Gastric-brooding frog

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Gastric-brooding frogs
Rheobatrachus silus.jpg
Southern gastric-brooding frog (Rheobatrachus silus)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Myobatrachidae
Genus:† Rheobatrachus
Liem, 1973
Species
Reobatrachus distribution2.png
The former distributions of Rheobatrachus silus (green) and Rheobatrachus vitellinus (blue)

Rheobatrachus, whose members are known as the gastric-brooding frogs or platypus frogs, is a genus of extinct ground-dwelling frogs native to Queensland in eastern Australia. The genus consisted of only two species, the southern and northern gastric-brooding frogs, both of which became extinct in the mid-1980s. The genus is unique because it contains the only two known frog species that incubated the prejuvenile stages of their offspring in the stomach of the mother. [3]

The combined ranges of the gastric-brooding frogs comprised less than 2,000 square kilometres (770 sq mi). Both species were associated with creek systems in rainforests at elevations of between 350 and 1,400 metres (1,150 and 4,590 ft). The causes of the gastric-brooding frogs' extinction are not clearly understood, but habitat loss and degradation, pollution, and some diseases may have contributed.

The assignment of the genus to a taxonomic family is hotly debated. Some biologists class them within Myobatrachidae under the subfamily Rheobatrachinae, but others place them in their own family, Rheobatrachidae. [4] Molecular genetics finds it sister to Mixophyes . [5]

Scientists at the University of Newcastle and University of New South Wales announced in March 2013 that the frog would be the subject of a cloning attempt, referred to as the "Lazarus Project", to resurrect the species. Embryos were successfully cloned, and the project eventually hopes to produce a living frog. [6] [7]

The southern gastric brooding frog has been listed as Extinct by the IUCN because it has not been recorded in the wild since 1981, and extensive searches over the last 35 years have failed to locate this species.

Taxonomy

The genus Rheobatrachus was first described in 1973 by David Liem [8] and since has not undergone any scientific classification changes; however its placement has been controversial. It has been placed in a distinct subfamily of Myobatrachidae, Rheobatrachinae; in a separate family, Rheobatrachidae; placed as the sister taxon of Limnodynastinae; and synonymized with Limnodynastinae. In 2006, D. R. Frost and colleagues found Rheobatrachus, on the basis of molecular evidence, to be the sister taxon of Mixophyes and placed it within Myobatrachidae. [9] [5]

Both species of gastric-brooding frogs were very different in appearance and behaviour from other Australian frog species. Their large protruding eyes and short, blunt snout along with complete webbing and slimy bodies differentiated them from all other Australian frogs. The largely aquatic behaviour exhibited by both species was only shared (in Australia) with the Dahl's aquatic frog and their ability to raise their young in the mother's stomach was unique among all frogs.

Common names

The common names, "gastric-brooding frog" and "platypus frog", are used to describe the two species. "Gastric-brooding" describes the unique way the female raised the young and "platypus" describes their largely aquatic nature.

Reproduction

What makes these frogs unique among all frog species is their form of parental care. Following external fertilization by the male, the female would take the eggs or embryos into her mouth and swallow them. [10] It is not clear whether the eggs were laid on the land or in the water, as it was never observed before their extinction. Interestingly, Darwin's frog, another species of frog, has been observed to exhibit similar mouth-brooding characteristics. This feature still remains extremely rare in nature.

Eggs found in females measured up to 5.1 mm in diameter and had large yolk supplies. These large supplies are common among species that live entirely off yolk during their development. Most female frogs had around 40 ripe eggs, almost double that of the number of juveniles ever found in the stomach (21–26). This means one of two things, that the female fails to swallow all the eggs or the first few eggs to be swallowed are digested.

At the time the female swallowed the fertilized eggs her stomach was no different from that of any other frog species. In the jelly around each egg was a substance called prostaglandin E2 (PGE2), which could turn off production of hydrochloric acid in the stomach. This source of PGE2 was enough to cease the production of acid during the embryonic stages of the developing eggs. When the eggs had hatched the tadpoles created PGE2. The mucus excreted from the tadpoles' gills contained the PGE2 necessary to keep the stomach in a non-functional state. These mucus excretions do not occur in tadpoles of most other species. Tadpoles that do not live entirely off a yolk supply still produce mucus cord, but the mucus along with small food particles travels down the oesophagus into the gut. With Rheobatrachus (and several other species) there is no opening to the gut and the mucus cords are excreted. During the period that the offspring were present in the stomach the frog would not eat.

Information on tadpole development was observed from a group that was regurgitated by the mother and successfully raised in shallow water. During the early stages of development tadpoles lacked pigmentation, but as they aged they progressively develop adult colouration. Tadpole development took at least six weeks, during which time the size of the mother's stomach continued to increase until it largely filled the body cavity. The lungs deflated and breathing relied more upon gas exchange through the skin. Despite the mother's increasing size she still remained active.

The birth process was widely spaced and may have occurred over a period of as long as a week. However, if disturbed the female may regurgitate all the young frogs in a single act of propulsive vomiting. The offspring were completely developed when expelled and there was little variation in colour and length of a single clutch. [11]

Cause of extinction

The cause for the gastric-brooding frogs' extinction is speculated to be due to human introduction of pathogenic fungi into their native range. Populations of southern gastric-brooding frogs were present in logged catchments between 1972 and 1979. The effects of such logging activities upon southern gastric-brooding frogs was not investigated but the species did continue to inhabit streams in the logged catchments. The habitat that the southern gastric-brooding frog once inhabited is now threatened by feral pigs, the invasion of weeds, altered flow and water quality problems caused by upstream disturbances. [12] Despite intensive searching, the species has not been located since 1976 or 1981 (depending on the source).

The Eungella National Park, where the northern gastric-brooding frog was once found, was under threat from bushfires and weed invasion. Continual fires may have destroyed or fragmented sections of the forest. [13] The outskirts of the park are still subject to weed invasion and chytrid fungus has been located within several rainforest creeks within the park. It was thought that the declines of the northern gastric-brooding frog during 1984 and 1985 were possibly normal population fluctuations. [14] Eight months after the initial discovery of the northern gastric-brooding frog, sick and dead Eungella torrent frogs, which cohabitat the streams with gastric brooding frogs, were observed in streams in Pelion State Forest. [15] Given the more recent understanding of the role of the amphibian disease in the decline and disappearance of amphibians, combined with the temporal and spatial pattern of the spread of the pathogen in Australia, it appears most likely that the disease was responsible for the decline and disappearance of the gastric-brooding frogs. Despite continued efforts to locate the northern gastric-brooding frog it has not been found. The last reported wild specimen was seen in the 1980s. In August 2010 a search organised by the Amphibian Specialist Group of the International Union for Conservation of Nature set out to look for various species of frogs thought to be extinct in the wild, including the gastric-brooding frog. [16]

Conservation status

Both species are listed as Extinct under both the IUCN Red List and under Australia's Environment Protection and Biodiversity Conservation Act 1999; however, they are still listed as Endangered under Queensland's Nature Conservation Act 1992.

De-extinction attempt

Scientists are making progress in their efforts to bring the gastric-brooding frog species back to life using somatic-cell nuclear transfer (SCNT), a method of cloning. [17]

In March 2013, Australian scientists successfully created a living embryo from non-living preserved genetic material. These scientists from the University of Newcastle Australia led by Prof Michael Mahony, who was the scientist who first discovered the northern gastric-brooding frog, Simon Clulow and Prof Mike Archer from the University of New South Wales hope to continue using somatic-cell nuclear transfer methods to produce an embryo that can survive to the tadpole stage. "We do expect to get this guy hopping again," says UNSW researcher Mike Archer. [18]

The scientists from the University of Newcastle have also reported successful freezing and thawing (cryopreservation) of totipotent amphibian embryonic cells, [19] which along with sperm cryopreservation [20] provides the essential "proof of concept" for the use of cryostorage as a genome bank for threatened amphibians and also other animals.

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<span class="mw-page-title-main">Conondale National Park</span> Protected area in Queensland, Australia

Conondale National Park is 130 km north of Brisbane in the Sunshine Coast Hinterland near the town of Conondale in the south east Queensland bioregion. The park covers an area of 35,648 hectares protecting large areas of subtropical rainforest, woodlands, wet and dry sclerophyll forest including Queensland's tallest tree. The park contains areas of regenerating forest which have been previously logged; areas of forest plantations also border the park. The park is currently managed by the Queensland Government under the Nature Conservation Act 1992.

<span class="mw-page-title-main">Eungella National Park</span> Protected area in Queensland, Australia

Eungella National Park is a protected area in Queensland, Australia. It is on the Clarke Range at the end of the Pioneer Valley 80 km west of Mackay, and 858 km northwest of Brisbane. Eungella is noted for the national park which surrounds it. It is considered to be the longest continual stretch of sub-tropical rainforest in Australia. The original inhabitants are the Wirri people. The park is covered by dense rainforest and is known for its platypuses.

<span class="mw-page-title-main">Ovoviviparity</span> Gestation type

Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop inside eggs that remain in the mother's body until they are ready to hatch.

<span class="mw-page-title-main">Egg incubation</span> The process by which certain egg-laying animals hatch their eggs

Egg incubation is the process by which an egg, of oviparous (egg-laying) animals, develops an embryo within the egg, after the egg's formation and ovipositional release. Egg incubation is done under favorable environmental conditions, possibly by brooding and hatching the egg.

<span class="mw-page-title-main">Darwin's frog</span> Species of amphibian

Darwin’s frog, also called the Southern Darwin's frog, is a species of Chilean/Argentinian frog of the family Rhinodermatidae. It was discovered by Charles Darwin during his voyage on HMS Beagle. on a trip to Chile. In 1841, French zoologist André Marie Constant Duméril and his assistant Gabriel Bibron described and named Darwin's frog. The diet of R. darwinii consists mostly of herbivore invertebrates. R. darwinii is currently classified as an endangered species by the International Union for Conservation of Nature.

<span class="mw-page-title-main">Pouched frog</span> Species of amphibian

The pouched frog, or hip pocket frog, is a small, terrestrial frog found in rainforests in mountain areas of south-eastern Queensland and northern New South Wales, Australia. It is one of two species within the genus Assa, the other being Assa wollumbin and is part of the family Myobatrachidae.

<i>Taudactylus</i> Genus of amphibians

Taudactylus is a genus of frogs in the family Myobatrachidae. These frogs are endemic to rainforest areas of coastal eastern Australia, most of this genus inhabit fast flowing streams in highland area. Most members of this genus have suffered serious declines, in which the disease chytridiomycosis appears to have played a significant role: T. diurnus is believed to be extinct, while all others except T. liemi are listed as critically endangered by the IUCN. These listings are conservative, and it is likely T. acutirostris, presently listed as critically endangered, already is extinct.

<span class="mw-page-title-main">Fletcher's frog</span> Species of amphibian

Fletcher's frog, commonly known as the sandpaper frog or black-soled frog, is a species of nocturnal, terrestrial frog native to eastern Australia. It is primarily found in wet sclerophyll forests along mountain ranges and the coast.

<span class="mw-page-title-main">Myobatrachidae</span> Family of amphibians

Myobatrachidae, commonly known as Australian ground frogs or Australian water frogs, is a family of frogs found in Australia and New Guinea. Members of this family vary greatly in size, from species less than 1.5 cm (0.59 in) long, to the second-largest frog in Australia, the giant barred frog, at 12 cm (4.7 in) in length. The entire family is either terrestrial or aquatic frogs, with no arboreal species.

<span class="mw-page-title-main">Amphibians of Australia</span>

Amphibians of Australia are limited to members of the order Anura, commonly known as frogs. All Australian frogs are in the suborder Neobatrachia, also known as the modern frogs, which make up the largest proportion of extant frog species. About 230 of the 5,280 species of frog are native to Australia with 93% of them endemic. Compared with other continents, species diversity is low, and may be related to the climate of most of the Australian continent. There are two known invasive amphibians, the cane toad and the smooth newt.

<span class="mw-page-title-main">Eungella torrent frog</span> Species of amphibian

The Eungella torrent frog or Eungella day frog is a species of stream dwelling frog endemic to Australia. It is restricted to ranges west of Mackay in mid-eastern Queensland.

<span class="mw-page-title-main">Desert froglet</span> Species of frog

The desert froglet, chirping froglet, or sparrow froglet is a species of frog in the family Myobatrachidae, endemic to Australia. Desert froglets occur mainly in dry or moist savanna habitats, principally from the mid-western border of Northern Territory, south-east into western Queensland and New South Wales and the north-east corner of South Australia. They can also be found along the Queensland coast where it has been recorded between Townsville and Cooktown, and as far south as Hervey Bay.

<span class="mw-page-title-main">Magnificent brood frog</span> Species of amphibian

The magnificent brood frog or magnificent broodfrog is a species of frog in the family Myobatrachidae. It is endemic to Queensland, Australia, and is known from near Ravenshoe in the southern Atherton Tableland and from Mount Spec in the Paluma Range. The specific name covacevichae honours Jeanette Covacevich, an Australian herpetologist.

<span class="mw-page-title-main">Eungella tinker frog</span> Species of amphibian

The Eungella tinker frog, also known as Eungella tinkerfrog, Liem's frog, or Liem's tinker frog, is a species of frog in the family Myobatrachidae. It is endemic to the Eungella area in Queensland, Australia. It lives in rocky margins of fast-flowing creeks and seepages in montane rainforest at elevations of 180–1,250 m (590–4,100 ft) above sea level, but it is more common above 600 m (2,000 ft). It is commonly heard but rarely seen. In contrast to other amphibians in the area, such as Taudactylus eungellensis, no adverse effects of the chytrid fungus Batrachochytrium dendrobatidis have been reported on this species. It is currently facing no major threats, although its habitat could be impacted by grazing and trampling of streamside vegetation by livestock. Also invasive cane toads are a potential future threat. Its range is with the Eungella National Park.

<i>Assa</i> (genus) Genus of frog

Assa is a genus of frog in the family Myobatrachidae. These frogs are endemic to a few parts of eastern Australia.

<span class="mw-page-title-main">Broodiness</span> Behavioral tendency to sit on a clutch of eggs to incubate them

Broodiness is the action or behavioral tendency to sit on a clutch of eggs to incubate them, often requiring the non-expression of many other behaviors including feeding and drinking. Being broody has been defined as "Being in a state of readiness to brood eggs that is characterized by cessation of laying and by marked changes in behavior and physiology". Broodiness is usually associated with female birds, although males of some bird species become broody and some non-avian animals also show broodiness.

Anstisia is a genus of frogs in the family Myobatrachidae. These frogs are endemic to southern Western Australia.

<i>Rheobatrachus silus</i> Extinct species of frog

Rheobatrachus silus, commonly called southern gastric-brooding frog, is an extinct species of gastric-brooding frog native to Australia.

Rheobatrachus vitellinus, commonly called northern gastric-brooding frog, is an extinct species of gastric-brooding frog native to Australia.

References

  1. ↑ IUCN SSC Amphibian Specialist Group (2022). "Rheobatrachus silus". The IUCN Red List of Threatened Species . 2022. IUCN: e.T19475A78430533.
  2. ↑ IUCN SSC Amphibian Specialist Group (2022). "Rheobatrachus vitellinus". The IUCN Red List of Threatened Species . 2022. IUCN: e.T19476A78430385.
  3. ↑ Barker, J.; Grigg, G. C.; Tyler, M. J. (1995). A Field Guide to Australian Frogs. Surrey Beatty & Sons. p. 350. ISBN   0-949324-61-2.
  4. ↑ Heyer, W. Ronald; Liem, David S. (1976). "Analysis of the inter-generic relationships of the Australian frog family Myobatrachidae" (PDF). Smithsonian Contributions to Zoology. 233 (233): 1–29. doi:10.5479/si.00810282.233.
  5. 1 2 Frost, Darrel R.; Grant, Taran; Faivovich, Julián; Bain, Raoul H.; Haas, Alexander; Haddad, Célio F.B.; De Sá, Rafael O.; Channing, Alan; Wilkinson, Mark; Donnellan, Stephen C.; Raxworthy, Christopher J.; Campbell, Jonathan A.; Blotto, Boris L.; Moler, Paul; Drewes, Robert C.; Nussbaum, Ronald A.; Lynch, John D.; Green, David M.; Wheeler, Ward C. (2006). "The amphibian tree of life". Bulletin of the American Museum of Natural History . 297: 1–370. doi: 10.1206/0003-0090(2006)297[0001:TATOL]2.0.CO;2 . hdl:2246/5781. S2CID   86140137.
  6. ↑ Yong, Ed (15 March 2013). "Resurrecting the Extinct Frog with a Stomach for a Womb". National Geographic . Archived from the original on 18 March 2013. Retrieved 15 March 2013.
  7. ↑ Dolak, Kevin (20 March 2013). "Frog That Gives Birth Through Mouth to be Brought Back From Extinction". ABC News.
  8. ↑ Liem, David S. (1973). "A new genus of frog of the family Leptodactylidae from S. E. Queensland, Australia". Memoirs of the Queensland Museum. 16 (3): 459–470.
  9. ↑ Amphibian Species of the World – Rheobatrahus (under "Comments"). research.amnh.org
  10. ↑ "Rheobatrachus vitellinus – Northern Gastric-brooding Frog, Eungella Gastric-brooding Frog". Department of the Environment, Canberra. 2015. Retrieved 25 May 2015.
  11. ↑ Tyler, M. J. (1994). Chapter 12, "Gastric Brooding Frogs", pp. 135–140 in Australian Frogs A Natural History. Reed Books
  12. ↑ Hines, H., Mahony, M. and McDonald, K. 1999. An assessment of frog declines in Wet Subtropical Australia. In: A. Campbell (ed.), Declines and Disappearances of Australian Frogs. Environment Australia.
  13. ↑ Winter, J.; McDonald, K. (1986). "Eungella, the land of cloud". Australian Natural History. 22 (1): 39–43.
  14. ↑ McDonald, K.R. (1990). "Rheobatrachus Liem and Taudactylus Straughan & Lee (Anura: Leptodactylidae) in Eungella National Park, Queensland: distribution and decline". Transactions of the Royal Society of South Australia. 114 (4): 187–194.
  15. ↑ Mahony, Michael. "Report to Queensland National Park on status of stream frogs in Pelion State Forest".{{cite journal}}: Cite journal requires |journal= (help)
  16. ↑ Black, Richard (9 August 2010). "Global hunt begins for 'extinct' species of frogs". BBC . Retrieved 9 August 2010.
  17. ↑ Nosowitz, Dan (15 March 2013) Scientists Resurrect Bonkers Extinct Frog That Gives Birth Through Its Mouth. popsci.com
  18. ↑ Messenger, Stephen (15 March 2013) Scientists successfully create living embryo of an extinct species. treehugger.com
  19. ↑ Moreira, Nei; Lawson, Bianca; Clulow, Simon; Mahony, Michael J.; Clulow, John (2013). "Towards gene banking amphibian maternal germ lines: short-term incubation, cryoprotectant tolerance and cryopreservation of embryonic cells of the frog, Limnodynastes peronii". PLOS ONE. 8 (4): e60760. Bibcode:2013PLoSO...860760L. doi: 10.1371/journal.pone.0060760 . ISSN   1932-6203. PMC   3618038 . PMID   23577155.
  20. ↑ Browne, Robert; Mahony, Clulow (2002). "A comparison of sucrose, saline, and saline with egg-yolk diluents on the cryopreservation of cane toad (Bufo marinus) sperm". Cryobiology. 44 (251–157): 251–7. doi:10.1016/S0011-2240(02)00031-7. PMID   12237090.

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