What is the Difference Between Chimera and Hybrid

Chimera and hybrid are two organisms created by combining elements between organisms of different species. In modern biotechnology, it is possible to combine elements between organisms of different species. There are various ways of deliberately mixing two species of animal or plant. Each of these produces a different outcome and raises different issues.

The key difference between chimera and hybrid is their creation. Chimera is an organism made up of cells that come from two genetically distinct individuals, while hybrid is the offspring organism produced by two different parent organisms from different species. 

CONTENTS

1. Overview and Key Difference
2. What is Chimera 
3. What is Hybrid
4. Similarities – Chimera and Hybrid
5. Chimera vs Hybrid in Tabular Form
6. Summary – Chimera vs Hybrid
7. FAQ – Chimera and Hybrid

What is Chimera?

Chimera is an organism that has cells from two different sources. This results in two sets of DNA. In humans, chimerism can occur when a mother is pregnant with twins. If one embryo dies naturally, the other one could possibly absorb the cells of the deceased twin. This phenomenon is known as vanishing twin syndrome. Chimerism can also occur in organ transplants, where an organ from a healthy donor replaces the damaged or diseased tissue in the recipient.

Figure 01: Chimera

In addition to humans, chimeras can also occur in ceratoid anglerfish, marmosets, marine sponges, and plants. Furthermore, interspecies chimeras, such as rat/mouse chimeras and rabbit/human mix, are also made in the laboratory.

What is Hybrid?

A hybrid is an organism where each cell contains genetic material from two organisms of different breeds, species, or genera. In animal and plant breeding, there are several kinds of hybrids formed from crosses within a species.  A hybrid is not mosaic like chimera. In animals, a hybrid is an organism created by combining eggs and sperm cells of different species. Moreover, in plants, a hybrid can be formed by crossing the pollens of one plant with the ovary of another plant belonging to a different species.

Figure 02: Hybrid

Liger is a cross between a lion/ and a tiger. This hybrid is created in captivity. Sweet corn is an example of a plant hybrid. Sweet corn hybrids are largely single crosses made by cross-pollinating two distinct inbreds or pure lines. Furthermore, scientists have successfully created part-human, part-monkey hybrids by injecting human stem cells into six-day-old macaque embryos.

Similarities Between Chimera and Hybrid

1. Chimera and hybrid are two organisms created by combining elements between organisms of different species.
2. Both can occur naturally or can be created in a laboratory.
3. They can occur in animals as well as plants.
4. Both contribute to the genetic variations among organisms.
5. Both have ethical issues.

Difference Between Chimera and Hybrid

Definition

1. Chimera is an organism containing cells from different parents.
2. Hybrid is an offspring organism of two animals or plants of different subspecies, breeds, varieties, species, or genera.

Genetics

1. Chimeras are a mix of genetically different cells to form a mosaic animal or plant.
2. Hybrids have intermediate features, and each cell is a mix of chromosomes from the parental species.

Mosaicism

1. Chimera is a mosaic organism.
2. Hybrid is not a mosaic organism.

Fertility

1. Some chimeras are fertile, and some are not.
2. Hybrids are not fully fertile.

Examples

1. Some examples of chimera are geep that was made by merging a sheep embryo with a goat embryo, absorbing the cells of the deceased embryo into the other embryo in case of twins, chimeras in ceratoid anglerfish, marmosets, marine sponges, plants (graft chimera), laboratory created rat/mouse chimeras and rabbit/human mix and viral chimera (CHIV viruses).
2. Some examples of hybrids are liger, sweetcorn, and laboratory-created part-human, part-monkey hybrids.

The following table summarizes the difference between chimera and hybrid.

Summary – Chimera vs Hybrid

Chimeras are not the same as hybrids. A chimera is the embryo of one species that has added cells from another species during its early development. Moreover, a chimera is a single organism that has cells with more than one distinct genotype. On the other hand, a hybrid is an organism produced by the cross-breeding of two genetically different varieties or species. A hybrid can appear within the species or within the genus.  This summarizes the difference between chimera and hybrid.

FAQ: Chimera and Hybrid

1. How rare is a chimera in humans?

• Chimera in humans is extremely rare. It is about 10%. Chimerism occurs when a woman is pregnant with twins, where the embryo absorbs the twin’s cells in the other embryo when it dies. Currently, genetic testing is being done to see if chimerism in humans is possible.

2. What famous person has chimerism?

• A famous person with chimerism is Taylor Muhl, a female singer. She has two-toned skin, which was diagnosed as a result of chimerism, a genetic condition that causes a person to have two sets of DNA.

3. What are the ethical issues of chimera?

• Many scientists oppose chimeric research due to concerns about backward evolution and disrupting evolutionary lineage. Additionally, there are moral objections to creating human-animal chimeras, as society generally prefers to maintain a clear separation between humans and animals.

4. What is hybridization in biology with an example?

• A liger is a hybrid animal born when a male lion reproduces with a female tiger. This is an example of interspecific hybridization. Another example is the mule; it is produced by the interspecific hybridization between a male donkey and a female horse.

5. What is hybridization in plant breeding?

• Hybridization in plants is the method of crossing two plants from different species that are genetically dissimilar. Some examples of popular plant hybrids include Stargazer lilies, sweet corn, Olympia spinach, Meyer lemons, plumcots, etc.

Reference:

1.  “Chimera.” Encyclopædia Britannica, Encyclopædia Britannica, inc.
2. “Hybrid (Biology).” Wikipedia, Wikimedia Foundation.

Image Courtesy:

1. “Backcrossing mice from chimera edit” By Upirix – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Liger – Shenzhen Safari Park 2023-02-03 01” By Dinkun Chen – Own work (CC BY-SA 4.0) via Commons Wikimedia

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