autogamy

Autogamy is a biological term describing self-fertilization, where gametes from the same individual unite to form offspring. The term is used primarily in botany to describe self-pollination within a single flower, but it is also used in zoology, microbiology, and phycology to describe selfing processes in hermaphroditic organisms and unicellular algae or fungi.

In plants, autogamy refers to self-pollination of a flower, or selfing by pollen from the same plant fertilizing its own ovules. It contrasts with geitonogamy (pollination between flowers on the same plant) and xenogamy (pollination between different plants). Cleistogamy is a form of autogamy in which flowers never open, ensuring self-pollination. Self-compatibility and flower structure influence autogamy rates; environments with scarce pollinators favor autogamy as reproductive assurance. Genetic consequences include reduced heterozygosity and potential inbreeding depression, though some purging of deleterious alleles can occur.

In animals and other organisms, autogamy describes self-fertilization in hermaphroditic individuals or cells. For example, many nematodes have hermaphroditic individuals capable of selfing; some ciliates such as Paramecium undergo autogamy as a late-stage sexual process that restores genetic variation within a single cell. Among unicellular algae and fungi, autogamy can also describe self-fertilization events that complete sexual cycles without a mating partner.

Evolutionary considerations of autogamy emphasize reproductive assurance and rapid population growth in stable or isolated environments, balanced against loss of genetic diversity and potential accumulation of deleterious mutations. The occurrence and degree of autogamy vary widely among taxa and ecological contexts.