a type of variation such that as one variable increases the other decreases
inverse proportionality
title: Human genetic variation text: individuals. Genetic variability is a measure of the tendency of individual genotypes in a population to vary (become different) from one another. Variability is different from genetic diversity, which is the amount of variation seen in a particular population. The variability of a trait is how much that trait tends to vary in response to environmental and genetic influences. In biology, a cline is a continuum of species, populations, races, varieties, or forms of organisms that exhibit gradual phenotypic and/or genetic differences over a geographical area, typically as a result of environmental heterogeneity. In the scientific study of human genetic title: Genetic variation text: Genetic variation Genetic variation means that biological systems – individuals and populations – are different over space. Each gene pool includes various alleles of genes. The variation occurs both within and among populations, supported by individual carriers of the variant genes. Genetic variation is brought about, fundamentally, by mutation, which is a permanent change in the chemical structure of chromosomes. Genetic recombination also produces changes within alleles. Genetic variation among individuals within a population can be identified at a variety of levels. It is possible to identify genetic variation from observations of phenotypic variation in either quantitative traits (traits that title: Disruptive selection text: Disruptive selection Disruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups. In this more individuals acquire peripheral character value at both ends of the distribution curve. Natural selection is known to be one of the most important biological processes behind evolution. There are many variations of traits, and some cause greater or lesser reproductive success of the individual. Selection's effect is to promote certain alleles, traits, and individuals title: Genetic variation text: (recessive alleles are only expressed in the less common homozygous individuals). Natural selection can also maintain genetic variation in balanced polymorphisms. Balanced polymorphisms may occur when heterozygotes are favored or when selection is frequency dependent. Genetic variation Genetic variation means that biological systems – individuals and populations – are different over space. Each gene pool includes various alleles of genes. The variation occurs both within and among populations, supported by individual carriers of the variant genes. Genetic variation is brought about, fundamentally, by mutation, which is a permanent change in the chemical structure of chromosomes. Genetic recombination also produces changes title: Human variability text: Human variability Human variability, or human variation, is the range of possible values for any characteristic, physical or mental, of human beings. Frequently debated areas of variability include cognitive ability, personality, physical appearance (body shape, skin color, etc.) and immunology. Variability is partly heritable and partly acquired ("nature vs. nurture" debate). As the human species exhibits sexual dimorphism, many traits show significant variation not just between populations but also between the sexes. Human variability is attributed to a combination of environmental and genetic sources including: For the genetic variables listed above, few of them are controlled by simple Mendelian inheritance.