Inbreeding is important in the creation of a strain. Inbreeding includes linebreeding.
In cockfighting, a strain of gamecock chickens will have closely homogenous genotype.
The genotype is the genetic makeup of a cell, an organism, or an individual (i.e. the specific allele makeup of the individual) usually with reference to a specific character under consideration.
The genotype of an organism is the inherited instructions it carries within its genetic code. Not all organisms with the same genotype look or act the same way because appearance and behavior are modified by environmental and developmental conditions. Likewise, not all organisms that look alike necessarily have the same genotype.
Genotype, in cockfighting, is mostly the raw fighting style of the strain of gamecock chickens. But let us not forget fertility, disease immunity, livability, mortality, and growth characteristics of our strain of gamecock chickens.
In the Philippines, Igon strain of gamecock chickens have good disease immunity and good fertility. Not to mention the good endurance stamina on long battles. Igon is an inbred strain of chickens. Igon come in medium size.
In Iran, Kabir strain of chickens have good disease immunity and good fertility. Kabir is an inbred strain of chickens. Not to mention the meaty carcass when butchered. Kabir come in huge size.
The selection process, of the best individual chickens of all time as brood stocks, prevents any of the negative results of inbreeding.
It is the wrong selection process which MAY produced smaller offsprings. If the breeder is not careful and patient enough.
Marriages in many cultures are made between healthy active couple. Thus, selection is the key to better offsprings – chicken or man.
Japanese people as a strain are inbred and they have one of the highest life expectancy in the world.
Chinese people as a strain are inbred. Swedish people as a strain are inbred. Indian people as a strain are inbred.
Today, Cousin marriage is legal in Japan and most countries. In fact, 26 States of the United States respect cousin marriage. Philippines and China are the only country that do not respect Love between cousins.
Olympic Games proved that each race or strain of man can excel in athletic competitions. These are inbred athletes mostly. Beginning from the african gene marathon and track stars.
– Gameness til the End
Inbreeding is the reproduction from the mating of two genetically related parents. Inbreeding results in increased homozygosity, which can increase the chances of offspring being affected by recessive or deleterious traits. This generally leads to a decreased fitness of a population, which is called inbreeding depression. A person who results from inbreeding is referred to as an inbred.
Livestock breeders often practice controlled breeding to eliminate undesirable characteristics within a population, which is also coupled with culling of what is considered unfit offspring, especially when trying to establish a new and desirable trait in the stock.
In plant breeding, inbred lines are used as stocks for the creation of hybrid lines to make use of the effects of heterosis. Inbreeding in plants also occurs naturally in the form of self-pollination.
Inbreeding may result in a far higher phenotypic expression of deleterious recessive genes within a population than would normally be expected. As a result, first-generation inbred individuals are more likely to show physical and health defects, including:
- Reduced fertility both in litter size and sperm viability
- Increased genetic disorders
- Fluctuating facial asymmetry
- Lower birth rate
- Higher infant mortality
- Slower growth rate
- Smaller adult size
- Loss of immune system function
Many individuals in the first generation of inbreeding will never live to reproduce. Over time, with isolation such as a population bottleneck caused by purposeful (assortative) breeding or natural environmental factors, the deleterious inherited traits are culled.
Island species are often very inbred, as their isolation from the larger group on a mainland allows for natural selection to work upon their population. This type of isolation may result in the formation of race or even speciation, as the inbreeding first removes many deleterious genes, and allows expression of genes that allow a population to adapt to an ecosystem. As the adaptation becomes more pronounced the new species or race radiates from its entrance into the new space, or dies out if it cannot adapt and, most importantly, reproduce.
The reduced genetic diversity that results from inbreeding may mean a species may not be able to adapt to changes in environmental conditions. Each individual will have similar immune systems, as immune systems are genetically based. Where a species becomes endangered, the population may fall below a minimum whereby the forced interbreeding between the remaining animals will result in extinction.
Natural breedings include inbreeding by necessity, and most animals only migrate when necessary. In many cases, the closest available mate is a mother, sister, grandmother, father, grandfather… In all cases the environment presents stresses to remove those individuals who cannot survive because of illness from the population.
There was an assumption that wild populations do not inbreed; this is not what is observed in some cases in the wild. However, in species such as horses, animals in wild or feral conditions often drive off the young of both genders, thought to be a mechanism by which the species instinctively avoids some of the genetic consequences of inbreeding. In general, many mammal species including humanity’s closest primate relatives avoid close inbreeding possibly due to the deleterious effects.
Inbreeding depression is the reduced fitness in a given population as a result of breeding of related individuals. It is often the result of a population bottleneck. In general, the higher the genetic variation within a breeding population, the less likely it is to suffer from inbreeding depression.
Inbreeding depression seems to be present in most groups of organisms, but is perhaps most important in hermaphroditic species. The majority of plants are hermaphroditic and thus are capable of the most severe degree of inbreeding depression.