Reproductive compensation was originally a theory to explain why recessive genetic disorders may persist in a

population Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...

. It was proposed in 1967 as an explanation for the maintenance of Rh negative blood groups. Reproductive compensation refers to the tendency of parents, seeking a given family size, to replace offspring that are lost to genetic disorders. It may also refer to the effects of increased maternal or parental investment in caring for disadvantaged offspring, seeking to compensate for genetic disadvantage. It is a theory that suggests that behavioral as well as physiological factors may play a role in the level of recessive genetic disorders in a population. According to Andrew Overall of the

University of Edinburgh The University of Edinburgh ( sco, University o Edinburgh, gd, Oilthigh Dhùn Èideann; abbreviated as ''Edin.'' in post-nominals) is a public research university based in Edinburgh, Scotland. Granted a royal charter by King James VI in 15 ...

, “Reproductive compensation may be particularly significant where economic or social factors mean that families are small compared to the maximum reproductive rate. Within small families, diseased infants may be more likely to be replaced. As a consequence, parents with otherwise reduced fertility have a greater influence on the frequency of recessive alleles in

future generations Future generations are cohorts of hypothetical people not yet born. Future generations are contrasted with current and past generations, and evoked in order to encourage thinking about intergenerational equity. The moral patienthood of future g ...

.” Ian Hastings has argued that reproductive technologies such as embryo

sex selection Sex selection is the attempt to control the sex of the offspring to achieve a desired sex. It can be accomplished in several ways, both pre- and post-implantation of an embryo, as well as at childbirth. It has been marketed under the title family ...

preimplantation genetic diagnosis Preimplantation genetic diagnosis (PGD or PIGD) is the genetic profiling of embryos prior to implantation (as a form of embryo profiling), and sometimes even of oocytes prior to fertilization. PGD is considered in a similar fashion to prenatal ...

with

in vitro fertilization In vitro fertilisation (IVF) is a process of fertilisation where an egg is combined with sperm in vitro ("in glass"). The process involves monitoring and stimulating an individual's ovulatory process, removing an ovum or ova (egg or eggs) f ...

, and selective termination of pregnancy may increase the frequency of genetic disorders through reproductive compensation. More recently the reproductive compensation hypothesis has been generalized to include, not only recessive genetic disorders, but in a more general sense, the effects of parental compensation when mate selection or breeding take place under constraints. According to Patricia Adair Gowaty, “The reproductive compensation hypothesis says that individuals constrained by ecological or social forces to reproduce with partners they do not prefer compensate for likely offspring viability deficits.” In human societies, such constraints include the manipulation of female mating options,

forced copulation Sexual coercion among animals is the use of violence, threats, harassment, and other tactics to help them forcefully copulate.Smuts, Barbara BMale Aggression and Sexual Coercion of Females in Nonhuman Primates and Other Mammals: Evidence and The ...

arranged marriages Arranged marriage is a type of marital union where the bride and groom are primarily selected by individuals other than the couple themselves, particularly by family members such as the parents. In some cultures a professional matchmaker may be us ...

assortative mating Assortative mating (also referred to as positive assortative mating or homogamy) is a mating pattern and a form of sexual selection in which individuals with similar phenotypes or genotypes mate with one another more frequently than would be ex ...

, and the trading of copulation for access to resources. Whereas

heterozygote advantage A heterozygote advantage describes the case in which the heterozygous genotype has a higher relative fitness than either the homozygous dominant or homozygous recessive genotype. Loci exhibiting heterozygote advantage are a small minority of ...

can explain the persistence of high carrier rates of

lethal alleles Lethal alleles (also referred to as lethal genes or lethals) are alleles that cause the death of the organism that carries them. They are usually a result of mutations in genes that are essential for growth or development. Lethal alleles may be rec ...

in certain regions (e.g.

sickle-cell disease Sickle cell disease (SCD) is a group of blood disorders typically inherited from a person's parents. The most common type is known as sickle cell anaemia. It results in an abnormality in the oxygen-carrying protein haemoglobin found in red blo ...

in Central and West Africa), Johan Koeslag and Stephen Schach have suggested that reproductive compensation might explain why different communities have high carrier rates for differing lethal alleles, despite living in similar or sometimes the same environment. Examples are

Tay–Sachs disease Tay–Sachs disease is a genetic disorder that results in the destruction of nerve cells in the brain and spinal cord. The most common form is infantile Tay–Sachs disease, which becomes apparent around three to six months of age, with the baby ...

amongst Ashkenazi Jews, cystic fibrosis amongst people of West European origin, and

phenylketonuria Phenylketonuria (PKU) is an inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine. Untreated PKU can lead to intellectual disability, seizures, behavioral problems, and mental disorders. It may also re ...

among persons from Ireland.

References

{{Reflist Autosomal recessive disorders