This week in AP Biology we began by learning about the different forces of evolutionary change. Since the days of Darwin, scientists have been discussing the idea of evolution, and evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection. Natural selection is when traits that improve survival or reproduction accumulate in the population. The other methods of natural selection are genetic drift, mutation, gene flow and sexual dimorphism.
During the Lizard Evolution Virtual Lab we did this week we examined the different characteristics of the lizards who live on every island in the Caribbean Islands. These lizards are called anoles and there are many different species on the islands. The lizards evolve their traits from one common ancestor and are closely related to the other lizards on their same island. Even though the lizards on the island look different and the tree anoles on one island may look similar to the tree anoles on a different island, they are not very closely related. We figured out that the lizards were actually not related when we looked at phylogenic trees. When we examined and really looked at the trees we could see the differences in DNA, which were partially caused by the environments of the lizards. During an experiment, Dr. Losos introduced two lizards from the mainland with long hind legs into an environment with small twigs and bushes. Over time, this caused their offspring to evolve smaller hindlegs so they could survive by balancing on twigs to get access to the food within the bushes. This example shows how traits are determined by how fit an organism is to its environment which is a primary example of natural selection.
This week we also did a virtual lab where we saw the evolution of fish into tetrapods through another virtual lab. By doing the lab we could see why over time due to the environment changes the fish had to evolve. They went from fish that swam in very deep water to fish to shallow water fish that had to develop lungs and a rib cage and live on land needing to access those land resources. Big Idea 1 which is about evolution was a huge player this week because all we did this week was discovering more about evolution and exploring different examples of evolution.
I would love to learn more and explore more about phylogenic trees, they are so interesting to me.
Mollie Alpaugh's AP Bio 