Charles Darwin and Natural Selection Notes

Charles Darwin

Natural Selection

Experimental Data

Who he was: He was a scientist that lived 1809-1882. He is famous for his research in the Galapagos Islands. He founded the principal of natural selection (theory).

What were his findings?During this same time frame a man named Charles Lyell published a book about rocks and fossils. He had a theory that rocks were very old, and he was able to prove that life was also old through fossils. Charles Darwin read this book on his voyage on the Beagle (the ship he took to the islands).

While on the Galapagos Islands he observed a number of animals that were similar to the ones that were on the main land, South America, but they weren’t exactly alike. He wondered if the animals were related in some way.

When Darwin came home he started thinking about how animals and plants change through time. He thought that maybe, different types of animals and plants could change…they could evolve! And he thought he knew why. Charles saw that individual animals and plants compete with each other for food, water and space: the things they need to live. They’re fighting for their lives! (Natural Selection)

What is natural selection? Darwin’s process of natural selection has four components.

  1. Variation. Organisms (within populations) exhibit individual variation in appearance and behavior. These variations may involve body size, hair color, facial markings, voice properties, or number of offspring. On the other hand, some traits show little to no variation among individuals—for example, number of eyes in vertebrates.
  2. Inheritance. Some traits are consistently passed on from parent to offspring. Such traits are heritable, whereas other traits are strongly influenced by environmental conditions and show weak heritability.
  3. High rate of population growth. Most populations have more offspring each year than local resources can support leading to a struggle for resources. Each generation experiences substantial mortality.
  4. Differential survival and reproduction. Individuals possessing traits well suited for the struggle for local resources will contribute more offspring to the next generation.

Experiment Conclusions:

  1. Variations (i.e. food)
  1. Inheritance (i.e. eye color, hair color)
  1. Population Growth (i.e. amount of offspring)
  1. Differential for survival (i.e. mating preferences)
  1. Examples given