Limia

From Wikipedia, the free encyclopedia

iLimia

Secure

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Cyprinodontiformes
Family:	Poeciliidae
Genus:	Limia Poey, 1854

Species

See text.

Limia is a genus of livebearing freshwater fishes belonging to the cyprinodontiform family Poeciliidae, which includes other livebearers such as platys, swordtails (genus Xiphophorous), guppies and mollies (genus Poecilia). Limias are found on the islands of the Greater Antilles, with 22 species on Hispaniola and single endemic species on the Cayman Islands, Cuba, and Jamaica. Limias are popular in aquaria among more advanced hobbyists.

1 Origin and evolution
2 Mating system
3 Species
4 References

[edit] Origin and evolution

Two schools of thought on the origin of the genus exist. The first suggests that limias arose from colonization by a seawater-tolerant species that crossed over shallow waters from the North or South American mainland. The strongest evidence for this model is that of the approximately 60 species of freshwater fish in the Antilles, all of them are secondary division freshwater fish. This indicates that the ancestors of all fish present on the islands at least had the ability to cross over shallow seas.

The second school of thought suggests that freshwater fish in the Antilles are the descendants of mainland species that became isolated when some of the Greater Antilles split from the mainland. The total lack of freshwater fish fossils from the Antilles means that this debate likely needs to be resolved through molecular evidence.

[edit] Mating system

Limias are ovoviviparous, meaning that eggs develop inside the mother with a yolk sac as a nutrient source. The female gives birth to live young, which have a higher chance of survival than eggs and earlier stage fry. Fertilization is achieved internally with the male's gonopodium, a modified anal fin used for sperm transfer. Because of the asymmetrical energy costs associated with internal fertilization, females in many Poeciliid species act as the choosy sex, with males exhibiting ornate coloration and morphology as well as elaborate courtship displays. Limias, however, mostly lack display or extreme sexual dimorphism/dichromism. Of the known species, only the Humpback Limia (L. nigrofasciata), Perugia's Limia (L. Perugiae) and the Blackbelly or Jamaican Limia (L. melanogaster) have been found to exhibit male courtship displays. The majority of limia species rely on sneak copulation, in which the male thrusts his gonopodium into the female's genital pore without a prior display. The consequence of this system of mating can be the undermining of female choice, halting the progression of sexual selection on male traits and in some cases inhibiting speciation.