Brendan L McEwen

McMaster University | McMaster · Department of Psychology, Neuroscience, and Behavior

Aposematic signals warn predators that prey should be avoided due to dangerous secondary defences. However, as warning signals do not always produce avoidance, warning colours may evolve as a trade-off balancing detectability against signal saliency. For Batesian mimics, which display salient signals but lack secondary defences, the costs of predat...

Among-individual variation in predator traits is ubiquitous in nature. However, variation among populations in this trait variation has been seldom considered in trophic dynamics. This has left unexplored (a) to what degree does among-individual variation in predator traits regulate prey populations and (b) to what degree do these effects vary spat...

Among-individual variation in predator traits is ubiquitous in nature. However, the role of intraspecific trait variation in trophic dynamics has been seldom considered in community ecology. This has left unexplored a) to what degree does among-individual variation in predator traits regulate prey populations and b) to what degree do these effects...

Among-individual variation in predator traits is ubiquitous in nature. However, the role of intraspecific trait variation in trophic dynamics has been seldom considered in community ecology. This has left unexplored a) to what degree does among-individual variation in predator traits regulate prey populations and b) to what degree do these effects...

Colour is an important component of many different defensive strategies, but signal efficacy and detectability will also depend on the size of the coloured structures, and how pattern size interacts with the background. Consequently, size-dependent changes in colouration are common among many different species as juveniles and adults frequently use...

Sensory and behavioural lateralization is thought to increase neural efficiency and facilitate coordinated behaviour across much of the animal kingdom. Complementary laterality, when tasks are lateralized to opposite sides, can increase the efficiency of multitasking, but predictable behaviour may increase predation risk. Laterality is, however, va...

Intra-group social stability is important for the long-term productivity and health of social organisms. We evaluated the effect of group size on group stability in the face of repeated social perturbations using a cooperatively breeding fish, Neolamprologus pulcher In a laboratory study, we compared both the social and physiological responses of i...

Camouflage patterns prevent detection and/or recognition by matching the background, disrupting edges, or mimicking particular background features. In variable habitats, however, a single pattern cannot match all available sites all of the time, and efficacy may therefore be reduced. Active color change provides an alternative where coloration can...

Many animal societies are susceptible to mass mortality events and collapse. Elucidating how environmental pressures determine patterns of collapse is important for understanding how such societies function and evolve. Using the social spider Stegodyphus dumicola, we investigated the environmental drivers of colony extinction along two precipitatio...

Intra-group social stability is important for the long-term productivity and health of social organisms. We evaluated the effect of group size on group stability in the face of repeated social perturbations using a cooperatively breeding fish, Neolamprologus pulcher . In a laboratory study, we compared both the social and physiological responses of...

Nest parasites attempt to shift the cost of rearing young from themselves to others. Despite strong selection to avoid this exploitation, there is considerable variation among-individuals in susceptibility to nest parasites. We evaluated the effects of individual variation in boldness, aggressiveness, and olfactory responsiveness on egg discriminat...

Identifying the traits that foster group survival in contrasting environments is important for understanding local adaptation in social systems. Here we evaluate the relationship between the aggressiveness of social spider colonies and their persistence along an elevation gradient using the Amazonian spider, Anelosimus eximius. We found that coloni...

Many animal societies are susceptible to mass mortality events and collapse. Elucidating how environmental pressures determine patterns of collapse is key for our understanding of social evolution. Using the social spider Stegodyphus dumicola we investigated the environmental drivers of colony extinction along two precipitation gradients across sou...

Identifying the traits that foster group survival in contrasting environments is important for understanding local adaptation in social systems. Here we evaluate the relationship between the aggressiveness of social spider colonies and their persistence along an elevation gradient using the Amazonian spider, Anelosimus eximius. We found that coloni...

Evolutionary ecologists often seek to identify the mechanisms maintaining intraspecific variation. In social animals, whole groups can exhibit between-group differences in their collective traits. We examined whether negative frequency-dependent selection (that is, a rare-type advantage) could help to maintain between-group variation. We engineered...

Particularly socially influential individuals are present in many groups [1-8], but it is unclear whether their emergence is determined by their social influence versus the social susceptibility of others [9]. The social spider Stegodyphus dumicola shows regional variation in apparent leader-follower dynamics. We use this variation to evaluate the...

Individual animals differ consistently in their behaviour, thus impacting a wide variety of ecological outcomes. Recent advances in animal personality research have established the ecological importance of the multidimensional behavioural volume occupied by individuals and by multispecies communities. Here, we examine the degree to which the multid...