This project aims to identify patterns of thermal adaptation. To accomplish this goal, the investigators will conduct evolution experiments using laboratory populations of the bacteriophage G4, a virus that infects the bacterium E. coli. The investigators will adapt virus populations to high and low temperatures, identify the mutations responsible for adaptation by sequencing whole genomes, and measure the performance of the evolved phages over a wide temperature range. The investigators will determine if the adaptive mutations tend to occur in the same or different genes and address two hypotheses concerning thermal adaptation. These hypotheses are: (1) Cold-adapted viruses will have lower maximal growth rates than hotter- adapted viruses; and (2) Adaptation to a new temperature will result in a loss of performance at different temperatures. Both of these predictions stem from the idea that there are constraints on biochemical reactions that limit or reduce an organism's performance at particular temperatures.
The ability of natural populations to tolerate thermal variation is crucial to geographic distribution and ultimately to species survival. Over short time scales--daily, seasonally, or yearly--thermal variation has tended to be predictable. However, changing temperatures across the world mean that thermal variation may not be so predictable in the future. The study of thermal adaptation should lead to a greater understanding of the effects of global warming, and it may be possible to identify populations at risk of extinction.
