Difference Between Self and Cross Fertilization

Key Difference – Self vs Cross Fertilization
 

The fusion of male and female gametes during the sexual reproduction to initiate the development of a new individual is ‘fertilization’. Fertilization can happen in two ways; self fertilization and cross fertilization. Self fertilization occurs between the male and female gametes of the same individual. Cross fertilization occurs between the male and female gametes of the different individuals of the same species. The key difference between the self and cross fertilization is that self fertilization involves only one individual whereas cross fertilization involves two different individuals of the same species.

CONTENTS

1. Overview and Key Difference
2. What is Self Fertilization
3. What is Cross Fertilization
4. Similarities Between Self and Cross Fertilization
5. Side by Side Comparison – Self vs Cross Fertilization in Tabular Form
6. Summary

What is Self Fertilization?

Self fertilization is the process of uniting female and male games of the same individual during the sexual reproduction. Self fertilization is seen comparatively less among the organisms. In plants, monoecious plants show self fertilization. Self fertilization reduces the genetic diversity of the organisms. Hence, most of the organisms use preventive methods to stop self fertilization and promote cross fertilization. Self fertilization is achieved through self pollination. By the self pollination, pollens of the same flowers drop into the stigma of the same flower for the self fertilization. Self fertilization is seen in bisexual organisms including protozoans, certain flowering plants and several invertebrates.

Self fertilization increases the chance of expressing harmful recessive characteristics in offsprings. Offsprings of the self fertilization are less adapted to the changing environments, and their survival is less compared to the offsprings of the cross fertilization. However, self fertilization is utilised to maintain desirable genetic traits in the offspring generations.

What is Cross Fertilization?

Fertilization is the process of uniting a male gamete with a female gamete. When a female sex cell fuses with a male sex cell of a different individual of the same species, it is known as cross fertilization. In other words, cross fertilization is the process of fusing male and female gametes of different individuals of the same species. In plants, cross fertilization occurs in dioecious plants. In animals, it occurs between separate female and male organisms. Even in animals possessing both female and male sex organs, cross fertilization can be seen due to different methodologies they follow to prevent self fertilization.

In aquatic environments, cross fertilization occurs externally. However, in terrestrial organisms, fertilization process occurs inside the body of the female, and it is known as internal fertilization. Cross fertilization is an important process since it increases the diversity of the organisms. Both parents contribute genes into gametes, and new gene combinations flow to the offsprings. Therefore, the offsprings are genetically diverse from their parents, and they are more adapted to survive in the new environments.

Cross pollination helps flowering plants for cross fertilization. Unisexual plants do cross pollination with the help of different factors such as insects, wind, water etc.

What are the Similarities Between Self and Cross Fertilization?

• In both processes, a fusion of sex cells occurs.
• Both fertilization methods produce an offspring.
• Both can be seen during the sexual reproduction.

What is the Difference Between Self and Cross Fertilization?

Summary – Self vs Cross Fertilization

Self-fertilization is the fusion of male and female gametes (sex cells) produced by the same individual. Cross fertilization is the fusion of male and female gametes produced by the different individuals. Self fertilization is allowed to maintain the local population and desirable genetic traits, yet it reduces the genetic variation among the offsprings. Cross fertilization increases the adaptability of the organisms to survive in the changing environments and also it reduces the emergence of the harmful traits that come from recessive alleles. This is the difference between self and cross fertilization.

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Reference:

1.The Editors of Encyclopædia Britannica. “Cross-Fertilization.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 20 July 1998. Available here 
2.“Autogamy.” Wikipedia, Wikimedia Foundation, 14 Jan. 2018. Available here  

Image Courtesy:

1.’Self-pollination(1)’By Jankula00 – Own work, (CC BY-SA 4.0) via Commons Wikimedia  
2.’Cross Pollination (468246966)’By Snap® from Kuwait, Kuwait – Cross Pollination, (CC BY 2.0) via Commons Wikimedia