"Causes of Biological Evolution" Biological Evolution PPT Courseware

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"Causes of Biological Evolution" Biological Evolution PPT Courseware

In the long process of evolution, why do some animals become extinct? How do new animals come into being? What is the reason that drives the evolution of living things?

Examples of biological evolution

The birch moth is called the "spotted moth" in English. It is so called because the species collected before the mid-19th century all had light gray wings with spots scattered on them.

What is causing changes in the numbers of two species of birch moths in Manchester?

1 Changes in the surrounding environment, the selective effects of the environment and birds on the birch moth

2. The polluted environment makes the light-colored betula moths easily preyed upon by birds and is at a selective disadvantage. The black betula moths have a protective color and are at a selective advantage.

What is protective color?

The body color of an animal is very similar to the color of its surrounding environment. This body color is called protective color.

What is the function of protective color?

It is not easy to be discovered by other animals, which is helpful for avoiding enemies or catching prey.

Simulation exploration: simulate the formation process of protective color

Ask the question: How are animals’ protective colors formed?

Assumptions:

The protective coloration of animals is the result of the selection of animals by the natural environment.

Kind tips

1. Each team member is in a group of five, and all team members follow the command of the team leader.

2. The color of the colored paper must be single, and each group can choose a different color; the colors should be diverse, but one of them should be consistent with the color of the colored paper.

3. When doing experiments, you must imagine yourself as a "predator". When selecting small pieces of colored paper, do not observe the position of the small pieces of paper in advance, and do not specifically look for small pieces of paper of a certain color.

4． The number of small pieces of paper should be recorded in time and analyzed.

5. Analyze and explore the discussion questions that follow.

Discussion and communication:

1. Which color of paper has the most “survivors” in the first and fifth generations? What does this have to do with the color of the paper?

Answer: Small pieces of paper with colors close to the colored paper have the most “survivors”. Different colors of colored paper represent different life backgrounds, and it is not easy to select small pieces of paper that are close to the color of the colored paper.

2. How does the number of “survivors” change between the first and second generations? What changes have occurred between the first and fifth generations?

Answer: The colors of the second-generation "survivors" have begun to diverge. The number of survivors in some colors is significantly greater than the number of "survivors" in other colors, and some colors have even begun to have no "survivors". By the fifth generation, there may be only one color of "survivor" left.

3. Comparing the "survivors" of the first and fifth generations, are there "survivors" in all colors? Why?

Answer: There are almost no "survivors" whose color is most different from the environment, because this color is the easiest to detect.

4. Through the above simulation experiment, can you infer the formation process of protective color? From this, can you simply analyze the reasons for biological evolution?

Answer: Animals all live in a certain environment. The body color of some animals is close to the color of the environment, while the body color of some animals is different from the color of the environment. When encountering a predator, those whose body color is significantly different from the color of the environment are the easiest to detect and will be preyed on first. Those whose body color is close to the color of the environment are not easily found. The body color protects oneself and can reproduce offspring. After the predator After multiple generations of selection, only those whose body color is close to the color of the environment are left. This body color is the protective color. It can be seen from this that the process of biological evolution is to retain the adaptable ones and eliminate the unfit ones.

natural selection

concept:

In the competition for survival, the fittest survive and the unfit are eliminated.

Organisms continue to evolve through heredity, mutation and natural selection.

3. Knowledge internalization (formation of knowledge structure)

Intrinsic causes: heritable variation

Causes of birth External causes: changes in the environment

Over-reproduction of animals---conditions that create a struggle for survival

The struggle for survival---the driving force for biological evolution

Chemistry, natural selection, genetic variation---the basis of biological evolution

The survival of the fittest---the result of biological evolution

Original factor---human beings

The result of artificial selection---meeting human needs

Evolution speed---faster

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Update Time: 2024-07-04

This template belongs to biology courseware People's Education Edition Biology for Grade 8, Volume 2 industry PPT template

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