''Poeciliopsis lucida'', the clearfin livebearer, is a species of small freshwater

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

in the family

Poeciliidae The Poeciliidae are a family of freshwater fishes of the order Cyprinodontiformes, the tooth-carps, and include well-known live-bearing aquarium fish, such as the guppy, molly, platy, and swordtail. The original distribution of the family was t ...

. Reproduction is

viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...

, and the female can have several clutches of young developing internally at the same time. It is one of several species of small livebearing fish

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

that were described in 1960 by the American

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 33,400 species of fish had been described as of Octobe ...

Robert Rush Miller Robert Rush Miller (April 23, 1916 – February 10, 2003) "was an important figure in American ichthyology and conservation from 1940 to the 1990s." He was born in Colorado Springs, earned his bachelor's degree at University of California, Berke ...

Description

Female ''Poeciliopsis lucida'' can grow to a maximum length of about and males to .

Ecology

''P. lucida'' is a livebreeder, producing live young in batches. The female can carry three batches of young at a time, each at a different stage of development, and batches are born at an average interval of 10.3 days. Maturity in the female is reached at an age of about eight weeks and a length of about . In the laboratory, brother-sister matings have been going on for many years without any sign of diminution of

fecundity Fecundity is defined in two ways; in human demography, it is the potential for reproduction of a recorded population as opposed to a sole organism, while in population biology, it is considered similar to fertility, the natural capability to pr ...

from

inbreeding Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and o ...

. ''P. lucida'' can hybridise with ''

Poeciliopsis monacha ''Poeciliopsis monacha'', or the headwater livebearer, is a species of freshwater fish in the family Poeciliidae. It is endemic to Mexico. Distribution and habitat ''Poeciliopsis monacha'' is endemic to northwestern Mexico where it is present in ...

''. When a male ''P. lucida'' mates with a female ''P monacha'', the offspring are

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...

and are all female. If a male ''P. lucida'' mates with these females, the offspring are all female but are

triploid Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...

. The all-female status is maintained by a process known as

hybridogenesis Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development ...

. The sperm is incorporated for a single generation and then excluded during the formation of the ovum. The triploid individual reproduces by

gynogenesis Gynogenesis, a form of parthenogenesis, is a system of asexual reproduction that requires the presence of sperm without the actual contribution of its DNA for completion. The paternal DNA dissolves or is destroyed before it can fuse with the egg. Th ...

, a process triggered by the presence of sperm but not involving gametic fusion. In the desert streams of Northwestern Mexico, several species of ''

Poeciliopsis ''Poeciliopsis'' is a genus of poeciliid fishes that primarily are native to Mexico and Central America. The only exceptions are ''P. turrubarensis'' where the range extends into Colombia, and ''P. occidentalis'' where the range extends into Ariz ...

'' are found. In the headwaters of the

Fuerte River The Fuerte River is a river in the state of Sinaloa, in northwestern Mexico. It flows from headwaters in the Sierra Madre Occidental to the Pacific Ocean in the Gulf of California. Course It begins at the junction of the Rio Verde (also called ...

, the

Sinaloa River The Sinaloa River is a river of Mexico. It runs across the state of Sinaloa from northeast to southwest, beginning in the Sierra Madre Occidental and emptying into the Gulf of California. Its flow is interrupted mostly by the Bacurato Dam which c ...

and the Mocorito River the only species is ''P. monacha''. Further downstream, ''P. lucida'' is also present and here the two species hybridise. The dominant ''P. lucida'' males tend to mate with their own species but those of lower rank tend to mate with ''P. monacha'', and the triploid hybrid is present throughout the lower reaches of these rivers. ''P. monacha'' are highly

cannibalistic Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species In biology, a species is the basic ...

and the

juvenile fish Fish go through various life stages between fertilization and adulthood. The life of a fish start as spawned eggs which hatch into immotile larvae. These larval hatchlings are not yet capable of feeding themselves and carry a yolk sac which ...

es tend to hide from their mother close to the substrate. ''P. lucida'' is the reverse, and the young swim beside their mother. Hybrids between the two species are intermediate between these two behaviours, with the triploid hybrids being more cannibalistic than the diploid hybrids.

References

{{Taxonbar, from=Q3763937

lucida Lucida (pronunciation: ) is an extended family of related typefaces designed by Charles Bigelow and Kris Holmes and released from 1984 onwards. The family is intended to be extremely legible when printed at small size or displayed on a low-resol ...

Endemic fish of Mexico Freshwater fish of Mexico Fish described in 1960