Question

Differentiate between- Hologamy and Autogamy.

Answer 1

Hologamy and Autogamy are the methods of fusion of cells or gametes for zygote formation. When gametes with a single set of chromosomes fuse it forms a diploid zygote. Depending on how the gametes fuse it is classified as autogamy and hologamy.

Complete answer:
In protozoans, both sexual and asexual type of reproduction occurs. Asexual reproduction takes place via binary fission, sporulation. Sexual reproduction occurs via Syngamy, conjugation.
Syngamy – Syngamy is the union of two specialized protozoan cells or the fusion of gametes to form the zygote. The zygote is also called an oospore.
Depending on how the fusion of gametes occurs syngamy is divided into the following types- Autogamy, Paedogamy, Hologamy, Merogamy, Isogamy, and Anisogamy.

In Hologamy, two mature individuals behave as gametes and fuse together to form a zygote. In Hologamy, true gametes are not formed. Example: Copromonas subtilis.
In Autogamy, gametes are derived from the same parent. True gametes originated from single-parent fuse together to form the zygote. For example, Paramecium aurelia.

Note: In Paedogamy, the individuals fuse to form a zygote but, fusing individuals are young. In merogamy, the uniting individuals are smaller than that of mature vegetative cells. These uniting cells are called merogametes. Isogamy is the uniting of gametes that are of the same size and shape. They unite together to form the zygote. Anisogamy the two fusing gametes are of different sizes and shapes often called hetero gametes and the process is sometimes referred to as, heterogamy.