Darwin and Natural Selection

Descent with modification

Observable fact children look and behave differently than their parents. Partially due to random genetic mutations.

Common descent

A single original species to have given rise to all life. A conclusion based on a massive collection of observable facts.

What did Darwin propose after visiting the Galapagos Islands?

Similarities can be explained with common descent. Offspring will go through descent with modification over thousands of years driven by natural selection to adapt to the environment. Evident by a tortoise from the island being similar to a mainland counterpart that went through adaptation. Potentially caused by a mainland tortoise drifting to the islands.

What is natural selection?

Beings in a natural environment only survive and reproduce with favorable traits. These are passed to their offspring, allowing offspring to do the same and eventually form new favorable traits. Meanwhile, others die off.

Specific example of natural selection?

Tree bark in moth habitats were light, so light moths survived better than dark moths as predators spotted the dark easier. Then bark became dark and this flipped. Predators killed light moths, dark moths survived and reproduced, becoming the majority of the population due to their favorable trait.

What is artificial selection?

Human intervention in breeding species. Humans select specific traits in a species and breed that being with others with favorable traits to produce offspring with that trait. This trait was made through descent with modification.

What is biological fitness determined by?

How many offspring a being/species has.

How is natural selection connected to evolution?

It is a mechanism of evolution. It favors traits that promote survival, reproduction, contributing to genetic changes in generations.

What is an adaptation?

A heritable functional trait that enhances an organism’s survival and reproductive success in its specific environment, driven by natural selection.

Explain how natural selection is related to bacterial resistance to antibiotics.

It drives bacterial resistance when antibiotics kill vulnerable bacteria. This allows the few, rare, resistant bacteria to survive, reproduce, and dominate the population.