All living organisms can produce new individuals like themselves and their cells have a nucleus containing chromosomes. In humans, there are 23 pairs of chromosomes, each chromosome has thousands of genes. A gene can carry the information that determines the character or trait being transmitted from the parent to offspring and creates the identity of an individual. Some traits are not received from the parents because the information about traits is not carried by genes. i.e, not encoded in DNA. These are non-heritable and acquired when the individual has an injury, disease, repeated activities, or other environmental influences. It may impact the overall phenotype of an organism.
An acquired trait is a character that develops to change the developmental processes in an unusual environment. It includes both physical and behavioural characteristics.
Lamarck and acquired traits
Jean-Baptiste Lamarck proposed that acquired traits are inheritable. He believed that organisms can alter their behaviour depending on the environmental conditions and their offspring can inherit the acquired characteristics.
For example, giraffes extend their neck to get the leaves from the taller trees for food. The long necks may be inherited by subsequent generations of offspring.
Therefore, he originally hypothesised that the acquired traits are transferred from the parent to offspring that may support the young individuals of the population to be convenient in the environment.
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Lamarckian inheritance
Darwin and acquired traits
Charles Darwin initially accepted Lamarck’s hypothesis in his first publication Theory of Evolution.
He believed that the changes in an organism do not create an evolution of the species.
The differences in the same species of organisms made some variations that help themselves to exist in the environment.
He observed some real-life examples that showed an individual can exercise, run, eat well, and become healthy, but fitness is not inherited from the parent to offspring.
Later, he removed the hypothesis of Lamarck while he had strong evidence that the acquired traits are not transferred to subsequent generations.
Acquired traits are received from the environment. Some of the examples of acquired traits are as follows:
Example 1
A person born to a bodybuilder need not have extremely large muscles.
The larger muscles are an acquired trait; they cannot be passed from parent to offspring even after the training and regular activities.
Example 2
An animal has specific traits depending on the food that affects body weight, size, and health. In some animals, it can change the body colour.
Flamingos are born with white feathers and their diet is larvae, algae, and shrimp. The feathers of the bird turn pink due to the presence of beta-carotene in algae and some other foods. Therefore, here the acquired trait is colour.
| Inherited traits | Acquired traits |
| These traits can be transferred from one generation to the next generation. | These traits or characteristics developed from the response of the environment and are not transferred to subsequent generations. |
| It can be developed from the birth of an individual. | It can be developed during the lifetime of an individual. |
| It is somatic variations and cannot be helpful for evolution. | It is genetic variations and direct evolution. |
| These traits are inherited that can pass through DNA. | These traits are not inheritable and can be acquired through learning and observation. |
| Examples: hair, eye colour, the shape of the nose, colour blindness, etc. | Examples: loss of body weight, large muscles, loss of finger in an accident, skills, etc. |
Purchased Traits
Acquired traits or characters are purchased traits that are developed by the special attempts, based on physical and environmental influences.
These features progress throughout the lifetime of an individual.
It may be physical traits or behavioural traits.
| Physical traits | Behavioural traits |
|
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Inheritance Laws
Gregor Johann Mendel described the hypothesis of inherited traits with his experiments in pea plants. He indicated that the visible traits in phenotype are called dominant traits and the invisible traits in phenotype are called recessive traits.
First Law: Law of Dominance
When the two alternative forms of character are present in an adult, only one of them expresses itself in the F1 generation and is called the dominant trait, while it does not express itself is called a recessive trait.
Second Law: Law of Segregation
The alleles do not show any mixing and are retrieved as such in the F2 generation, although one of the two is not spotted in the F1 generation. This law is also called the law of purity of gametes.
When two sets of traits are recombined, the separation of one pair of characters is autonomous during gamete formation.
Acquired and inherited traits are in contrast to each other. The former is developed after the birth, that is during the lifetime of a person, while the latter was developed from their birth. The acquired traits are obtained from learning or some accidental incidents and cannot pass to offspring. But, the inherited traits are received by nature and can pass to the next generation. Lamarck believed acquired traits were inherited, but Darwin found that they could not be linked to inheritance. Mendel explained the inherited traits by the laws of inheritance using the law of dominance, the law of segregation, and the law of independent assortment.
1. How are inherited traits usually transferred to the offspring?
Inherited traits are genetic variations; these are usually transferred through the DNA to an individual from his birth.
2. What are the traits or characters acquired during the lifetime of an individual?
Acquired traits such as learning skills, the large size of muscles, singing, painting, dancing, swimming and so many other traits can be developed during a lifetime.
3. Why did Darwin remove Lamarck’s hypothesis from his first publication?
Darwin initially accepted Lamarck’s hypothesis, but later he identified the strong evidence that the acquired traits are not inherited. So he removed the wrong statement about the acquired traits.
4. Write a short note on Lamarck’s view on acquired traits.
He believed that organisms can change their behaviour or phenotype because of environmental factors and it can be inherited by subsequent generations. For example, the extending feature of the giraffe's neck to reach the leaves on trees is inherited to the offspring.
5. How are acquired traits helpful for evolution?
Acquired traits are not genetic variations; these are somatic variations and not inherited. So, it cannot be helpful for evolution.
List out at least five inherited traits.
Eye colour
Height of tree
Shape of nose
Colour blindness
Blood group
The alleles expressing their effect on the phenotype of a living organism are called dominant traits, and the alleles not expressing their effect on the phenotype are called recessive traits.
Acquired and Inherited Traits Explained - The Education. The Education. (2022). Retrieved 19 May 2022, from https://theeducationlife.com
Can Acquired Traits Be Passed onto Offspring?. ThoughtCo. (2022). Retrieved 19 May 2022, from https://www.thoughtco.com
Ford, E. (1967). Mendelism and evolution. Methuen.
Mendel’s Laws | BioNinja. Ib.bioninja.com.au. (2022). Retrieved 19 May 2022, from https://ib.bioninja.com.au.
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