Law of Segregation vs Law of Independent Assortment: Difference and Comparison

If you look really closely, science can be found almost anywhere. Science offers an answer for everything, from the appearance of tears while chopping an onion to the growth of a tiny seed into a fully formed tree. Various notable scientists and ideologists have offered their thoughts and interpretations on a wide range of scientific topics from time to time. 

Gregor John Mendel was one of these scientists who, in the 18th century, provided the world with three genetic principles. The Law of Segregation and the Law of Independent Assortment are two of these laws. While these two are related, there are considerable differences between them. 

Key Takeaways

1. The Law of Segregation states that each parent passes on only one of their two alleles for each trait to their offspring.
2. The Law of Independent Assortment explains that one trait’s inheritance doesn’t influence another trait’s inheritance.
3. Both laws, proposed by Gregor Mendel, serve as foundational principles of modern genetics.

Law of Segregation vs Law of Independent Assortment 

The law of segregation is one of the fundamental principles of genetics. It explains that during gamete formation, alleles separate from each other. Dependent assortment, which is also a principle of genetics, states that genes are inherited independently of each other.

The law of Segregation outlines that when reproduction takes place, each of the parents passes on one trait to their offspring. This trait is not passed by the original gene but by the copies of that gene, popularly known as an allele. These copies are separated before being passed on, and it occurs so that no trait is repeated or so that only one allele is carried on further in the offspring. These copies are then said to reunite after fertilization. 

On the other hand, the Law of Independent Assortment signifies that the genes independently pass on to the offspring without prior segregation into copies. According to this law, different genes related to different traits can be passed on to the end result.  

Comparison Table

Parameters of Comparison	Law of Segregation	Law of Independent Assortment
Meaning	It denotes the theory of the separation of copies of genes before reproduction.	It denotes those multiple genes pertaining to similar traits can be passed on to the offspring without any segregation before.
Ratio of offspring	3:1 is the ratio.	9:3:3:1 is the ratio.
Position	It is the third law given by Mendel.	It is the second law propounded by Mendel and comes after the previous one.
States about	Segregation of alleles	Behavior and end result of alleles
Number of alleles	Only one allele of one gene is passed on to the offspring.	Multiple genes pertaining to similar traits can be passed on to the offspring.

What is Law of Segregation? 

The Law of Segregation outlines that when reproduction occurs, the copies of particular genes separate from one another and appear again after fertilization. This can better be understood by looking at the experiment Mendel conducted.  

• He chose two plants having different genes for a similar trait, such as a plant with red flowers and a plant with yellow flowers. 
•  After choosing these plants, he made them reproduce with one another and waited for a few days.  
• After a few days, the flowers which took birth out of these two parental plants had red color only.  
• But after these plants, which had a red color, were fertilized by themselves, the end result plants had both white and red colors in them.  
• The ratio of plants having these two colors was roughly 3:1. 

 Based on this theory, Mendel stated that in the first generation of offspring, the less dominant trait, i.e., the white color disappeared and came back in the second generation. Segregation of genes in this manner paved the way for the conceptualization of the Law of Segregation.  

What is Law of Independent Assortment? 

This particular law states that two or more different traits having different genes can come together as a unit and will be selected randomly and independently after fertilization. This can better be explained by the following example- 

• He chose two plants, one with pink color and tall height while one with blue color and dwarf height.  
• When these were made fertilized, the first generation appeared to be all having pink colors and tall height. This proved that pink as color and tall as height were dominant traits and suppressed the other traits.  
• But when this first generation was left to fertilize, the second-generation plants showed all traits in different ratios.  
• There were pink plants with tall height, pink plants with dwarf height, blue plants with tall height, and blue plants with dwarf height.  

A similar experiment was carried out by Mendel, which led him to believe in the Law of Independent Assortment.  

Main Differences Between Law of Segregation and Law of Independent Assortment 

1. The Law of Segregation stands as the third rule of inheritance propounded by Mendel, while the Law of Independent Assortment stands as the second rule of inheritance. 
2. The Law of Segregation states that the alleles of a gene get separated from the original gene and get passed on to the offspring by way of reproduction, while the Law of Independent assortment states that a gene can pass on more than one allele to the offspring by way of reproduction.  
3. The ratio of offspring in the former happens to be 3:1, while in the latter, this ratio happens to be 9:3:3:1.  
4. The law of Segregation talks about the separation of alleles, while the Law of Independent Assortment talks about the behavior that these alleles show after reaching an offspring.  
5. In the law of Segregation, only one copy of one gene can be passed on, while in the Law of Independent Assortment, many copies can be passed on.  

References

1. http://v3r.esp.org/foundations/genetics/classical/holdings/v/hdv-00.pdf  
2. https://rave.ohiolink.edu/etdc/view?acc_num=csu1611776149127827