16.3- Darwin Presents His Case Flashcards
What is the struggle for existence?
More organisms are born than can be supported. Animals must compete for food and living space,
What is variation?
Variation is a heritable trait that makes all individuals different from each other. Some variations help the individual compete.
What is an adaptation?
An adaptation is a heritable characteristic that increases an organisms ability to survive and reproduce.
Give an example of variation.
Being faster to run away from predators
Give an example of an adaptation.
Camouflage
What is fitness?
How well an organism can survive and reproduce in an environment.
What is natural selection?
When organisms with variations most suited to their environment leave more offspring. Evolution occurs when the a lot of individuals acquire that trait.
When does natural selection occur?
It occurs when more individuals are born that can survive, there is natural variation, and there is variable fitness among individuals.
There must be overproduction of offspring and variation among the heritable traits.
How does natural variation affect evolution?
It’s necessary if some organisms have higher fitness, and have a greater chance of passing their traits onto the next generation.
