Research

a) The ecological impacts of stress

 

Understanding interactions between organisms and their environment is a fundamental goal of ecology.  Changes in the environment are increasingly frequent and can impose significant stress on natural populations.  Extensive biomedical research suggests that stress will have important implications for natural systems; but these implications remain largely unstudied.  Understanding the ecological consequences of stress is critical for understanding how communities persist in this changing world, and for predicting and managing the impacts of environmental perturbations.

 

We are in the early stages of a research program that takes advantage of the “natural” experiment provided by the introduction of fire ants to quantify the stress caused by invasion, measure the ecological consequences of stress across levels of biological organization, and determine how long-term exposure to increased stress levels alters the stress-tolerance of populations.  This research will help us to understand how stress modifies ecological and evolutionary processes within natural populations.

 

Relevant publications:

 

Shine R., Langkilde T., Wall M. and Mason R.T. 2005. The fitness correlates of scalation asymmetry in garter snakes Thamnophis sirtalis parietalis. Functional Ecology 19: 306-314

 

 

b) Stress and behavior

 

The negative impacts of stress (particularly for health) have received much research attention.  However, the important role stress plays in facilitating adaptive responses to threatening situations is relatively poorly understood.  Stress plays an important role in responding to threatening stimuli, mobilizing energy to fuel the response and eliciting appropriate behaviors.  Although some threats incur an innate stress, and corresponding behavioral response (such as loud noises), others require conditioning or evolution to elicit a response (such as the introduction of non-native species).  In these situations, the absence of an appropriate stress and behavioral response may reduce an animal’s ability to survive invasion.

 

The system of invasive fire ants and native lizards provides an excellent opportunity to understand the role stress plays in facilitating adaptive behavioral responses to threats.

We are examining whether the behavioral response to fire ants is driven by differences in the perceived threat imposed by these invaders. This can have important implications for the role of stress caused by anthropogenic change in promoting population persistence.

 

Relevant publications:

Langkilde T. 2009. Invasive fire ants alter behavior and morphology of native lizards. Ecology 90: 208-217

 

Shine R., Wall M., Langkilde T. and Mason R.T. 2005. Scaling the heights: thermally-driven arboreality in garter snakes.  Journal of Thermal Biology 30: 179-185

 

Langkilde T., Shine R. and Mason R.T. 2004. Predatory attacks to the head versus body modify behavioural responses of garter snakes.  Ethology 110: 937-947

 

 

c) Stress and research

 

Ecologists should preferentially use research approaches that have a minimal impact on their study organism; both for ethic reasons and to ensure their data are biologically relevant. The choice of research protocols is often based on intuition – a notoriously unreliable criterion when dealing with animals phylogenetically distant from humans. We objectively evaluated the stress imposed by research practices, by measuring plasma corticosterone levels in lizards.  Our data suggest that intuition provides a poor basis for evaluating the levels of stress induced by research. We urge researchers to scientifically assess the impact of alternative research approaches, rather than relying upon subjectivity and anthropomorphism in making these evaluations.

 

Relevant publications:

 

Langkilde T. and Shine R. 2006. How much stress do researchers inflict on their study animals? A case study using a scincid lizard, Eulamprus heatwolei. Journal of Experimental Biology 209: 1035-1043

 

Langkilde T. and Alford R. 2002. The tail wags the frog:  attached transponders affect movement behaviour in Litoria lesueuri. Journal of Herpetology 36:711-715

 

 

Stress is becoming increasingly prevalent, both in human society and in natural animal systems.  The role of stress hormones (including corticosterone) is still debated, but likely includes avoiding pathological costs of stress, preparing an individual to respond to future threats, and permitting and stimulating appropriate responses to such threats when they happen. Research on humans and model systems revealed important implications for health, reproduction, and growth, but we don’t have an integrated understanding of ecological implications of stress.  Our research aims to address this important need.

 

The Ecological Role and Consequences of Stress

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