Intragenomic conflict and the evolution of uniparental inheritance of cytoplasmic organelles
This project will test if the presence of cytoplasmic organelles originating from more than one individual leads to conflict among such organelles at the detriment of the organism.
Most organisms reproduce sexually. During sexual reproduction, fusion occurs between two gametes - a large egg and a small sperm, or between gametes that are of the same size but of different mating types. In evolutionary terms, why are there usually two sexes or mating types, rather than just one, or three, or four? We do not really understand this most basic element of reproduction. One clue may come from the fact that in most sexually reproducing organisms, only one of the two mating partners is responsible for transferring the cytoplasmic organelles (mitochondria and chloroplasts), even when gametes are of the same size. Why? The conflict hypothesis posits that asymmetrical transfer of cytoplasm is an adaptation that prevents the mixing of cytoplasmic organelles of different origins in one individual. Modelling studies suggest that the combination of cytoplasmic organelles from two parents may generate within-individual competition among organelles, with detrimental effects on organismal fitness. As a result, the nuclear genome may have been selected to ensure uniparental inheritance of cytoplasm, thereby preventing the emergence of genetically selfish organelles.
To date, this intriguing hypothesis about intragenomic conflict has not been tested experimentally. This project will test the ‘conflict hypothesis’ by studying mitochondrial inheritance in the acellular slime mould Physarum polycephalum. In this exceptional species, mitochondrial transmission is established after zygote formation – and in some instances, mitochondria inherit biparentally. Thus, the aims are to study mitochondrial inheritance in Physarum to determine:
- modes of transmission of mitochondria in acellular slime moulds;
- the costs associated with biparental inheritance of mitochondria; and
- the regulation of inheritance of mitochondria in slime moulds.
The above described project is only one example. I am also interested in supervising students who are interested in behavioural ecology using social insects as model system. For example, behavioural studies on social insects can be combined with mathematical modelling in collaboration with Mary Myerscough (School of Mathematics and Statistics). Or field observations on honeybee can be combined with using microsatellite analysis to answer evolutionary questions. Such project would include Ben Oldroyd as a supervisor.
The Behaviour and Genetics of Social Insects Lab offers top-up scholarships to PhD students. For students interested in a project that combines biology and mathematics, top-up scholarships are available via the Centre for Mathematical Biology.
Our lab is well funded and we encourage students to attend national and international conferences. Our students are also encouraged to participate in one of our many international collaborations. We collaborate with researchers in Thailand, South Africa, Sweden, Germany and Japan.
Check our web site (http://sydney.edu.au/science/biology/social_insects/) for current projects and our research interests.
Projects can also be tailored to Honours students.
Want to find out more?
The opportunity ID for this research opportunity is: 1292
Other opportunities with Professor Madeleine Beekman