She-oak skink (Cyclodomorphus casuarinae)
Application for Scientific Permit – Available for Public Comment
Public comment on the following application for a Scientific Research (Fauna) Permit is open until 2 December 2019.
Applicant: School of Natural Sciences, University of Tasmania
Species/Taxon: She-oak skink (Cyclodomorphus casuarinae)
Location: Eastern and south-eastern Tasmania
Title of research: Asynchronous live birth and social dynamics of She-oak skinks (Cyclodomorphus casuarinae)
Aim of project: The major aim of this project is to determine if Cyclodomorphus casuarinae skinks give birth asynchronously and, in doing so, potentially alter the social dynamic of their brood.
Justification: This research will provide fundamental insights into a crucial biological innovation - the evolution of live birth – and how this influences family social dynamics. Though heavily studied, the evolution of live birth remains somewhat of a mystery. One of the key components of the transition to live birth is lengthening the time that offspring are held within the mother. Some species of Egernia take this step further by precisely extending the time between individual births. Specifically, some species give birth to all offspring within the same day, some species display facultative prolonged birth in which some individuals give birth to all their offspring on the same day and others over several days, while others display obligate prolonged birth in which there is always a delay in parturition. Understanding how and why this happens will provide crucial insight into not only the evolution of birth, but also how this altered timeline impacts family dynamics. Asynchronous birth is thought to influence familial relationships much like asynchronous hatching in birds. Many species of bird are known to stagger the hatching of chicks to influence sibling competition, allowing older or earlier hatched chicks to successfully outcompete their siblings. However, we have data on the birthing patterns of only a very small number of Egernia species and even less data on how birthing asynchrony influences family life. Collecting data on C. casuarinae will provide crucial information on these traits in an unstudied species of the Egernia group which will contribute significantly to a large comparative data set that we are constructing on variation in birthing asynchrony across the Egernia group and its associated influence on family dynamics.
Maximum likely numbers of individuals involved: We will capture and use thirty pregnant females in this experiment.
Activities undertaken and methods: Thirty Cyclodomorphus casuarinae will be collected from their natural habitat and returned to the University’s terrestrial ecology facilities. There they will be housed with food and water until the end of gestation. Females will be observed daily for signs of birth. Once all individuals within a litter are born, they will be assayed for family conflict. This will involve filming litters for a two-hour period in the morning following the birth of the final offspring. We will record all aggressive interactions between siblings and between offspring and their mother.
Fate of animals: All individuals are released at their site of capture. All offspring born in the laboratory will be released at their mother’s site of capture.
Likely impact on species involved (including any by-catch): She-oak skinks are a very common reptile species throughout eastern and southern Tasmania. Collecting the numbers needed for this project is unlikely to affect the population.