Evolution

Evolution What’s the Standard? S7L5. Students will examine the evolution of living organisms through inherited characteristics that promote survival of organisms and the survival of successive generations of their offspring. a. Explain that physical characteristics of organisms have changed over successive generations (e.g. Darwin’s finches and peppered moths of Manchester).

Charles Darwin: Who is this guy?

Charles Darwin Checkpoint: What did Darwin say is the difference between artificial selection (selective breeding) and natural selection? Answer: Selective breeding (like in the horses) is when we intentionally breed two organisms together to produce offspring with desirable traits. Natural selection, however, is when organisms choose their own mate to produce offspring that will hopefully survive.

Marine Iguanas

Similarities and Differences Checkpoint: How did Darwin think plants and animals had originally come to the Galapagos Islands? Answer: Perhaps they had been blown out to sea or set adrift on a fallen log. Question: What similarities and differences do these two species have? Both species have spines, claws, and scaly skin. Green iguanas are green, have smaller claws, and live in trees. Marine iguanas are gray, have large claws, and live on rocks near the ocean.

Adaptations What is an Adaptation? An adaptation is a trait that helps an organism adjust to its environment, survive and reproduce. What are some other specific adaptations you can name? Pythons hinged jaws. Mullet fishes flat body. Stingray’s flat body. Vultures bald heads for feeding on dead animals.

Adaptation: Giraffe This video is half about the giraffe and half about the lion. You may wish to click on the video to stop it when it reaches the lions for pacing of the lesson. – C. Bohannon

Adaptation: Giraffe Answer: Checkpoint: What types of adaptations allow giraffes to feed on a diet of leaves from treetops? Answer: The body structure of the giraffe has adapted over time. This is a question that will show up on the sample CRCT quiz that goes along with the S7L5a standard. Discuss skin coverings, body markings, and visual ability.

Evolution What is Evolution? Darwin believed that species changed over time becoming better adapted to their environment. This process is slow and takes many generations.

Evolution What makes an idea a Theory? It is well tested and explains many observations. How does a Theory different from a fact? A fact is a specific observation, known to be true; a Theory is a broad concept, thought to be true because it explains many facts. These questions are from the text helping to address misconceptions about theories.

Natural Selection What is Natural Selection? Natural selection is the process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species. Survival of the fittest! Who's Going to Survive?

Natural Selection This video introduce some of the concepts of natural selection such as overproduction of offspring and competition.

Natural Selection There are several factors that Darwin identified that affect the process of natural selection: Overproduction of offspring Competition Variations

Overproduction Competition Variation Natural Selection This a menu screen that links to the factors of natural selection.

Overproduction Most species produce far more offspring than can possibly survive.

Competition Competition is the struggle between organisms for the limited resources in a habitat.

Variation Variation is any difference between individuals of the same species.

Natural Selection: Examples Are these two butterflies the same species? Question: Why is the result of this type of natural selection called mimicry? Answer: Because natural selection results in one species looking like, or mimicking, another species. These are the Monarch and Viceroy butterflies. The Monarch on the left is poisonous and the Viceroy is not. Question: Why would it be beneficial for the Viceroy to look like the Monarch?

Natural Selection: Examples Checkpoint: A species of hare (rabbit) that is found in a cold tundra environment. How are oversized feet an advantage to the Arctic Hare? Large feet enable the artic hare to have a better grip on the snow. This adaptation along with coloration, eye size, fur density and color changes enable the artic hare to get away from predators.

Natural Selection: Examples How many moths do you see?

How Do New Species Form? 1. Geographic isolation 2. Adapt to their new environment 3. Groups can no longer interbreed

How Do New Species Form? Have the Kaibab Squirrel and the Abert Squirrel been isolated long enough to become a new species?

Summary Question Directions: On a separate sheet of paper, please write down the question that appears next. Write out a few sentences answering the question using some of the concepts we have learned so far. Upon which facts did Darwin base his theory of evolution? Please give examples that support this theory. This may be used as a ticket out the door if necessary. Answers should discuss that species have evolved differently exhibiting many similarities and differences. These similarities and differences are due to adaptations to their specific environment.