Inbreeding is technically the reproduction of animals that are closely linked by ancestry than the average relationship. It is considered contrary to the biological purpose of mating, which normally is infusing fresh strains of DNA during the mating process.
While inbreeding has a practical application in evolutionary theory and conservation biology, its cost remains unknown. Classifying inbreeding depends on the closeness of the biological link between the mates. While mating between closely related animals is considered inbreeding, there are differences of opinion on what constitutes inbreeding.
In humans, DNA is grouped into 23 chromosome pairs. There are innumerable genes in each chromosome. Every gene has a couple of copies called alleles. It is the genes that define various aspects of your body, including your appearance, hair, and eyes, and also the biological aspects such as blood type.
Genes are categorized into recessive genes and dominant genes. The dominance of one gene results in gaining the attributes of that dominant gene. But for traits origination from a recessive gene, the genes need to be both recessive.
For instance, the gene that results in brown eyes is the dominant one. So the presence of even one of them inside a pair of genes will cause the eyes to be brown. But in blue eyes, the gene is recessive. Thus an offspring will have blue eyes only if both genes are blue eyes. The example of the House of Habsburg is cited as an example of the disaster of inbreeding, at least in humans. This family ruled spread beyond Spain, Hungary, and Austria but the last of the family, Charles II of Spain suffered all the classic deformities associated with inbreeding.
Inbreeding In Animals
Inbreeding wasn’t just used to ensure purity among royals, albeit with absurd results. Man has also used it to maintain the purity of some breeds, like rottweilers. Boxers and Border Collies also have restricted genetic variation, the Collies have a genetic populace of just 50 with a population of around 12,000.
For most breeds, inbreeding weakens their immunity and has other negative impacts rather than positive ones. Two of the largest Koala populations could be decimated if afflicted by any disease as they were subject to heavy inbreeding.
A study of pedigree dogs, which are subject to inbreeding to preserve certain genetic traits like their color, quality of the fur, height, etc.
Incest is part of the lifecycle of certain animals and isn’t just the result of human interference in the reproduction process. The reproductive pattern of the Pyemotes boylei, a variety of mite, are designed for inbreeding. In an interesting process, the mother holds on to her eggs till the mites are mature. The first batch to hatch are males, and they wait outside the genitals of their mother. As soon as the next wave of female eggs hatches, the males set about impregnating them.
The Negative Impact Of Inbreeding
But this emphasis on inbreeding has led to a large proportion of them suffering from conditions that are generally associated with it. An overwhelming proportion of pedigree dogs generally suffer from heart disease, abnormal development and deformities in their hips, and deafness. The problem has developed alarming proportions. In boxer dogs, for instance, around 20,000 pedigree dogs have the genetic variety of a mere 70 dogs.
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A limited pool of genes thus can lead to a negative impact on the quality of the successive generation. This process is referred to as Inbreeding Depression. It denotes a fall in population and their health due to a lack of vigorous mates from outside their gene pool.
There is an unassuming solution to such problems. Bringing in breeding mates from outside their gene pool. In Sweden, adders that were breeding in isolated pockets due to the presence of farms were facing a problem of stillbirths that was affected their population severely. the Artificial introduction of mates from outside their gene pool worked wonders and the population increased rapidly. This process of outbreeding might be the ideal solution but it is not possible for many breeds because of their dwindling population. The Black Robin (petroice traverse) an endangered species cannot be bred with a population from outside as their numbers are too small for it.
Perhaps inbreeding is best left to some species that were engineered to inbreed, like the mite. Forcing it in other species leaves the offspring vulnerable to numerous genetic diseases and congenital defects.
Inbreeding Also Used To Improve Growth In Fish And Livestock
Inbreeding can also be used in certain cases to improve productivity and hence, profits. A thorough knowledge helps a hatchery manager or farmer to manage the genetic aspects of his farm population. Inbreeding is one of the 3 major breeding programs traditionally used by breeders to produced livestock, and plants that are genetically improved.
Inbreeding might be one of the most important techniques also used for breeding laboratory animals because laboratories need rats and mice that are genetically uniform.
It is also vital in agronomy as many plants can thus be self-fertilized. Artificial pollination can be used for mating and a large number can be raised easily in a small plot.
Inbreeding programs have also been used for fish as many varieties can be stripped to create mating combinations not possible in livestock breeding. Secondly, fish exhibit the capability of producing an abundance of offspring which is not possible for livestock.
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Certain species prevent inbreeding using different methods. In many social species, members of one gender usually leave the group, and they mostly are females. This dispersal behavior evolved as it became evident that the female of the species that left their home had more offspring. Other species, like wild house mice, use specially evolved proteins present in their urine to sniff out and avoid mating with close relatives.