### alteration | variation:

Genetic variation
* Most genetic variation affects capacity
  - comes from reproduction
  - has components
  - leads to heterogeneity
* Some genetic variation affects body chemistry
  - fitnesses
  - people
  - phenotypes
  - treatments
  - leads to characteristics
* are the touchstone of genetists for insight into the development of an organism.
* arises due to mutations that occur in the genomes of all organisms
  - through two processes, mutation and recombination
* can account for later language acquisition
  - explain a substantial portion of the variation in neuron number
* causes potential.
* enables a species to adapt and evolve to new circumstances.
* includes how genes become mutated or are involved in disease and aging.
* is critical to the ability of organisms to accommodate changes in the environment
  - extremely important to the survival of species
  - increased by gene mutations
  - lost through drift and selection and regenerated by mutation
  - necessary for propagation and survival of the species
  - preserved or eliminated from a population through natural selection
  - raw material for evolution and adaptation
  - situations
* is the basis for natural selection
  - clay that evolution molds into whatever shape selection dictates
* is the raw material for evolution
  - of evolutionary change
  - variation in the genetic make-up of the cow population
* key ingredient of evolution.
* lead to a spectrum of observable differences, such as eye and hair color.
* leads to evolution
* occur, producing conditions which can create problems for the individual.
* occurs within and between populations.
* occurs, unlike mitosis.
* provides information.
* refers to all the different gene versions that are present in a population
  - diversity in gene frequencies
* results in differences.
+ Evolution, Darwin's theory, Variation, Inherited variation: History of science
  * Genetic variation is increased by gene mutations. DNA does not always reproduce exactly. Rare changes occur, and these changes can be inherited. This gives rise to genetic variation, which is the seed-corn of evolution. Sexual reproduction, by the crossing over of chromosomes during meiosis, spreads variation through the population. Other events, like natural selection and drift, reduce variation.

Geographic variation
* have some effect on their color.
* is explicable by evolutionary processes
  - part of biodiversity, if an under-appreciated part
  - widespread and exists in all species

Great variation
* exists among human societies today with respect to sex specific behaviors
  - in color, leaf width and internode length
* occurs in shapes
  - shell shapes

Heritable variation
* encompasses reproduction, genetics, development and mutation.
* is based on variation in the alleles present among individuals in a population.

Individual variation
* affects the ability to survive and reproduce in an environment.
* develops because of maladaption, exposure, and lifestyle.
* reduces demographic stochasticity.
* represents individual skin barrier threshold for disease.

Mongrel
* are the result of countless generations of interbreeding between the different races.
* is variation

Natural variation
* are the main reasons climate changes happen.
* is the differences among individuals within a species.

Neutral variation
* is especially common at the molecular level.
* refers to any trait which seems to have no effect on evolutionary fitness.