1) Alternation of generations 2) Digenesis 3) Heterogenesis 4) Xenogenesis 1) Digenesis 
• (n.) Alternation of sexual and asexual or gemmiparous generations; -- in distinction from heterogamy. • (n.) The change of form which one animal species undergoes in a series of successively produced individuals, extending from the one developed from the ovum to the final perfected individual. Hence, metagenesis involves the production ...
1. <biology> The change of form which one animal species undergoes in a series of successively produced individuals, extending from the one developed from the ovum to the final perfected individual. Hence, metagenesis involves the production of sexual individuals by nonsexual means, either directly or through intervening sexless generations. ...
(met″ә-jen´ә-sis) alternation of generations used specifically to denote the regular alternation of sexual and asexual modes of reproduction in the life cycle, as in certain fungi.
Met`a·gen'e·sis noun [ Prefix meta- + genesis .] 1. (Biol.) The change of form which one animal species undergoes in a series of successively produced individuals, extending from the one developed from the ovum to the final perfected individual. Hence, metagenesis involves...
[n] - alternation of sexual and asexual generations
digenesis noun alternation of sexual and asexual generations