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By analogy, the term ‘inbreeding’ refers to the genetic abnormalities and other effects that can result from the expression of negative or recessive traits resulting from incestuous sex relations and consanguinity.Inbreeding causes homozygosity, which increases the chances of negative or recessive traits affecting offspring, usually reducing a population’s biological fitness or survival and reproduction, at least temporarily.
Inbreeding Formula
The inbreeding coefficient indicates the likelihood that a person has two similar alleles for a particular gene. Recall that alleles are simply different versions of the same genotype.
We can have two copies for each of our chromosomes because we have two versions of each of our genetic material (except Y in males). There are many different alleles in a population, and people often acquire different ones out of each parent. Since they generally come from the same corresponding gene in her family tree, this inbred individual would have two identical alleles for a few of her genes.
The inbreeding coefficient can be calculated using the formula,
F= ∑ [(1/2)n * (1+Fa)
where
F = inbreeding coefficient
N = no. of individuals in the inbreeding path
Fa = common inbred individual parent
What is Inbreeding Depression?
Inbreeding depression is defined as a decrease or loss of strength and fitness caused primarily by inbreeding. In its simplest form, inbreeding depression occurs when relatives in a low population mate, reducing the population’s ability to adapt and reproduce.
This phenomenon can be seen in all wild animals, plants, and humans, indicating genetic differences in human beings and animals. Inbreeding depression is essential in crop breeding and the development of crossbreeding mating systems. The severity of inbreeding depression varies by mating system. C.elegans, a hermaphrodite species, has lower levels of inbreeding depression. C.remanei, an outcrossing nematode, suffers from severe inbreeding depression.
Inbreeding Depression in Plants
Inbreeding depression in plants occurs in four types or levels—high level to no inbreeding depression. The differences among them are mentioned below.
High Inbreeding Depression
Self-pollination produces a large percentage of plants that suffer from severe inbreeding depression and are lethal. Due to loss of vitality and fertility, maintaining the breeding border after 3 to 4 generations is extremely difficult. These are mostly found in Alfalfa and carrots, which belong to the pea family.
Moderate Inbreeding Depression
Sublethal impacts seen in the gametes are produced by self-pollination, in addition to lethal effects. Fertility has decreased significantly, as several of the works created are very poor and have been lost. Plants like maize, pearl millet, and great millet are examples of moderate inbreeding depression.
Low Inbreeding Depression
Only a small percentage of plants have lethal characteristics. There is less vigour and fertility loss. Plants with low inbreeding depression include onions, squash, pumpkin, and sunflowers, to name a few.
No Inbreeding Depression
This phenomenon is primarily observed in self-pollinated species, which do not exhibit inbreeding depression despite the absence of heterosis. It’s because they reproduce through both self-pollination and cross-pollination, with developed homozygous stability and heterozygous balance.
Inbreeding Depression in Animals & Humans
The European adder, also referred to as the European viper, is the common name for Vipera berus. It’s a poisonous snake found all over Western East Asia and Europe.
When a gang of 40 Vipera berus went through inbreeding depression, the isolated population produced more deformed and stillbirths offspring than the larger population. They replicated by recovering a developed fraction of viable offspring after introducing Vipera berus from other occupants into the isolated population.
The recovery is based on the fact that Vipera berus species with a single recessive negative or detrimental allele are healthier and can decrease the carrier’s fitness. As a result, the next generation receives fewer copies.
Conclusion
Inbreeding is an interesting concept of study in biology, and various studies are conducted worldwide. The consequences of inbreeding are fairly less in a bigger population since the chances of giving birth to offspring with negative traits are decreased significantly. Also, this issue is extremely rare for humans and can only be seen in tightly related ancestry.
