metagenese

Metagenesis, also known as alternation of generations, is a life cycle that alternates between two or more distinct forms in the process of reproduction. In organisms that exhibit metagenesis, sexual reproduction produces a form that then reproduces asexually, and this asexual form, in turn, produces the sexually reproductive form. This cycle can involve different life stages, morphologies, or even ploidy levels.

This type of life cycle is common in various groups of organisms, including plants, algae, fungi, and some invertebrates like jellyfish and corals. For example, in the life cycle of a jellyfish, a free-swimming medusa (sexual stage) produces eggs and sperm, which develop into a sessile polyp stage (asexual stage). The polyp then buds off new medusae, continuing the cycle. In plants, the sporophyte generation (diploid, produces spores) alternates with the gametophyte generation (haploid, produces gametes).

The advantage of metagenesis often lies in its ability to combine the benefits of both sexual and asexual reproduction. Sexual reproduction promotes genetic diversity, which can be advantageous for adaptation to changing environments. Asexual reproduction, on the other hand, allows for rapid population growth and colonization when conditions are favorable, as it does not require finding a mate. The specific forms and transitions in metagenetic life cycles vary widely across different species and phyla.