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Tropical Clawed Frog

Xenopus tropicalis (Gray 1864)

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Description

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Typical body shape of a pipid frog; tentacle below the eye that is 0.5 times the length of the eye diameter; foot with four horny claws. A small clawed frog with small protruding eyes located almost on the top of the head. Body flattened. SVL of mature specimens 28-40 mm. A small tentacle below the eye barely reaches 0.3 to 0.5 times the lenght of the eye diameter. No visible tympanum. The skin is finely granular. Starting at the posterior border of the eye, a double line of elongate, vaguely alternating and unpigmented dermal tubercles stretch along the flanks,that are though to be lateral line sense organs; sensual tubercles according to Vigny (1977). The outer line comprises 18 - 20 tubercles arranged at right angles to the body axis, whereas the 15-16 inner tubercles run parallel to this. 3-4 additional tubercles are situated in the neck region, and the inferior border of the lower jaw also bears 9-11 tubercles. Numerous unpigmented wart-like dermal elevations are scattered across the jaw and the dorsum. They are also present on the digits which are not broadened at all, so that the skin appears scaly. On breeding males, the outer parts of the fingers are blackish. The dermal lobes situated above the vent are better developed in females. The hind limbs are fully webbed. They have 3-5 toes with black horny claws. The inner metatarsal tubercle has been transformed into a fourth claw. The SVL is 45 mm according to Arnold & Lamotte (1968), whereas Fischberg et al. (1982) indicate 32-39 mm for adult males (x = 36 mm) and 48-55 mm for adult females (x = 50 mm). According to the latter authors, 3-7 (x= 4.5) sensory tubercles are arranged around the eyes. Noble (1924) report on a 56 mm long specimen, but his specimens were composite, including X. fraseri. Frétey & Dewynter (1998) cite a 42mm specimen from Gabon (but compare "range"). Dorsal parts of body and limbs light to dark brown with numerous fine gray and black spots which never form larger spots. The iris is yellowish. Venter whitish to yellowish, vaguely mottled with black. Some specimens have scattered black dots on the white belly, which become more numerous on the hind limbs. Arnoult & Lamotte (1968) report on beige ventral surfaces bearing brown spots, and Böhme (1994c) figures a specimen whose belly is vaguely spotted. Perret (1966) mentions frogs from Cameroon bearing yellow vertebral stripes on their neck regions. However, it is rather doubtful whether these animals are really X. tropicalis. Loveridge (1955a) reports on a cream-pink female whose belly showed irregular mottling. Coloration in alcohol corresponds largely to live coloration. In most cases, neither the black dots of the dorsum nor the mottled pattern of the venter remain visible in alcohol, and animals generally become beige-gray to brown, the belly and the ventral parts of the limbs become white. One female turned totally black, and the black claws of another specimen turned white.This account was taken from Rödel, M.-O. (2000). Herpetofauna of West Africa vol. I. Amphibians of the West African Savanna. with kind permission from Edition Chimaira (http://www.chimaira.de/) publishers, Frankfurt am Main.

References

  • Arnoult, J. and Lamotte, M. (1968). ''Les Pipidae de l'Ouest africain et du Cameroun.'' Bulletin de l’Institut fondamental d’Afrique noire, Série A, 30, 270-306.
  • Barbour, T. and Loveridge, A. (1930). ''Reptiles and amphibians from Liberia.'' The African Republic of Liberia and the Belgian Congo, based on the observations made and material collected during the Harvard African Expedition 1926-1927, Vol. 2. R. P. Strong, eds., Greenwood Press, New York, 769-786.
  • Bergerard, Y. and Lamotte, M. (1949). ''L'emploi d'un crapaud Ouest-Africain, Xenopus tropicalis (Gray) (X. calcaratus Peters) pour le diagnostic de la grossesse.'' Notes Africaines, Dakar, 41, 25-26.
  • Bougart, R., Roure, C. and Kulo, S.-D. (1996). ''Nouvelles donnees sur les Trematodes d'amphibiens d'Afrique Occidentale. Description d'Haematoloechus aubriae n. sp.'' Revue Suisse de Zoologie, 103, 383-394.
  • Böhme, W. (1994). ''Frösche und Skinke aus dem Regenwaldgebiet Südost-Guineas, Westafrika. I. Einleitung; Pipidae, Arthroleptidae, Bufonidae.'' Herpetofauna, 16(92), 11-19.
  • Böhme, W., Meinig, H. and Rödel, M.-O. (1996). ''New records of amphibians and reptiles from Burkina Faso and Mali.'' British Herpetological Society Bulletin, 55, 7-26.
  • Euzet, L., Combaz, C. and Knoepffler, L.-P. (1966). ''Parasites d'amphibiens du Gabon: Polystomatidae (Monogenea).'' Biologia Gabonica, 2, 215-233.
  • Euzet, L., Combaz, C., and Knoepffler, L.-P. (1969). ''Parasites d'amphibiens de Cote d'Ivoire et du Liberia: Polystomatidae (Monogenea).'' Biologia Gabonica, 3, 217-221.
  • Fischberg, M., Colombelli, B. and Picard, J.-J. (1982). ''Diagnose preliminaire d'une espece nouvelle de Xenopus du Zaire.'' Alytes, 1(4), 53-55.
  • Fretey, T. and Dewynter, M. (1998). ''Amphibiens anoures de la Forêt des Abeilles (Gabon).'' Journal of African Zoology, 112(3), 171-184.
  • Frost, D. R. and Savage, J. M. (1987). ''Gender of Hemisus and correct formation of the family-group name.'' Journal of the Herpetological Association of Africa, 33, 24.
  • Gruschwitz, M., Lenz,S. and Böhme, W. (1991). ''Zur Kenntnis der Herpetofauna von Gambia (Westafrika), Teil 2: Schlangen (Reptilia, Serpentes), herpetofaunistische Bewertung.'' Herpetofauna, 13(75), 27-34.
  • Guibé, J. and Lamotte, M. (1958). ''Les Ptychadena (Batraciens, Ranides) du Cameroun.'' Bulletin de l’Institut fondamental d’Afrique noire. Série A, 20(4), 1448-1463.
  • Hellsten, U., Harland, R. M., Gilchrist, M. J., and others (2010). ''The Genome of the Western Clawed Frog Xenopus tropicalis.'' Science, 328, 633-636.
  • Hulselmans, J. L. J. (1970). ''Preliminary notes on African Bufonidae.'' Revue de Zoologie Africaine, 81, 149-155.
  • Joger, U. (1982). ''Zur Herpetofaunistik Kameruns (II).'' Bonner Zoologische Beiträge, 33(2-4), 313-342.
  • Jones, S. (1991). ''The Gambian Dwarf Crocodile project, preliminary report 1990.'' South Western Herpetological Society, 2, 11-17.
  • Knoepffler, L.-P. (1967). ''Description du tetard de Bufo camerunensis camerunensis (Parker, 1936).'' Biologia Gabonica, 3, 403-406.
  • Kobelt, F. and Linsenmair, K. E. (1986). ''Adaptations of the Reed Frog Hyperolius viridiflavus (Amphibia: Anura: Hyperoliidae) to its arid environment, I. The skin of Hyperolius viridiflavus nitidulus in wet and dry season conditions.'' Oecologia, 68, 533-541.
  • Lamotte, M. (1967). ''Le problème des Ptychadena (fam. Ranidae) du groupe mascareniensis dans l'Ouest Africain.'' Bulletin du Muséum National d’histoire Naturelle, Série 2, 39(4), 647-656.
  • Lamotte, M. (1969). ''Le parc national du Niokolo–Koba, Fasciule III; XXX. Amphibiens (deuxième note).'' Mémoires de l'Institut fondamental d'Afrique noire, 84, 420-426.
  • Lamotte, M. (1977). ''Tendances adaptives à l'affranchissement du milieu aquatique chez les amphibiens anoures.'' La Terre et la Vie, 31, 225-311.
  • Lamotte, M. (1985). ''Les amphibiens a têtards torrenticoles dans l'Ouest Africain.'' Notes Africaines, 187, 88-92.
  • Laurent, R.F. (1953). ''Une méthode pour la recherche des meilleurs caractères taxonomiques fournis par les proportions.'' Annales de la Société Royale Zoologique de Belgique, 84, 271-282.
  • Laurent, R.F. (1961). ''Notes on some South African amphibians.'' Publications de l'Université de l'État à Élisabethville, 1, 197-209.
  • Loumont, C. (1983). ''Deux espèces nouvelles de Xenopus du Cameroun (Amphibia, Pipidae).'' Revue Suisse de Zoologie, 90, 169-177.
  • Loumont, C. (1984). ''Current distribution of the genus Xenopus in Africa and future prospects.'' Revue Suisse de Zoologie, 91, 725-746.
  • Loumont, C. (1986). ''Xenopus pygmaeus, a new diploid pipid frog from rain forest of equatorial Africa.'' Revue Suisse de Zoologie, 93(33), 735-764.
  • Loveridge, A. (1941). ''Report on the Smithsonian-Firestone expedition collection of reptiles and amphibians from Liberia.'' Proceedings of the United States National Museum, 91(3128), 113-140.
  • Loveridge, A. (1955). ''Amphibian additions to the Gold Coast herpetofauna.'' Copeia, 1955(3), 257-258.
  • Maeder, A.-M., Combaz, C. and Knoepffler, L.-P. (1969). ''Parasites d'amphibiens du Gabon: Mesocoeliidae (Digenea). Taxonomie et chronologie du genre Mesocoelium Odhner, 1911.'' Biologia Gabonica, 5, 283-288.
  • Maesey, G.J. and Tinsley, R.C. (1997). ''Mating behaviour of Xenopus wittei (Anura: Pipidae).'' Copeia, 1997(3), 601-609.
  • Measey, G.J. and Tinsley, R.C. (1998). ''Feral Xenopus laevis in South Wales.'' Herpetological Journal, 8, 23-27.
  • Mertens, R. (1939). ''Über das Hohenvorkommen der Froschlurche am Grossen Kamerun-Berge.'' Abhandlungen und Berichte des Museums für Naturkunde, Magdeburg, 7, 121-128.
  • Nieden, F. (1908). ''Die Amphibienfauna von Kamerun. Mit einer Bestimmungstabelle.'' Mitteilungen des zoologischen Museums Berlin, 3, 489-518.
  • Nieden, F. (1910). ''Neue Reptilien und Amphibien aus Kamerun.'' Arkiv für Naturgeschichte, 76(1), 234-246.
  • Nieden, F. (1910). Die Fauna der deutschen Kolonien, Reihe I Kamerun, Heft 2 Die Reptilien (außer den Schlangen) und Amphibien. Friedländer and Sohn, Berlin.
  • Nieden, F. (1915). ''Neues Verzeichnis der Kriechtiere (außer den Schlangen) von Deutsch-Ostafrika. II. Teil: Amphibia.'' Mitteilungen des zoologischen Museums Berlin, 7, 345-390.
  • Noble, G.K. (1926). ''The importance of larval characters in the classification of South African Salientia.'' American Museum Novitates, 237, 1-10.

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Distribution and Habitat

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So far, this species has been found mainly in rainforest regions, a fact which explains its presence in the gallery forests of the Comoé National Park. These habitats are immediately connected with the proper coastal rainforest belt by the river Comoé. According to Lamotte (1966), it is restricted to the West African rainforest belt, but Böhme et al. (1996) report on a population in Burkina Faso, i.e. in arid continental West Africa. According to Frost (1985), X. tropicalis inhabits the forest regions of West Africa, i.e. an area stretching from Senegal to Cameroon and eastern Zaire. However, Loumont (1983) maintains that the range of this species just includes the western part of the above-mentioned region (from Senegal to western Cameroon), the southern and eastern sector being occupied by X. epitropicalis. The river Sanaga separates the ranges of the species. The frogs occurring on the islands of Fernando Póo, Principe, Sao Tomé and Annobón represent the species Xenopus andrei (Loumont 1983). According to Laurent (1952e), Gorham (1966) and Schiøtz (1967), the range of X. tropicalis also includes Angola. In particular, this species has been recorded from the following countries: Senegal, Gambia, Guinea Bissau, Sierra Leone, Liberia, Guinea, Burkina Faso, Ivory Coast, Ghana, Togo, Benin, Nigeria, Cameroon, Gabon, Congo, R.D. Congo, Angola; reported in the following references: Peters (1875) , (1876) , (1877) , Müller (1885b) , Johnston (1906) , Nieden (1908) , (1910a) , (b) , Noble (1924) , Barbour & Loveridge (1930a) , Witte (1934) , Parker (1936a) , (c) , Sanderson (1936) , Mertens (1938b) , Loveridge (1941) , (1955a) , Laurent (1952e) , (1961b) , Romer (1953) , Guibé & Lamotte (1958a) , Taylor & Weyer (1958) , Schiøtz (1963) , (1964a) , (b) , (1967) , Euzet et al. (1966) , (1969) , Gorham (1966) , Perret (1966) , Knoepffler (1967) , Lamotte (1967b) , (1971), 1998, Arnoult & Lamotte (1968) , Walker (1968) , Maeder (1969) , Vigny (1977b) , (1979) , Joger (1981) , Loumont (1983) , (1984) , Böhme 1987, (1994c) , Hughes (1988) , Gruschwitz et al. (1991a) , Böhme et al. (1996) , Bourgat et al. (1996) , Pauwels & Meirte (1996) , Rödel (1996) , (1998b) , Frétey & Dewynter (1998) . At Comoé National Park, this species is mainly restricted to pools in the gallery forests. However, some populations are found in savanna ponds not too far away from those forests. This species is generally considered a forest-dweller, as cited in: Loveridge (1955a), Perret (1966), Lamotte (1967b), Schiøtz (1967), Arnoult & Lamotte (1968), Hughes (1988). Böhme (1994c)). In this habitat, it occupies still and slow-running waters. Noble (1924) cites shallow brooks that drain the rain forest. The presence of this species in the savanna has also been reported by Lamotte (1967b), Schiøtz (1963) and Joger (1981). Walker (1968) even found it, alhough rather rarely, in temporary ponds of the northern Guinea and Sudan savannas.
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Life History, Abundance, Activity, and Special Behaviors

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Voice: In the Comoé National Park, no calls have been registered so far. According to Vigny (1979), the call of other specimens from Ivory Coast can be characterized as a rather low, vibrating thrill lasting about 1-10.5 sec whose dominant frequency is around 1 kHz, and which vaguely sounds like "rooa" or "roa ooa". Eggs: No eggs have been found so far in the national park. According to Arnoult & Lamotte (1968), single eggs are attached to the stems and leaves of aquatic plants. Swisher (1969) reports on couples turning over in the water while spawning, similar to Pipa pipa. He wrote that the eggs remain at the water surface. Tadpoles: A typical pipid tadpole with a broad mouth, quite similar to that of a catfish. No jaws or keradonts (denticles). Long thin tentacles arise on the upper lip on both sides of the mouth, reaching the dorsal inset of the tail fin when held against the body. The ventral fin is considerably broader than the dorsal one. The fin is only slightly convex between body and vent. Tadpoles found in clear-water forest pools are generally orange to flesh-colored with almost transparent tail fins whose lower margins are often black. In rather somber habitats, the fin is blackish. One paired spiracle on the venter. Measured and weighed specimens showing no trace of limbs brought the following results (TL in mm, weight in g): 23/0.12; 27/0.18; 31/0.22. The forelimbs emerge at a BL of approx. 17 mm (TL:42-46 mm). Metamorphosis begins when the tadpoles measure less than 5 cm (TL). Young larvae are found throughout the rainy season. In 1992, we found the first tadpoles in early May. Two weeks later, all the animals had developed hind limbs, and their forelimbs were beginning to emerge. When the latter were present, their BL was 12.2-15.5 mm (TL: 44 mm). The last frogs had metamorphosed within one month, showing then a SVL of 11.5 to 15.5 mm. According to Arnoult & Lamotte (1968) , tadpoles measuring 6 mm still bear external gills but do not bear any tentacles. When the forelimbs had emerged, their TL was 49-52 mm (BL: 31-44 mm). However, these data sharply contradict the size at which the tadpoles are said to metamorphose (SVL: 14.4 mm). Altig & Johnston (1986) refer to this description. In the analysis of diverse pipid larvae, Sokol (1977) also examined X. tropicalis tadpoles. During the dry season, X. tropicalis migrates from its breeding sites to the riverbanks where it spends the day under flat stones, in holes in the banks or under roots. At night, this species is occasionally found in small rock-pools. Other authors also report that this species spends all of the year in its water habitats, as referred to in Guibé & Lamotte (1958a) , Perret (1966) , Lamotte (1967b) . If this proves to be impossible, the frogs will burrow into the mud (Arnoult & Lamotte 1968) or seek refuge in humid litter (Schiotz 1963). As soon as the rainy season sets in, the frogs migrate to the forests. Looking for appropriate spawning sites, they even colonize tiny water bodies, e.g. the buckets filled with washing water we usually put in front of our huts. At night, during periods of heavy rainfall, X. tropicalis occasionally covers considerable distances beyond its preferred habitat. On these excursions, it sometimes succeeds in colonizing savanna ponds in close vicinity to the gallery forest. Tadpoles are found exclusively in large forest pools most of which harbor abundant vegetation of floating plants and clear water during the rainy season. Yet X. tropicalis equally inhabits rather muddy ponds that lack any vegetation. At Tai National Park I regularly recorded X. tropicalis tadpoles in water filled holes of the dwarf crocodile (Osteolaemus tetraspis). During the day the adult frogs hide under dead trunks in shallow water. At night they forage for food all over the water. Their diet comprises any animal prey they are able to overwhelm. Prey landing on the surface of the pools is also devoured (Romer 1953). New observations on X. laevis showed that platannas are able to feed terrestrially, from the pond bank, as well as underwater (Measey 1998) . Earthworms, insect larvae and tadpoles are reported to form the bulk of their diet as seen in Loveridge (1955a) , Guibé & Lamotte (1958a) , and Arnoult & Lamotte (1968) . Noble (1924) wrote that prey mostly consists of arthropods but recorded tadpoles in the stomach of adult X. tropicalis, as well. Their prey is sucked into the broad mouth and crammed in by means of the forelimbs. According to other authors, X. tropicalis is a purely aquatic species inhabiting permanent waters floating regularly at the surface and retiring if necessary into the dense vegetation (Johnston 1906) . Gruschwitz et al. (1991a) found this species throughout the year in small ponds near the riverside. Other habitats mentioned in the literature comprise small muddy ponds within and beyond the forest belt as seen in Guibé & Lamotte (1958a) , Joger (1981) and stagnant waters in secondary and tertiary forests (Sanderson 1936) . Arnoult and Lamotte (1968) expressly exclude running waters as potential habitats. However, Böhme (1995) found this species in fast-running spring brooks in Senegal. Amplexus is inguinal. They attach their eggs to aquatic plants. Tadpoles are found at Comoé National Park throughout the rainy season. According to Böhme (1994c) , in certain residuary rainforests of Guinea the frogs collected in July are exclusively freshly metamorphosed young, whereas those caught in October are generally adult ones. According to Guibé & Lamotte (1958a) and Arnoult & Lamotte (1968) , the frogs spawn from July to August. At Mt. Nimba, metamorphosis is reported to take place in November (an observation which contradicts the observations made by Böhme). In the vicinity of Lamto, Ivory Coast, froglets were found in May, December and January, whereas tadpoles are reported to occur throughout the year (Lamotte 1967b) , here, most tadpoles were found in ponds in the gallery forests. At Comoé National Park, the tadpoles are often restricted to certain sections of the ponds, and they always form huge swarms in open water, whenever possible in sunlit sectors of the ponds. Almost parallel to each other, the tadpoles either swim on the spot, filtering the water with their heads pointing downward, or they will move forward rather slowly, regulating their positions by rotating movements of the tips of their tails. According to my experiments, these swarms are formed even if no predators are present. A phenomenon which contrasts with that shown by the tadpoles of Phrynomantis microps Rödel & Linsenmair (1997). As all tadpoles in a swarm are of similar size, one might assume that they are close relatives.
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Relation to Humans

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Like Xenopus laevis, X. tropicalis was formerly used in pregnancy tests (Bergerard & Lamotte 1949). The genome of X. tropicalis has been sequenced (Hellsten et al. 2010). This is the first amphibian genome to be sequenced, enabling new insights into vertebrate evolution and the last common ancestor of tetrapods. Despite amphibians having diverged about 360 mya from mammals, birds, and reptiles, Hellsten et al. (2010) report that there is considerable sequence and gene order conservation. However, mammalian genomes have undergone far more chromosomal rearrangements. Many aspects of the vertebrate immune system are conserved, but unique to the amphibian genome are genes that code for antimicrobial peptides.
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Western clawed frog

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The western clawed frog (Xenopus tropicalis) is a species of frog in the family Pipidae, also known as tropical clawed frog.[2] It is the only species in the genus Xenopus to have a diploid genome.[3][4] Its genome has been sequenced,[5][6] making it a significant model organism for genetics that complements the related species Xenopus laevis (the African clawed frog),[7] a widely used vertebrate model for developmental biology. X. tropicalis also has a number of advantages over X. laevis in research, such as a much shorter generation time (<5 months), smaller size (4–6 cm (1.6–2.4 in) body length), and a larger number of eggs per spawn.[8]

It is found in Benin, Burkina Faso, Cameroon, Ivory Coast, Equatorial Guinea, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Nigeria, Senegal, Sierra Leone, Togo, and possibly Mali. Its natural habitats are subtropical or tropical moist lowland forests, moist savanna, rivers, intermittent rivers, swamps, freshwater lakes, intermittent freshwater lakes, freshwater marshes, intermittent freshwater marshes, rural gardens, heavily degraded former forests, water storage areas, ponds, aquaculture ponds, and canals and ditches.

Description

The western clawed frog is a medium-sized species with a somewhat flattened body and a snout-vent length of 28 to 55 mm (1.1 to 2.2 in), females being larger than males. The eyes are bulging and situated high on the head and there is a short tentacle just below each eye. A row of unpigmented dermal tubercles runs along the flank from just behind the eye, and are thought to represent a lateral line organ. The limbs are short and plump, and the fully webbed feet have horny claws. The skin is finely granular. The dorsal surface varies from pale to dark brown and has small grey and black spots. The ventral surface is dull white or yellowish with some dark mottling.[9]

Distribution and habitat

The western clawed frog is an aquatic species and is found in the West African rainforest belt with a range stretching from Senegal to Cameroon and eastern Zaire. It is generally considered a forest-dwelling species and inhabits slow-moving streams, but it is also found in pools and temporary ponds in the northern Guinea and Sudan savannas.[9]

Biology

In the dry season, this frog lives in shallow streams and hides under tree roots, under flat stones, or in holes in the riverbank. It feeds primarily on earthworms, insect larvae and tadpoles. When the rainy season starts it migrates across the forest floor at night to find temporary pools. Spawning may take place in large pools with much vegetation, but tadpoles are also sometimes found in muddy pools with no vegetation. Single eggs may be attached to plants or they may float. The tadpoles have broad mouths and no jaws, but have long tentacles on their upper lips. The ventral fins of their tails are broader than the dorsal ones. Their body colour is generally orange and the tail transparent but in darker locations the tail may be blackish. The tadpoles feed by filtering zooplankton from the water. In large water bodies, they may form dense swarms. Metamorphosis takes place when the tadpoles measure about 5 cm (2 in) in length.[9]

Sex determination

Sex determination in the vast majority of amphibians is controlled by homomorphic (morphologically indistinguishable) sex chromosomes.[10] As a result of this difficulty in sex chromosome identification, only a relatively small proportion of anuran species that have been karyotyped have also had their sex chromosomes identified.[11] Of the species in the genus Xenopus, all have homomorphic sex chromosomes.[11] Additionally, the DM-W gene on the W chromosome in some Xenopus species is the only sex-determining gene that has been identified in amphibians.[11] This DM-W gene was first identified in X. laevis, however it is not found in X. tropicalis.[11] Experimentation involving sex-reversed individuals, gynogenesis, triploids, and conventional crosses, has determined that X. tropicalis has three sex chromosomes: Y, W, and Z.[11] These three sex chromosomes produce three different male genotypes, YW, YZ, and ZZ (all are phenotypically identical) and two different female genotypes, ZW, and WW (all are phenotypically identical).[11] As a result, offspring of X. tropicalis can have sex ratios that differ from the commonly known 1:1 usually found in species with only two different sex chromosomes. For example, offspring resulting from a ZW female and a YZ male will have a sex ratio of 1:3 females to males and offspring resulting from a WW female and a ZZ male will be all female.[11] As a result of this sex determination system, both male and female X. tropicalis can be either heterogametic or homogametic which is extremely rare in nature.[11] The exact genetic mechanism and the exact alleles underlying this system is not yet known.[12] One possible explanation is that the W chromosome contains a female-determining allele that has function that is not found on the Z chromosome while the Y chromosome contains an allele that acts a negative regulator that is dominant over the female-determining allele on the W chromosome.[12]

Although X. tropicalis does have these three sex chromosomes, the frequency of these three sex chromosomes is not evenly distributed among this species' populations throughout its natural range. The Y chromosome has been identified from two localities in Ghana and in a laboratory strain that originated in Nigeria and the Z chromosome has been confirmed to exist in individuals from western and eastern Ghana.[12] Additionally, all three sex chromosomes have been found to exist together in X. tropicalis populations in Ghana and potentially elsewhere in its range as well.[12] Additionally, having irregular sex ratios in offspring is generally thought to be disadvantageous so whether or not the existence of three sex chromosomes in X. tropicalis is evolutionarily stable or an indication that the species is going through a sex chromosome transition (turnover), is still a question.[12] It seems likely that the emergence of the Y chromosome is the most recent event in the evolution of this species' sex chromosomes.[12] It is possible that in the future extinction of the Z chromosome would make it so that the W chromosome transitions into a X chromosome making this species with sex determined by an XY system.[12] It is also possible that if the Y chromosome were to go extinct, this species will have reverted to using an ancestral ZW system.[12]

Status

The IUCN lists the western clawed frog as "Least Concern" because it has a wide distribution and is an adaptable species living in a range of habitats, and the population trend seems to be steady.[1]

Use as a genetic model system

See also Xenopus#Model organism for biological research

Xenopus embryos and eggs are a popular model system for a wide range of biomedical research.[3][13] This animal is widely used because of its powerful combination of experimental tractability and close evolutionary relationship with humans, at least compared to many model organisms.[13]

Unlike its sister species X. laevis, X. tropicalis is diploid and has a short generation time, facilitating genetic studies.[3] The complete genome of X. tropicalis has been sequenced.[5] This species has n=10 chromosomes.[14]

X. tropicalis has three transferrin genes, all of which are close orthologs of other vertebrates. They are relatively far from non-vertebrate chordates, and widely divergent from protostome orthologs.[15]

Online Model Organism Database

Xenbase[16] is the Model Organism Database (MOD) for both Xenopus laevis and Xenopus tropicalis.[17]

References

  1. ^ a b IUCN SSC Amphibian Specialist Group (2019). "Xenopus tropicalis". IUCN Red List of Threatened Species. 2019: e.T89256756A107607050. doi:10.2305/IUCN.UK.2019-2.RLTS.T89256756A107607050.en. Retrieved 11 November 2021.
  2. ^ Frost, Darrel R. (2014). "Xenopus tropicalis (Gray, 1864)". Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History. Retrieved 3 March 2015.
  3. ^ a b c Harland RM, Grainger RM (December 2011). "Xenopus research: metamorphosed by genetics and genomics". Trends in Genetics. 27 (12): 507–15. doi:10.1016/j.tig.2011.08.003. PMC 3601910. PMID 21963197.
  4. ^ Amaya E, Offield MF, Grainger RM (July 1998). "Frog genetics: Xenopus tropicalis jumps into the future". Trends in Genetics. 14 (7): 253–5. doi:10.1016/s0168-9525(98)01506-6. PMID 9676522.
  5. ^ a b Hellsten U, Harland RM, Gilchrist MJ, Hendrix D, Jurka J, Kapitonov V, et al. (2010-04-30). "The genome of the Western clawed frog Xenopus tropicalis". Science. 328 (5978): 633–636. Bibcode:2010Sci...328..633H. doi:10.1126/science.1183670. PMC 2994648. PMID 20431018.
  6. ^ JGI X. tropicalis v4.1
  7. ^ Bowes JB, Snyder KA, Segerdell E, Gibb R, Jarabek C, Noumen E, et al. (January 2008). "Xenbase: a Xenopus biology and genomics resource". Nucleic Acids Research. 36 (Database issue): D761-7. doi:10.1093/nar/gkm826. PMC 2238855. PMID 17984085.
  8. ^ "Bringing Genetics To Xenopus: Half The Genome, Twice As Fast". University of Virginia. Retrieved 2009-10-24.
  9. ^ a b c M. O. Roedel; Vance Vredenburg; M. J. Mahoney; Tate Tunstall; Kellie Whittaker (2010-05-01). "Xenopus tropicalis". AmphibiaWeb. Retrieved 2013-12-06.
  10. ^ Bachtrog, Doris; Mank, Judith E.; Peichel, Catherine L.; Kirkpatrick, Mark; Otto, Sarah P.; Ashman, Tia-Lynn; Hahn, Matthew W.; Kitano, Jun; Mayrose, Itay; Ming, Ray; Perrin, Nicolas (July 2014). "Sex determination: why so many ways of doing it?". PLOS Biology. 12 (7): e1001899. doi:10.1371/journal.pbio.1001899. ISSN 1545-7885. PMC 4077654. PMID 24983465.
  11. ^ a b c d e f g h Roco, Álvaro S.; Olmstead, Allen W.; Degitz, Sigmund J.; Amano, Tosikazu; Zimmerman, Lyle B.; Bullejos, Mónica (August 2015). "Coexistence of Y, W, and Z sex chromosomes in Xenopus tropicalis". Proceedings of the National Academy of Sciences of the United States of America. 112 (34): E4752-61. Bibcode:2015PNAS..112E4752R. doi:10.1073/pnas.1505291112. ISSN 0027-8424. PMC 4553762. PMID 26216983.
  12. ^ a b c d e f g h Furman, Benjamin L. S.; Cauret, Caroline M. S.; Knytl, Martin; Song, Xue-Ying; Premachandra, Tharindu; Ofori-Boateng, Caleb; Jordan, Danielle C.; Horb, Marko E.; Evans, Ben J. (2020-11-09). Peichel, Catherine L. (ed.). "A frog with three sex chromosomes that co-mingle together in nature: Xenopus tropicalis has a degenerate W and a Y that evolved from a Z chromosome". PLOS Genetics. 16 (11): e1009121. doi:10.1371/journal.pgen.1009121. ISSN 1553-7404. PMC 7652241. PMID 33166278.
  13. ^ a b Wallingford, J., Liu, K., and Zheng, Y. 2010.Current Biology vol. 20, p. R263–4
  14. ^ "Xenopus tropicalis (ID 80) - Genome - NCBI". www.ncbi.nlm.nih.gov. Retrieved 2020-12-01.
  15. ^ Gabaldón, Toni; Koonin, Eugene V. (2013-04-04). "Functional and evolutionary implications of gene orthology". Nature Reviews Genetics. Nature Portfolio. 14 (5): 360–366. doi:10.1038/nrg3456. ISSN 1471-0056. PMC 5877793. PMID 23552219.
  16. ^ Karimi K, Fortriede JD, Lotay VS, Burns KA, Wang DZ, Fisher ME, et al. (January 2018). "Xenbase: a genomic, epigenomic and transcriptomic model organism database". Nucleic Acids Research. 46 (D1): D861–D868. doi:10.1093/nar/gkx936. PMC 5753396. PMID 29059324.
  17. ^ "Xenopus model organism database". Xenbase.org.

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Western clawed frog: Brief Summary

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The western clawed frog (Xenopus tropicalis) is a species of frog in the family Pipidae, also known as tropical clawed frog. It is the only species in the genus Xenopus to have a diploid genome. Its genome has been sequenced, making it a significant model organism for genetics that complements the related species Xenopus laevis (the African clawed frog), a widely used vertebrate model for developmental biology. X. tropicalis also has a number of advantages over X. laevis in research, such as a much shorter generation time (

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