Everything about an organism's life can be looked at as a trade-off. The energy acquired from eating a banana, for example, can be used for skeletal growth or to augment fat reserves or invested in gametes; but the same energy cannot be distributed in multiple places at once. Choices - however unconscious - must be made.

Performance trade-offs occur at many different levels. At the level of the whole-animal, we know that particular types of muscles perform better for sprinting than endurance running, and that the rapid growth of tadpoles associated with certain thermal environments can affect their post-metamorphic jumping abilities. Specialised morphology that makes an animal a better fighter may also hinder its ability to escape from predators.

Performance is also strongly affected by an individual's behaviour. Time - like energy - must be allocated throughout the day, and time spent doing one activity inhibits other activities. For example, time spent hiding from predators means less time for feeding - which we know to have important carry-on effects on growth, development and motor performance.

Trade-offs in performance even occur within cells and tissues, because the allocation of energy and the waste by-products of motor performance (e.g. lactic acid, reactive oxygen species, etc) affect other essential, non-motor systems like immunity. Currently, we're interested in how these mechanistic trade-offs facilitate variation in rapid growth, breeding and early death among populations of northern quolls.