Although guppies might be common pet store commodities, they're evolutionary geniuses in the world of fish. Over their long period of evolution, guppies have developed distinct color patterns and methods to populate new areas. Guppy reproduction is similar to that of many other fish. It involves copulation, and females give birth to live young.
Sexual maturity in guppies varies between males and females; it also depends greatly on the conditions of the water, food supply and other factors. In captivity, males can reproduce around 1 month of age, but they reach true sexual maturity around the middle of their third month. Females don't reach reproductive maturity until around 3 months old.
Over at least 500,000 years of guppy evolution, one distinct trait has remained constant in the males: an orange patch. Wild female guppies show preference to the males with certain hues of orange -- not too red and not too yellow. The color preference varies between females: 6-month-old female virgins preferred more ornamental males, but 1-year-old virgins and postpartum females did not differentiate between the coloration.
The male's anal fin develops into his sexual organ as he matures. The third, fourth and fifth rays of the anal fin form the gonopodium. This sexual organ has several hooks that grasp onto the female during copulation. The gonopodium transfers his sperm into the female's cloaca. The forming of the gonopodium marks when males are able to reproduce, but not necessarily when they are mature.
One of the most distinctive features of guppy breeding is that the female can consecutively give birth to several broods, sometimes without copulating again. The female guppy has several folds in her genital area that can store sperm for up to 10 months. In the wild, this allows female guppies to move to new areas without guppy populations and populate them with her young. The different broods can have different fathers, providing genetic differences to avoid interbreeding and restricted gene pools.
Guppies are oviviparous, meaning their eggs are fertilized by the male's sperm internally inside the female. The mother guppy gives birth to live, fully formed young in broods that average between 20 and 40 young. Guppy fry are ready to fend for themselves directly upon birth, and they begin swimming, feeding and living without the protection of their mother.
- Marks Pet Fish: Guppy Sexual Maturity, When Do Guppies Mature?
- UCLA Newsroom: They Call It 'Guppy Love': UCLA Biologists Solve an Evolutionary Mystery
- "The American Naturalist": Age and Experience Affect Female Choice in the Guppy
- Tropical Fish Hobbyist Magazine: Back to the Basics: Breeding Guppies
- University of California, Riverside: UCR Today: Research Shows Male Guppies Reproduce Even After Death
- Hemera Technologies/PhotoObjects.net/Getty Images