Tuesday, June 1, 2010
Biology:The birds and the beans
Building upon what the kids already know about adaptation, we began to discuss natural selection. If individuals with one version of a trait are fitter than individuals with other versions of the trait, what happens to the distribution of this trait in the population over time?
To understand this concept, we carried out the following simulation. A lab group was given 50 red beans and 50 white beans, representing the parent generation. Each group worked in 1 of 3 different environments: the white floor, the red sidewalk, and the green (very green - oh how I love my astroturf!) grass. One kid/bird from each group would hunt for 75 beans, and then the 25 remaining survivors would reproduce, having 3 offspring, each one the same color as the parent. The kids repeated the simulation 2 more times, and then observed the long-term effects of living in a particular environment on the frequency of red and white beans in the population.
As for the results, they don't call 'em bean counters for nothin...all that counting takes a lot of time. Next week we'll review and discuss our findings.