Isogamy is a form of sexual reproduction that involves gametes of the same morphology (indistinguishable in shape and size), and is found in most unicellular eukaryotes.[5][6] Isogamous species often have two mating types (heterothallism), but sometimes can occur between two haploid individuals that are mitotic descendents (homothallism).Isogamous reproduction evolved independently in several lineages of plants and animals into anisogamy (species with gametes of male and female types) and subsequently into oogamy (species in which the female gamete is much larger than the male and has no ability to move).This pattern may have been driven by the physical constraints on the mechanisms by which two gametes get together as required for sexual reproduction.[1][14] In some multicellular fungi, such as basidiomycetes, sexual reproduction takes place between two mycelia, but there is no exchange of gametes.