Androgenesis

Androgenesis occurs when a zygote is produced with only paternal nuclear genes. During standard sexual reproduction, one female and one male parent each produce haploid gametes (such as a sperm or egg cell, each containing only a single set of chromosomes), which recombine to create offspring with genetic material from both parents. However, in androgenesis, there is no recombination of maternal and paternal chromosomes, and only the paternal chromosomes are passed down to the offspring (the inverse of this is gynogenesis, where only the maternal chromosomes are inherited, which is more common than androgenesis). The offspring produced in androgenesis will still have maternally inherited mitochondria, as is the case with most sexually reproducing species.

One of two things can occur to produce offspring with exclusively paternal genetic material: the maternal nuclear genome can be eliminated from the zygote, or the female can produce an egg with no nucleus, resulting in an embryo developing with only the genome of the male gamete.

Androgenesis blurs the lines between sexual and asexual reproduction–it is not strictly a form of asexual reproduction because both male and female gametes are required. However, it is not strictly a form of sexual reproduction because the offspring have uniparental nuclear DNA that has not undergone recombination, and the proliferation of androgenesis can lead to exclusively asexually reproducting species.

Androgenesis is seen in nature in the stick insect Bacillus rossius, the Tassili cypress tree Cupressus dupreziana, the little fire ant Wasmannia auropunctata, several species of the clam genus Corbicula, and occasionally in fruit flies Drosophila melanogaster carrying a specific mutant allele. It has also been induced in many crops and fish via irradiation of an egg cell to destroy the maternal nuclear genome.