Heterosis has been observed and, in some cases, harnessed in many diverse systems. Examples of interspecies crosses of mammals that produce heterotic phenotypes include the mule resulting from a cross between a male donkey and a female horse, and the liger resulting from a cross between a lion and a tiger. What is called heterosis?
heterosis, also called hybrid vigour, the increase in such characteristics as size, growth rate, fertility, and yield of a hybrid organism over those of its parents. Plant and animal breeders exploit heterosis by mating two different pure-bred lines that have certain desirable traits.
What is heterosis and its importance?
Abstract. Heterosis or hybrid vigor is a phenomenon where hybrid progeny have superior performance compared to their parental inbred lines. This is important in the use of F1 hybrid cultivars in many crops and vegetables. What is meant by epistasis?
Epistasis is a phenomenon in genetics in which the effect of a gene mutation is dependent on the presence or absence of mutations in one or more other genes, respectively termed modifier genes. … Originally, the term epistasis specifically meant that the effect of a gene variant is masked by that of a different gene.
What is the term heterozygous mean?
(HEH-teh-roh-ZY-gus JEE-noh-tipe) The presence of two different alleles at a particular gene locus. A heterozygous genotype may include one normal allele and one mutated allele or two different mutated alleles (compound heterozygote). What is meant by male sterility?
Male sterility is defined as the failure of plants to produce functional anthers, pollen, or male gametes.
Frequently Asked Questions(FAQ)
What is heterosis Class 12?
Complete answer: Heterosis is the phenomenon in which progeny of various varieties of a species or crosses between species exhibit greater biomass, as well as the speed of development, and fertility of either of the parents.
What is outbreeding in biology?
Outbreeding refers to matings between individuals from different populations, subspecies, or species. Outbreeding can result in a decline in reproductive fitness known as outbreeding depression, but this is less common than inbreeding depression.
What is Pseudoheterosis?
Pseudoheterosis. Also termed as luxuriance. Progeny possess superiority over parents is in vegetative growth, but not in yield and adaptation, usually sterile or poorly fertile. This concept cannot be utilized in hybrid varieties production.
How do you get heterosis?
The general formula for calculating percent heterosis is given below: crossbred avg.- purebred avg.% heterosis = x 100 purebred avg.
Do humans have hybrid vigor?
What are the main features of heterosis?
The main features of heterosis are listed below: (i) The hybrid F1 exhibits superiority over both parents in yield, adaptation, quality, maturity etc. (ii) The superiority is confined to F1 generation. (iii) The superiority (heterosis) is under genetic control.
What are advantages of heterosis?
Advantages of maternal heterosis are seen in maternal ability, reproduction, longevity, calf survivability, pounds of calf weaned and younger age at puberty. Paternal heterosis is similar to maternal heterosis in that it is the genetic advantage provided by the sire; benefits are also seen as increased bull fertility.
What are the physiological causes of heterosis?
Physiological Causes: (i) Greater initial capital hypothesis: This hypothesis was proposed by Ashby (1930). He studied the physiology of inbreeds and hybrids of maize and tomato and concluded that hybrid vigour is due to an increased initial embryo size.
What is co dominant?
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What are linked genes?
When genes are close together on the same chromosome, they are said to be linked. That means the alleles, or gene versions, already together on one chromosome will be inherited as a unit more frequently than not.
What is epigenetic expression?
Epigenetics is the study of how your behaviors and environment can cause changes that affect the way your genes work. … Gene expression refers to how often or when proteins are created from the instructions within your genes.
What does the notation TT mean to geneticists?
An organism can be either homozygous dominant (TT) or homozygous recessive (tt). If an organism has two different alleles (Tt) for a certain gene, it is known as heterozygous (hetero means different).
What happens when both parents are heterozygous?
If both parents are heterozygous (Ww), there is a 75% chance that any one of their offspring will have a widow’s peak (see figure). A Punnett square can be used to determine all possible genotypic combinations in the parents.
What is a purebred genotype?
Purebred – Also called HOMOZYGOUS and consists of gene pairs with genes that are the SAME. … Genotype is the actual GENE makeup represented by LETTERS. Phenotype is the PHYSICAL appearance of a trait, such as a YELLOW (or BLUE) body color.
What do you mean by pollen sterility?
Abstract. Male sterility in plants implies an inability to produce or to release functional pollen, and is the result of failure of formation or development of functional stamens, microspores or gametes.
What is a maintainer line?
Maintainer line( B ) line maintains the sterility of the CMS (A) line and is used to produce the seed of the CMS line by crossing A x B lines.Restorer line (R) line on the other hand carries fertility restorer genes and therefore restores the fertility upon crossing with CMS A line.
What is female sterility in plants?
The flowers of these plants are both male and female sterile. The male sterility results from a failure of anther dehiscence, and the female sterility results from premature arrest of ovule development.
What is heterosis Class 11?
Complete answer: In heterosis, the genes of the parents are mixed to produce superior offspring. The term ‘heterosis’ given by G. H. Shull replaced the term heterozygous which was used earlier. … Major crops produced by heterosis to increase their yield are maize, rice, sunflower, sorghum, sugar beet, onion, etc.
What is crossbreeding in animals?
In animal breeding: Crossbreeding. Crossbreeding involves the mating of animals from two breeds. Normally, breeds are chosen that have complementary traits that will enhance the offsprings’ economic value. An example is the crossbreeding of Yorkshire and Duroc breeds of pigs.
What is animal inbreeding?
Technically, inbreeding is defined as the mating of animals more closely related than the average relationship within the breed or population concerned. Matings between animals less closely related than this, then, would constitute outbreeding.
Graduated from ENSAT (national agronomic school of Toulouse) in plant sciences in 2018, I pursued a CIFRE doctorate under contract with Sun’Agri and INRAE in Avignon between 2019 and 2022. My thesis aimed to study dynamic agrivoltaic systems, in my case in arboriculture. I love to write and share science related Stuff Here on my Website. I am currently continuing at Sun’Agri as an R&D engineer.