Cross-fostering
Encyclopedia
Cross-fostering is a technique used in animal husbandry
, animal science
, genetic
and nature versus nurture
studies, and conservation, whereby offspring
are removed from their biological parent
s at birth and raised by surrogates. This can also occasionally occur in nature.
because litters with up to 15 piglets are common. A sow with a large litter may have difficulty producing enough milk for all piglets, or the sow may not have enough functional teats to feed all piglets simultaneously. When this occurs, smaller or weaker piglets are at risk of starving to death. Herd managers will often transfer some piglets from a large litter to another lactating sow which either has a smaller litter or has had her own biological piglets recently weaned. Herd managers will typically try to equalize litters by number and also weight of individuals. When done successfully, cross-fostering reduces piglet mortality.
similar to their biological parents and dissimilar from their foster parents, a behavior can be shown to have a genetic basis. Similarly if the offspring develops traits dissimilar to their biological parents and similar to their foster parents environmental factors are shown to be dominant. In many cases there is a blend of the two, which shows both genes
and environment play a part.
In animal studies, genetically hypertensive offspring reared by normotensive dams shown to have lower blood pressure compared to the controls. This shown that hypertensive genotype could be modified by the changes of the postnatal environment. Besides this, hyperkinetic animals reared by a normal dam shown to have lower locomotion activity compared to its controls.
In selective livestock breeding this can be used to combine desirable genetic qualities such as weight, fat distribution or appearance with environmentally influenced ones such as temperament.
In humans, studies of children in foster care
have shown that alcoholism
is both genetic and environmental: early onset alcoholism can be linked to biological parentage, whereas adult onset alcoholism is often influenced by the alcohol abuse by foster parents.
such as the rearing of Black Robin
chicks by other species. In this instance the species was so close to extinction
, with literally a handful of surviving individuals and a single mother, there was little chance of raising many offspring. In this case a related species were used to raise the eggs, with their own eggs being replaced by conservation workers with those of the robin. In this case imprinting
is one of the concerns, as species raised in a different environment may not be able to recognize their own species
.
Cross fostering may occasionally occur in natural situations. In Australia
, the closely related species from the cockatoo
family, Eolophus roseicapilla (the galah
) and Cacatua leadbeateri (the pink cockatoo), have overlapping ranges
, and compete
for nest
ing holes. However, two pairs of birds may share the same nest for a time, as they do not become aggressive until several eggs have been laid and incubation
begins. When they do, the pink cockatoos are always the victors, evicting the galahs in what is termed interference competition. They are not consciously aware that some of the eggs in the nest were laid by the other bird however, and thus raise offspring of both species. These natural experiment
s have been used by Australian ornithologists Graeme Chapman and Ian Rowley to investigate the relative importance of genes and environment. For example, they discovered that the galah chicks gave normal begging calls and alarm calls, but their contact calls
(used to maintain social cohesion
) were more like those of the pink cockatoos with which they lived.
Such natural instances of cross fostering can also lead to hybridization between species that would not normally breed. A case of this is offered by the Galapagos finches. Two species of the genus Geospiza
, the Medium Ground-finch
(Geospiza fortis) and the Common Cactus-finch
(Geospiza scandens) occasionally hybridize. The birds' song
s are a barrier to interbreeding, but sometimes young birds will not learn their own species song, e.g. if their father dies and they are nesting near another species. Another situation where birds can imprint
on the wrong song is when one species takes over the nest of another, but fails to remove all of its eggs. Cross fostered young can then hybridize with their foster parents' species, allowing gene flow
between the two populations. Hybrids experience reduced fitness
, however, so the two species can remain separate.
Animal husbandry
Animal husbandry is the agricultural practice of breeding and raising livestock.- History :Animal husbandry has been practiced for thousands of years, since the first domestication of animals....
, animal science
Animal science
Animal Science is described as "studying the biology of animals that are under the control of mankind". Historically, the animals studied were farm animals, including livestock and horses, but courses available now look at a far broader area to include companion animals, for example dogs, cats and...
, genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
and nature versus nurture
Nature versus nurture
The nature versus nurture debate concerns the relative importance of an individual's innate qualities versus personal experiences The nature versus nurture debate concerns the relative importance of an individual's innate qualities ("nature," i.e. nativism, or innatism) versus personal experiences...
studies, and conservation, whereby offspring
Offspring
In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...
are removed from their biological parent
Parent
A parent is a caretaker of the offspring in their own species. In humans, a parent is of a child . Children can have one or more parents, but they must have two biological parents. Biological parents consist of the male who sired the child and the female who gave birth to the child...
s at birth and raised by surrogates. This can also occasionally occur in nature.
Animal husbandry
Cross-fostering young animals is usually done to equalize litter size. Individual animals born in large litters are faced with much more competition for resources, such as breast milk, food and space, than individuals born in smaller litters. Herd managers will typically move some individuals from a large litter to a smaller litter where they will be raised by a non-biological parent. This is typically done in pig farmingPig farming
There are various methods of pig farming depending on the method of management adopted. Variables include:* Money or capital available* The type of animals kept* Local requirements and market conditions* The level of management skills...
because litters with up to 15 piglets are common. A sow with a large litter may have difficulty producing enough milk for all piglets, or the sow may not have enough functional teats to feed all piglets simultaneously. When this occurs, smaller or weaker piglets are at risk of starving to death. Herd managers will often transfer some piglets from a large litter to another lactating sow which either has a smaller litter or has had her own biological piglets recently weaned. Herd managers will typically try to equalize litters by number and also weight of individuals. When done successfully, cross-fostering reduces piglet mortality.
In research
Cross-fostering can be used to study the impact of postnatal environment on genetic-linked diseases as well as on behavioural pattern. In behavioral studies, if cross-fostered offspring show a behavioral traitTrait (biology)
A trait is a distinct variant of a phenotypic character of an organism that may be inherited, environmentally determined or be a combination of the two...
similar to their biological parents and dissimilar from their foster parents, a behavior can be shown to have a genetic basis. Similarly if the offspring develops traits dissimilar to their biological parents and similar to their foster parents environmental factors are shown to be dominant. In many cases there is a blend of the two, which shows both genes
Gênes
Gênes is the name of a département of the First French Empire in present Italy, named after the city of Genoa. It was formed in 1805, when Napoleon Bonaparte occupied the Republic of Genoa. Its capital was Genoa, and it was divided in the arrondissements of Genoa, Bobbio, Novi Ligure, Tortona and...
and environment play a part.
In animal studies, genetically hypertensive offspring reared by normotensive dams shown to have lower blood pressure compared to the controls. This shown that hypertensive genotype could be modified by the changes of the postnatal environment. Besides this, hyperkinetic animals reared by a normal dam shown to have lower locomotion activity compared to its controls.
In selective livestock breeding this can be used to combine desirable genetic qualities such as weight, fat distribution or appearance with environmentally influenced ones such as temperament.
In humans, studies of children in foster care
Foster care
Foster care is the term used for a system in which a minor who has been made a ward is placed in the private home of a state certified caregiver referred to as a "foster parent"....
have shown that alcoholism
Alcoholism
Alcoholism is a broad term for problems with alcohol, and is generally used to mean compulsive and uncontrolled consumption of alcoholic beverages, usually to the detriment of the drinker's health, personal relationships, and social standing...
is both genetic and environmental: early onset alcoholism can be linked to biological parentage, whereas adult onset alcoholism is often influenced by the alcohol abuse by foster parents.
In conservation
Cross fostering has been used in conservation biologyConservation biology
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...
such as the rearing of Black Robin
Black Robin
The Black Robin or Chatham Island Robin is an endangered bird from the Chatham Islands off the east coast of New Zealand. It is closely related to the New Zealand Robin . It was first described by Walter Buller in 1872. The binomial commemorates the New Zealand botanist Henry H. Travers...
chicks by other species. In this instance the species was so close to extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
, with literally a handful of surviving individuals and a single mother, there was little chance of raising many offspring. In this case a related species were used to raise the eggs, with their own eggs being replaced by conservation workers with those of the robin. In this case imprinting
Imprinting
Imprinting may refer to:* Genomic imprinting , a mechanism of regulating gene expression* Imprinting , in psychology and ethology* Molecular imprinting, in polymer chemistry...
is one of the concerns, as species raised in a different environment may not be able to recognize their own species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
.
In nature
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, the closely related species from the cockatoo
Cockatoo
A cockatoo is any of the 21 species belonging to the bird family Cacatuidae. Along with the Psittacidae and the Strigopidae , they make up the parrot order Psittaciformes . Placement of the cockatoos as a separate family is fairly undisputed, although many aspects of the other living lineages of...
family, Eolophus roseicapilla (the galah
Galah
The Galah , Eolophus roseicapilla, also known as the Rose-breasted Cockatoo, Galah Cockatoo, Roseate Cockatoo or Pink and Grey, is one of the most common and widespread cockatoos, and it can be found in open country in almost all parts of mainland Australia.It is endemic on the mainland and was...
) and Cacatua leadbeateri (the pink cockatoo), have overlapping ranges
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
, and compete
Interspecific competition
Interspecific competition, in ecology, is a form of competition in which individuals of different species compete for the same resource in an ecosystem...
for nest
Nest
A nest is a place of refuge to hold an animal's eggs or provide a place to live or raise offspring. They are usually made of some organic material such as twigs, grass, and leaves; or may simply be a depression in the ground, or a hole in a tree, rock or building...
ing holes. However, two pairs of birds may share the same nest for a time, as they do not become aggressive until several eggs have been laid and incubation
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...
begins. When they do, the pink cockatoos are always the victors, evicting the galahs in what is termed interference competition. They are not consciously aware that some of the eggs in the nest were laid by the other bird however, and thus raise offspring of both species. These natural experiment
Experiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...
s have been used by Australian ornithologists Graeme Chapman and Ian Rowley to investigate the relative importance of genes and environment. For example, they discovered that the galah chicks gave normal begging calls and alarm calls, but their contact calls
Bird song
Bird vocalization includes both bird calls and bird songs. In non-technical use, bird songs are the bird sounds that are melodious to the human ear. In ornithology and birding, songs are distinguished by function from calls.-Definition:The distinction between songs and calls is based upon...
(used to maintain social cohesion
Social behavior
In physics, physiology and sociology, social behavior is behavior directed towards society, or taking place between, members of the same species. Behavior such as predation which involves members of different species is not social...
) were more like those of the pink cockatoos with which they lived.
Such natural instances of cross fostering can also lead to hybridization between species that would not normally breed. A case of this is offered by the Galapagos finches. Two species of the genus Geospiza
Geospiza
Geospiza is a genus of bird in the Thraupidae family; all species of Geospiza are endemic to the Galápagos Islands; together with related genera they are collectively known as Darwin's finches...
, the Medium Ground-finch
Medium Ground-finch
The Medium Ground Finch is a species of bird in the Emberizidae family. It is endemic to the Galapagos Islands. Its natural habitats are subtropical or tropical dry forests and subtropical or tropical dry shrubland...
(Geospiza fortis) and the Common Cactus-finch
Common Cactus-finch
The Common Cactus Finch or Small Cactus Finch is a species of bird in the Darwin's finch group of the tanager family Thraupidae. It is endemic to the Galapagos Islands, where it is found on most islands, with the notable exception of Fernandina, Española, Genovesa, Darwin and Wolf...
(Geospiza scandens) occasionally hybridize. The birds' song
Birdsong
Birdsong may refer to:* Bird vocalization, the sounds of birds* Birdsong , a 1993 novel by Sebastian Faulks* Birdsong, Arkansas, USA* Birdsong , a channel on the UK Digital One digital radio multiplex...
s are a barrier to interbreeding, but sometimes young birds will not learn their own species song, e.g. if their father dies and they are nesting near another species. Another situation where birds can imprint
Imprinting
Imprinting may refer to:* Genomic imprinting , a mechanism of regulating gene expression* Imprinting , in psychology and ethology* Molecular imprinting, in polymer chemistry...
on the wrong song is when one species takes over the nest of another, but fails to remove all of its eggs. Cross fostered young can then hybridize with their foster parents' species, allowing gene flow
Gene flow
In population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...
between the two populations. Hybrids experience reduced fitness
Fitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...
, however, so the two species can remain separate.
See also
- Brood parasiteBrood parasiteBrood parasites are organisms that use the strategy of brood parasitism, a kind of kleptoparasitism found among birds, fish or insects, involving the manipulation and use of host individuals either of the same or different species to raise the young of the brood-parasite...
- Captive rearing
- Phenotypic plasticityPhenotypic plasticityPhenotypic plasticity is the ability of an organism to change its phenotype in response to changes in the environment. Such plasticity in some cases expresses as several highly morphologically distinct results; in other cases, a continuous norm of reaction describes the functional interrelationship...
- Supplementary feeding
- Twin studies
Primary sources
- http://www.southalabama.edu/biology/faculty/obrien/teaching/bly122/Chapter%2047.pdf
- Alcock, J.John Alcock (behavioral ecologist)John Alcock is an American behavioral ecologist and author. He is currently the Emeritus' Professor in the School of Life Sciences at Arizona State University. His research interests include the evolution of diversity in insect populations, studying the adaptive value of different ways in which...
(1998) Animal Behavior: An Evolutionary Approach (6th edition). Sinauer Associates, Inc. Sunderland, Massachusetts. ISBN 0-87893-009-4