Darwin's Natural Selection Worksheet Answer Key

Understanding Darwin's Natural Selection

Charles Darwin’s groundbreaking theory of natural selection is a fundamental concept in biology, explaining how species adapt and evolve over time. This worksheet will guide you through the key principles and mechanisms of natural selection, helping you grasp the intricacies of this fundamental theory.

What is Natural Selection?

Natural selection is the process by which populations of living organisms adapt and evolve in response to environmental pressures. It is a key driving force behind the diversity of life on Earth. The theory of natural selection was first introduced by Charles Darwin in his book “On the Origin of Species” in 1859.

Key Components of Natural Selection

For natural selection to occur, the following components must be present:

• Variation: A population must exhibit genetic variation, meaning individuals must have different traits or characteristics.
• Heritability: The traits or characteristics must be heritable, meaning they are passed down from parents to offspring.
• Differential reproduction: The traits or characteristics must affect an individual’s ability to reproduce, with some individuals having an advantage over others.
• Adaptation: The environment must present challenges or pressures that favor the survival and reproduction of individuals with certain traits.

The Process of Natural Selection

Here’s a step-by-step explanation of the natural selection process:

1. Mutation and genetic drift: Genetic mutations occur, introducing new traits or characteristics into a population.
2. Variation in population: The population exhibits genetic variation, with individuals having different traits or characteristics.
3. Environmental pressure: The environment presents challenges or pressures that affect the population’s survival and reproduction.
4. Selection: Individuals with traits that are better suited to the environment are more likely to survive and reproduce, passing their advantageous traits to their offspring.
5. Adaptation: Over time, the population adapts to the environment as the advantageous traits become more common.

🔍 Note: Natural selection is a slow process that occurs over many generations.

Examples of Natural Selection

Here are some examples of natural selection in action:

• Peppered moths: Prior to the Industrial Revolution, moths in England had a light-colored, speckled appearance, allowing them to blend in with lichen-covered trees. However, with the increase in air pollution, the trees became darker, and a genetic variation in the moth population resulted in dark-colored moths. The dark-colored moths were better camouflaged on the dark trees and had a selective advantage.
• Antibiotic resistance: Bacteria that are susceptible to antibiotics die off, leaving behind bacteria that are resistant to the antibiotics. Over time, the resistant bacteria become more common, making the antibiotic less effective.

Mechanisms of Natural Selection

There are several mechanisms of natural selection, including:

• Directional selection: A single trait or characteristic is favored, resulting in a shift in the population’s mean value.
• Stabilizing selection: The population’s mean value remains the same, but the variation around the mean decreases.
• Disruptive selection: Two or more traits or characteristics are favored, resulting in a split in the population.

Conclusion

Natural selection is a fundamental concept in biology, explaining how species adapt and evolve over time. By understanding the key components and mechanisms of natural selection, we can gain insight into the diversity of life on Earth.

Related Terms:

• Natural selection Worksheet pdf
• Evolution by natural selection Worksheet