Class Notes: Natural Selection

1. Class Notes: Natural Selection • In Darwin’s time, animal and plant breeders used selective breeding to produce organisms with the traits they desired. Darwin called selective breeding artificial selection because the breeders selected the desired traits to produce changes in a species over a few generations. • In wild animals and plants, Darwin believed that traits were selected by the environment. He called this process natural selection.

2. What is natural selection? • Natural selection is the process by which organisms with favorable adaptations survive and reproduce at a higher rate that organisms with less favorable adaptations.

3. The Principles of Natural Selection 1. Over reproduction 2. Individuals in a population vary (genetic variations) 3. Favorable adaptations are selected (struggle to survive) 4. Favorable adaptations accumulate (successful reproduction)

4. Over Reproduction • All organism produce more offspring than can survive to adulthood and reproduce. • This means that many of those offspring will die with out reproducing and survivors are able to reproduce pass their traits on to their offspring.

5. Individuals in a populations vary (genetic variations) • There is a random variation in traits among individuals in a population of a species. • The variations each individuals possesses happen by chance. • Those variations are inherited.

6. Favorable adaptations are selected (struggle to survive) • The changing environment causes a selection of favorable traits (adaptations). Adaptations that fit well with the environment are passed on to offspring in greater numbers than adaptations that do not fit well.

7. Favorable adaptations accumulate (successful reproduction) • Favorable adaptations accumulate over many generations. This may lead to new species.

9. Activity: Natural Selection Simulation • Overview - Students will model natural selection by using various utensils to "capture food“.

10. Activity: Materials • Bags of beans (northern or lima) • Plates holding the beans • Clothespins • Plastic spoons, plastic forks, plastic knives • Tweezers • Any utensil or item can serve as a mouthpart, use your imagination or improvise with available materials.

11. Activity: Natural Selection Simulation • Scene - On a distant planet there exists 5 species of a creature called a Woolybooger. Each Woolybooger is similar except their mouth has variations. All woolyboogers eat beans. Some woolyboogers have a clothespin mouth. Some woolyboogers have a tweezermouth, some have a needle mouth. One year a new species of woolybooger was discovered, this woolybooger was called the Spoon-Mouthed Woolybooger. • Each of you will play the part of a woolybooger on this planet. The spoon-mouth wooly booger is rare, so only two of you will get to be this type of wooly booger.

12. Activity:Procedure You will run through several trials. Each trial will require your woolybooger to gain at least 20 beans. If 20 beans are not acquired during the time period, your woolybooger has died. • When a woolybooger dies, the student can play the offspring of the surviving woolyboogers. Give them a new utensil (probably a spoon or tweezer) for the next trial.

13. #Activity: Discussion Questions • 1. What happens to animals that cannot compete as well with other animals in the wild? • 2. Can you think of any real-life examples of the woolybooger, where one species has a definite advantage over another? • 3. Sometimes animals that are introduced into an area that they never lived in before, out-compete and endanger resident species, why do you think this happens? • 4. If only one species is considered the "fittest", why do we still have so many variations among species. Why do some birds have very long pointy beaks, while other birds have short flat beaks? • 5. How do you think diseases can affect natural selection?

14. Homework • #115 Unit 3: Genetics Study Guide • #121 11.2 Section Review