Assignment Overview
Evolution is the change in populations over time. The frequencies of genes in a population change which results in changes in characteristics. The fossil record, biochemical evidence, genetic evidence, and other observations clearly show that these changes have occurred and are continuing to occur.
The mechanism for changes in populations is natural selection which is the differential survival and reproduction of individuals based on genetic differences among them. Organisms produce many more offspring than can survive. Because individuals have genetic differences, some are better able to survive and reproduce in a given environment. Populations change over time because of differences in individual survival and reproductive success.
Darwin observed that organisms often compete for mates. As a result, some individuals may produce many more offspring than others. For example, a peacock with brightly colored feathers and a complex courtship display is more likely to attract the attention of peahens and have an opportunity to pass his genes to the next generation. Male elephant seals compete with each other for breeding territories on beaches. A male without a territory is usually unable to attract females. The biggest, most aggressive males are usually the most successful. The advantage of having a large number of offspring outweighs the costs and perils. At some point a balance is reached between reproductive success and the costs of secondary sexual characteristics that can reduce survival (such as having bright feathers that attract predators as well as mates for example).
It is important to understand that natural selection acts upon an individual organism. The individual cannot evolve, but can only live or die, have offspring or not. The overall effect of natural selection is on the population.
Case Assignment
Answer the following questions in essay format. See the assignment expectations below for details on how to format your essay. You will be selecting one species from the video below to address questions 4 and 5 (video is approximately 12 minutes in length). You will need to conduct additional research to complete the essay in detail.
In your own words define natural selection and evolution.
What are four key components of natural selection?
What kinds of variable traits might natural selection act upon within a population?
Choose one species from the video below (examples include the peacock or North American Elk) to complete the remaining two questions for your Case Assignment:
Conboy, R. Evolution – Why Sex? Retrieved March 13, 2018 from https://www.youtube.com/watch?v=5AiHTcWejjQ
Sexual selection is a “special case” of natural selection. Define sexual selection (explain the concepts of male competition and female choice in your answer)
How do the unique traits of the animal you have chosen increase its fitness (in reproductive terms)?
Assignment Expectations
Organize this essay assignment using subtitles that summarize the topic from each question above. For example, to answer Question 1, use a descriptive subtitle like the following: Natural Selection and Evolution.
Your essay should be approximately 2-3 pages in length. Answer each question under the subtitle using complete sentences that relate back to the question. Be sure to use APA formatting throughout your essay with 1-inch margins, 12-point type and double spacing throughout. Include a title page, introduction, answers to the questions with subtitles and concluding paragraph. Remember to include in-text citations within the body of the essay referencing your resources (i.e. Murray, 2014).