Guppies
The guppy (Poecilia reticulata), also known as millionfish and rainbow fish,[1] is one of the world's most widely distributed tropical fish, and one of the most popular freshwater aquarium fish species. It is a member of the Poeciliidae family and, like all other members of the family, is live-bearing.[2] Guppies, whose natural range is in northeast South America, were introduced to many habitats and are now found all over the world. They are highly adaptable and thrive in many different environmental and ecological conditions.[3] Male guppies, which are smaller than females, have ornamental caudal and dorsal fins, while females are duller in colour. Wild guppies generally feed on a variety of food sources, including benthic algae and aquatic insect larvae. Guppies are used as a model organism in the field of ecology, evolution, and behavioural studies.
Distribution and habitat
Guppies are native to Antigua and Barbuda, Barbados, Brazil, Guyana, Jamaica, the Netherlands Antilles, Trinidad and Tobago, the U.S. Virgin Islands, and Venezuela.[6][7] However, guppies have been introduced to many different countries on every continent except Antarctica. Sometimes this has occurred accidentally, but most often as a means of mosquito control. The guppies were expected to eat the mosquito larvae and help slow the spread of malaria, but in many cases, these guppies have had a negative impact on native fish populations.[8] Field studies reveal that guppies have colonized almost every freshwater body accessible to them in their natural ranges, especially in the streams located near the coastal fringes of mainland South America. Although not typically found there, guppies also have tolerance to brackish water and have colonized some brackish habitats.[3] They tend to be more abundant in smaller streams and pools than in large, deep, or fast-flowing rivers
Description
Guppies exhibit sexual dimorphism. While wild-type females are grey in body color, males have splashes, spots, or stripes that can be any of a wide variety of colors.[10] The size of guppies vary, but males are typically 1.5–3.5 cm (0.6–1.4 in) long, while females are 3–6 cm (1.2–2.4 in) long.
A variety of guppy strains are produced by breeders through selective breeding, characterized by different colours, patterns, shapes, and sizes of fins, such as snakeskin and grass varieties. Many domestic strains have morphological traits that are very distinct from the wild-type antecedents. Males and females of many domestic strains usually have larger body size and are much more lavishly ornamented than their wild-type antecedents.[11]
Guppies have 23 pairs of chromosomes, including one pair of sex chromosomes, the same number as humans.[12] The genes responsible for male guppies' ornamentations are Y-chromosome linked and are heritable.
Life cycle
Two or three generations of guppies per year occur in the wild. Guppies are well developed and capable of independent existence without further parental care by the time they are born. Young guppies school together and perform antipredator tactics. Brood size is extremely variable, yet some consistent differences exist among populations depending on the predation level and other factors.[3] Females of matching body sizes tend to produce more numerous but smaller-sized offspring in high predation conditions. Female guppies first produce offspring at 10–20 weeks of age, and they continue to reproduce until 20–34 months of age. Male guppies mature in 7 weeks or less.[3] Total lifespan of guppies in the wild varies greatly, but it is typically around 2 years.[14] Variations in such life historic characteristics of guppies are observed in different populations, indicating that different evolutionary pressures exist.
No comments:
Post a Comment