The Amazon molly has no males, so it borrows sperm from a relative
The Amazon molly is an all-female fish. To reproduce it needs sperm from a related species, the sailfin molly, but only to trigger development; the father's genes are discarded. It is one of many ways life copies itself without sex, from bacteria splitting in two to Komodo dragons laying eggs no male ever fertilised.
Asexual reproduction skips the fusion of sex cells, so offspring inherit the whole genome of a single parent and are close or exact copies. It is the main strategy of bacteria and archaea, which divide by binary fission into two identical daughters, though they can still swap genes through processes like conjugation. Some protists split several ways at once. Baker's yeast and the freshwater hydra bud off offspring that start smaller than the parent, and the parasite Toxoplasma gondii grows daughters inside a mother cell, which they consume before separating.
Plants excel at cloning. Strawberries send out runners, tulips and dahlias regrow from bulbs and tubers, and kalanchoe sprouts miniature plantlets along its leaves, so one clonal population can spread across a large area. Planarians, many worms and sea stars regenerate whole bodies from fragments, and lichens break off dusty packets called soredia that carry both the fungus and its photosynthetic partner.
Parthenogenesis, development from an unfertilised egg, is documented in over 2,000 species, from aphids and stick insects to reptiles, fish and even domestic birds. Some species use it only as a fallback: female zebra sharks resort to it when no mate is available. Aphids alternate, cloning rapidly through the summer and breeding sexually in autumn. The desert grassland whiptail lizard, a hybrid that would normally be sterile, relies on it entirely. Once thought limited to small vertebrates, it has now been recorded in the Komodo dragon, over 300 pounds.
The reverse also exists. In androgenesis, seen in clams, some ants, fish and amphibians, offspring carry only the father's nuclear genes, either because the mother's genome is lost from the zygote or because the egg had no nucleus to begin with. Even then, mitochondria still come from the mother. Plants have their own version, apomixis, in which seeds form without fertilisation, as in the European dandelion.
Source: Asexual reproduction
