Search results for "prey"

A risk assessment of the effects of mercury on Baltic Sea, Greater North Sea and North Atlantic wildlife, fish and bivalves

2021

Abstract: A wide range of species, including marine mammals, seabirds, birds of prey, fish and bivalves, were investigated for potential population health risks resulting from contemporary (post 2000) mercury (Hg) exposure, using novel risk thresholds based on literature and de novo contamination data. The main geographic focus is on the Baltic Sea, while data from the same species in adjacent waters, such as the Greater North Sea and North Atlantic, were included for comparative purposes. For marine mammals, 23% of the groups, each composing individuals of a specific sex and maturity from the same species in a specific study region, showed Hg-concentrations within the High Risk Category (H…

How to fight multiple enemies : target-specific chemical defences in an aposematic moth

2017

Animals have evolved different defensive strategies to survive predation, among which chemical defences are particularly widespread and diverse. Here we investigate the function of chemical defence diversity, hypothesizing that such diversity has evolved as a response to multiple enemies. The aposematic wood tiger moth (Arctia plantaginis) displays conspicuous hindwing coloration and secretes distinct defensive fluids from its thoracic glands and abdomen. We presented the two defensive fluids from laboratory-reared moths to two biologically relevant predators, birds and ants, and measured their reaction in controlled bioassays (no information on colour was provided). We found that defensive…

Snake richness predicts breeding distribution of short-toed snake eagle in central Italy.

2017

Birds of prey, as top predators, play a key role in ecosystem functioning by regulating prey populations and, by means of cascade effects, promoting biodiversity. This makes them adequate sentinels of ecosystem health. Here we analyse the relationship between the occurrence of breeding short-toed snake eagle (Circaetus gallicus) and both the richness of potential prey species and landscape characteristics by taking into account two different spatial scales (i.e. nest-site scale and landscape scale). The short-toed snake eagle offers an interesting case study for investigating the relationships between top predators, prey diversity, and habitats, because it is an extremely specialised raptor…

Deimatism: a neglected component of antipredator defence

2017

Deimatic or ‘startle’ displays cause a receiver to recoil reflexively in response to a sudden change in sensory input. Deimatism is sometimes implicitly treated as a form of aposematism (unprofitability associated with a signal). However, the fundamental difference is, in order to provide protection, deimatism does not require a predator to have any learned or innate aversion. Instead, deimatism can confer a survival advantage by exploiting existing neural mechanisms in a way that releases a reflexive response in the predator. We discuss the differences among deimatism, aposematism, and forms of mimicry, and their ecological and evolutionary implications. We highlight outstanding questions …

Olfactory cues and the value of information: voles interpret cues based on recent predator encounters

2018

Abstract Prey strategically respond to the risk of predation by varying their behavior while balancing the tradeoffs of food and safety. We present here an experiment that tests the way the same indirect cues of predation risk are interpreted by bank voles, Myodes glareolus, as the game changes through exposure to a caged weasel. Using optimal patch use, we asked wild-caught voles to rank the risk they perceived. We measured their response to olfactory cues in the form of weasel bedding, a sham control in the form of rabbit bedding, and an odor-free control. We repeated the interviews in a chronological order to test the change in response, i.e., the changes in the value of the information.…

Biased predation could promote convergence yet maintain diversity within Müllerian mimicry rings of Oreina leaf beetles.

2019

Mullerian mimicry is a classic example of adaptation, yet Muller's original theory does not account for the diversity often observed in mimicry rings. Here, we aimed to assess how well classical Mullerian mimicry can account for the colour polymorphism found in chemically defended Oreina leaf beetles by using field data and laboratory assays of predator behaviour. We also evaluated the hypothesis that thermoregulation can explain diversity between Oreina mimicry rings. We found that frequencies of each colour morph were positively correlated among species, a critical prediction of Mullerian mimicry. Predators learned to associate colour with chemical defences. Learned avoidance of the green…

Social transmission of avoidance among predators facilitates the spread of novel prey.

2018

Warning signals are an effective defence strategy for aposematic prey, but only if they are recognized by potential predators. If predators must eat prey to associate novel warning signals with unpalatability, how can aposematic prey ever evolve? Using experiments with great tits (Parus major) as predators, we show that social transmission enhances the acquisition of avoidance by a predator population. Observing another predator’s disgust towards tasting one novel conspicuous prey item led to fewer aposematic than cryptic prey being eaten for the predator population to learn. Despite reduced personal encounters with unpalatable prey, avoidance persisted and increased over subsequent trials.…

Eco‐evolutionary dynamics driven by fishing : from single species models to dynamic evolution within complex food webs

2020

Evidence of contemporary evolution across ecological time scales stimulated research on the eco‐evolutionary dynamics of natural populations. Aquatic systems provide a good setting to study eco‐evolutionary dynamics owing to a wealth of long‐term monitoring data and the detected trends in fish life‐history traits across intensively harvested marine and freshwater systems. In the present study, we focus on modelling approaches to simulate eco‐evolutionary dynamics of fishes and their ecosystems. Firstly, we review the development of modelling from single‐species to multispecies approaches. Secondly, we advance the current state‐of‐the‐art methodology by implementing evolution of life‐history…

Can multiple-model mimicry explain warning signal polymorphism in the wood tiger moth, Arctia plantaginis (Lepidoptera: Erebidae)?

2018

Modelling prey-predator interactions in Messina beachrock pools

2020

Abstract The Strait of Messina (Sicily, Italy) attracts the interest of marine ecologists for the presence of a large variety of habitat and mutually-interacting communities. Among them, beachrock formations, despite their wide geographic distribution, which also includes the Mediterranean area, have been poorly investigated from the biotic viewpoint. In this paper, the spatial and seasonal variability of benthic megafauna from the Messina microtidal beachrock is described. Combining in situ collected data (measurements of abiotic parameters and underwater visual census) with theoretical post-processing analyses (analysis of similarity percentages and cluster analysis), we deduced the possi…