They, with many others, clearly established the basic processes which causedpopulations to change over time: selection, genetic drift, migration, and mutation. The change in the genetic makeup of a population over time, usually measured in terms of allele frequencies, is equivalent to evolutionary change.
A change in the genetic makeup of a population is called evolution.
What is evolution?
"Evolution is change in the heritable characteristics of biological populations over successive generations."
It is a slow process.
It causes due to natural selection, gene flow, genetic drift and migration.
The new generation differs from their parental species.
The individuals with features or traits that function well in their local environment will be more likely to survive, passing on their genes to their offspring.
This results in the change of genes of the two species.
