Tropical fish are fish found in aquatic tropical environments around the world. Fishkeepers often keep tropical fish in freshwater and saltwater aquariums . The term "tropical fish" is not a taxonomic group , but rather is a general term for fish found in such environments, particularly those kept in aquariums.
86-502: Poecilioides reticulatus (W. Peters, 1859) The guppy ( Poecilia reticulata ), also known as millionfish or the rainbow fish , 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 family Poeciliidae and, like almost all American members of the family, is live-bearing . Guppies originate from northeast South America, but have been introduced to many environments and are now found all over
172-428: A chimera that might contain two different sets of DNA one XX and the other XY. It could also result from exposure, often in utero, to chemicals that disrupt the normal conversion of the allosomes into sex hormones and further into the development of either ambiguous outer genitalia or internal organs . There is a gene in the Y chromosome that has regulatory sequences that control genes that code for maleness, called
258-511: A WZ system. Some gymnosperms, such as Johann's Pine ( Pinus johannis ), have homomorphic sex chromosomes that are almost indistinguishable through karyotyping . Cosexual angiosperms with either monoecious or hermaphroditic flowers do not have sex chromosomes. Angiosperms with separate sexes (dioecious) may use sex chromosomes or environmental flowers for sex determination. Cytogenetic data from about 100 angiosperm species showed heteromorphic sex chromosomes in approximately half, mostly taking
344-468: A Y. Females in such species receive an X chromosome from each parent while males receive an X chromosome from their mother and a Y chromosome from their father. It is thus the male's sperm that determines the sex of each offspring in such species. However, a small percentage of humans have a divergent sexual development, known as intersex . This can result from allosomes that are neither XX nor XY. It can also occur when two fertilized embryo fuse, producing
430-496: A clean tank, a balanced diet, and regular monitoring can help in preventing these diseases. Ichthyophthirius multifiliis , commonly known as ich, is a protozoan parasite that infects guppies and other freshwater fish. The infection is characterized by white cysts appearing on the skin, gills, and fins of the affected fish, giving a distinct white spot appearance which is often referred to as "white spot disease". The life cycle of Ichthyophthirius multifiliis involves three stages:
516-414: A decrease in reproductive rate and somatic growth rate, and a corresponding increase in juvenile mortality rate due to cannibalism. It was confirmed that in low-predation environments, guppy populations are in part regulated by density. Guppies have the mating system called polyandry , where females mate with multiple males. Multiple mating is beneficial for males because the males' reproductive success
602-410: A full sibling male, a significant bias in paternity towards the unrelated male was observed. Female guppy choice plays an important role in multiple mating. Female guppies are attracted to brightly colored males, especially ones with orange spots on the flank. Orange spots can serve as an indicator of better physical fitness, as orange-spotted males are observed to swim longer in a strong current. There
688-474: A higher risk of being noticed by predators than duller males. Male guppies evolve to be more dull in color and have fewer, smaller spots under intense predation both in wild and in laboratory settings. Female guppies in a high-predation environment also evolve to prefer brightly colored males less, often rejecting them. When guppies encounter a potential predator, some of them approach the predator to assess danger. This behavior, called predator inspection, benefits
774-402: A non-inspector, the inspectors remain at higher risk due to proximity to the predator. Risk-taking behaviors such as predator inspection can be evolutionarily stable only when a mechanism prevents selfish individuals from taking advantage of "altruistic" individuals. Guppies may adopt a conditional-approach strategy that resembles tit for tat . According to this hypothesis, guppies would inspect
860-442: A period of one to six hours. The female guppy has drops of two to 200 fry at a time, though typically ranging between 30 and 60. Well-fed adults do not often eat their own young, although sometimes safe zones are required for the fry. Specially designed livebearer birthing tanks, which can be suspended inside the aquarium, are available from aquatic retailers. These also serve to shield the pregnant female from further attention from
946-639: A range of parasites and one of these, Gyrodactylus turnbulli , has been used as a model system for studying host-parasite interactions . Recent work on this has shown that the interaction between exposure to chronic anthropogenic noise and G. turnbulli can decrease guppy survival. While a short burst of underwater noise has positive effects on parasite densities on the host. Most likely resulting in negative fitness effects for guppies. Wild guppies feed on algal remains, diatoms, invertebrates, zooplankton, detritus, plant fragments, mineral particles, aquatic insect larvae, and other sources. Algal remains constitute
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#17327933248271032-587: A result species have evolved mechanisms to avoid inbreeding. Inbreeding depression is considered to be due largely to the expression of homozygous deleterious recessive mutations. Numerous inbreeding avoidance mechanisms operating prior to mating have been described. However, inbreeding avoidance mechanisms that operate subsequent to copulation are less well known. In guppies, a post-copulatory mechanism of inbreeding avoidance occurs based on competition between sperm of rival males for achieving fertilization. In competitions between sperm from an unrelated male and from
1118-566: A significant increase in mortality at 6 months of age, while those from low-predation environments do not suffer increased mortality until 16 months. However, guppies from high-predation environments were found to have longer lifespans because their reproductive lifespans are longer. No significant difference is seen in postreproductive lifespans. In addition to senescence pattern, resource availability and density also matter in regulation of guppy populations. Guppies reduce their fecundity and reproductive allocation in response to scarce food. When food
1204-506: A typical XX individual (traditional female) and a sex-reversed XX man was that the typical individuals lacked the SRY gene. It is theorized that in sex-reversed XX men, the SRY mistakenly gets translocated to an X chromosome in the XX pair during meiosis . Diverse mechanisms are involved in the determination of sex in animals. For mammals, sex determination is carried by the genetic contribution of
1290-699: A wide variety of colors. The development and exhibiting of color patterns in male guppies is usually due to the amount of thyroid hormone that they contain. The thyroid hormones not only influence color pattern, but control endocrine function in response to their environment. The size of guppies vary, but males are typically 1.5–4 cm (0.6–1.6 in) long, while females are 3–7 cm (1.2–2.8 in) long. A variety of fancy 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
1376-428: Is a common condition which impairs their ability to maintain buoyancy. This condition is associated with the swim bladder, a gas-filled organ that aids fish in remaining buoyant at varying water depths. The symptoms of swim bladder disease are quite distinctive and include difficulty in maintaining buoyancy which causes the fish to either float to the top or sink to the bottom, abnormal swimming patterns such as swimming on
1462-456: Is a prevalent ailment caused by the dinoflagellate parasites of the genus Oodinium . When these parasites attach to a fish's skin, gills, and eyes, they trigger a range of symptoms. Notable symptoms include a fine gold or rust-colored dust appearing on the fish's body, clamped fins, scratching against objects, rapid gill movement due to irritation, decreased feeding, lethargy, and, in advanced stages, respiratory distress. Swim bladder disease
1548-454: Is a process defined as when the type of the sex chromosome changes as a product of a change in the identity of the sex-determining genes (such as by mutation) or by a change in their location. In other cases, sex chromosomes may grow substantially with respect to their ancestral forms as a result of fusion events with autosomes, and autosome-sex chromosome fusions result in what are called neo-sex chromosomes. Five examples of this are now known in
1634-416: Is a term commonly used to refer to fish that are kept in heated aquariums. Freshwater tropical fish are more commonly kept than saltwater tropical fish due to the common availability of fresh water sources, such as tap water, whereas salt water is not commonly available and has to be recreated by using fresh water with sea salt additions. Salt water has to be monitored to maintain the correct salinity because of
1720-557: Is abundant, they increase brood size. Differential reproductive allocation can be the cause of seasonality of life-history characteristics in some guppy populations. For example, during the wet season from May to December, guppies in the Northern Range of Trinidad reduce their investment in reproduction regardless of predation level, possibly in response to decreased food resources. Population density also matters in simpler environments because higher intraspecific competition causes
1806-416: Is also related to age. Older females produce offspring with reduced size and at increased interbrood intervals. One major factor that affects wild guppies' senescence patterns is the mortality rate caused by predation. Guppies from high-predation environments suffer high extrinsic mortality rate because they are more likely to be killed by predators. Female guppies from high-predation environments experience
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#17327933248271892-701: Is also the concept of color association to possibly explain mate choice since one of the food sources wild guppies compete vigorously for is the fruit of cabrehash trees ( Sloanea laurifolia ), an orange carotenoid -containing fruit. The orange coloration that female guppies select for in males is composed of carotenoids, the saturation of which is affected by the male's carotenoid ingestion and parasite load. Guppies cannot synthesize these pigments by themselves and must obtain them through their diet. Because of this connection, females are possibly selecting for healthy males with superior foraging abilities by choosing mates with bright orange carotinoid pigments, thus increasing
1978-434: Is also used as model for the study of sex chromosomes evolution. Based on the phylogenetic topology distribution there are three regions on sex chromosomes. One region that stops recombining in the ancestor of H. lupulus , second that stops recombining in modern H. lupulus and the third region called pseudoautosomal region. H. lupulus is the rare case in plants in which Y is smaller than X, while its ancestor plant has
2064-404: Is always present as the 23rd chromosome in the ovum , while either an X or Y chromosome may be present in an individual sperm . Early in female embryonic development, in cells other than egg cells, one of the X chromosomes is randomly and permanently partially deactivated : In some cells, the X chromosome inherited from the mother deactivates; in other cells, it is the X chromosome inherited from
2150-399: Is determined in a single XY system. In a more complicated system, the sandalwood species Viscum fischeri has X1X1X2X2 chromosomes in females, and X1X2Y chromosomes in males. Amplification of transposable elements, tandom repeats especially accumulation of long tandom repeats ( LTR ) retrotransposones are responsible for plant sex chromosome evolution. The insertion of retrotransposons
2236-714: Is directly related to how many times they mate. The cost of multiple mating for males is very low because they do not provide material benefit to the females or parental care to the offspring. Conversely, multiple mating can be disadvantageous for females because it reduces foraging efficiency and increases the chances of predation and parasitic infection. However, females gain some potential benefits from multiple mating. For example, females that mate multiple times are found to be able to produce more offspring in shorter gestation time, and their offspring tend to have better qualities such as enhanced schooling and predator evasion abilities. Female guppies mate again more actively and delay
2322-502: Is estimated to have arisen only 4000 years ago, post-domestication of the plant. The genetic architecture suggests that either the Y chromosome has an X-inactivating gene, or that the Y chromosome has an X-activating gene. Allosomes not only carry the genes that determine male and female traits, but also those for some other characteristics as well. Genes that are carried by either sex chromosome are said to be sex linked . Sex linked diseases are passed down through families through one of
2408-462: Is its propensity for breeding, and it can breed in both freshwater and marine aquaria. Guppies prefer water temperatures around 22.2–26.1 °C (72–79 °F) for reproduction. Pregnant female guppies have enlarged and darkened gravid spots near their anal vents. Just before birth, the eyes of fry may be seen through the translucent skin in this area of the female's body. When birth occurs, individual offspring are dropped in sequence, typically over
2494-404: Is more complex than that in humans. This is because even flowering plants have a variety of mating systems, their sex determination primarily regulated by MADS-box genes. These genes code for proteins that form the sex organs in flowers. Plant sex chromosomes are most common in bryophytes , relatively common in vascular plants and unknown in ferns and lycophytes . The diversity of plants
2580-452: Is more favored by evolution in populations of guppies under high predation pressure, exerted either by predator type or predator density. Male guppies rely on schooling, in particular the behavioral responses of females, to make antipredator decisions. Coloration of guppies also evolves differentially in response to predation. Male guppies that are brighter in color have an advantage in mating as they attract more females in general, but they have
2666-578: Is preferred in high-predation regions, but not in low-predation regions. When guppies with a high tendency to shoal were isolated from high-predation regions and were relocated to predator-free environments, over time, they decreased their shoaling behavior, supporting the hypothesis that shoaling is less preferred in low-predation environments. Guppies are highly prolific livebearers . The gestation period of guppies varies considerably, ranging from 20 to 60 days at 25 to 27 C and depending on several environmental factors. Reproduction typically continues through
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2752-720: Is probably the major cause of y-chromosome expansion and plant genome size evolution. Retrotransposones contribute in size determination of sex chromosomes and its proliferation varies even in closely related species. LTR and tandom repeats play dominant role in the evolution of S. latifolia sex chromosomes. Athila is new family of retroelements, discovered in Arabidopsis thaliana , present in heterochromatin region only. Athila retroelements overrepresented in X but absent in Y while tandem repeats enriched in Y-chromosome. Some chloroplast sequences have also been identified in
2838-557: Is reflected in their sex-determination systems, which include XY and UV systems as well as many variants. Sex chromosomes have evolved independently across many plant groups. Recombination of chromosomes may lead to heterogamety before the development of sex chromosomes, or recombination may be reduced after sex chromosomes develop. Only a few pseudoautosomal regions normally remain once sex chromosomes are fully differentiated. When chromosomes do not recombine, neutral sequence divergences begin to accumulate, which has been used to estimate
2924-518: Is seeing a gradual rise in their popularity. Many marine tropical fish, particularly those of interest to fishkeepers, are those that live among or in close relation to coral reefs . Coral reefs form complex ecosystems with tremendous biodiversity . Among ocean inhabitants, tropical fish stand out as particularly colorful. Hundreds of species can exist in a small area of a healthy reef, many of them hidden or well camouflaged . Reef fish have developed many ingenious specialisations adapted to survival on
3010-507: Is small in the diets of those guppies. Guppies often forage in groups because they can find food more easily. Shoaling guppies spend less time and energy on antipredatory behavior than solitary ones and spend more time on feeding. However, such behavior results in food that is found being shared with other members of the group. Studies also show when an evolutionary cost exists, guppies that tend to shoal are less aggressive and less competitive with regards to scarce resources. Therefore, shoaling
3096-409: Is sometimes exhibited between male guppies or towards other top swimmers like members of the genus Xiphophorus (platies and swordtails), and occasionally other fish with prominent fins, such as angelfish . Guppies should not be kept as a single fish in an aquarium because both males and females show signs of shoaling , and are usually found in large groups in the wild. Its most famous characteristic
3182-444: Is when both matching genes must be abnormal to cause disease. If only one gene in the pair is abnormal, the disease does not occur, or is mild. Someone who has one abnormal gene (but no symptoms) is called a carrier. A carrier can pass this abnormal gene to his or her children. X chromosome carry about 1500 genes, more than any other chromosome in the human body. Most of them code for something other than female anatomical traits. Many of
3268-452: The SRY gene . This gene produces a testis-determining factor ("TDF"), which initiates testis development in humans and other mammals. The SRY sequence's prominence in sex determination was discovered when the genetics of sex-reversed XX men (i.e. humans who possess biological male-traits but actually have XX allosomes) were studied. After examination, it was discovered that the difference between
3354-504: The X or Y chromosomes. Since usually men inherit Y chromosomes, they are the only ones to inherit Y-linked traits. Men and women can get the X-linked ones since both inherit X chromosomes. An allele is either said to be dominant or recessive . Dominant inheritance occurs when an abnormal gene from one parent causes disease even though the matching gene from the other parent is normal. The abnormal allele dominates. Recessive inheritance
3440-696: The Y-chromosome of S. latifolia . S. vulgaris has more retroelements in their sex chromosomes compare to S. latifolia . Microsatellite data shows that there is no significant difference between X and Y-chromosome microsatellites in both Silene species. This would conclude that microsatellites do not participate in Y-chromosome evolution. The portion of Y-chromosome that never recombine with X-chromosome faces selection reduction. This reduced selection leads to insertion of transposable elements and accumulation of deleterious mutation . The Y become larger and smaller than X due to insertion of retroelement and deletion of genetic material respectively. The genus Humulus
3526-460: The age of sex chromosomes in various plant lineages. Even the oldest estimated divergence, in the liverwort Marchantia polymorpha , is more recent than mammal or bird divergence. Due to this recency, most plant sex chromosomes also have relatively small sex-linked regions. Current evidence does not support the existence of plant sex chromosomes more ancient than those of M. polymorpha . The high prevalence of autopolyploidy in plants also impacts
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3612-477: The autosomes. There is variation even within this system, including UU/V and U/VV chromosome arrangements. In some bryophytes, microchromosomes have been found to co-occur with sex chromosomes and likely impact sex determination. Dioecy is common among gymnosperms , found in an estimated 36% of species. However, heteromorphic sex chromosomes are relatively rare, with only five species known as of 2014. Five of these use an XY system, and one ( Ginkgo biloba ) uses
3698-485: The biggest proportion of wild guppy diet in most cases, but diets vary depending on the specific conditions of food availability in the habitat. For example, a study on wild Trinidad guppies showed that guppies collected from an oligotrophic upstream region (upper Aripo River) mainly consumed invertebrates, while guppies from a eutrophic downstream region (lower Tacarigua River ) consumed mostly diatoms and mineral particles. Algae are less nutritious than invertebrates, and
3784-457: The bred-in-captivity species, the most expensive freshwater species include arowanas and flowerhorn cichlids . Some male flowerhorns are sterile due to many cross breedings. Marine fish that are sold as tropical fish are generally sourced from the wild, usually from the coral reefs around the world. This is because only a few species of marine fish have been successfully bred in captivity with any regularity. The price of marine fish coupled with
3870-596: The bryophytes, including liverworts, hornworts and mosses, sex chromosomes are common. The sex chromosomes in bryophytes affect what type of gamete is produced by the gametophyte, and there is wide diversity in gametophyte type. Unlike seed plants, where gametophytes are always unisexual, in bryophytes they may produce male, female, or both types of gamete. Bryophytes most commonly employ a UV sex-determination system, where U produces female gametophytes and V produces male gametophytes. The U and V chromosomes are heteromorphic with U larger than V and are frequently both larger than
3956-453: The common name even as Girardinus guppii is now considered a junior synonym of Poecilia reticulata . Guppies are native to Antigua and Barbuda , Barbados , Brazil , Guyana , Trinidad and Tobago , and Venezuela . 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
4042-403: The courtship dance, called sigmoid display, in which the males flex their bodies into an S shape and vibrate rapidly. Female mating choice may also be influenced by another female's choice. In an experiment, female guppies watched two males, one solitary and the other actively courting another female, and were given a choice between the two. Most females spent a longer time next to the male that
4128-451: The development of a brood when the anticipated second mate is more attractive than the first male. Experiments show that remating females prefer a novel male to the original male or a brother of the original male with similar phenotypes . Females' preference for novel males in remating can explain the excessive phenotypic polymorphism in male guppies. Inbreeding ordinarily has negative fitness consequences ( inbreeding depression ), and as
4214-415: The difficulty in keeping them alive in aquaria makes them less of a popular choice for aquarists to keep. However, because of the more vivid colours, patterns and behaviour of marine fish compared to freshwater fish, they are still reasonably popular. The advances in filtration technology and increase in available knowledge on how to maintain marine fish as well as the increasing number of aquarium-bred species
4300-669: The effects of evaporation. Freshwater tropical aquariums can be maintained by simply topping up with fresh water. Tropical fish are popular choices for aquariums due to their often bright coloration, which typically derives from both pigmented cells and iridescent cells. Tropical fish may include wild-caught specimens, individuals born in captivity including lines selectively bred for special physical features, such as long fins, or particular colorations, such as albino . Some fish may be hybrids of more than one species. Most fish that are sold as tropical fish are freshwater species. Most species available are generally bred from fish farms in
4386-457: The far east and Florida where tropical temperatures make the commercial production more viable. Mass production of tropical fish from farms has led to many inexpensive fish available to aquarists. Tropical freshwater fish are the most popular group of fish because of the low price and ease of keeping in aquaria. Some species are difficult to breed in captivity and so are still sourced from the wild. These species are generally more expensive. Among
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#17327933248274472-611: The father. This ensures that both sexes always have exactly one functional copy of an X chromosome in each body cell. The deactivated X chromosome is silenced by repressive heterochromatin that compacts the DNA and prevents expression of most genes. This compaction is regulated by PRC2 (Polycomb Repressive Complex 2). All diploid organisms with allosome-determined sex get half of their allosomes from each of their parents. In most mammals, females are XX, and can pass along either of their Xs; since males are XY they can pass along either an X or
4558-483: The female shows receptive behavior following the male's courtship display, the male briefly inserts the gonopodium into the female's genital pore for internal fertilization. However, in the case of sneaky mating where copulation is forced , the male approaches the female and thrusts the gonopodium at the female's urogenital pore. Once inseminated, female guppies can store sperm in their ovaries and gonoducts, which can continue to fertilize ova up to eight months. Because of
4644-624: The fish have become less hardy than their wild counterparts. Immense inbreeding of guppies has been found to affect body size, fertility and susceptibility to diseases. Guppies prefer a hard-water aquarium with a temperature between 25.5 and 27.8 °C (78 and 82 °F) and salt levels equivalent to one tablespoon per 19 L (5 US gal). They can withstand levels of salinity up to 150% that of normal seawater , which has led to them being occasionally included in marine tropical community tanks, as well as in freshwater tropical tanks. Guppies are generally peaceful, though nipping behaviour
4730-527: The form of XY sex-determination systems. Their Y is typically larger, unlike in humans; however there is diversity among angiosperms. In the Poplar genus ( Populus ) some species have male heterogamety while others have female heterogamety. Sex chromosomes have arisen independently multiple times in angiosperms, from the monoecious ancestral condition. The move from a monoecious to dioecious system requires both male and female sterility mutations to be present in
4816-486: The fry when they are born. Young fry take roughly three or four months to reach maturity. Feeding fry live foods, such as baby brine shrimp , microworms , infusoria and vinegar eels , is recommended. Alternatives include finely ground flake food, egg yolk, and liquid fish food, though the particulates in these may be too large for the youngest fry to eat. Guppies are susceptible to various diseases, which may stem from bacterial, parasitic, or fungal infections. Maintaining
4902-427: The guppies that feed mainly on algae have poor diets. Guppies have also been observed eating native fishes' eggs, occasionally expressing cannibalism, also eating its own young, when kept in laboratory conditions. Guppies' diet preference is not simply correlated to the abundance of a particular food. Laboratory experiments confirmed that guppies show 'diet switching' behavior, in which they feed disproportionately on
4988-451: The guppies' head instead of their body's center of mass. Perhaps counterintuitively, this predator divertive behavior allows guppies to rapidly pivot out of the way as predators lunge where the guppies' head was; this "matador-like" anti-predator behavior was first described in guppies but may be found in other animal species with bright, attention-grabbing coloration located on vital organs, such as epaulette sharks . Guppies are also host to
5074-512: The hybrids are always male and appear to be infertile. The guppy has also been hybridised with the Endler's livebearer ( Poecilia wingei ) to produce fertile offspring, with the suggestion that, despite physical and behavioural differences, Endler's may represent a subspecies of Poecilia reticulata rather than a distinct species. Due to the extensive selective breeding of guppies for desirable traits such as greater size and colour, some strains of
5160-409: The inspector since it gains information, but puts the inspector at a risk of predation. To reduce the risk, inspectors avoid the predator's mouth area—called the 'attack cone'—and approach the predator from the side or back. They may also form a group for protection, the size of which is larger in high-predation populations. Although evidence indicates predators are less likely to attack an inspector than
5246-615: The males, which is important because the males sometimes attack the females while they are giving birth. It also provides a separate area for the newborn young as protection from being eaten by their mother. However, if a female is put in the breeder box too early, it may cause her to have a miscarriage. Well-planted tanks that offer barriers to adult guppies shelter the young quite well. Guppy grass , water sprite , water wisteria , duckweed , water lettuce and java moss are all good choices. A continuous supply of live food, such as Daphnia or brine shrimp , keep adult fish full and may spare
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#17327933248275332-407: The more abundant food when they are offered two food choices. The result shows that different groups of guppies have weak and variable food preference. Diet preference in guppies could be related to factors such as the presence of competitors. For example, the lower Tacarigua River has a larger variety of species and competition for invertebrate prey is higher; therefore, the proportion of invertebrates
5418-827: 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. 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 environments. They tend to be more abundant in smaller streams and pools than in large, deep, or fast-flowing rivers. They also are capable of being acclimated to full saltwater like their molly cousins. Guppies exhibit sexual dimorphism . While wild-type females are grey in body colour, males have splashes, spots, or stripes that can be any of
5504-403: The non-sex determining X-linked genes are responsible for abnormal conditions. The Y chromosome carries about 78 genes. Most of the Y chromosome genes are involved with essential cell house-keeping activities and sperm production. Only one of the Y chromosome genes, the SRY gene, is responsible for male anatomical traits. When any of the 9 genes involved in sperm production are missing or defective
5590-717: The onset and progression of the disease, as they create an environment conducive for bacterial growth and can compromise the fish's immune system. Columnaris , also known as cotton mouth disease or cotton wool disease, is a common bacterial infection in guppies and other freshwater fish, caused by the bacterium Flavobacterium columnare . This bacterium thrives in warm, freshwater environments. Treatment for columnaris should commence promptly to prevent severe mortality. Common treatment measures include: improving water quality, antibacterial medications such as kanamycin , erythromycin , or oxytetracycline , and in extreme cases, antibiotic injections. Velvet , also known as gold dust disease,
5676-442: The population. Male sterility likely arises first as an adaptation to prevent selfing. Once male sterility has reached a certain prevalence, then female sterility may have a chance to arise and spread. In the domesticated papaya ( Carica papaya ), three sex chromosomes are present, denoted as X, Y and Y . This corresponds with three sexes: females with XX chromosomes, males with XY, and hermaphrodites with XY . The hermaphrodite sex
5762-427: The predator on the first move, but if their co-inspectors do not participate in the predator inspection visits or do not approach the predator close enough, they can retaliate by copying the defector's last move in the next predator inspection visit. The hypothesis was supported in laboratory experiments. When guppies detect a predator, their irises rapidly darken from silver to jet black, which draws predators to attack
5848-508: The reefs. Some recreational scuba divers keep lists of fish species they have observed while diving, especially in tropical marine environments. Coral reefs occupy less than 1% of the surface area of the world oceans, yet they provide a home for 25% of all marine fish species. Reef habitats are a sharp contrast to the open water habitats that make up the other 99% of the world's oceans. However, loss and degradation of coral reef habitat, increasing pollution , and overfishing including
5934-404: The result is usually very low sperm counts and infertility. Examples of mutations on the X chromosome include more common diseases such as the following: Other complications include: Sex chromosomes evolve from standard pairs of autosomal chromosomes. In a large number of organisms, the sex-determination systems presently observed are products of sex chromosome turnover. Sex chromosome turnover
6020-415: The same genes (regions of DNA) in the same order along their chromosomal arms. The 23rd pair of chromosomes are called allosomes. These consist of two X chromosomes in females, and an X chromosome and a Y chromosome in males. Females therefore have 23 homologous chromosome pairs, while males have 22. The X and Y chromosomes have small regions of homology called pseudoautosomal regions . An X chromosome
6106-472: The same form in a diploid cell , members of an allosome pair may differ from one another. Nettie Stevens and Edmund Beecher Wilson both independently discovered sex chromosomes in 1905. However, Stevens is credited for discovering them earlier than Wilson. In humans, each cell nucleus contains 23 pairs of chromosomes, a total of 46 chromosomes. The first 22 pairs are called autosomes . Autosomes are homologous chromosomes i.e. chromosomes which contain
6192-406: The same size of both X and Y chromosomes. This size difference should be caused by deletion of genetic material in Y but that is not the case. This is because of complex dynamics like the larger size of X than Y-chromosome may be due to duplication or retrotransposition and size of Y remains same. Ferns and lycophytes have bisexual gametophytes , so there is no evidence for sex chromosomes. In
6278-468: The side or upside down, and a bloated appearance or a visibly enlarged belly. Several factors can contribute to the onset of swim bladder disease. Overfeeding is a common cause, leading to constipation which may press against the swim bladder. Bacterial or viral infections affecting the swim bladder can also trigger this condition. Physical injury or congenital deformities of the swim bladder are other potential causes. Tropical fish Tropical fish
6364-422: The sperm-storage mechanism, males are capable of posthumous reproduction, meaning the female mate can give birth to the male's offspring long after the male's death, which contributes significantly to the reproductive dynamics of the wild guppy populations. The guppy has been successfully hybridised with various species of molly ( Poecilia latipinna or P. velifera ), e.g., male guppy and female molly. However,
6450-492: The spermatozoon. Many lower chordates, such as fish, amphibians and reptiles, have systems that are influenced by the environment. Fish and amphibians, for example, have genetic sex determination but their sex can also be influenced by externally available steroids and incubation temperature of eggs. In some reptiles, e.g. sea turtles , only the incubation temperature determines sex ( temperature-dependent sex determination ). Many scientists argue that sex determination in plants
6536-413: The structure of their sex chromosomes. Polyploidization can occur before and after the development of sex chromosomes. If it occurs after sex chromosomes are established, dosage should stay consistent between the sex chromosomes and autosomes, with minimal impact on sex differentiation. If it occurs before sex chromosomes become heteromorphic, as is likely in the octoploid red sorrel Rumex acetosella , sex
6622-438: The survival chance of her offspring. Due to the advantage in mating, male guppies evolve to have more ornamentation across generations in low-predation environments where the cost of being conspicuous is lower. The rate and duration of courtship display of male guppies also play an important role in female guppies' mating choice. Courtship behavior is another indicator of fitness due to the physical strength involved in maintaining
6708-551: The trophont stage, the tomont stage, and the theront stage. Fin rot is primarily caused by bacterial infections, although fungal infections can also be a culprit. The condition manifests through the progressive decay or fraying of the fins, often accompanied by discoloration, usually turning the edges of the fins white, black, or red. The primary causative agents of fin rot are gram-negative bacteria such as Pseudomonas fluorescens and Aeromonas hydrophila . Poor water quality, overcrowding, and stress are significant contributors to
6794-554: The use of destructive fishing practices , are threatening the survival of the coral reefs and the associated reef fish. Sex chromosomes Sex chromosomes (also referred to as allosomes , heterotypical chromosome, gonosomes , heterochromosomes , or idiochromosomes ) are chromosomes that carry the genes that determine the sex of an individual. The human sex chromosomes are a typical pair of mammal allosomes. They differ from autosomes in form, size, and behavior. Whereas autosomes occur in homologous pairs whose members have
6880-770: The wild varies greatly, but it is typically around 2 years. Variations in such life historic characteristics of guppies are observed in different populations, indicating that different evolutionary pressures exist. Guppies' body sizes are positively correlated with age, and their size at maturation varies highly depending on the predation risk of the occupied environments. Male and female guppies from high-predation regions mature faster and start reproducing earlier, and they devote more resources to reproduction than those from low-predation regions. Females from high-predation regions reproduce more frequently and produce more offspring per litter, indicating that they are more fecund than low-predation females. Female guppies' reproductive success
6966-430: 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. Guppies have 23 pairs of chromosomes , including one pair of sex chromosomes , the same number as humans. The genes responsible for male guppies' ornamentations are Y-chromosome linked and are heritable . Two generations of guppies per year occur in
7052-651: 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 anti-predator tactics . Brood size is extremely variable, yet some consistent differences exist among populations depending on the predation level and other factors. 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. Total lifespan of guppies in
7138-697: The world. They are highly adaptable and thrive in many different environmental and ecological conditions. Male guppies, which are smaller than females, have ornamental caudal and dorsal fins . 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 fields of ecology , evolution , and behavioural studies . Guppies were first described in Venezuela as Poecilia reticulata by Wilhelm Peters in 1859 and as Lebistes poecilioides in Barbados by De Filippi in 1861. It
7224-416: The year, and the female becomes ready for conception again quickly after parturition . Male guppies, like other members of the family Poeciliidae , possess a modified tubular anal fin called the gonopodium , located directly behind the ventral fin . The gonopodium has a channel-like structure through which bundles of spermatozoa , called spermatozeugmata, are transferred to females. In courted mating, where
7310-507: Was courting. Female guppies' preference for fit males allows their descendants to inherit better physical fitness and better chance of survival. Guppies have many predators, such as larger fish and birds, in their native range. Some of their common predators in the wild are Crenicichla alta , Anablepsoides hartii , and Aequidens pulcher . Guppies' small bodies and the bright coloration of males make them easy prey, and like many fish, they often school together to avoid predation. Schooling
7396-571: Was named Girardinus guppii by Albert Günther in honor of Robert John Lechmere Guppy , who sent specimens of the species from Trinidad to the Natural History Museum in London. It was reclassified as Lebistes reticulatus by Regan in 1913. Then in 1963, Rosen and Bailey brought it back to its original name, Poecilia reticulata . While the taxonomy of the species was frequently changed and resulted in many synonyms, "guppy" remains
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