A day of guest posts – this from Justa Heinen-Kay. Thanks Justa!
Imagine yourself walking down a street in a town known for its low crime rate. How would you behave? Would you explore new areas? Would you walk by yourself? Now imagine yourself walking down a similar street, but in a neighborhood known to have a high murder rate. Would you behave as you imagined in the safe neighborhood? Perhaps you would be less likely to explore an unknown street, and prefer to be with a group of others that you know? Many animals also experience environments that differ in riskiness, which could drastically impact how they behave. We tested this idea using the Bahamas mosquitofish that lives in inland blue holes across Andros Island, The Bahamas. These blue holes have fairly similar environments, except that a voracious predatory fish that specializes on mosquitofish inhabits some blue holes, but not others.
Using field and laboratory experiments, we found consistent and predictable behavioral differences between mosquitofish living in high predation risk vs low predation risk blue holes lacking predators (link to paper here). First, mosquitofish from predator-free populations were much more exploratory than their counterparts from risky environments. Mosquitofish from risky blue holes congregate in larger groups, showing more shoaling behavior. This is thought to be an anti-predator defense mechanism, because a predator is less likely to eat any one fish in a group than if by themselves. In predator-free blue holes, females were bolder and males were less aggressive (in general, male mosquitofish are much bolder than females). Differences in behavior can have cascading ecological and evolutionary consequences, so understanding how predictably animals behave in different ecological conditions is critical in a rapidly changing world.
Here is the paper abstract…..
Many animals show complex behaviours that can have important ecological and evolutionary consequences. Environmental variation can lead to divergent selection that consistently favours particular behaviours in different environments; but how predictably multiple aspects of animal behaviour diverge in response to different environmental conditions remains unclear. We tested whether populations evolving under different levels of predation risk show predictable and repeatable population-level behavioural differences in all five primary components of animal personality: aggression, sociability, boldness, activity and exploration. We formulated and tested a priori predictions of divergence for each behaviour using the adaptive radiation of Bahamas mosquitofish, Gambusia hubbsi (family Poeciliidae), inhabiting vertical water-filled caves (blue holes) where they have evolved for thousands of years in either the presence or absence of predatory fish. Mosquitofish behaviours differed consistently, and largely predictably, between predation regimes: low-predation mosquitofish showed reduced sociability and greater exploration of a novel environment compared to high-predation counterparts. However, some differences were sex dependent: only females showed greater boldness and only males displayed reduced aggressiveness in low-predation populations. Activity levels did not differ between predation regimes. All populations showed a behavioural syndrome characteristic of either proactive or reactive stress-coping styles with regard to exploration. Exploration behavioural syndromes were more similar among populations that evolved in similar predation regimes, regardless of genetic relatedness. Using laboratory-born, high-predation mosquitofish, we confirmed that exploratory behaviours have a genetic basis and show significant within-individual repeatability. Our results suggest that environmental variation, such as chronic predation risk, can lead to repeatable, and often predictable, changes in multifarious animal behaviours, and that various aspects of behaviour can diversify more or less independently of one another. Considering the ecological importance of these behaviours, the ability to forecast behavioural shifts in a rapidly changing world could serve as a valuable conservation tool. © 2016 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.