What is the Difference Between Syngamy and Fertilisation

There is no significant difference between syngamy and fertilisation. Both describe the fusion of male and female gametes to form a zygote. Generally, syngamy is the fusion of haploid male and female gametes to form a diploid embryo. Moreover, it is the most common mode of sexual reproduction in both animals and plants. Here, the male gametes are sperms while the female gametes are egg cells. There are two types of syngamy in plants. They are endogamy (self-fertilization) and exogamy (cross-fertilization). Based on the structure of gametes fused during fertilisation, there are three types of syngamy. They are isogamy, anisogamy, and hologamy. Furthermore, internal and external fertilization are the two main types of fertilization in animals. 

Key Areas Covered 

1. What is Syngamy/Fertilisation
     – Definition, Explanation
2. Syngamy in Plants
     – Different Types
3. Syngamy in Animals
    – Different Types
4. What is the Difference Between Syngamy and Fertilisation
     – Comparison of Differences

Key Terms 

Endogamy, Exogamy, External Fertilisation, Fertilisation, Internal Fertilisation, Gametes, Syngamy in Animals, Syngamy in Plants,

What is Syngamy/Fertilisation 

Syngamy is the fusion of gametes, initiating the development of a new individual. Here, male and female gametes produced by gametogenesis undergo fusion to form a diploid zygote. Additionally, the male gametes are sperm cells, while female gametes are egg cells. However, both male and female gametes are haploid as their precursor cells have undergone meiosis. Thereby, syngamy is a process of sexual reproduction of both animals and plants. Also, it occurs after gametogenesis. Furthermore, the other names for syngamy are fertilisation, fertilization, generative fertilisation, etc. 

Syngamy in Plants

In plants, there are two types of syngamy based on the source of fusing gametes. They are endogamy and exogamy. Here, endogamy is the fusion of gametes of the same plant. Therefore, these gametes are uniparental. Another name for this process is self-fertilization. On the contrary, exogamy is the fusion of gametes of separate plants of the same species. Therefore, these gametes are biparental; hence, this process is also known as cross-fertilization.

Figure 1: Syngamy in Plants

Moreover, based on the structure of fusing gametes, there are three types of syngamy. They are isogamy, anisogamy, and hologamy. In isogamy, the fusing gametes are both morphologically and physiologically similar. Therefore, these gametes are known as homogametes. Moreover, in anisogamy, the fusing gametes are different from each other, both morphologically and physiologically. Therefore, these gametes are known as heterogamtes. Especially, the male gametes are microgamete or sperm cells, while female gametes are macrogamete or egg cells. On the other hand, in hologamy, two organisms themselves serve as gametes. 

Syngamy in Animals

In animals, there are two types of fertilisation known as internal and external fertilisation. Here, internal fertilization occurs inside the female organism. Also, male gametes come from a selected individual in internal fertilization. On the other hand, this type of fertilization requires the production of a small number of gametes. Additionally, this method is successful in harsh environmental conditions. Therefore, it shows higher survival rates of the embryo. Generally, internal fertilization occurs in ovoviviparous and viviparous animals, including mammals, reptiles, and birds. However, it also occurs in plants including angiosperms, gymnosperms, pteridophytes, and bryophytes as their fertilization occurs inside the female gametophyte. 

Figure 2: Internal Fertilization

Besides, external fertilization is the fusion of gametes outside the female organisms or, in other words, in the external environment. Here, a large number of gametes has to be produced to obtain successful fertilization events. Also, it is only successful in mist environments. Therefore, external fertilization has a lower survival rate of the embryo. Generally, oviparous animals, including frog, fish, crustaceans, and molluscs, undergo external fertilization. Moreover, some plants like algae undergo external fertilization. 

Difference Between Syngamy and Fertilisation 

• There is no significant difference between syngamy and fertilisation. 

Conclusion 

Syngamy and fertilisation are two synonymous terms used to describe the fusion of male and female gametes to form a zygote. Here, both types of gametes are haploid, and the forming zygote is diploid. Generally, they are one of the several processes that occur in the sexual reproduction of organisms. On the other hand, different types of syngamy or fertilisation can be identified based on the characteristics of gametes involved in and method of their fusion. However, there is no significant difference between syngamy and fertilisation. 

References:

1. Samiksha, S. “Sexual Reproductions in Animals: Syngamy and Conjugation | Biology.” Your Article Library, 19 Feb. 2014, Available Here.
2. “Fertilisation.” Wikipedia, Wikimedia Foundation, 5 June 2019, Available Here.

Image Courtesy:

1. “Angiosperm life cycle diagram-en” By LadyofHats Mariana Ruiz (Public Domain) via Commons Wikimedia   
2. “Blausen 0404 Fertilization” By BruceBlaus – Own work (CC BY 3.0) via Commons Wikimedia