Mighty Mice!
When organisms reproduce, genetic information from each parent is passed to their offspring, as genes carry the “instructions” for the traits of offspring. Since offspring inherit half of their genetic information from each parent, variations in traits can be seen in the offspring generation; offspring are not clones of their parents! However, depending on the environment an organism finds itself in, its traits can either be beneficial or harmful to their survival. Organisms that express traits that are well-suited for their environments will survive and reproduce, passing on the successful traits to their offspring. Those that do not express the traits that are well-suited for their environment will most likely not survive or reproduce offspring. Over time, changes in populations occur as the successful traits continue to reappear generation after generation. This process is called natural selection, as organisms with traits that best suit their environment pass their traits onto the next generation. In this lesson, students will develop a model to explain how natural selection may lead to increases and decreases of specific traits in populations over time.