In genetics, outcrossing refers to the breeding of two individuals that are not closely related or those who come from different populations. This is in contrast to inbreeding that involves breeding individuals that are closely related.
In plants, outcrossing can occur naturally through cross-pollination between different plants, or it can be intentionally induced through a controlled pollination. In animals, it occurs through mate selection outside of close relatives. It might also occur through the introduction of individuals from other populations.
Is outcrossing same as outbreeding?
The terms outcrossing and outbreeding are closely related and can sometimes be used interchangeably. However, but they do have slight differences depending on the context.
Outcrossing refers to the mating between two individuals that are not closely related or that come from different populations. While outbreeding refers to breeding between individuals that are not related within a given family or breeding line.
In both cases, the aim is to increase genetic diversity and reduce the negative effects of inbreeding.
What are the differences between incrossing and outcrossing?
| Incrossing (Inbreeding) | Outcrossing |
| Incrossing or inbreeding involves the breeding of closely related individuals within a population. | It involves the breeding of unrelated individuals from different populations. |
| It leads to a reduction in genetic diversity within a population | This can increase genetic diversity by introducing new alleles into the population. |
| This can lead to the expression of deleterious recessive traits | It reduce the frequency of such traits by introducing new alleles |
| Inbreeding increase the expression of dominant traits | It can lead to greater phenotypic variation. |
| Inbreeding can result in inbreeding depression (a reduction in fitness by the expression of deleterious traits) | Crossbreeding can improve fitness by introducing new genetic variation |
What are the advantages of Outcrossing?
Cross amalgamation can have a number of genetic implications.
It can introduce new alleles (different versions of a gene) into the population which can provide greater genetic variation for natural selection. This increases the genetic diversity can also reduce the likelihood of genetic disorders.
Some of the advantages are:
Increased genetic diversity
It can introduce new genetic variation into a population, which can increase the number of alleles and genotypes. This can increase the potential for evolutionary adaptation to changing environmental conditions, and can also help to prevent the loss of beneficial traits due to genetic drift.
Reduced inbreeding depression
Inbreeding can lead to the expression of harmful recessive traits, which can reduce fitness. Crossbreeding can introduce new alleles into the population which can reduce the frequency of harmful recessive traits and help to restore genetic fitness.
Heterosis or hybrid vigor
The progeny of an outcross can exhibit hybrid vigor, which is an increased performance or fitness compared to their parents. This is due to the combination of favorable traits from both parents. This can lead to increased growth, survival, and reproduction.
Restoration of genetic variability
It help to restore genetic variability in populations that have undergone a bottleneck or founder effect, where genetic diversity has been lost due to a reduction in population size or the isolation of a small group of individuals.
Adaptation to new environments
Crossbreeding can introduce new alleles that are better adapted to local environmental conditions. This can improve the chances of survival and reproduction of the offspring in a changing environment.
What are the disadvantages of crossbreeding?
While outcrossing can have many benefits, there are also some potential disadvantages associated with this breeding strategy. They are:
The dilution of locally-adapted alleles
In some cases lead to the loss of locally-adapted alleles and can reduce the fitness of the offspring in their original environment.
Reduced uniformity
This can lead to greater phenotypic variation within a population which could be a major disadvantage in some cases. This mostly occurs in agricultural settings where uniformity is desirable.
Decreased performance of hybrid progeny
While hybrid vigor can sometimes occur as a result of crossbreeding, this is not always the case. In many instances, the hybrid offspring may have reduced fitness or performance compared to their parents.
Loss of valuable traits
This strategy can lead to the loss of valuable traits that have been developed through selective breeding or genetic manipulation, which can be a disadvantage in some agricultural or breeding contexts.
Increased risk of disease transmission
Introducing new individuals into a population can increase the risk of disease transmission and other pathogen transfer, which can negatively impact population health.