No Sex Please, We’re Fungi!

Is having sex really a great advantage – evolutionarily-speaking, that is? Reproduction can either occur by combining genes from two individuals together: having sex, or by dividing in half to form two identical clones. Sex requires complicated reproductive structures, sexual attraction, and care of the young. So what is the benefit of it? The general argument is that combining and rearranging genes produces offspring that can survive better, but is this really the case, and will all species that currently do it continue to do so?

A research team led by Dr Jan Schmid from Massey University has been awarded a Marsden grant to investigate if sex really does give offspring a survival advantage. They will use the fungus, Candida albicans, which causes infections in humans such as thrush. Candida is an interesting species to test the advantage of sex, because it only does it rarely – it usually reproduces simply by dividing in two. Why is this? One idea is that being able to switch to sexual reproduction could give the species an advantage in certain situations – perhaps it could generate new combinations of genes that make it better at infecting people and more resistant to antifungal drugs.

Dr Schmid will mate strains and test if the offspring are better at surviving than their parents. If they are hardier, then occasional sex could be giving the fungus an advantage. But if the parents are better at surviving than the offspring, sex is not providing Candida with an obvious survival advantage….so perhaps sex is on the way out for this species.

The study will investigate a fundamental belief: the superiority of sex over reproducing by dividing in two. It could also help in designing treatment for medical conditions caused by Candida, by understanding how the fungus evolves.

Total Funding:    $769,000
Researchers:    Dr Jan Schmid, Institute of Molecular BioSciences, Massey University, Palmerston North.
Associate Professor Richard Cannon, University of Otago
Dr Barbara Holland, Massey University
Associates:    Professor Paul Magee, University of Minnesota, USA
Mrs Beatrice Magee, University of Minnesota, USA