Overview
Topic status: We're looking for students to study this topic.
Of the estimated 200+ species of Australian freshwater fish, only a handful can be traced back to Gondwanan ancestry or beyond. It is apparent therefore that the majority of species have evolved from marine ancestors since that time. The primary physiological barrier to marine species invading freshwater systems is overcoming problems associated with osmoregulation. Freshwater species need to be able to limit the loss of ions and to restrict uptake of water to maintain an appropriate ion balance in their cells for functional metabolism. The function of the hormone prolactin (PRL) has been identified as one of the principal pathways that allow marine species to tolerate freshwater conditions. While fluctuating PRL activity in the gills, intestines, kidneys and skin has clearly been demonstrated in freshwater acclimation studies, the specific cause and effect relationships remain relatively poorly resolved. Is variation in freshwater tolerance among taxa facilitated by i) variation in the particular structure of the PRL protein (i.e. variation in gene sequence that affects protein structure); ii) variation in gene regulation; iii) variation at PRL receptors; or iv) some combination of these factors? Of particular interest is 'if specific DNA polymorphisms in the gene itself are responsible (option i above), has the same mutation/s arisen independently many times in diverse groups of Australian FW fish taxa that enabled multiple marine/freshwater transitions'?
The aim of this project is to examine the relative role of PRL in adaptation to freshwater in a number of Australian fish taxa.
The aims of this project will be achieved by comparing Single Nucleotide Polymorphisms (SNPs) in prolactin DNA sequence within and among a series of geminate groups representing several taxonomic levels (i.e. each pair will consist of either conspecifics, congeneric or confamilial samples, one freshwater and one marine in each pair). These data will also be compared with neutral DNA sequence variation among taxa in order to further investigate the role of natural selection in PRL gene evolution. The project will require some field work to collect samples (i.e. fish sampling), however the majority of the research will be undertaken in the Ecological Genetics lab at QUT.
- Study level
- Honours
- Supervisors
- QUT
- Organisational unit
Science and Engineering Faculty
- Research area
- Contact
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Please contact the supervisor.
Dr David Hurwood
Dr Ana Pavasovic
