What is the difference between heterosis and inbreeding depression?
These two terms are used to describe parent distance that affects the fitness of the offspring. They play a key role in the discovery of biological evolutionary in organisms.
The main difference between heterosis and inbreeding depression is that heterosis is the enhancement of traits through mixing two genes during outbreeding while inbreeding depression tends to reduce offspring biological fitness due to increased homozygosity.
Comparison Table (Heterosis vs Inbreeding Depression)
| Basic Terms | Heterosis | Inbreeding Depression |
| Meaning | Refers to increase the function of any biological quality in hybrid | Refers to reduce biological fitness in a population due to inbreeding |
| Parents Genetic Variation | Offspring occur as a result of genetic distant parents | Offspring occur as a result of closely related parents |
| Homozygosis/Heterozygosity | Heterozygosity | Homozygosity |
| The appearance of Parents Genetic Variations | F1 individual of a genetic uniform population | Present with the population |
| Occurrence | Outbreeding | Inbreeding |
| Phenotypic Trait Effect | Beneficial augmentations | Detrimental reductions |
| Genetic Drift Effect of Small Population | Higher | Lower |
| Consequences of Outbreeding Depression | Tend to lower the magnitude of heterosis | Do not affect the magnitude of inbreeding depression |
| Characteristics | Offspring show superior traits than parents | Offspring show inferior traits than parents |
| Environmental Adaptation | Adapt well to the environment | Unable to adapt to the environment |
Read More: Difference between Oogenesis and Spermatogenesis
What Is Heterosis?
Heterosis is the process of increasing the function of any biological quality in hybrids. It occurs as a result of crosses between different species.
The offspring exhibit better progeny than both parents. Thus, heterosis is also known as an outbreeding enhancement or hybrid vigor.
The main aim of outbreeding enhancement is to increase the biological fitness of the offspring. It enables the offspring to adapt faster to the new environment.
What Is Inbreeding Depression?
Inbreeding depression is a reduced biological fitness of the population due to inbreeding. It occurs as a result of crossing related species.
The process tends to make the species lose genetic variety. The offspring find it difficult to adapt to changes in the environment.
Inbreeding depression tends to trigger the accumulation of recessive genes since the crossing species are similar. Hence, the offspring become homozygous.
Main Difference between Heterosis and Inbreeding Depression
- Heterosis refers to increase the functionality of any biological quality in hybrids while inbreeding depression refers to reduce biological fitness in a population.
- Heterosis occurs as a result of breeding different species while inbreeding depression occurs as a result of breeding related species
- Offspring of heterosis can adapt to changes in the environment while those of inbreeding depression are unable
- Heterosis offspring have improved traits while those of inbreeding depression have inferior traits
- Heterosis result in offspring that are heterozygous while inbreeding depression results in offspring that are homozygous
- Genetic drift in heterosis is higher in a small population while that of inbreeding depression is lower.
Similarities between Heterosis and Inbreeding Depression
- Both affect the biological fitness of the offspring
- Both are two effects of parental distance
- Both occur as a result of inbreeding and outbreed the natural population
- Both are the main goals of evolutionary biology
Read More: Difference between F1 and F2 Generation
Heterosis vs Inbreeding Depression FAQs
Does Inbreeding Increase Heterosis?
Yes. Research shows that a cross between purebreds would result in progeny exhibiting individual heterosis. Hence, it indicates improved survival rates.
What Is A Major Disadvantage Of Inbreeding?
It is detrimental to reproductive performance, preweaning, and postweaning growth. Inbreeding is the cross between closely related species.
How Can Inbreeding Depression Be Prevented?
Inbreeding tends to prevent the evolution of self-fertilization plants. Therefore, natural selection against partially recessive deleterious alleles will reduce inbreeding depression.
What Is The Most Inbred Country?
Countries with the highest level of inbreeding are Brazil, Japan, India, and Israel. It is the reason why they tend to experience unique diseases due to offspring having homozygous genes.
Can Inbreeding Be Reversed?
Inbreeding is irreversible. If the inbred are of the small population then there are no other strains that can mate with them.
Comparison Video
Summary
Heterosis tends to help improve the biological functionality of phenotypic traits. Inbreeding depression reduce the biological quality of phenotypic traits.
Also, heterosis occurs as a result of outbreeding enhancement in the offspring of genetically distant parents. Inbreeding depression occurs as a result of crossing closely related species.
More Sources and References
Genetics. NCBI
Heterosis and Outbreeding Depression. Nature