Evolution

Introduction

Evolution is a process that results in heritable changes in a population spread over many generations. This process is a central concept in biology and forms the foundation of the field of evolutionary biology, which seeks to explain the diversity of life on Earth.

The Theory of Evolution

The Theory of Evolution is a scientific theory that essentially states that species change over time. There are many different ways species change, but most of them can be described by the idea of natural selection. The theory of evolution through natural selection was the first scientific theory that put together evidence of change through time as well as a mechanism for how it happens.

Natural Selection

Natural Selection is the process where organisms with favorable traits are more likely to reproduce. In doing so, they pass on these traits to the next generation. Over time this process allows organisms to adapt to their environment. The concept of natural selection was proposed by Charles Darwin and Alfred Russel Wallace in the 19th century.

Genetic Drift

Genetic Drift is a change in the frequency of an existing gene variant in a population due to random sampling of organisms. This results in changes in population genetics over time and can result in genetic traits being lost from a population or becoming widespread.

Mutation

In biology, a Mutation is a change in a DNA sequence, the genetic material of life, that can result in a change in phenotype or appearance. Mutations can be beneficial, neutral, or harmful for the organism, but mutations do not "try" to supply what the organism "needs." In combination with the genetic variation within a population, mutation can cause the next generation of organisms to be genetically different from their parents.

Speciation

Speciation is the evolutionary process by which populations evolve to become distinct species. It is a major focus of evolutionary biology. There are four modes of natural speciation, based on the extent to which speciating populations are isolated from one another: allopatric, peripatric, parapatric, and sympatric.

Evolution of Populations

Evolution can occur in populations when parameters such as size, lifespan, and reproductive success change over time (biological evolution). This process is driven by the mutation, non-random mating, gene flow, genetic drift, and natural selection.

Evidence of Evolution

The Evidence of Evolution has been accumulated over many years and comes from many sources, including the fossil record, changes in species distributions over time, the similarities and differences between species, and the genetic sequences of different organisms.

Evolution and Society

Understanding evolution is critical for understanding biology. As the preeminent scientist Theodosius Dobzhansky stated, "Nothing in biology makes sense except in the light of evolution." Evolution is a cornerstone of modern science, accepted as one of the most reliably established of all facts and theories in science, and is therefore taught as part of science education in schools and universities all over the world.