Interspecific aggression and character displacement in the damselfly Calopteryx splendens
2004
Problems in species recognition are thought to affect the evolution of secondary sexual characters mainly through avoidance of maladaptive hybridization. Another, but much less studied avenue for the evolution of sexual characters due to species recognition problems is through interspecific aggression. In the damselfly, Calopteryx splendens, males have pigmented wing spots as a sexual character. Large-spotted males resemble males of another species, Calopteryx virgo, causing potential problems in species recognition. In this study, we investigate whether there is character displacement in wing spot size and whether interspecific aggression could cause this pattern. We found first that wing …
Maintenance of male reaction to the congeneric song in the Hippolais warbler hybrid zone
1999
Both hybridization and competition may induce character shift on communication systems in hybrid zones, leading either to convergence or divergence. Melodious warblers Hippolais polyglotta and Icterine warblers H. icterina are interspecifically territorial and hybridize along a narrow contact zone. This spatial distribution is favoured by a reaction to the congeneric song. A character displacement, e.g. a decrease of the reaction, was expected within the hybrid zone because of reproduction costs lower than in allopatry. We investigated the pattern of variation of the interspecific reaction by comparing allopatric and sympatric populations. However, our data did not support the hypothesis ch…
Selection on size and secondary sexual characters of the damselfly Calopteryx splendens when sympatric with the congener Calopteryx virgo
2011
Male mating success is often determined by body size or secondary sexual characters because of female mate choice or competition for females. In addition to intraspecific interactions, interspecific interactions may interfere with intraspecific selection. In this study, we investigated sexual selection on size and sexual characters of male banded demoiselle ( Calopteryx splendens (Harris, 1780)) in wild populations sympatric with the beautiful demoiselle ( Calopteryx virgo (L., 1758)). As secondary sexual characters, male C. splendens have pigmented wing spots whose size appears to be under positive selection. Male C. virgo resemble male C. splendens that have the largest wing spots, leadi…
Crossed induction of sex in sympatric congeneric rotifer populations
2009
The transition from asexual to sexual reproduction in rotifers of the genus Brachionus (Monogononta) is triggered by a chemical signal produced and released by the rotifers themselves; the signal accumulates in the environment as population density increases. The response to this signal has been hypothesized to be speciesspecific. If not, the timing of sex and final diapausing egg production of a species might not be optimized. In this study, a set of experiments—based on individual and mass culture approaches—was carried out to investigate the differentiation in sex induction signals between sympatric and allopatric congeneric Brachionus populations by analyzing the capability of the mediu…
The enigmatic case of the genus Argyresthia in the Azores Islands (Lepidoptera Argyresthiidae)
2020
The species composition of the genus Argyresthia Hübner, 1825 in the Azores is examined. Argyresthia brumella, sp. nov., is described and illustrated from Terceira and Flores Islands. Argyresthia minusculella Rebel, 1940, syn. nov. and Tinea poecilella Rebel, 1940, syn. nov. are synonymized with Argyresthia atlanticella Rebel, 1940. The high variability of A. atlanticella is revealed through the polymorphic wing pattern and the intraspecific genetic divergence of the DNA barcode COI in the specimens examined.
The systematics of Soldanella (Primulaceae) based on morphological and molecular (ITS, AFLPs) evidence
2002
Based on the observation of more than 6300 herbarium specimens and molecular (ITS, AFLPs) evidence, Soldanella is divided into 16 species and four subspecies. Soldanella angusta, S. oreodoxa and S. rugosa are described as new, and the circumscriptions of S. marmarossiensis, S. major, S. pusilla ssp. pusilla and S. hungarica are emended. Nine hybrid names are lectotypified. All non-hybrid taxa are described in detail and distribution maps are provided. Interspecific relationships are discussed on the background of morphological and molecular variation.
A contribution to the mathematical modeling of immune-cancer competition
2018
Abstract This paper deals with the modeling of interactions between the immune system and cancer cells, in the framework of the mathematical kinetic theory for active particles. The work deepens a previous paper of Belloquid et al. that assumes spatial homogeneity and discrete values of the activity of cancer and immune cells. A number of simulations are made with the aim to investigate how the state of the various cell populations evolves in time depending on the choice of the free parameters.
Environmental taxation, information precision, and information sharing
2022
We analyze how environmental taxes should be optimally levied when the regulators and firms face costs uncertainties in a Stackelberg-Cournot game. We allow linear-quadratic payoffs functions coupled with an affine information structure encompassing common and private information with noisy signals. In the first period, the regulator chooses the intensity of emissions taxes in order to reduce externalities. In the second period, facing industry-related and firm-specific shocks, firms compete in the marketplace as Cournot rivals and choose outputs. We show that, given costs uncertainties with non-uniform quality of signals across firms, the regulator sets differentiated tax policy. We also e…
Strategic interactions on differentiated markets and public policies
2017
In economy, the competition analysis among firms have a significance importance because of the complexity of some elements. This thesis examines the strategic interactions on differentiated markets in general equilibrium while proposing the public policies to reduce the distortions due to the imperfect behaviors. This thesis takes into account the differentiation of products in order to obtain the new conclusions and/or to extend those existing. We thus pursues two objectives. Fisrt, the construction of a model of imperfect competition on differentiated markets in a general equilibrium framework. Second, the evaluation of the consequences of the model in terms of economic policies. At begin…
The Illegible Doctor’s Writing as a Visual Artifact and Creative Stimulation for Art Education
2014
El presente artículo analiza las posibilidades educativas de la particular escritura de los médicos, estudiando la componente gráfica de sus documentos, tanto históricos como recientes. Defendemos la escritura manual como un elemento gráfico importante para la educación artística, a partir de las premisas de la cultura visual. Nos basamos en los resultados positivos de la exposición “Caligrafías de la enfermedad. Letra de médico”, una muestra en la que los visitantes son protagonistas, intérpretes y constructores de significados. Utilizamos la metodología de los estudios de caso, incorporando la observación directa de varios grupos de visitantes. También aportamos otros datos de la experien…