Search results for "selection"

Habitat Differences and Variability in the Lek Mating System of Black Grouse

1996

Spatially fixed territoriality has been regarded to be a general feature in lek mating systems. In the absence of territories, however, the nature of leks may change remarkably. We compared leks of black grouse in areas, where territoriality was governed by habitat characteristics. On ice-covered lakes, where the lekking ground was homogeneous and offered no landmarks by which the displaying males would be able to recognize territory boundaries, the male aggregations were mobile. 'Classical' leks on bogs, however, were stable. It also appeared that on mobile leks, as compared to stable leks, the opportunities for females to choose their mates were reduced. The distribution of mating success…

Fluctuating asymmetry and copulation success in lekking black grouse

1997

Abstract In lekking black grouse, Tetrao tetrix males at the centre of the leks obtain more copulations than males at the edges. We found that males with territories at the edge of the lek obtained fewer matings and also have the most asymmetric tarsi. However, when considering the tail ornament (the lyre) no correlation between asymmetry and mating success was found. Although females are unlikely to select males on the basis of tarsus symmetry, asymmetry in this trait may reflect male condition. We suggest that males in poor condition, as reflected by higher levels of fluctuating asymmetry in the tarsi, do not achieve central positions on the lek arena. This would account for the lower suc…

Personality and body condition have additive effects on motivation to feed in Zebra Finches Taeniopygia guttata

2012

Several hypotheses have been proposed to account for the adaptive evolution of person-ality, defined as inter-individual differences in behaviour that are consistent over timeand across situations. For instance, the ‘pace-of-life syndrome’ hypothesis suggests thatpersonality evolved as a behavioural correlate of life-history trajectories that vary withinpopulations. Thus, proactivity, corresponding to higher exploratory tendencies or higherboldness levels, has been linked to higher productivity or mortality rates. However, theextent to which proactivity is associated with a higher motivation to forage remainspoorly understood. Moreover, although personality and its effects on foraging behavi…

Density‐dependent influence of male characters on mate‐locating efficiency and pairing success in the waterlouse Asellus aquaticus: an experimental s…

2005

Population density is likely to determine the form of competition in which males are engaged for access to females. At low density, scramble competition should be of paramount importance because of the low probability of encounter between males and females. Consequently, sexual selection should favour characters that allow rapid detection of females. Conversely, at high population density, sexual selection should favour attributes that raise the fighting ability of males because of the more frequent contacts between males. These general predictions were tested in this study for the precopulatory mate-guarding isopod, Asellus aquaticus. In this species, male-biased sexual dimorphisms are rep…

BLOOD PARASITES AND MALE FITNESS IN THE PIED FLYCATCHER

1993

In vertebrates the effect of parasites on host ecology has almost been ignored. Recently the view that well-adapted parasites do not harm their hosts has been challenged and there is growing evidence that parasites do have a present-day effect on a great variety of host fitness components. The pied flycatcher is a small migratory passcrine bird. Any decrease in condition caused by disease should affect its ability to cope with physical demands of migration. Here we examine whether blood parasites have any effect on male arrival time. Males infected with Trypanosoma arrived on average 2 days later than males with no Trypanosoma infection. Infected males also had shorted tails and tended to h…

Context-dependent effects of tail-ornament damage on mating success in black grouse

1994

Selection and long-term cultures of high-yielding Digitalis obscura plants: RAPD markers for analysis of genetic stability

1996

Fifteen wild-growing plants of Digitalis obscura collected in three differents regions were characterized according to their capacities to biosynthesize cardenolides and to proliferate in vitro. Great genotype-dependent variabilities were found in both parameters. Selected genotypes were differentiated using randomly amplified polymorphic DNA (RAPD) markers. Once an elite genotype with high-yielding properties was isolated and micropropagated during 2 years, identity of the donor plant and the regenerants was confirmed by RAPD analysis.

Use of molecular topology in the selection of new cytostatic drugs

2000

Abstract Connectivity indices are the topological descriptors that are able to predict different chemical and biological properties of the organic compounds. Recently, our research group has demonstrated their usefulness in selecting new cytostatic compounds, all of them showing antibacterial activity. In this paper we realize that this ability is considerably increased by using our home-made pharmacological distribution diagrams (PDDs) together with the topological charge indices, so that the efficient selection of new candidates within heterogeneous sets of compounds is possible. This is a straightforward way for the design and/or selection of new active compounds on virtually any type of…

The effect of periodic bottlenecks on the competitive ability of Drosophila pseudoobscura lines.

1993

Competition experiments between several Drosophila pseudoobscura strains that were previously subjected to periodic bottlenecks of different sizes and D. willistoni have been carried out. Contrary to previous results with these two species, where stable coexistence was detected, populations of D. pseudoobscura displaced D. willistoni in a few generations. By using a relative fitness measure, the control lines (that had not gone through bottlenecks) outcompeted D. willistoni faster than bottlenecked lines. One of these, corresponding to the minimum possible bottleneck size of one pair, also shows significantly lower relative fitness than the other strains. These results are discussed in rela…

Ensemble feature selection with the simple Bayesian classification

2003

Abstract A popular method for creating an accurate classifier from a set of training data is to build several classifiers, and then to combine their predictions. The ensembles of simple Bayesian classifiers have traditionally not been a focus of research. One way to generate an ensemble of accurate and diverse simple Bayesian classifiers is to use different feature subsets generated with the random subspace method. In this case, the ensemble consists of multiple classifiers constructed by randomly selecting feature subsets, that is, classifiers constructed in randomly chosen subspaces. In this paper, we present an algorithm for building ensembles of simple Bayesian classifiers in random sub…