Honours supervisors and projects

Dr Damian Dowling

Phone: 990 20479
E-mail: Damian.Dowling@sci.monash.edu.au

I am offering a variety of research projects in the field of evolutionary biology. My research is the interface between behavioural ecology and evolutionary genetics, and I use both invertebrates and vertebrates to answer some of the hot questions in evolutionary biology. Prospective students have the opportunity to design their own exciting projects under my supervision that best match their research interests, or to embark on one of the projects suggested below.

Project 1: Maternal genetic effects on male fertility

On the face of it, it seems a bit absurd to suggest that many male-specific fitness traits (e.g. sperm performance) might be encoded by genes that exhibit maternal-biased transmission. The extreme case in point is the example in which male fitness would be encoded by alleles that lie within the mitochondrial genome, which is strictly maternally inherited. Remarkably, recent findings suggest that aspects of sperm quality, which are vitally important in determining male reproductive success, are indeed under mitochondrial genetic control. These findings are exciting because they challenge a key evolutionary belief – namely that sperm traits will evolve adaptively under sperm competition. In this project, the honours student will take a novel approach to exploring the extent to which male fitness parameters are under maternal genetic control.

Project 2 (joint supervision with Dr Carla Sgro): Conservation biology – is there an optimal level of outbreeding?

We know a great deal about the nasty consequences that stem from inbreeding. It might seem strange, but counter to this we actually know very little about the consequences (be they good or bad) of outbreeding with very distantly related mates. In theory, mating with individuals from distant populations can actually result in a breakdown in fitness that we call outbreeding depression, if it results in the break-up of locally adapted gene complexes that have been coevolving over long periods of time. When it comes to research on animals, studies that have examined the question of whether there is an optimal level of inbreeding / outbreeding have typically employed flawed experimental designs that are unlikely to uncover evidence for outbreeding depression even when it occurs in nature. The honours student will redress this problem using a solid experimental design. This research has obvious implications for conservation management, such as the question of how to manage captive breeding populations in the long term.

Project 3 (joint supervision with Dr Carla Sgro): Adaptation to climatic stress: is thermal adaptation limited by a trade-off between heat and cold tolerance?

Climate change is thought to be the biggest threat to the long-term future of almost every species. This is because temperature, and in particular temperature stress, is a key determinant of species distributions and abundances. Understanding if and how a species will adapt to temperature extremes is crucially important in allowing us to assess the likely threats imposed by climate change. One way to study climatic adaptation is to study populations collected from along latitudinal clines. This is because latitude can be thought of as a surrogate for climate; as latitude changes, so do climatic variables like temperature and humidity. Repeated clines in different geographic regions or in related taxa strongly implicate the occurrence of adaptation under natural (climatic) selection. Levels of thermal tolerance have been shown to vary with latitude in many species; tropical populations have higher heat tolerance but lower cold tolerance than their temperate counterparts. In this project, the Honours student will merge conservation biology with classic predictions of life-history evolution, to test whether species face a trade-off when it comes to investing in heat or cold tolerance. Such information will provide valuable insights into how species will respond in the face of ongoing climate change.

Project 4 (joint supervision with Dr Bob Wong): Sperm competition in fish

The females of many species mate many times in quick succession, and this creates fierce competition between males over fertilizations. This is known as sperm competition, and it is regarded as a major selection pressure shaping the evolution of male fertility, given that a male’s lifetime reproductive success is determined largely by his success in sperm competition. Fish are ideal subjects to examine the evolutionary importance of sperm competition, because many species are external fertilizers. This gives us a great opportunity to experimentally manipulate the stage on which sperm competition is played out, and in the process gain important evolutionary insights.