Natural Selection of the Galapagos Origami Bird

Background

The process of natural selection has been shown to be the primary way by which new species can evolve from previous species. There are three conditions on which evolution by natural selection is based:

1. Inheritable traits vary in a population (random trait variation)
2. Differences in fitness (ability to survive and reproduce) depends on the interaction of those traits in a population with the particular environment occupied by that population (differential survival); and...
3. Traits passed on and accumulate: The inheritable traits of the fitter individuals tend to accumulate and characterize the features of the new population.

Figure 1: Visual illustration of the three conditions of evolution by natural selection

Understanding these conditions can be tricky. Part of the difficulty stems from the fact that misconceptions acquired over time (from home, the media, teachers, books and movies) become deeply set and hard to repair. One of the most common misconceptions is about random mutations (unpredictable changes in the genes of individuals).

Many people also fail to realize that there is a non-random part of natural selection. It's the "selective" process, where certain gene combinations in a given environment enable some individuals to survive and produce more offspring than other gene combinations in the same environment. The word "selection" does sound like somebody is doing the selecting, and since people often make selections based on their needs or desires, we tend to think (incorrectly) that natural selection is a process for meeting a need. But it really does not work that way. That is a "Lamarckian" view of evolution, and many studies have consistently shown that the Lamarckian idea does not fit the observations.

This lesson is intended to provide you with experiences to show how random mutation and natural selection for fitness actually do operate to change traits in living populations over multiple generations.