One of WA’s most widespread freshwater fish, the western rainbowfish, may yield new insight into the processes of species evolution, thanks to PhD candidate Michael Young (24), a researcher in The University of Western Australia’s Centre for Evolutionary Biology in the School of Animal Biology. “I found that there was little published research on rainbowfishes, and none on their remarkable colour patterns, so I decided to focus on identifying the factors that have led to the evolution of the striking colour variations found among populations of the western rainbowfish in WA,” Mr Young said. Like the drosophila, or fruit fly, which has been used as a model species by scientists for more than a century, the western rainbowfish may also prove to be a valuable model for helping us to better understand complex evolutionary processes, he said. About 11cm long, the males exhibit beautiful and varied colours, hence their name, and possibly varieties of body-shapes, despite being of the same species, while the females tend to be duller and of a uniform, sleek shape. The western rainbowfish is very widespread, occurring throughout the Pilbara, Kimberley and Northern Territory, is super-abundant and easy to keep in captivity. These attributes, in addition to its physical variation, make it exactly the species Charles Darwin would have enjoyed using in his own studies of evolutionary processes. “To further our understanding of how evolution works, we need greater knowledge of how natural selection acts upon specific traits of individuals in order to increase or decrease the ability of those individuals to reproduce. If this process results in enough genetic changes accumulating, then ultimately new species will be produced,” Mr Young said. “I will try to find out whether forces such as mating competition and predation have caused the evolution of colour pattern variation in these fish. In the process, I need to determine whether the variation has a genetic basis or whether the colour patterns may be a product of the environment.” If, as he thinks, the patterns are genetic, Mr Young will apply scientific techniques for which Darwin would have given his right arm, including studying the fishes’ DNA to determine to what extent natural selection can account for these differences. A high-tech spectroradiometer, recently acquired by the Centre, will also be used to measure the fishes’ colour patterns. This will eliminate the need to make subjective observations with the human eye, as typically done up until recently in this kind of study. The final stage of his project is to work out whether sexual selection has also influenced the evolution of the fishes’ colour patterns. He will try to discover whether the brightest males are more attractive to the females – and in the process, perhaps his insights into the mind of the female fish will help explain what might be going on right now in your home aquarium.
Michael Young 61 8 6488 4512