Sexual reproduction form involving gametes of the same size
Not to be confused with
Isogyny, marriage between people of similar status or age
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.[1] Because both gametes look alike, they generally cannot be classified as
male or
female.[2] Instead, organisms undergoing isogamy are said to have different
mating types, most commonly noted as "+" and "−" strains.[3]
Etymology
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adding to it. (August 2021)
The literal meaning of isogamy is "equal marriage" which refers to equal contribution of resources by both gametes to a zygote.[4] The term isogamous was first used in the year 1887.[who?][5]
Characteristics of isogamous species
Isogamous species often have two mating types. Some isogamous species have more than two mating types, but the number is usually lower than ten. In some extremely rare cases a species can have thousands of mating types. In all cases,
fertilization occurs when gametes of two different mating types fuse to form a
zygote.[6]
It is generally accepted that isogamy is an ancestral state for
anisogamy[1][7] and that isogamy was the first stage in the evolution of
sexual reproduction. Isogamous reproduction
evolved independently in several lineages of plants and animals to
anisogamous species with
gametes of male and
female types and subsequently to
oogamous 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.[8]
Isogamy is the norm in
unicellular eukaryote species, although it is possible that isogamy is evolutionarily stable in multicellular species.[1]
^Kumar R, Meena M, Swapnil P (2019). "Anisogamy". In Vonk J, Shackelford T (eds.). Anisogamy. Encyclopedia of Animal Cognition and Behavior. Cham: Springer International Publishing. pp. 1–5.
doi:
10.1007/978-3-319-47829-6_340-1.
ISBN978-3-319-47829-6.
^Heitman, Joseph; Howlett, Barbara J.; Crous, Pedro W.; Stukenbrock, Eva H.; James, Timothy Yong; Gow, Neil A. R. (2020-07-10).
The Fungal Kingdom. John Wiley & Sons. p. 149.
ISBN978-1-55581-958-3.
Archived from the original on 2023-10-06. Retrieved 2021-07-24.