School of Animal Biology

Michael Young

Thesis

The evolution of geographical colour pattern variation in the western rainbowfish, Melanotaenia australis (Castelnau 1875)

Summary

The western rainbowfish is a small, endemic freshwater fish distributed throughout the north of Western Australia. Whenever suitable habitat is present, it is usually very abundant.

This species exhibits sexual dichromism, with plain females and brightly coloured males, and the morphology and colour patterns of male western rainbowfish vary among populations over a variety of spatial scales. The aim of my research is to determine how this among-population phenotypic variation has evolved.

First I will determine whether the phenotypic differences among populations reflect genetic differences.

I will then isolate microsatellite loci within the genome of the western rainbowfish and use them to determine whether genetically-based phenotypic differences among populations represent adaptations to different local environments.

Finally, I will identify the importance of predation and sexual selection as factors promoting adaptation to different local environments in the western rainbowfish.

Why my research is important

This research will be the first to formally document the behaviour of the western rainbowfish, and the relative importance of neutral and adaptive genetic divergence among its populations. The western rainbowfish is potentially a good, new model species for studies in behavioural ecology, and this work will bring it to the attention of the scientific community for the first time.

The isolation of microsatellites in this species will also be of great utility, as later scientists will be able to use them for a multitude of tasks, such as DNA fingerprinting, selective breeding, assignment of kinship, and genome mapping, as well as for answering questions in population genetics and phylogeography.

Besides addressing fundamental topics in evolutionary biology, this project will provide new data on a native species that will be of use for conservation and management. Ultimately, by studying Australia's native fauna I hope to increase the public's appreciation of our unique environment.

Funding

• Holsworth Wildlife Endowment (ANZ Trustees)
• Australia New Guinea Fishes Association (ANGFA)
• Australian Geographic Society
• School of Animal Biology, The University of Western Australia