 In Assignment 6, you began
investigating the "What,
Why and How" of organisms changing over time. The What group
should
have provided the class with several examples or organisms that have
changed
across time. It was the responsibility of the How and Why
groups
to provide you with an explanation of the methods of and reasons for
this
change in the organisms. In your discussion you probably began to
discuss
the topics of mutation, natural selection, and genetic drift. If
you
discussed these topics, a  possible summary of your
discussion may read as follows:
Mutation produces random (chance) variation in the genetic makeup of a species or a population--that is, individuals of the same species living in the same area. Natural selection sorts out these random changes according to their value in enhancing the individual's reproduction and survival. Such selection ensures that variations that make a species better adapted to its environment will pass on to future generations. At the same time, natural selection eliminates variations that make a species less able to survive and reproduce. (Coyne, 1995)In addition to mutation, natural selection, and genetic drift, you probably also discussed other related topics including speciation, gradualism, and punctuated equilibrium. As a review, speciation is a phenomena that "occurs when gene flow has effectively ceased between populations where it previously existed and is brought about by isolation mechanisms." (Hale and Margham, 1991, p. 498) An isolation mechanism is any feature or event that separates different populations of animals so they can no longer interbreed. What do you think some examples of isolation mechanisms could be? Gradualism and punctuated equilibrium express different approaches to the process of change in organisms over time. From its root word, how do you think gradualism proposes changes take place in organisms? Opposite gradualism lies punctuated equilibrium. How do you think punctuated equilibrium proposes change occurs in various organisms? Today, you will study how species changes over time by using computer simulations that mimic natural selection. These simulations involve many of the concepts and terms that you have already worked with in Assignment 6 and read about in the introduction to this assignment. You will see how mutations and the various phenotypes they produce are involved with the process of changing species over time. While the activity will demonstrate the process of changing organisms over time in a few minutes, it accurately models the actual process of evolution that occurs over decades to millions of years. Your Instructor will provide you with
directions
for using the computer simulations and for completing any written work
that
you need to turn in. |