Outcrossing is the practice of introducing unrelated genetic material into a breeding line. It increases genetic diversity, thus reducing the probability of diseases or other undesirable traits occurring due to genetic abnormalities. Genetic diversity is a characteristic of ecosystems and gene pools that describes an attribute which is commonly held to be advantageous for survival -- that there are many different versions of otherwise similar organisms. ...

In most breeding programs, outbreeding is avoided until absolutely necessary. Breeders inbreed within their genetic pool, thus ensuring the maintenance of desirable traits. When undesirable traits begin to appear, they then outbreed to eliminate the problems. This may also set back some desirable traits, requiring further inbreeding efforts. Inbreeding is breeding between close relatives, whether plant or animal. ...

In nature, where breeding is not managed, outcrossing rates may be estimated by genetic analysis. This allows calculation of the amount of genetic exchange between populations, and thus provides insights into the biogeography and phytogeography of species. Biogeography is the science which deals with patterns of species distribution and the processes that result in such patterns. ... Phytogeography is the branch of biogeography that is concerned with the geographic distribution of plant species. ...

Gregor Mendel used outcrossing in his experiments with flowers; as opposed to selfing. Gregor Johann Mendel Gregor Johann Mendel (July 20[1], 1822 – January 6, 1884) was an Augustinian abbot who is often called the father of modern genetics for his study of the inheritance of traits in pea plants. ...