Archive for March 25th, 2011

March 25, 2011

Hybrid Vigor

grolar bear

Heterosis, or hybrid vigor or outbreeding enhancement, is the increased function of any biological quality in a hybrid offspring. It is the occurrence of a genetically superior offspring from mixing the genes of dissimilar parents. Heterosis is the opposite of inbreeding depression, which occurs in the offspring of closely related parents.

The term often causes controversy, particularly in regard to selective breeding of domestic animals, because sometimes it’s inaccurately claimed, that all crossbred plants or animals are genetically superior to their parents. It’s only true in certain circumstances. When a hybrid is seen to be superior to its parents, this is known as hybrid vigor. When the opposite happens, and a hybrid inherits traits from its parents that makes it unfit for survival, the result is referred to as outbreeding depression. Typical examples of this are crosses between wild and hatchery fish that have incompatible adaptations.

March 25, 2011

Miscegenation

Miscegenation

Miscegenation [mi-sej-uh-ney-shuhn] (Latin: miscere ‘to mix,’ genus ‘kind’) is the mixing of different racial groups, a social construct, through marriage, cohabitation, sexual relations, and procreation. The term miscegenation has been used since the 19th century to refer to interracial marriage and interracial sex, and more generally to the process of racial interbreeding, which has taken place since ancient history.

The term entered historical records during European colonialism, but societies such as China and Japan also had restrictions on marrying with peoples they considered different. Historically the term has been used in the context of laws banning interracial marriage and sex, so-called anti-miscegenation laws.

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