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Poecilidae
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 the Southeastern United States to north of Río de la Plata, Argentina, and Africa, including Madagascar. Due to release of aquarium specimens and the widespread use of species of the genera ''Poecilia'' and ''Gambusia'' for mosquito control, though, poeciliids can today be found in all tropical and subtropical areas of the world. In addition, ''Poecilia'' and ''Gambusia'' specimens have been identified in hot springs pools as far north as Banff, Alberta. Live-bearing Although the whole family Poeciliidae is known as "live bearers" (viviparous), some species are egg-scattering with external fertilization. All African species are egg-layers, and (with the exception of the members of the genus ''Tomeurus''), all American species are live ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poecilia
''Poecilia'' is a genus of fishes in the family Poeciliidae of the order Cyprinodontiformes. These livebearers are native to fresh, brackish and salt water in the Americas, and some species in the genus are euryhaline. A few have adapted to living in waters that contain high levels of toxic hydrogen sulfide ()Palacios, Arias-Rodriguez, Plath, Eifert, Lerp, Lamboj, Voelker, & Tobler (2013). The Rediscovery of a Long Described Species Reveals Additional Complexity in Speciation Patterns of Poeciliid Fishes in Sulfide Springs.' PLoS ONE 8(8): e71069. and a population of '' P. mexicana'' lives in caves (other populations of this species are surface-living). Some common and widespread species are often kept as aquarium fish, while other have very small ranges and are seriously threatened. All species in ''Poecilia'' are called mollies except for the Endler's livebearer (''P. wingei'') and the well-known guppy (''P. reticulata'') which have a distinctly different body shape from the r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green Swordtail
The green swordtail (''Xiphophorus hellerii'') is a species of freshwater/brackish fish in family Poeciliidae of order Cyprinodontiformes. A live-bearer, it is closely related to the southern platyfish or 'platy' (''X. maculatus'') and can crossbreed with it. It is native to an area of North and Central America stretching from Veracruz, Mexico, to northwestern Honduras. Description The male green swordtail grows to a maximum overall length of and the female to . The name 'swordtail' is derived from the elongated lower lobe of the male's caudal fin (tailfin). Sexual dimorphism is moderate, with the female being larger than the male, but lacking the 'sword'. The wild form is olive green in color, with a red or brown lateral stripe and speckles on the dorsal and, sometimes, caudal fins. The male's 'sword' is yellow, edged in black below. Captive breeding has produced many color varieties, including black, red, and many patterns thereof, for the aquarium hobby. All varieties sha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhexipanchax
''Rhexipanchax'' is a genus of poeciliid fishes native to tropical West Africa West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Maurit .... Species There are currently four recognized species in this genus: * '' Rhexipanchax kabae'' ( Daget, 1962) * '' Rhexipanchax lamberti'' ( Daget, 1962) (Lambert's lampeye) * '' Rhexipanchax nimbaensis'' ( Daget, 1948) (Mt. Nimba lampeye) * '' Rhexipanchax schioetzi'' ( Scheel, 1968) (Schiötz' lampeye) References Poeciliidae * Freshwater fish genera Ray-finned fish genera {{Cyprinodontiformes-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superfetation
Superfetation (also spelled superfoetation – see fetus) is the simultaneous occurrence of more than one stage of developing offspring in the same animal. In mammals, it manifests as the formation of an embryo from a different menstrual cycle while another embryo or fetus is already present in the uterus. When two separate instances of fertilisation occur during the same menstrual cycle, it is known as superfecundation. Humans While proposed cases of superfetation have been reported in humans, the existence of this phenomenon in humans has been deemed unlikely. Better explanations include differential growth between twins due to various reasons such as twin-to-twin transfusion syndrome. Artificially induced superfetation has been demonstrated, although only up to a short period after insemination. A 2008 French study found evidence to suggest that superfetation is a reality for humans, but that it is so rare that there have been fewer than 10 recorded cases in the world. In 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, the equivalent Latin term ''cladus'' (plural ''cladi'') is often used in taxonomical literature. The common ancestor may be an individual, a population, or a species (extinct or extant). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over the last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic. Some of the relationships between organisms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poeciliopsis Prolifica
''Poeciliopsis prolifica'', or the blackstripe livebearer, is a species of small freshwater fish in the family Poeciliidae. It is endemic to Mexico. It is a viviparous species and the female can have several clutches of young developing internally at the same time, hence the specific name ''prolifica'', from the Latin ''proles'', "offspring" and ''ferax'', "rich, fruitful" in reference to the great number of young produced. Description ''Poeciliopsis prolifica'' is a small, slender silvery fish growing to a maximum length of about for males and for females. Adult males can be told from females by the presence of a gonopodium, an extended rod-shaped anal fin that acts as an intromittent organ to introduce sperm into the female during mating. Distribution and habitat The species is endemic to Mexico where it is only found on the eastern side of the Gulf of California, between the states of Sonora and Nayarit. It is a shallow-water, freshwater fish, tolerant of brackish water and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poeciliopsis Lucida
''Poeciliopsis lucida'', the clearfin livebearer, is a species of small freshwater fish in the family Poeciliidae. Reproduction is viviparous, 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 to Mexico that were described in 1960 by the American ichthyologist Robert Rush Miller. 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 from inbreeding. ''P. lucida'' can hybridise with ''Poeciliopsis monacha' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 the upper reaches of streams and arroyos on the western side of the Sierra Madre Occidental mountain range. Some of these watercourses dry up during the summer and the fish may have to survive in springs and pools. Conditions are harsh in winter in the headwaters of the streams at altitudes of around ; there may be frosts and snow may fall. The fish become torpid at temperatures below about , but there are some hot springs, and water exposed to the sun may warm up during the day. In the summer, no precipitation occurs, much of the water evaporates, and fish may have to survive in dwindling pools where temperatures above about will be lethal. Ecology In addition to the stress factors induced by trying to survive in summer in decreasing an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 Arizona and New Mexico. Species There are currently 24 recognized species in this genus: * ''Poeciliopsis baenschi'' ( M. K. Meyer, Radda, Riehl & Feichtinger, 1986) (Golden livebearer) * ''Poeciliopsis balsas'' ( C. L. Hubbs, 1926) (Balsas livebearer) * ''Poeciliopsis catemaco'' (R. R. Miller, 1975) (Catemaco livebearer) * ''Poeciliopsis elongata'' ( Günther, 1866) (Elongate toothcarp) * '' Poeciliopsis fasciata'' (Meek, 1904) (San Jeronimo livebearer) * '' Poeciliopsis gracilis'' ( Heckel, 1848) (Porthole livebearer) * '' Poeciliopsis hnilickai'' ( M. K. Meyer & Vogel, 1981) (Upper Grijalva livebearer) * '' Poeciliopsis infans'' ( Woolman, 1894) (Lerma livebearer) * '' Poeciliopsis latidens'' (Garman, 1895) (Lowland livebearer) * ''Poec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Matrotrophy
Matrotrophy is a form of maternal care during organism development, associated with live birth (viviparity), in which the embryo of an animal or flowering plant is supplied with additional nutrition from the mother (e.g. through a placenta). This can be contrasted with lecithotrophy, in which the only source of nutrition for the embryo is yolk originally contained within its egg. Vegetal matrotrophy In plants, matrotrophy is considered a critical evolutionary development preceding the origin of embryophytes and therefore essential to the evolution of land plants. Matrotrophy is facilitated by cytological and ultrastructural modifications on one or both sides of the generational junction, a region called the placenta. Specialization of the placental cells pertains further to their cytological and ultrastructural characteristics: the cytoplasm is often dense and rich in lipids, the vacuole is typically reduced but large in ''Sphagnum'', the endoplasmic reticulum extensive, mitochon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oocyte
An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female germ cells produce a primordial germ cell (PGC), which then undergoes mitosis, forming oogonia. During oogenesis, the oogonia become primary oocytes. An oocyte is a form of genetic material that can be collected for cryoconservation. Formation The formation of an oocyte is called oocytogenesis, which is a part of oogenesis. Oogenesis results in the formation of both primary oocytes during fetal period, and of secondary oocytes after it as part of ovulation. Characteristics Cytoplasm Oocytes are rich in cytoplasm, which contains yolk granules to nourish the cell early in development. Nucleus During the primary oocyte stage of oogenesis, the nucleus is called a germinal vesicle. The only normal human type of secondary oocyte has t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lecithotrophic
Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and monotremes. In traditional usage, most insects (one being ''Culex pipiens'', or the common house mosquito), molluscs, and arachnids are also described as oviparous. Modes of reproduction The traditional modes of reproduction include oviparity, taken to be the ancestral condition, traditionally where either unfertilised oocytes or fertilised eggs are spawned, and viviparity traditionally including any mechanism where young are born live, or where the development of the young is supported by either parent in or on any part of their body. However, the biologist Thierry Lodé recently divided the traditional category of oviparous reproduction into two modes that he named ovuliparity and (true) oviparity respectively. He distinguished the two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
