Glendale Community College Enviromental Science Essay

THE ASSIGNMENT:

This assignment challenges you to put together many of the key concepts we’ve covered in this class in units 1 and 2, and to successfully apply them, using a bit of imagination. Read the directions below, and write your answer. Turn in your answer as a .doc, .docx, or .pdf file. Double-space your answer.

(By the way, this assignment is where you test yourself to see if you’ve really mastered the ideas you need to have mastered up to this point in the course. I’m checking to see that. It’s not an assignment to be done in a hurry. So, if you’re unsure about any of the concepts involved, this is the time to go back and really work on getting them before you complete the assignment. That’s what this assignment is for!)

DETAILS:

Imagine that there is a kind of animal called a “critter.” At first, there is only one species of critter. For this writing assignment, your job is to describe how that one species evolves into two separate species that have several important traits that differ from each other.

Your description must make use of the following concepts, identifying each one by NAME, EXPLAINING what each concept means, and APPLYING the concept to the story of how the one species of critter evolved into two, separate species:

• ecological niche
• genetic mutation
• reproductive isolation
• natural selection
• fitness
• genetic drift

You are not required to use the concepts in the order listed above. However, by the end of your description it should be clear how the evolution occurred, how each of these concepts was involved in the process, and how the resulting two species differ from each other as a result of this evolutionary process.

Please examine the GRADING RUBRIC (below) to see how your answer will be evaluated. Note how it requires each concept to be NAMED, each one to be fully EXPLAINED, and each one to be APPLIED to the evolution of the critter into two separate species.

ANSWER LENGTH:

There is no official minimum length. However, if your answer is less than about 350 words, I suggest that you have not written enough to answer the question thoroughly, to really show you know the concepts in question – and you probably want to shoot for more than the bare minimum if you’re trying for a high score! (I tried answering this question myself. My answer was 420 words long. It was about one and a half pages, double-spaced.)

TIPS and REMINDERS:

• Don’t forget that separate species will not evolve without reproductive isolation occurring first! So, you’ll probably want to have the population of critters divided into two near the beginning of your paper. How that happens is up to you. Remember, reproductive isolation does not need to take place in one, sudden moment. It can develop slowly.
• Once you have two separate populations, the environment that each one lives in can begin to diverge from each other (different climate? different food sources? different predators? etc). This would lead to each population evolving a somewhat different niche. You can show you understand the connection between natural selection and the way traits evolve to be adapted to a particular niche.
• When you talk about genetic mutation, make sure to give some details about what this means in terms of things like gametes and DNA.
• Remember that whenever a trait becomes more common or less common in a population because having that traits helps or hurts fitness, this is a matter of natural selection, not genetic drift. “Genetic drift” refers only to situations in which a trait becomes more common or less common over time completely due to random chance, having nothing to do with the value of the trait itself.
• Remember that evolution can take place over LONG periods of time. Don’t try to have your two species evolve in the span of a generation or a few generations. Similarly, if you’re going to have the environment a population lives in change over time, and have the population evolve to adapt to it, you’ll probably want to have that environment change SLOWLY, giving the population time to adapt through evolution. If the environment changes rapidly and in extreme ways, the population is more likely to just die off and go extinct before it has enough time to evolve successful adaptations!