What must be true for natural selection to happen?

Answer 1

There must be genetic variation in the population

The system must not be in hardy-weinberg equilibrium.

resources must be limited in the ecosystem

Answer 2

Competition + Variation.

Classic example:

Giraffes not always had long necks. There were variation in the species. When food sauces grew low competition increases and those with longer necks survived (more fruit/food at the top of trees) as they were more suited to the conditions. These long necked giraffes then breed and the offspring have long necks, thus natural selection of a "fitter" species. Hense - survival of the fittest.

Answer 3

resources must be limited in the ecosystem

Answer 4

There are four things that must be true for natural selection to occur. They are that reproduction is not random, that there are various individuals within a species, that those individual's variation is due to genetics, and that the majority of offspring they make will continue to reproduce.

Answer 5

Some sort of environmental pressure, like loss of food supply or low water supply.

Answer 6

There must be genetic variation in an environment.

apex

Answer 7

There must be competition for resources

Answer 8

there must be no competition for resources

Answer 9

There must be genetic variation in the population.