Runners and fighters: clutch effects and body size drive innate
antipredator behaviour in hatchling lizards
Julia L. Riley
Martin J. Whiting
Received: 7 February 2018 /Revised: 29 April 2018 /Accepted: 3 May 2018 /Published online: 28 May 2018
Springer-Verlag GmbH Germany, part of Springer Nature 2018
Innate antipredator responses are integral for survival in many species, particularly those which lack parental care. Antipredator
responses include both active (fight or flight) and passive behaviours (immobility). As the success of antipredator responses
directly relates to survival and fitness, investigating the drivers that explain variance in these traits is key to understanding how
predation shapes the instinctive behaviour of animals. We quantified innate antipredator behaviour of hatchling Australian water
dragons (Intellagama lesueurii) immediately after hatching using a model snake to simulate a series of attacks, and scored their
behaviour using a fight or flight index. Then we explored which factors were related to dragon antipredator behaviour, such as
habitat disturbance, origin population, morphology, and parental genetic effects and phenotype (clutch effects). We developed
multiple hypotheses and used model selection to determine which factors drive variation in hatchling antipredator behaviour.
Clutch effects explained a significant proportion of variation in innate antipredator responses, suggesting a heritable component.
We also found an effect of body size on innate antipredator behaviour: larger hatchlings were more prone to flight behaviour (e.g.
short-distance runs and long-distance sprinting), while smaller individuals were more prone to standing their ground and being
aggressive (e.g. throat puffing, mouth gaping, biting). Clutch effects also explained a significant proportion of the variance in
dragon body size. Our study provides evidence that the innate antipredator responses of water dragons are heritable in origin
(directly through clutch effects, and indirectly through body size) and not associated with particular populations or habitat types.
We suggest future research examine the survival implications of these responses.
The action an animal takes in response to a predator is a life or death decision, and can be required immediately after birth. These
innate antipredator behaviours may be genetically linked, and enable individuals to emerge into their environment with the
necessary behaviour to promote survival. We examined what factors drive hatchling lizards to exhibit different innate antipredator
behaviour. Our study found that body size affected their innate behaviour: larger hatchlings were more prone to flee and smaller
hatchlings were more likely to fight. Interestingly, parental genetics and phenotype (clutch effects) also significantly explained
the variation in innate antipredator behaviour, which supports the hypothesis that these behaviours are heritable. Understanding
what drives variation is a cornerstone of evolutionary biology, and our findings raise questions about how selection acts on
antipredator behaviour and the degree to which they are plastic.
Keywords Behavioural ecology
Fight or flight
Communicated by T. Madsen
Electronic supplementary material The online version of this article
(https://doi.org/10.1007/s00265-018-2505-7) contains supplementary
material, which is available to authorized users.
* James Baxter-Gilbert
Department of Biological Sciences, Macquarie University,
Sydney, New South Wales 2109, Australia
Ecology and Evolution Research Centre, School of
Biological, Earth, and Environmental Sciences, University
of New South Wales, Sydney, New South Wales 2052,
Behavioral Ecology and Sociobiology (2018) 72: 97