Social network centrality predicts dietary decisions in a wild bird population.

How individuals balance costs and benefits of group living remains central to understanding sociality. In relation to diet, social foraging provides many advantages but also increases competition. Nevertheless, social individuals may offset increased competition by broadening their diet and consuming novel foods.

Predator selection on multicomponent warning signals in an aposematic moth.

Aposematic prey advertise their unprofitability with conspicuous warning signals that are often composed of multiple color patterns. Many species show intraspecific variation in these patterns even though selection is expected to favor invariable warning signals that enhance predator learning. However, if predators acquire avoidance to specific signal components, this might relax selection on other aposematic traits and explain variability.

Sensory collectives in natural systems.

Groups of animals inhabit vastly different sensory worlds, or umwelten, which shape fundamental aspects of their behaviour. Yet the sensory ecology of species is rarely incorporated into the emerging field of collective behaviour, which studies the movements, population-level behaviours, and emergent properties of animal groups. Here, we review the contributions of sensory ecology and collective behaviour to understanding how animals move and interact within the context of their social and physical environments.

Concurrent invasions of European starlings in Australia and North America reveal population-specific differentiation in shared genomic regions.

A species' success during the invasion of new areas hinges on an interplay between the demographic processes common to invasions and the specific ecological context of the novel environment. Evolutionary genetic studies of invasive species can investigate how genetic bottlenecks and ecological conditions shape genetic variation in invasions, and our study pairs two invasive populations that are hypothesized to be from the same source population to compare how each population evolved during and after introduction. Invasive European starlings (Sturnus vulgaris) established populations in both Australia and North America in the 19th century.

Ontogeny of color development in two green-brown polymorphic grasshopper species.

Many insects, including several orthopterans, undergo dramatic changes in body coloration during ontogeny. This variation is particularly intriguing in gomphocerine grasshoppers, where the green and brown morphs appear to be genetically determined (Schielzeth & Dieker, 2020, , 20, 63; Winter et al., 2021, , 127, 66).

In paired preference tests, domestic chicks innately choose the colour green over red, and the shape of a frog over a sphere when both stimuli are green.

Many animals express unlearned colour preferences that depend on the context in which signals are encountered. These colour biases may have evolved in response to the signalling system to which they relate. For example, many aposematic animals advertise their unprofitability with red warning signals.

The evolution and ecology of multiple antipredator defences.

Prey seldom rely on a single type of antipredator defence, often using multiple defences to avoid predation. In many cases, selection in different contexts may favour the evolution of multiple defences in a prey. However, a prey may use multiple defences to protect itself during a single predator encounter.

Antioxidant availability trades off with warning signals and toxin sequestration in the large milkweed bug ().

In some aposematic species the conspicuousness of an individual's warning signal and the concentration of its chemical defense are positively correlated. Several mechanisms have been proposed to explain this phenomenon, including resource allocation trade-offs where the same limiting resource is needed to produce both the warning signal and chemical defense. Here, the large milkweed bug (: Heteroptera, Lygaeinae) was used to test whether allocation of antioxidants, that can impart color, trade against their availability to prevent self-damage caused by toxin sequestration.

The price of defence: toxins, visual signals and oxidative state in an aposematic butterfly.

In a variety of aposematic species, the conspicuousness of an individual's warning signal and the quantity of its chemical defence are positively correlated. This apparent honest signalling is predicted by resource competition models which assume that the production and maintenance of aposematic defences compete for access to antioxidant molecules that have dual functions as pigments and in protecting against oxidative damage. To test for such trade-offs, we raised monarch butterflies () on different species of their milkweed host plants (Apocynaceae) that vary in quantities of cardenolides to test whether (i) the sequestration of cardenolides as a secondary defence is associated with costs in the form of oxidative lipid damage and reduced antioxidant defences; and (ii) lower oxidative state is associated with a reduced capacity to produce aposematic displays.

AMYLOIDOSIS IN CAPTIVE EUROPEAN EASTERN BONGO (): PREVALENCE, PREDICTIVE FACTORS, ORGAN PREDILECTION, AND SERUM AMYLOID A CONCENTRATIONS.

Amyloidosis is frequently identified during postmortem examination of captive eastern bongo () in the European Endangered Species Programme (EEP). However, its significance and etiopathogenesis are poorly understood. The objective of this study was to investigate the prevalence of amyloidosis within this population and identify potential predictive factors for the presence of disease.

New Structures, Spectrometric Quantification, and Inhibitory Properties of Cardenolides from Seeds.

Cardiac glycosides are a large class of secondary metabolites found in plants. In the genus , cardenolides in milkweed plants have an established role in plant-herbivore and predator-prey interactions, based on their ability to inhibit the membrane-bound Na/K-ATPase enzyme. Milkweed seeds are eaten by specialist lygaeid bugs, which are the most cardenolide-tolerant insects known.

Epistatic Effects Between Amino Acid Insertions and Substitutions Mediate Toxin resistance of Vertebrate Na+,K+-ATPases.

The recurrent evolution of resistance to cardiotonic steroids (CTS) across diverse animals most frequently involves convergent amino acid substitutions in the H1-H2 extracellular loop of Na+,K+-ATPase (NKA). Previous work revealed that hystricognath rodents (e.g.

Defence mitigation by predators of chemically defended prey integrated over the predation sequence and across biological levels with a focus on cardiotonic steroids.

Predator-prey interactions have long served as models for the investigation of adaptation and fitness in natural environments. Anti-predator defences such as mimicry and camouflage provide some of the best examples of evolution. Predators, in turn, have evolved sensory systems, cognitive abilities and physiological resistance to prey defences.

Additive genetic variation, but not temperature, influences warning signal expression in moths (Lepidoptera: Arctiinae).

Many aposematic species show variation in their color patterns even though selection by predators is expected to stabilize warning signals toward a common phenotype. Warning signal variability can be explained by trade-offs with other functions of coloration, such as thermoregulation, that may constrain warning signal expression by favoring darker individuals. Here, we investigated the effect of temperature on warning signal expression in aposematic moths that vary in their black and orange wing patterns.

Activation of the Nucleus Taeniae of the Amygdala by Umami Taste in Domestic Chicks ().

In chickens, the sense of taste plays an important role in detecting nutrients and choosing feed. The molecular mechanisms underlying the taste-sensing system of chickens are well studied, but the neural mechanisms underlying taste reactivity have received less attention. Here we report the short-term taste behaviour of chickens towards umami and bitter (quinine) taste solutions and the associated neural activity in the nucleus taeniae of the amygdala, nucleus accumbens and lateral septum.

The peppered moth Biston betularia.

Hannah Rowland and colleagues introduce the peppered moth whose industrial melanism was an early evidence for evolution.

Evidence for morph-specific substrate choice in a green-brown polymorphic grasshopper.

Orthopteran insects are characterized by high variability in body coloration, in particular featuring a widespread green-brown color polymorphism. The mechanisms that contribute to the maintenance of this apparently balanced polymorphism are not yet understood. To investigate whether morph-dependent microhabitat choice might contribute to the continued coexistence of multiple morphs, we studied substrate choice in the meadow grasshopper The meadow grasshopper occurs in multiple discrete, genetically determined color morphs that range from uniform brown to uniform green.

Dietary wariness.

What causes an animal to resist trying new food or incorporating it into their diet? In this Quick guide, Heyworth et al. discuss the phenomenon known as dietary wariness.

Social transmission in the wild can reduce predation pressure on novel prey signals.

Social transmission of information is taxonomically widespread and could have profound effects on the ecological and evolutionary dynamics of animal communities. Demonstrating this in the wild, however, has been challenging. Here we show by field experiment that social transmission among predators can shape how selection acts on prey defences.

The antipredator benefits of postural camouflage in peppered moth caterpillars.

Camouflage is the most common form of antipredator defense, and is a textbook example of natural selection. How animals' appearances prevent detection or recognition is well studied, but the role of prey behavior has received much less attention. Here we report a series of experiments with twig-mimicking larvae of the American peppered moth Biston betularia that test the long-held view that prey have evolved postures that enhance their camouflage, and establish how food availability and ambient temperature affect these postures.

Nectarivorous Bird Emphysematous Ingluvitis (NBEI): A Novel Disease in Loriinae Birds Associated With Infection.

A retrospective study revealed ten cases of emphysematous ingluvitis in Loriinae birds from two zoological collections between 2009 and 2020. Common clinical features were sudden death with gas distention of the crop, subcutaneous cervical emphysema and poor body condition, but also included collapse, hypothermia and abandonment. Macroscopic examination revealed moderate crop enlargement, distention and thickening with minimal intraluminal content, and moderate to severe submucosal to transmural gas-filled cysts (emphysema).

Social learning within and across predator species reduces attacks on novel aposematic prey.

To make adaptive foraging decisions, predators need to gather information about the profitability of prey. As well as learning from prey encounters, recent studies show that predators can learn about prey defences by observing the negative foraging experiences of conspecifics. However, predator communities are complex.

The effect of social information from live demonstrators compared to video playback on blue tit foraging decisions.

Video playback provides a promising method to study social interactions, and the number of video playback experiments has been growing in recent years. Using videos has advantages over live individuals as it increases the repeatability of demonstrations, and enables researchers to manipulate the features of the presented stimulus. How observers respond to video playback might, however, differ among species, and the efficacy of video playback should be validated by investigating if individuals' responses to videos are comparable to their responses to live demonstrators.

Adaptive colour change and background choice behaviour in peppered moth caterpillars is mediated by extraocular photoreception.

Light sensing by tissues distinct from the eye occurs in diverse animal groups, enabling circadian control and phototactic behaviour. Extraocular photoreceptors may also facilitate rapid colour change in cephalopods and lizards, but little is known about the sensory system that mediates slow colour change in arthropods. We previously reported that slow colour change in twig-mimicking caterpillars of the peppered moth () is a response to achromatic and chromatic visual cues.