Speaker
Description
How can organisms cope with environmental change? Some evolutionary strategies, such as adaptive tracking (adapting directly to a changed environment via mutations) or phenotypic plasticity (sensing and responding to previously-experienced changes via physiology or development) can be readily tested experimentally. But adaptive bet-hedging, the strategy of producing random variation to insure against random or unpredictable changes, is more challenging to investigate. I argue that chromosome mis-segregation in yeast is an adaptive bet-hedging mechanism. Mis-segregation causes aneuploidy, a reversible change in the copy number of specific chromosomes. Aneuploids typically grow slowly but are resistant to environmental stresses, including anti-fungal drugs. Natural yeast populations contain many aneuploids, and different yeast chromosomes have different rates of mis-segregation; differences which are evolutionarily conserved, with interesting implications for chromosomal evolution. Furthermore, the rates of chromosome mis-segregation can be manipulated by altering centromere sequences, making the system ideal for evolution experiments on bet-hedging. I will present some of our results on experimental evolution of chromosome mis-segregation as a mechanism for bet-hedging.
