Adaptation. 713/813, Lecture 7. The most conspicuous evidence of evolution by natural selection is the fit of organisms to their environment. Yet quantifying adaptation continues to elude biologists. How do you measure adaptation?.
713/813, Lecture 7
The most conspicuous evidence of evolution by natural selection is the fit of organisms to their environment.
Yet quantifying adaptation continues to elude biologists.
Fitness = Ln [ N 1 (Day 1) / N1 (Day 0) ]
Ln [ N 2 (Day 1) / N2 (Day 0) ]
Adaptation may be quantified directly
Plate on agar to determine the ratio of 1 :2
Ratio of realized growth
Studying evolution, and usually adaptation, in action
The outcome of selection for high and low oil content
in the Illinois corn experiment.
Selected for thermotolerance of microorganisms
60 F 158 F
Unfortunately incubator destroyed along with samples
Generation 0 ------------------------- Generation 20,000+ è
Sniegowski et al., Nature 387, 703-705 (1997)
“I call this experiment ‘replaying life’s tape.’ You press the rewind button and, making sure you thoroughly erase everything that actually happened, go back to any time and place in the past – say to the seas of the Burgess Shale. Then let the tape run again and see if the repetition looks at all like the original.”
“The bad news is that we cannot possibly perform the experiment…”
-S.J. Gould, Wonderful Life: the Burgess Shale and the nature of history (1989)
Replicate populations evolving under identical conditions address whether evolution is repeatable.
Do you predict phenotypic repeatability (parallelism)?
Do you predict genetic repeatability?