What are the requirements of natural selection?
- biodiversity 2. environmental stress or change.3. limited resources, 4. over abundance of populations
Natural selection does not created change. Natural selection can only select from the variations already existing in a population,
For natural selection to work there must be existing biodiversity for natural selection to select from.
Note the cheetah population in east Africa is greatly endangered because there is almost no genetic diversity. The Cheetah is so highly adapted to its environment that a change in the environment would likely result in extinction.)
Natural selection has the greatest effect where there is an environmental change or stress. The "Darwin" finches show the greatest changes during times of drought that create an environmental stress on the population. The finches separate into different "sub species" . When the drought ends these "sub species" interbreed creating hybrids that are better adapted to the normal environment.
Limited resources create an opportunity for natural selection The fastest fox will find food while a slower individual might starve and not pass on its genes. This is part of the problem with the Cheetah. The limited resources have selected only the fastest individuals so that there is now little genetic diversity.
Organism tend to overproduce offspring. If all of mice produced survived there would soon not be enough food to feed them all. Some of the mice must die. The overproductions allows natural selection to cause the unfit to die and the well adapted to pass on their genes.
Natural Selection does not create genes or biodiversity. On the contrary Natural selection reduces biodiversity and genetic information. Natural selection must start with a great deal of existing diversity and large populations, Environmental stress and limited resources will reduce the population and genetic diversity through natural selection.