There is considerable evidence across a wide range of organisms that larger individuals have a higher probability of surviving to reproduce, and have more offspring. However, this positive selection does not appear to be resulting in the evolution of larger individuals within populations. There are several possible explanations for why selection does not lead to evolution, but ultimately it suggests that alleles causing larger size do not also cause individuals to have better survival or more offspring. We are taking several approaches using the native Australian vinegar fly, Drosophila serrata, to understand more about how size variation is generated, and what it means for fitness.

Supervisor: Dr Katrina McGuigan