Metagenesis is the process through which one generation of plants and animals reproduced asexually before giving birth to a sexually reproducing generation.
It is the transition between sexual and asexual phases of an organism in its lifecycle.
Both the sexual and asexual phases are diploid (two sets of chromosomes).
Example of metagenesis:
Metagenesis is commonly observed in the life cycle of coelenterates.
Obelia is a coelenterate in which a sexual sessile form known as polyp is formed which reproduces asexually by budding.
Whereas, the sexual form is free-living and is known as medusa which reproduces sexually.
Obelia alternates between the polyp form and the medusa form.