Variation And Selection Flashcards
What causes variation?
Give examples
Genetic-this describes variation due to genetic make-up, like eye colour
Environmental-this describes variation due to the environment, like the appearance of peas in different light conditions.
What are the two types of variation?
Continuous and discontinuous
Explain and give an example of continuous variation.
Gradual change in a characteristic of a population with no distinct categories; most individuals will be around the mode/mean with fewer at the either extreme
Explain and give an example of discontinuous variation
Individuals can be grouped into distinct groups with no overlap, like tongue rolling.
Who was the fist to understand Natural selection?
Charles Darwin
Summarise Natural selection
Variation exists between individuals in a population
If there is resource competition, there will be a struggle for existence
The best adapted survive-survival of the fittest
They then breed and pass on their genes
What is an example of natural selection in action?
Antibiotic resistance
Why may some bacteria already be resistant to an antibiotic?
What happens to these that are resistant?
Due to a mutation
These bacteria survive as the rest are killed and breed, becoming dominant type in population
What can natural selection explain about species?
How species over time have changed gradually in a process called EVOLUTION
Is evolution happening right now?
Evolution is a continuing process as all species are subject to natural selection and therefore change
Define extinct
Sometimes entire species may not be well enough adapted to survive in a changing world and can no longer survive, e.g. Mammoths and dinasours
Define endangered
At risk of extinction due to climate change, hunting, habitat destruction, etc. Examples of endangered species are mountain gorillas and pandas
What is variation?
It is the different ways living organisms of the same species differ.
