Natural selection

The title of the Project: Natural selection

This virtual laboratory is intended for use in 8th grade classes on the following topics:

  • “Fitness, or adaptation, of organisms”
  • “Heredity and variability.”

Purpose of the virtual laboratory work:

  • to understand and visualize natural selection process
  • to explore the impact of various parameters affecting the survival of population
  • to test and refine existing theories

Theoretical part

The environment encompasses all living (biotic) and non-living (abiotic) factors that interact and influence each other in complex ways. Take a hare in a forest; it directly interacts with plants and foxes, but also indirectly interacts with the soil and its moisture (through the plants). Every plant and animal exemplifies fitness in its own way, with those unable to adapt ultimately perishing [1].

Imagine a new coloration arises in an organism due to a mutation. If this color renders it invisible to predators, it gains a survival advantage. This organism will leave more offspring due to enhanced protection, and its descendants will inherit the beneficial coloration, further increasing their survival and reproductive success compared to their differently colored counterparts. Consequently, over several generations, the entire population or a significant portion of it will adopt the advantageous coloration. These adaptations, acquired through random mutations and inherited variations, become permanently fixed within their gene pool.

In contrast, if a mutation results in a coloration that makes the organism more conspicuous to predators, it will likely perish quickly [2].

Sources:

  1. Fitness, or adaptation, of organisms. (2018). Biology. Textbook for 8th grade of secondary school.
  2. Heredity and variability. (2018). Biology. Textbook for 8th grade of secondary school.

Practical part:

The “Natural Selection” simulation from PhET allows you to explore how environmental pressures and mutations can influence the evolution of a virtual bunny population. It demonstrates the core principles of natural selection, where traits that offer survival advantages become more common in successive generations.

1. Start the simulation. Choose between “Intro” and “Lab” modes.

2. Select “Intro” mode. Observe a white rabbit hopping amidst green plants (food) in a desert environment (e.g., sand) with a brown background. Click the “ button to initiate breeding. Now you have two rabbits.

3. Watch the population increase (4 rabbits added each generation). A generation counter “” displays at the top of the screen.

4. Hold down the “” button for faster breeding. Remember, as the 6th generation progresses, power reaches its peak and the simulation ends. Click the reset “” button to restart.

Virtual Experiment No. 1

5. Now begin experimenting. At the top right, find the brown fur mutation in rabbits. Select this trait as Dominant.

6. Rabbits with brown fur appear among the individuals. In an equatorial environment, brown rabbits blend better with the background, making them less visible to predators and increasing their survival. To test this hypothesis, introduce wolves (predators) by checking the box next to their image in the “Environmental Factors” section.

7. Wolves hunt white rabbits, shrinking their “hunting grounds.” Consequently, brown rabbits gradually become more common in this habitat.

8. Monitor the population for at least 10 generations. Change the radio button on the “Proportions” item to display population ratios.

9. Reset and repeat steps 5-8. This time, test the impact of limited food resources by selecting the “Limited Food” option in “Environmental Factors” instead of “Wolves”.

10. Observe the population for 10 generations. Then, compare the population trends and data between the wolf and limited food experiments. What changes did you observe?

Virtual Experiment No. 2

11. In this experiment, observe the population scenario development in a snowy habitat. Start the simulation again and change the environment at the top from Equator”  to Alaska”. Now, a white rabbit is hopping around on a white background. Introduce breeding.

12. Repeat steps 5-8 of the first experiment for this environment. Wolves would struggle to find white rabbits here, but brown rabbits, more visible against the snow, would be easier prey. Therefore, the brown fur mutation, previously advantageous, might now be detrimental.

13. Evaluate the results compared to the first experiment.

14. Reset and run the experiment with the Limited Food scenario. Compare the results with the first experiment. Did you notice any changes?

Remember, the key is to actively experiment, observe, and analyze to understand how natural selection works in shaping populations.

Conclusion:

In this virtual laboratory students observed how natural selection operates in real-time, making it a valuable tool for both educational and scientific purposes, promoting understanding of evolution, fostering critical thinking, and contributing to the study of this fundamental biological process.

Terminology

Natural selection – Естественный отбор – Табиғи сұрыпталу 

Mutation – Мутация – Мутация

Dominant trait – Доминантный признак – Доминантты белгі

Recessive trait – Рецессивный признак – Рецессивті белгі

Brown fur – Коричневый мех – Қоңыр жүнді

White fur – Белый мех – Ақ жүнді

Straight ears – Прямые уши – Тікқұлақты

Floppy ears – Висячие уши – Салпаңқұлақты

Long teeth – Длинные зубы – Ұзын тісті

Short teeth – Короткие зубы – Қысқа тісті

Environmental factors – Факторы окружающей среды – Қоршаған орта факторлары

Wolves – Волки – Қасқырлар

Limited food – Ограниченные пищевые ресурсы – Шектелген қоректік ресурстар

Tough food – Жесткие пища – Қатты қорек

Population – Популяция – Популяция

Proportions – Пропорции – Пропорциялар

Pedigree – Родословная – Шежіре

Alleles – Аллели – Аллельдер

Generation – Поколение – Ұрпақ