androgenesis

thumb|upright=1.3|Corbicula leana is one of the species of its genus known to be capable of reproducing androgenetically without females. Androgenesis is a system of asexual reproduction that requires the presence of eggs and occurs when a zygote is produced with only paternal nuclear genes. During standard sexual reproduction, one female parent 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 the more common gynogenesis, where only the maternal chromosomes are inherited). The offspring produced in androgenesis 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. Although androgenesis requires both male and females gametes, it is not strictly considered 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 reproducing species.