Natural Selection and the Galapagos Finches
Access the Lab Exercise from Lab 2: Genetics and Evolution of Human Populations. Read the background content and complete the lab exercise. I suggest taking notes through the whole process (it isn’t overly demanding). Pay attention to the context of the research, its significance, all dataset material, and the conclusions. You should ask yourself, “what did I learn from this?” and “how does this relate to our previous lesson?”.
In this activity, you are studying finch variation on Daphne Major during the 1977 drought. It becomes immediately apparent that some finches are dying from drought conditions while some are not. You want to know why. It has been long established that finches are variable in beak size and so you want to determine whether beak size is influencing the survivorship of these birds. To do so, you begin measuring the beak depth of living and recently dead individuals.
After 35 measurements, you have a good idea of which beak shapes survived the drought and which ones did not. Thus, you have calculated what percentage of individuals with each beak depth survived. To convey the survivorship, you plot your data on a graph using a subsample of eight individuals. You plot each beak size from the subsample according to how many individuals (from the larger sample) survived the drought.
The results of this study should reflect a survivorship curve. This is a graphical representation of the number of individuals within a population that survive to a given age or through a catastrophic event. The data gleaned from the survivorship curve will then allow you to interpret how selection is acting on the Finch population of Daphne Major (the Lab material mistakenly labeled the island as Daphne Mayor…typos happen).
Enjoy.