Lizard caudal autotomy

 One of our main study species – Lygodactylus capensis – the southern African dwarf gecko

Autotomy is a dramatic, last-ditch, anti-predator tactic of some animals whereby  part of the body is voluntarily shed, usually along a breakage plane, and under central control (i.e. as a ‘choice’) to escape a predator that has grasped it.  Despite the extreme nature of this behaviour it is recorded across multiple invertebrate and vertebrate taxa and with multiple types of appendages (typically limbs and tails) being shed, indicating its independent evolution in myriad lineages and reflecting its fundamental adaptive advantage in ensuring survival.

Despite the near-ubiquity of autotomy (it is found in 13 of the approximately 20 families of lizard), there have been few studies that have examined it in detail.  The benefit of autotomy is huge  – shedding a limb or tail in the face of predation is aimed at allowing the organism to survive, but such a huge benefit is therefore likely to come trailing multiple different associated costs. An organism that has autotomized part of its body is left in a compromised state that is unique: autotomy is effectively a ‘wound’ received in a predatory encounter that, although compromising, is not necessarily debilitating.  The organism therefore, now exists in a changed state: smaller, potentially with reduced resources and, in many cases, with a dramatically different anatomy (e.g. some lizards can be reduced by over 75% of their length by losing a tail), and has to make adaptive, economic ‘decisions’ post-autotomy to allow it to continue feeding, courting, hold territories, mate and survive future predatory encounters in the face of costs to health, locomotion, energy reserves etc.

A PhD on caudal autotomy in lizards will attempt to quantify short- and long-term costs of tail autotomy and tail regeneration and combine empirical physiological and behavioural data on individual animals with analysis of museum data to capture patterns across species.  Short term costs include how to immediately deal with a radically altered body form and the effects of that on locomotion, interactions with conspecifics and future encounters with predators, while long term costs include regenerating the tail and resources lost from having shed the tail.

This project will take a comparative approach to investigate the effects of caudal autotomy on the mechanics and physiology of locomotion in small lizards and will quantify short- and long-term costs of tail autotomy and identify behavioural responses that reflect fitness in reptiles such as: willingness to lose tail (facility of autotomy) and tail regeneration rate; and the effect of autotomy and tail regeneration on: resting metabolic rate – due to growth of tissue and changing body composition; locomotory ability – speed, stamina, mobility, metabolic costs; behavioural responses – prey handling and habitat selection.

Requirements: Students will need to successfully obtain admission to Curtin University’s postgraduate program, and it is expected that they will also apply for an Australian Postgraduate Award (APA) and/or a Curtin University Postgraduate Scholarship (CUPS). Applications close October 2015. Please see the Curtin Website for more information about admission and scholarships.

Benefits: Curtin University provides a generous top-up to the standard APA/UPA funding of $24,653 pa, so that the total value of an APA is $32,500 pa and a CUPA $27,500 pa. Students in the Department of Environment and Agriculture also receive a laptop for the duration of their candidature.

Contact: Bill Bateman