If, when and how natural sex ratio bias occurs in Gambusia holbrooki?: consequences for management of pest populations

Supervisory Team:

Primary supervisor: Jawahar Patil

Co-supervisor: Chris Bolch

Additional supervisors: James Haddy

Brief project description:

Understanding the mechanisms of population declines is critical for both conservation of endangered species as well as for implementing sex-ratio biased extinction/eradication strategies for management of pest populations. Regardless of the mechanism that creates a sex ratio bias within a population, increased numbers of one sex over the other can result in behaviors that impose additional fitness costs, such as mating harassment, increasing the risk of population extinctions. Despite, what appears a naturally occurring adult sex ratio bias, the invasive G. holbrooki are known to exhibit normal sex ratios (1:1) at birth and their populations thrive, particularly in invaded habitats. Therefore, it is not clear if the bias is real or reflects observational artifact, on count of size dimorphism. If the former, questions remain as to at what life stage do these differences manifest, what are the drivers and how do G holbrooki populations compensate and thrive? As a first step to address these questions, this honours project will systematically, investigate sex ratio of wild and laboratory reared populations, employing multiple techniques, including molecular markers of sex. The outcome will directly inform the development and implementation of genetic control options to eradicate this invasive species from Tasmania and Australia.

Skills students will develop during this research project:

Management of fish populations and molecular biology. Importantly, student will have opportunity to interact with community volunteers at the Tamar Island Wetland Reserve