Search results for "psychology [Dementia]"
showing 10 items of 5946 documents
Predator encounters have spatially extensive impacts on parental behaviour in a breeding bird community.
2016
Predation risk has negative indirect effects on prey fitness, partly mediated through changes in behaviour. Evidence that individuals gather social information from other members of the population suggests that events in a community may impact the behaviour of distant individuals. However, spatially wide-ranging impacts on individual behaviour caused by a predator encounter elsewhere in a community have not been documented before. We investigated the effect of a predator encounter (hawk model presented at a focal nest) on the parental behaviour of pied flycatchers ( Ficedula hypoleuca ), both at the focal nest and at nearby nests different distances from the predator encounter. We show tha…
Feeding on clean food? Potential effects of electric organ discharges by Torpedo spp. (Torpediniformes: Torpedinidae) on their trophically transmitte…
2021
Members of the Torpedinidae (torpedoes) and Hypnidae (coffin ray) use electric organ discharges (EOD) to stun or kill their prey before consumption. We investigated whether EOD could also negatively affect the helminth larvae infecting these preys through a surrogate model: we applied electric discharges to individuals of blue whiting, Micromesistius poutassou, that harbored live larvae of Anisakis. Larval mortality throughout a 6-h period was significantly higher in the treatment group, suggesting that EODs could significantly hamper helminth recruitment. We then tested whether torpedinids and hypnids ("strong-EOD" families) harbored species-poor helminth (cestode) assemblages compared wit…
Symmetry breaking in mass-recruiting ants: extent of foraging biases depends on resource quality.
2016
Abstract The communication involved in the foraging behaviour of social insects is integral to their success. Many ant species use trail pheromones to make decisions about where to forage. The strong positive feedback caused by the trail pheromone is thought to create a decision between two or more options. When the two options are of identical quality, this is known as symmetry breaking, and is important because it helps colonies to monopolise food sources in a competitive environment. Symmetry breaking is thought to increase with the quantity of pheromone deposited by ants, but empirical studies exploring the factors affecting symmetry breaking are limited. Here, we tested if (i) greater …
How Do Infanticidal Male Bank Voles (Myodes glareolus) Find the Nest with Pups?
2016
Infanticide, the killing of conspecific young, occurs in most mammal species, like in our study species, the bank vole (Myodes glareolus). Infanticide by adult males is regarded as a strong factor affecting recruitment of young into population. It is considered as an adaptive behaviour, which may increase male fitness via resource gain or an increased access to mates. When an intruder is approaching the nest, the mother should not be present, as her nest guarding is very aggressive and successful. Pups use ultrasonic vocalisation to call their mother when mother leaves nest for foraging but it is not know which cues do infanticidal males use to find the nest with vulnerable pups to commit i…
Divergence is not speciation, or why we need females : a comment on Tinghitella et al
2018
Postprint Peer reviewed
Seasonal survival in a non-hibernating Mediterranean garden dormouse population
2020
The seasonal survival pattern of a garden dormouse Eliomys quercinus population was studied in a Mediterranean agricultural field area from East Spain, a geographical location in which this species does exhibit no hibernation. Individuals were captured from nest—boxes checked monthly during a 4-year period. Data were analysed using an open population Cormack–Jolly–Seber model including sex, age class and season as factors. Best models included the effect of age and differences in survival between adult males and females. Survival rate was more variable between seasons in males than in females or juveniles. Maximum adult male survival was reached in autumn, decreased in winter and dropped to…
Energetic costs of size and sexual signalling in a wolf spider
1998
A prerequisite for honest handicaps is that there are significant condition–dependent costs in the expression of sexual traits. In the wolf spider Hygrolycosa rubrofasciata (Ohlert), sexual signalling (drumming) is costly in terms of increased mortality. Here we investigated whether this mortality may be caused by increased energy expenditure. During sexual signalling, metabolic rate was 22 times higher than at rest and four times higher than when males were actively moving. Metabolic rate per unit mass was positively related to absolute body mass during sexual signalling but not during other activities. This positive relationship is novel to any studies of metabolic rates. Indeed, it seems…
Insect personality: what can we learn from metamorphosis?
2018
6 pages; International audience; Ontogeny of animal personality is still an open question. Testing whether personality traits correlated with state variables (e.g. metabolic rate, hormones) and/or life history traits, and which ones are involved, requires more empirical studies. Insects with metamorphosis represent a good opportunity to tackle this question. Because of the various degrees of internal (physiological, nervous) and environmental changes linked to metamorphosis they allow testing whether these modifications drive consistency in personality traits between immature and adult stages. In this review, we establish general predictions for the effects of metamorphosis on personality i…
Risk of inbreeding : problem of mate choice and fitness effects?
2016
Mating with close kin may cause inbreeding depression with negative consequences to offspring and local populations. There exist mechanisms like kin-recognition or sex-specific dispersal to avoid mating with kin. In fluctuating population densities, like in many small mammals, both very low and very high densities provide conditions for inbreeding, if kin males are prone to stay in their natal area. Females are choosy and male dominance is thought to be the key feature when selecting mating partners. The aim of this study was to test the possible discrepancy in mate choice and negative fitness effects of inbreeding in two experiments, one in the laboratory and one in field enclosures. We as…
Maternal investment in relation to sex ratio and offspring number in a small mammal - a case for Trivers and Willard theory?
2009
Summary 1. Optimal parental sex allocation depends on the balance between the costs of investing into sons vs. daughters and the benefits calculated as fitness returns. The outcome of this equation varies with the life history of the species, as well as the state of the individual and the quality of the environment. 2. We studied maternal allocation and subsequent fecundity costs of bank voles, Myodes glareolus, by manipulating both the postnatal sex ratio (all-male ⁄ all-female litters) and the quality of rearing environment (through manipulation of litter size by )2 ⁄ +2 pups) of their offspring in a laboratory setting. 3. We found that mothers clearly biased their allocation to female ra…