The key difference between Allogamy and Autogamy is that Allogamy is the fusion of male and female gametes that come from two different individuals while Autogamy is the fusion of male and female gametes of the same individual. Another difference between allogamy and autogamy with respect to the offspring produced is that the allogamy produces a genetically different offspring while autogamy produces a genetically identical offspring.
Fusion of a male gamete with a female gamete is fertilization. A zygote develops as a result of fertilization and then it undergoes cell division to produce a new offspring. Furthermore, fertilization can be two types; self-fertilization or cross-fertilization. Allogamy is a synonym for cross-fertilization and Autogamy is a synonym for self-fertilization.
CONTENTS
1. Overview and Key Difference
2. What is Allogamy
3. What is Autogamy
4. Similarities Between Allogamy and Autogamy
5. Side by Side Comparison – Allogamy vs Autogamy in Tabular Form
6. Summary
What is Allogamy?
Allogamy is a type of fertilization that occurs between an egg cell of one individual and a sperm of another individual. Therefore, it is a type of cross-fertilization. The best example of allogamy is the fertilization that occurs in human. Nevertheless, in plants, allogamy is categorized into two parts; geitonogamy and xenogamy. Geitonogamy refers to the transfer of pollen from the anther to the stigma of another flower of the same plant. Although it is described under the cross-fertilization, genetically it is a type of self-pollination. Xenogamy occurs between two genetically different individuals. In xenogamy, pollen from one plant deposit on the stigma of the flowers of another plant.
Figure 01: Allogamy
Allogamy is useful in masking deleterious effects of recessive alleles in the progeny. When considering the xenogamy, it is an evolutionary important phenomenon which increases genetic diversity among the organisms in a population.
What is Autogamy?
Autogamy is a mode of self-fertilization in which the fusion of two gametes of the same individual occurs. It is mainly visible in flowering plants. It can be termed as self-pollination as well, because, during the self-pollination, pollen grains fall onto the stigma of the same flower. When gametes are from the same individual, they are genetically identical. Hence, it produces genetically identical offspring population that is evolutionarily not important.
Figure 02: Autogamy
To enhance self-pollination, certain plants show different adaptations. Autogamy is highly feasible when the flowers are closed than when they are opened. Examples of plants that utilize this process include sunflower, orchid, peas, and tridax.
What are the Similarities Between Allogamy and Autogamy?
- Fusion of gametes occurs in both processes.
- Both Allogamy and Autogamy take place in flowering plants.
- Both Geitonogamy (a part of Allogamy) and Autogamy are types of self-pollination
What is the Difference Between Allogamy and Autogamy?
Allogamy is the fusion of gametes derived from two individuals. Autogamy is the fusion of gametes derived from the same individual. Further, in Allogamy, there can be two types; geitonogamy and xenogamy.
With regard to the production of offsprings, allogamy produces a genetically different offspring population while autogamy produces a genetically identical offspring population. Furthermore, allogamy is an evolutionary important process since it produces genetically diverse population. And autogamy is not important since it produces a genetically identical population.
Summary – Allogamy vs Autogamy
Allogamy and autogamy are synonyms for cross-fertilization and self-fertilization respectively. Fusion of two gametes that derived from two individuals occurs in allogamy while in autogamy, the fusion of the two gametes derived from the same individual occurs. Geitonogamy and xenogamy are two types of allogamy. Xenogamy occurs between two different individuals which are genetically different. In geitonogamy, two genetically identical individuals are involved similar to autogamy which occurs between male and female parts of the same flower. This is the difference between allogamy and autogamy.
Reference:
1.“Autogamy.” Encyclopædia Britannica, Encyclopædia Britannica Inc. Available here
Image Courtesy:
1.’Creation-Via-Pollination’By Jessie Eastland – Own work, (CC BY-SA 3.0) via Commons Wikimedia
2.’95387-004-63854D5B(1)’By Jankula00 – Own work, (CC BY-SA 4.0) via Commons Wikimedia