Answer:
-It occurs over many generations.
-It happens at the genetic level.
Step-by-step explanation:
Biological evolution corresponds to the process of modification and adaptation of species over logns periods of time.
The current diversity of living beings is the result of processes of transformation and adaptation of species to various environments, constituting biological evolution.
The theory of neodarwinism considers the following mechanisms as contributing factors to evolutionary changes:
Mutations
The mutation corresponds to any change in the genetic material of an organism, which may give rise to a new trait. If this new feature offers the individual any advantage, the allele tends to be preserved by natural selection.
Genetic Drift
Genetic drift is a process of random change in the allelic frequencies of a population. Genetic drift changes the allelic frequency of a population at random. It does not work to produce adaptations.
Natural selection
Natural selection is one of the fundamental mechanisms of evolution. Through it, the individuals best suited to a particular condition are selected. Thus, they are more likely to survive, reproduce and transmit their traits to descendants.