Inbreeding
Inbreeding is reproduction from the mating between related individuals. Inbreeding is a form of nonrandom mating.[1] A mating between relatives is commonly referred to as consanguineous mating. An inbred line is the result from animals being mated brother to sister, generation after generation.[2] Among humans, excessive inbreeding may be avoided with the help of elaborate cultural traditions[3] and religious principles. However in some cultural traditions, consanguineous marriages are preferred and often prescribed as is the case with some followers of the Dravidian tradition.[4]
Measurements of inbreeding
Inbreeding is measured using the inbreeding coefficient, that can range from 0 to 1, which is a measure of of the probability that two alleles are identical by descent. This coeficient is usually denoted by F.[1] It is defined as the proportionate reduction in the frequency of heterozygous genotypes in a population of inbred organisms (HI) compared with the value (2pq) that would be expected with random mating.[5] This coefficient denotes the fraction by which it is reduced the proportion of heterozygotes expected.[5] The formula is:
F = (2pq - HI)/2pq
where
F = The inbreeding coefficient.
p = Frequency of the dominant allele.
q = Frequency of the recessive allele.
HI = Frequency of heterozygous genotypes in a population of inbred organisms.
Inbreeding depression
The increasing emergence of lethal and deleterious traits due to inbreeding is called inbreeding depression.[1]
References
- ↑ 1.0 1.1 1.2 Pierce, Benjamin A (2008). Genetics: A Conceptual Approach (3rd ed.). New York: W. H. Freeman and Company. p. 687-688. ISBN 978-0-7167-7928-5.
- ↑ Snustad, Peter; Simmons, Michael J (2010). Principles of Genetics (5th ed.). River Street, Hoboken, NJ: John Wiley & Sons. p. 80. ISBN 978-0-470-39842-5.
- ↑ Brahmachary, R.L.; Sarkar, Mousumi Poddar; Dutta, J (1993). "Evolution of Chemical Signals". In Majumder, Partha P. Human Population Genetics: A Centennial Tribute to J.B.S.Hadane. London: Plenum Press. p. 96. ISBN 0-306-44572-7.
- ↑ Malhotra, Kailash C.; Vasulu, T. S (1993). "Structure of Human Populations in India". In Majumder, Partha P. Human Population Genetics: A Centennial Tribute to J.B.S.Hadane. London: Plenum Press. p. 207-233. ISBN 0-306-44572-7.
- ↑ 5.0 5.1 Hartl, Daniel L (2011). Essential Genetics: A Genomics Perspective (5th ed.). Sudbury, Massachusetts: Jones and Bartlett Publishers. p. 481. ISBN 978-0-7637-7364-9.
