Chapter 14, Lesson 1 "Change over Time"

Materials:

• Changes in a population sheet

Objective:

• Students will define evolution
• Students will relate genes and mutations to the process of evolution
• Students will describe how new species can form.

Anticipatory Set:* Students will compare and contrast pictures of extinct species with pictures of animals alive today. Precrocodile, crocodile.galamimus and an ostrich, dinoembryo, chicken embryo.

Teacher Input:* Students will define evolution and then explain why this picture does not really show evolution. (change in a population). Students will then look at this picture to explain how the fossil record shows the changes in the fossil record of dinosaurs. Then students will look at this picture to see how giraffes may have evolved.

Remind the students of the distinction between population, and species. What lasts longer, a population of organisms or an individual organism? Evolution does not happen in a lifetime, it takes many generations and millions of years for an entire population to change. We know you can't say to yourself "I want a baby who is a great basketball player" and then have a baby that grows 7 feet tall. Does anyone know what can cause changes between individuals and their offspring. Sometimes a species can be breed in isolation to create what seems to be a whole different species, dachshund, St. Bernard. But this is not really mother nature's way of changing population.

A natural change in the genes of an individual is a mutation. This change can happen a couple different ways, It can happen in the bodies cells while the organism is alive an extreme example of this is the hulk. Or it can happen in the gametes which affects the offspring but not the individual with the gametes.This is the one that can drive evolution because it can be passed on from generation to generation.

If a mutation occurred to make a person look like this they would most likely not reproduce and the trait would die with them. The person with the fish tongue would be the same way. They would have a difficult time finding someone that would want to marry them and the trait would die with them as well. There are also many mutations that don't allow the embryo to live. These too do not get passed on. (This is called a lethal mutation) Mutations are very rare and the traits affected are very unlikely to be detrimental or advantageous to an organism.

Explain how in some populations a certain trait like a long neck of the Giraffe may not matter until there is an environmental change. Use these two pictures.

giraffe1, giraffe 2.

Discuss how isolation and splitting of a population can lead to two different species. Grand canyon1, Grand canyon2.AustralianWildlife

Discuss the six ways that a species can become two species.

Guided Practice:* Students will complete the worksheet: Changes in a Population

Check for Understanding:* Students will take the quiz over lesson 1.

Duration:

30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).

Alaska Content Standards Addressed in this lesson:

• SCI A-11 Students will understand that similar features are passed on by genes through reproduction (Heredity).
• SCI A-12 Students will distinguish the patterns of similarity and differences in the living world in order to understand the diversity of life and understand the theories that describe the importance of diversity for species and ecosystems.
• SCI A-13 Students will understand the theory of natural selection as an explanation for evidence of changes in life forms over time (Evolution and Natural Selection).
• SCI A-14 Students will understand
  • the interdependence between living things and their environments:,
  • that the living environments consists of individuals, populations, and communities: and
  • that a small change in a portion of an environment may affect the entire environment (Interdependence);

• SCI A-15 Students will use science to understand and describe the local environment (Local Knowledge); and: