The essence of Darwin’s theory is that natural selection will occur if three conditions are met. These conditions, highlighted in bold above, are a struggle for existence, variation and inheritance. These are said to be the necessary and sufficient conditions for natural selection to occur.

Natural selection is a simple mechanism that causes populations of living things to change over time. In fact, it is so simple that it can be broken down into five basic steps, abbreviated here as VISTA: Variation, Inheritance, Selection, Time and Adaptation.

Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations.

Darwin’s process of natural selection has four components.

• Variation. Organisms (within populations) exhibit individual variation in appearance and behavior.
• Inheritance. Some traits are consistently passed on from parent to offspring.
• High rate of population growth.
• Differential survival and reproduction.

Natural selection occurs if four conditions are met: reproduction, heredity, variation in physical characteristics and variation in number of offspring per individual.

Natural selection is an inevitable outcome of three principles: most characteristics are inherited, more offspring are produced than are able to survive, and offspring with more favorable characteristics will survive and have more offspring than those individuals with less favorable traits.

Overproduction of offspring is the idea that species produce far more offspring than an environment can support because most of the juveniles will not make it to adulthood. This allows only the fittest to survive and reproduce.

The role of overproduction in evolution is to produce the best adapted organisms to survive up to adulthood and reproduce. An example of overproduction in animals is sea turtle hatchlings. A sea turtle can lay up to 110 eggs but most of them won’t survive to reproduce fertile offspring.

Overproduction of organisms plays a role in natural selection by making it so that there will not be enough food for all of the species, which will bring about competition, where only the organisms with favorable traits will survive.

Competition is an interaction between organisms or species in which both the organisms or species are harmed. According to evolutionary theory, this competition within and between species for resources is important in natural selection.

Genetic variation is an important force in evolution as it allows natural selection to increase or decrease frequency of alleles already in the population. Genetic variation is advantageous to a population because it enables some individuals to adapt to the environment while maintaining the survival of the population.

a natural process resulting in the evolution of organisms best adapted to the environment. (1) Natural selection is a key element of Darwin’s theory of evolution. (2) Natural selection ensures only the fittest survive to pass their genes on to the next generation.

First, natural selection is not all-powerful; it does not produce perfection. The population or individual does not “want” or “try” to evolve, and natural selection cannot try to supply what an organism “needs.” Natural selection just selects among whatever variations exist in the population. The result is evolution.