Natural Selection Flashcards
Natural selection is a ________ process
Non-random
Nature selects organisms that are…
Adequate enough to grow up (survive), mate and produce offspring
Natural selection
A nonrandom process by which traits are selected for by nature because they provide some survival benefit
4 main principles of natural selection
Variation
Overproduction
adaptation
descent with modification
Variation
In any population not all organisms are the same
Overproduction
More babies are born than will survive
Adaptation
Something that the organism has that is beneficial (a trait)
Descent with modification
The next generation with slightly different characteristics
Fitness
The measure of survival ability and ability to produce more offspring in the population
Differential reproduction
Unequal number of offspring produced by breeding pairs of the same species
Natural selection acts on…
Existing variation and traits that already exist
3 modes of selection
Directional selection
stabilizing selection
disruptive selection
Directional selection
1 of 2 extreme phenotypes is clearly favored
Stabilizing selection
The middle phenotype is favored
Disruptive selection
Both extreme phenotypes are favored, middle is no good
