Search results for "PREY"

Conservation implications of change in antipredator behavior in fragmented habitat: Boreal rodent, the bank vole, as an experimental model

2015

Abstract Habitat fragmentation is known to cause population declines but the mechanisms leading to the decline are not fully understood. Fragmentation is likely to lead to changes in predation risk, which may cause behavioral responses with possible population level consequences. It has recently been shown that the awareness of predator presence, resulting in a fear response, strongly affects behavior and physiology of the prey individuals. Costs arising from fear may be as important for the prey population size as the direct killing of prey. We tested how predation risk in the form of scent of a specialist predator, the least weasel (Mustela nivalis nivalis), affects bank vole (Myodes glar…

Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs

2014

Aposematic signal variation is a paradox: predators are better at learning and retaining the association between conspicuousness and unprofitability when signal variation is low. Movement patterns and variable colour patterns are linked in non-aposematic species: striped patterns generate illusions of altered speed and direction when moving linearly, affecting predators' tracking ability; blotched patterns benefit instead from unpredictable pauses and random movement. We tested whether the extensive colour-pattern variation in an aposematic frog is linked to movement, and found that individuals moving directionally and faster have more elongated patterns than individuals moving randomly and…

Experiments on Concurrent Artificial Environment

2001

We show how the simulation of concurrent system is of interest for both behavioral studies and strategies of learning applied on prey-predator problems. In our case learning studies into unknown environment have been applied to mobile units by using genetic algorithms (GA). A set of trajectories, generated by GA, are able to build a description of the external scene driving a predators to a prey. Here, an example of prey-predator strategy,based on field of forces, is proposed. The evolution of the corespondent system can be formalized as an optimization problem and, for that purpose, GA can be use to give the right solution at this problem. This approach could be applied to the autonomous r…

Anxiété et manipulation parasitaire chez un invertébré aquatique : approches évolutive et mécanistique

2020

Trophically transmitted parasites induce changes in their host’s phenotype. These changes are supposed to increase transmission probability to definitive hosts through the predation of intermediate hosts. This phenomenon is known as ‘parasite manipulation’ has been hypothesized to be an adaptive trait of parasites for a long time. As manipulation involves predator-prey interactions, it is therefore necessary to understand how antipredatory behaviours are modulated by exogenous (predation pressure) and endogenous (infection, emotional state) factors. We tried to go into this phenomenon in depth, in amphipods, by responding toseveral questions : (1) what is the extent of the multidimensionali…

Antipredator strategies of pupae: how to avoid predation in an immobile life stage?

2019

Antipredator strategies of the pupal stage in insects have received little attention in comparison to larval or adult stages. This is despite the fact that predation risk can be high during the pupal stage, making it a critical stage for subsequent fitness. The immobile pupae are not, however, defenceless; a wide range of antipredator strategies have evolved against invertebrate and vertebrate predators. The most common strategy seems to be ‘avoiding encounters with predators' by actively hiding in vegetation and soil or via cryptic coloration and masquerade. Pupae have also evolved behavioural and secondary defences such as defensive toxins, physical defences or deimatic movements and soun…

Protist predation can select for bacteria with lowered susceptibility to infection by lytic phages

2015

Background: Consumer-resource interactions constitute one of the most common types of interspecific antagonistic interaction. In natural communities, complex species interactions are likely to affect the outcomes of reciprocal co-evolution between consumers and their resource species. Individuals face multiple enemies simultaneously, and consequently they need to adapt to several different types of enemy pressures. In this study, we assessed how protist predation affects the susceptibility of bacterial populations to infection by viral parasites, and whether there is an associated cost of defence on the competitive ability of the bacteria. As a study system we used Serratia marcescens and i…

Lotic life stages of the European river lamprey (Lampetra fluviatilis) : anthropogenic detriment and rehabilitation

2015

Latvijas Vēstures Institūta Žurnāls. 2018, Nr. 2 (107) 

2018

Žurnāls sagatavots LU Akadēmiskās attīstības projekta “Zinātniskā periodiskā izdevuma “Latvijas Vēstures Institūta Žurnāls” sagatavošana un izdošana 2018. gadā” (vad. Guntis Zemītis) ietvaros

Analysis of the Allee threshold via moving least square approximation

2016

Cooperation is a common behavior between the members of predators species, because it can improve theirs skill in hunt, especially in endangered eco-systems. This behavior it is well known to induce the Strong Allee effect, that can induce the extinction when the initial populations’ is under a critical density called ”Allee threshold ”. Here we investigate the impact of the pack hunting in a predator-prey system in which the predator suffers of an infectious disease with frequency and vertical transmission. The result is a three dimensional system with the predators population divided into susceptible and infected individuals. Studying the system dynamics a scenario was identified in which…

The price of safety: food deprivation in early life influences the efficacy of chemical defence in an aposematic moth

2018

Aposematism is the combination of a primary signal with a secondary defence that predators must learn to associate with one another. However, variation in the level of defence, both within and between species, is very common. As secondary defences influence individual fitness, this variation in quality and quantity requires an evolutionary explanation, particularly as it may or may not correlate with variation in primary signals. The costs of defence production are expected to play a considerable role in generating this variation, yet studies of the cost of chemical defence have focused on species that sequester their defences, while studies in species that produce them de novo are scarce. …