Conflict between background matching and social signalling in a colour-changing freshwater fish.

The ability to change coloration allows animals to modify their patterning to suit a specific function. Many freshwater fishes, for example, can appear cryptic by altering the dispersion of melanin pigment in the skin to match the visual background. However, melanin-based pigments are also used to signal dominance among competing males; thus colour change for background matching may conflict with colour change for social status signalling.

How well can body size represent effects of the environment on demographic rates? Disentangling correlated explanatory variables.

Demographic rates are shaped by the interaction of past and current environments that individuals in a population experience. Past environments shape individual states via selection and plasticity, and fitness-related traits (e.g.

Costs of colour change in fish: food intake and behavioural decisions.

Many animals, particularly reptiles, amphibians, fish and cephalopods, have the ability to change their body colour, for functions including thermoregulation, signalling and predator avoidance. Many fish plastically darken their body colouration in response to dark visual backgrounds, and this functions to reduce predation risk. Here, we tested the hypotheses that colour change in fish (1) carries with it an energetic cost and (2) affects subsequent shoal and habitat choice decisions.

Mixed-phenotype grouping: the interaction between oddity and crypsis.

Aggregations of different-looking animals are frequently seen in nature, despite well-documented selection pressures on individuals to maintain phenotypically homogenous groups. Two well-known theories, the 'confusion effect' (reduced ability of a predator to accurately target an individual in a group) and the 'oddity effect' (preferential targeting of phenotypically distinct, 'odd', individuals) act together to predict the evolution of behaviours in prey that lead to groups of animals that are homogeneous in appearance. In contrast, a recently proposed mechanism suggests that mixed groups could be maintained if one species in a mixed group is more conspicuous against the habitat than the other, as confusion effects generated by the conspicuous species impede predator targeting of the cryptic species; thus, cryptic species benefit from association with conspicuous ones.