What Is The Plant Breeding Term For Inbreeding Depression?

Inbreeding depression is a phenomenon that results from the breeding of related individuals, leading to reduced biological fitness. This loss of genetic diversity is primarily due to small population sizes and depends on past mutation, selection, and genetics. Inbreeding depression affects both plants and animals, indicating that variation for heritable fitness traits can be caused by inbreeding.

Inbreeding depression is a fundamental selective pressure that shapes mating systems and population genetic structures in plants. It is a manifestation of mutation load in populations, thought to be caused primarily by the expression of deleterious recessive alleles. The reduction in fitness and fertility of offspring produced by consanguineous mating is a significant issue in both plants and animals.

When researchers introduce adders from other populations, an example of outbreeding, the isolated population recovers and produces a higher proportion of viable offspring. If the rate of inbreeding increases rapidly in such populations, there may be a reduction in the adaptation of the progeny, which can be associated with reduced germination, slower growth, and reduced height or fertility compared to non-inbred plants.

What is inbreeding in plant breeding?

Inbreeding is the crossing of closely related individuals in nature or plantations, resulting in plants with high homozygosity. This process can reduce genetic diversity in offspring and decrease heterozygosity, while inbred depression can reduce viability. Studies have shown that transgenerational epigenetic variation can impact complex traits, such as floral symmetry. Epialleles via DNA methylation can have consequences for plant evolution, while an epigenetic mutation responsible for natural variation in floral symmetry can also contribute to plant evolution. Understanding the impact of transgenerational epigenetic variation on complex traits is crucial for understanding plant evolution and its implications.

What is the theory of inbreeding depression?

Inbreeding depression is caused by the evolutionary history of a population, where dominant deleterious alleles are expressed, lowering the carrier’s fitness and reducing the number of copies in the next generation. However, recessive deleterious alleles are hidden from natural selection by dominant non-deleterious counterparts, allowing individuals carrying a single recessive deleterious allele to pass it into the next generation.

When populations are large, many recessive deleterious alleles are rarely expressed. However, when populations become small, close relatives may mate, resulting in offspring inheriting two copies of the same allele. This can lead to stillborn offspring and deformities.

In the case of the Swedish adders, the solution was to introduce adders from other populations. However, the northern hairy-nosed wombat suffers from inbreeding depression, and there are no other populations that can rescue it. Understanding the evolutionary history of a population and the likelihood of carrying recessive deleterious alleles is crucial for conservation efforts, as inbreeding depression may jeopardize the species’ survival.

What is the definition of inbreeding depression?

Inbreeding depression is a condition where offspring of related individuals are less likely to survive and reproduce, affecting both wild animals and plants. This can lead to increased yield through heterosis. Darwin’s work on cross and self-fertilization in the vegetable kingdom, orchids’ fertilization by insects, and the different forms of flowers on plants of the same species provide further insights.

What is heterosis and inbreeding depression in plant breeding?

Heterosis, or hybrid vigor, is a breeding technique that enhances characteristics in offspring by crossing two genetically different parents. Inbreeding depression, on the other hand, is a reduction in fitness in offspring due to inbreeding. Both techniques are used by breeders to obtain traits and characteristics according to their needs. However, they can either enhance or reduce the fitness of offspring. Understanding the differences between these two techniques is crucial for successful breeding.

How do you fix inbreeding depression?

The survival of a population may result in the long-term fixation of deleterious alleles, which could lead to a reduction in fitness and potentially contribute to the loss of genetic variation at other loci.

What is the difference between inbreeding and inbreeding depression?

Inbreeding, also known as “consanguinity”, occurs when mates are related to each other due to incest, assortative mating, small population size, or population sub-structuring. This results in an excess of homozygotes and a deficiency of heterozygotes, which exposes recessive genetic variation otherwise hidden by heterozygosity with dominant alleles relative to random mating. Interest in inbreeding arose from its use in animal and plant breeding programs to expose such variation and fix variants in genetically homogenous lines.

Geneticists have widely exploited inbreeding as a research tool since Gregor Mendel’s experiments with peas. Charles Darwin wrote an entire book on the effects of inbreeding as measured in fifty-two taxa of plants, noting that most plants and animals go to great lengths to avoid inbreeding, suggesting that inbreeding has high costs that often outweigh the benefits of inbreeding. Benefits of inbreeding include increased genetic transmission while the costs of inbreeding manifest as inbreeding depression when deleterious, mostly recessive alleles otherwise hidden as heterozygotes emerge in homozygote form upon inbreeding.

Inbreeding also reduces fitness when heterozygotes are more fit than both homozygotes, but such overdominance is rare. Recurrent mutation continuously generates deleterious recessive alleles that create a genetic “load” of deleterious mutations mostly hidden within heterozygotes in outcrossing populations. Upon inbreeding, the load is expressed when deleterious alleles segregate as homozygotes, causing often substantial inbreeding depression.

Although inbreeding alone does not change allele frequencies, it does redistribute genetic variation, reducing it within families or populations while increasing it among families or populations. Inbreeding can also increase selection by exposing deleterious recessive mutations, a process called purging that can deplete genetic variation.

Classical population genetics has long concerned itself with the systems of mating and population structures that generate inbreeding and inbreeding depression, the decline in fitness due to inbreeding. Population geneticists explore the forces that generate and maintain genetic variation, analyzing how the steady flow of deleterious mutations is countered by selection resulting in an equilibrium genetic load (mutation-selection balance).

Which crop shows high inbreeding depression?

Inbreeding depression, a phenomenon affecting the biological fitness of individuals in a population, is primarily observed in Alfalfa and carrots. This occurs due to common mating between relatives in small populations, which can lower the population’s ability to persist and reproduce. This phenomenon is present in all wild animals, plants, and humans, indicating genetic differences in fitness traits within and among normal populations. Inbreeding depression is crucial in crop breeding and the evolution of outcrossing mating systems.

What is an example of inbreeding depression in plants?

Inbreeding depression is a phenomenon observed in various plant species, including onions, carrots, maize, and sunflowers. These plants reproduce through self-pollination or cross-pollination processes. High inbreeding depression results in severe lethal effects, making it difficult to maintain breeding lines after three to four generations. Moderate inbreeding depression also results in sublethal effects, with many offspring experiencing a decrease in fertility.

Examples of plants showing moderate inbreeding depression include maize, pearl, millet, and great millet. These plants face challenges in maintaining their breeding lines after three to four generations due to the loss of vigor and fertility.

How to prevent inbreeding depression in plants?

A farmer can use pedigrees to determine which matings will prevent undesired levels of inbreeding in their fish. Some types of consanguineous matings produce moderate amounts of inbreeding, while others produce virtually no inbreeding. If low levels of inbreeding are desired, a farmer can restrict consanguineous matings to those less related than first cousins. A regular inbreeding program of second cousin matings is effective but can be complicated.

If fish are not marked, individual inbreeding values cannot be determined, so a farmer must manage their population’s N e. Two important decisions must be made before a farmer or hatchery manager can manage N e to prevent inbreeding from exceeding the desired maximum level: deciding the maximum inbreeding value and choosing the level of risk. Each farmer or hatchery manager is free to choose their level of risk and customize the maximum level of inbreeding for their population.

Why is inbreeding depression bad?

Inbreeding depression is a condition where inbred individuals’ survival and reproduction abilities are reduced, leading to population decline and eventual extinction. This can also affect an individual’s ability to adapt to stressful conditions like disease. The impact of inbreeding depends on factors such as historical population size, speed of population decline, interbreeding with other populations, affected fitness components, age classes, and breeding and social structure. In some cases, inbreeding depression is beneficial, while in others, it can be detrimental.

Which crop has highest inbreeding depression?

Inbreeding depression, a phenomenon affecting the biological fitness of individuals in a population, is primarily observed in Alfalfa and carrots. This occurs due to common mating between relatives in small populations, which can lower the population’s ability to persist and reproduce. This phenomenon is present in all wild animals, plants, and humans, indicating genetic differences in fitness traits within and among normal populations. Inbreeding depression is crucial in crop breeding and the evolution of outcrossing mating systems.