Natural Selection

Fitness
Stabilizing Selection
Directional Selection
Disruptive Selection
Speciation
Extinction

Lab:

Extinctions

References:

Paleozoic Extinctions
Great Dying
Asteroid or comet may have caused Earth's biggest extinction
Comet may have caused extinction
Mass Extinctions Punctuate Geologic Record
Mass Extinctions
Mass Extinctions and Punctuated Evolution
The Mother Of Mass Extinctions
The Late Pleistocene Extinctions

Return SAS Home
e-mail Kevin C. Hartzog

Natural Selection

Extinction

Evolution can have three results. In one, a species can be successfully in all changes in the environment, undergoing very few changes. In this case, the species will exist for a long time. In a second case, a species can natural selection can induce speciation, changing a older species into a new species. In the third case, a species could find that it does not have traits within its genepool to survive changes in the environment. In this last case, in the face of disruptive selection, and a sudden shift in the environment such as a loss of habitat, a species may not been able to live long enough to reproduce. If this happens, then the species will become extinct, will die and be loss from Earth's future forever.