Search results for "Colouration"

Multimodal Aposematic Signals and Their Emerging Role in Mate Attraction

2018

Experimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals

2017

AbstractSpecular reflection appears as a bright spot or highlight on any smooth glossy convex surface and is caused by a near mirror-like reflectance off the surface. Convex shapes always provide the ideal geometry for highlights, areas of very strong reflectance, regardless of the orientation of the surface or position of the receiver. Despite highlights and glossy appearance being common in chemically defended insects, their potential signalling function is unknown. We tested the role of highlights in warning colouration of a chemically defended, alpine leaf beetle, Oreina cacaliae. We reduced the beetles’ glossiness, hence their highlights, by applying a clear matt finish varnish on thei…

Melanism is related to behavioural lateralization in nestling barn owls.

2017

5 pages; International audience; Behavioural laterality is a commonly observed phenomenon in many species suggesting there might be an advantage of using dominantly one side over the other for certain tasks. Indeed, lateralized individuals were often shown to be more successful in cognitive tasks compared to non-lateralized conspecifics. However, stressed individuals are also often, but not always, more strongly lateralized. Because barn owl (Tyto alba) females displaying larger black spots on the tip of their ventral feathers produce offspring that are more resistant to a variety of environmental stressful factors, we examined whether laterality is associated with melanin-based coloration.…

Camouflage in arid environments: the case of Sahara-Sahel desert rodents

2020

Deserts and semi-deserts, such as the Sahara-Sahel region in North Africa, are exposed environments with restricted vegetation coverage. Due to limited physical surface structures, these open areas provide a promising ecosystem to understand selection for crypsis. Here, we review knowledge on camouflage adaptation in the Sahara-Sahel rodent community, which represents one of the best documented cases of phenotype-environment convergence comprising a marked taxonomic diversity. Through their evolutionary history, several rodent species from the Sahara-Sahel have repeatedly evolved an accurate background matching against visually-guided predators. Top-down selection by predators is therefore …

Seeing red? Colour biases of foraging birds are context dependent.

2020

Funder: Suomen Kulttuurirahasto; doi: http://dx.doi.org/10.13039/501100003125

Ground-level predation on artificial caterpillars indicates no enemy-free time for lepidopteran larvae

2017

Lepidoptera is one of the most diverse orders of insects, their larvae are very abundant in many habitats, and frequent prey of various predators. To decrease predation risk, caterpillars developed several means of defence, among them timing their activity to avoid predators (seeking enemy-free time). Although the enemy-free time hypothesis is often invoked to explain caterpillar behaviour, empirical evidence for it is scarce. We tested whether such enemy-free time exists in a temperate forest by comparing predation pressure on artificial caterpillars during day and night on the ground in forest fragments in Denmark. We found a high predation rate, 23.9% d(-1), and higher predation rate at …

Multimodal Aposematic Signals and Their Emerging Role in Mate Attraction

2018

Chemically defended animals often display conspicuous color patterns that predators learn to associate with their unprofitability and subsequently avoid. Such animals (i.e., aposematic), deter predators by stimulating their visual and chemical sensory channels. Hence, aposematism is considered to be “multimodal.” The evolution of warning signals (and to a lesser degree their accompanying chemical defenses) is fundamentally linked to natural selection by predators. Lately, however, increasing evidence also points to a role of sexual selection shaping warning signal evolution. One of the species in which this has been shown is the wood tiger moth, Arctia plantaginis, which we here put forward…

Behavioural, ecological, and evolutionary aspects of diversity in frog colour patterns

2017

The role of colours and colour patterns in behavioural ecology has been extensively studied in a variety of contexts and taxa, while almost overlooked in many others. For decades anurans have been the focus of research on acoustic signalling due to the prominence of vocalisations in their communication. Much less attention has been paid to the enormous diversity of colours, colour patterns, and other types of putative visual signals exhibited by frogs. With the exception of some anecdotal observations and studies, the link between colour patterns and the behavioural and evolutionary ecology of anurans had not been addressed until approximately two decades ago. Since then, there has been eve…