Evolution by Natural Selection Flashcards
What is evolution?
Evolution is the slow, continual change over many generations
What does evolution result in?
Evolution may result in a new species that is better adapted to its environment (and the extinction of others)
What is memorable about Charles Darwin?
In the 1830’s, Charles Darwin created a testable theory of evolution, studying life on the Galapagos Island, including the different types of finch.
What was Charles Darwin’s theory based around?
- Individuals show variation (differences due to genes)
- There’s competition for food and friends. Also, disease and predators keep population sizes constant in spite of many offspring.
- Those better adapted are more likely to survive and reproduce while others die out. This is ‘survival of the fittest’
- Survivors pass on genes to their offspring, resulting in an improved organism evolving over generations.
How did Darwin link these points?
Darwin linked all these observations and deduced that the best adapted organisms would survive and reproduce.
What does his theory of natural selection rely on?
Variation caused by the genes and the environment.
What is the difference between genetic variation and environmental variation?
Only genetic variation, usually caused by mutation, can be passed on, and only then if it has occured in the sex cells. Environmental variation , such as loss of a finger, can’t be passed on.
Why is the evidence still incomplete?
Because scientists can’t ever be certain or how life began; evidence is incomplete, new discoveries are being made and theories can change according to the known evidence