What is the Difference Between Maternal Effect and Maternal Inheritance

The main difference between maternal effect and maternal inheritance is that maternal effect is the presence of a phenotype of maternal inheritance, whereas maternal inheritance is the presence of a genotype inherited from the mother.

Maternal effect and maternal inheritance are two types of effects that correlate to the mother. Organisms inherit factors mainly from the mother in asexual reproduction and sexual reproduction.

Key Areas Covered

1. What is the Maternal Effect
     – Definition, Features, Importance
2. What is the Maternal Inheritance
     – Definition, Features, Importance
3. Similarities Between Maternal Effect and Maternal Inheritance
     – Outline of Common Features
4. Difference Between Maternal Effect and Maternal Inheritance
     – Comparison of Key Differences

Key Terms

Maternal Effect, Maternal Inheritance

What is the Maternal Effect

The maternal-effect is a situation in which the genotype of the mother undergoes expression in the offspring. Therefore, the expected phenotype comes from the genotype of the mother. This expression occurs irrespective of the genotype of the offspring. This often occurs due to the supply of messenger RNA or proteins to the egg.  The expression of maternal phenotype can also occur due to the presence of maternal environment in cases where the offspring express the size, sex, as well as behavior. In addition to that, maternal effects that lead to the phenotype are adaptive and increase the fitness of the offspring. It is generally called phenotypic plasticity.

Figure 1: Maternal Effect

Furthermore, in the maternal effect, the phenotype of the offspring comes from the genotype of the mother. For example, when there is a mutation with a maternal effect recessive, a female organism that is homozygous for the mutation can appear normal. But, the offspring of the female can show the mutant phenotype.

What is Maternal Inheritance

Maternal inheritance is the presence of maternal genotype in the offspring. This occurs due to the expression of extracellular DNA that is present in the ovum during fertilization. Therefore, in maternal inheritance, certain traits of the offspring are solely attributed to the genetic material inherited from the mother. This is due to the retainment of mitochondria of the ovum during fertilization. Hence, most mitochondria are in the maternal origin of the offspring. This is because the fertilizing sperms only contribute the nuclear genetic material to the formation of the zygote. The mitochondria present in the tail of sperm are typically few in number and eventually disintegrate.

Figure 2: Mitochondrial DNA vs Nuclear DNA Inheritance

Moreover, most hereditary diseases associated with mitochondria are inherited from the mother. However, some mitochondria from the sperms can pass into the zygote; hence, diseases of mitochondria with paternal origin can also transfer to the offspring.

Similarities Between Maternal Effect and Maternal Inheritance

• Maternal effect and maternal inheritance are two methods of how factors from the mother influence the next generation of organisms.
• It mainly occurs in methods of asexual reproduction.

Difference Between Maternal Effect and Maternal Inheritance

Definition

The maternal effect refers to the situation where the phenotype of the offspring is influenced by the environment experienced by the mother, while maternal inheritance refers to a form of inheritance wherein the traits of the offspring are maternal in origin due to the expression of extranuclear DNA present in the ovum during fertilization.

Influence

In the maternal effect, the mother influences the phenotype of the organism, but in the maternal inheritance, the mother influences the genotype of the organism.

Expression

In maternal effect, the mother’s factors undergo expression, while in maternal inheritance, the mother’s factors may or may not undergo expression.

Causes

The maternal-effect can occur due to the passing of messenger RNA and proteins from the mother to the egg while the maternal inheritance can occur due to the expression of extracellular DNA in the ovum during fertilization.

Conclusion

In brief, maternal effect and maternal inheritance are two types of influences in which the mother’s factors impact the traits or characteristics of the offspring. The maternal effect expresses the phenotype of the mother. Therefore, the mother’s factor in these offspring undergoes expression. It can also occur due to the passage of messenger RNA and proteins from the other to the egg. In comparison, in maternal inheritance, only the genotype of the mother passes to the next generation. However, the mother’s factor does not undergo expression in maternal inheritance. Hence, it can occur due to the expression of extracellular DNA in the ovum during fertilization. In conclusion, the main difference between the maternal effect and maternal inheritance is the expression of the mother’s factors.

References:

1. Maternal effect. Biology Articles, Tutorials & Dictionary Online. 
2. Maternal inheritance. Biology Articles, Tutorials & Dictionary Online. 

Image Courtesy:

1. “Maternal effect crosses1” By Celefin – Own work (CC-BY SA 3.0) via Commons Wikimedia
2. “Mitochondrial DNA versus Nuclear DNA” By University of California Museum of Paleontology (UCMP) and the National Center for Science Education – Own Work (CC-BY SA 3.0) via Commons Wikimedia