Amphibians of Australia

The S of Amphibien S originating in Australia are all members of Neobatrachia which forms largest of the sub-orders of the Anoure S. Environ 230 species out of the 5.280 species of the sub-order live in Australia and 93% of them are endemic. Compared with that of other continents, the diversity is weak. It east can be related to the climate of a country made up for its greater part of zones Semi-aride S. to announce an Amphibian imported voluntarily and become invasive, the Crapaud buffalo.

Origin

The oldest fossil of known Australian batrachian is Vieraella herbsti ; the species lived before the separation of the Supercontinent Pangée in Gondwana and Laurasia there are 180 My. The fossils of this species are gone back to 188 My to 213 My and are present on several current continents, confirming the theory of the continental drift.

Certain families of species remained very close, in spite of the distance of the continents. Thus of terrestrial frogs South American of the Leptodactylidae is relatively close to that South-African of the Heleophrynidae , and of the Australian family of the Myobatrachidae .

Whereas the data suggest that the Hylidae , of arboricolous frogs, are originating in South America, one thinks that they emigrated in Australia via the the Antarctic. The similarities of the Mélanosome S between the species of the S Litoria and Phyllomedusa let think of a recent common origin whereas the immunological indices would show an old origin.

The Indian family and sychelloise of the Sooglossidae is regarded as close relation of the Australian family of the Myobatrachidae . The Sooglossidae being more narrowly close to the Myobatrachidae than of the African or South American families. What is logical since, the India, Madagascar and the Seychelles separated from Gondwana there are roughly 130 My.

The principal continental masses consisted the Australia island and the New Guinea remained, except exception, separated by seas, making the migration of the species impossible. However, during certain glacial periods, as 10.000 years ago, the circulation of fauna at possible summer between these masses. This was also possible with the Eurasia, for example during the Glaciation of Würm. Thus it is probable that the Litoria caerulea migrated from Australia to New Guinea because of their broad distribution geographical to Australia and very sectorized in New Guinea. Even thing for the species of the kind Nyctimystes and for the families of Microhylidae and Ranidae , which, very present in the northern hemisphere, occupies only extreme Australian north. Two species out of fifty-nine for the Microhylidae , and only one on seven hundred and fifty of Ranidae are regarded as natives in Australia. When they could be established, the majority of the ecological niches were occupied by local batrachians.

Current populations

See also: Fauna of Australia, Extinction of Holocene the, Biodiversity

The population of batrachians decreased since the Années 1980. Three species disappeared. Others became rare, 4 species have not been found for 15 years and are surely extinct. The Biotope S were modified, leaving less place to the batrachians as for examples the bush fires or Brûlis caused by the man is regarded as directly responsible for the disappearance of the Heleioporus australiacus , a giant digger frog, increasing urbanization is another illustration. Other causes like the appearance of the Chytridiomycose, a fatal fungic disease do nothing but worsen the problem. In certain cases, all the species of the same kind declined as for the kind Philoria . However, all the causes of the decline are not known.

Extinct species

Species in critical danger

species in danger

Cophixalus mcdonaldi
Cophixalus monticola
Cophixalus neglectus
Litoria brevipalmata
Litoria cooloolensis
Litoria nannotis
Litoria raniformis
Litoria rheocola
Mixophyes fleayi
Mixophyes iteratus
Nyctimystes dayi
Philoria kundagungan
Philoria loveridgei
Philoria pughi
Philoria richmondensis
Philoria sphagnicolus
Pseudophryne covacevichae
Pseudophryne pengilleyi

Chorologie

The distribution of the frog species depends directly on the climate, the largest biodiversity being in the zones tropical and moderate wet of the Australian circumference. The differences of pluviometry and temperature due to altitude are another factor of Spéciation. The not very significant number of specimen and species in Australia is explained by the conditions which reign there in the greatest part. Thus, in the Flat of Nullarbor, the temperatures in day can reach 48,5°C whereas the temperature can go down in lower part from zero the night and, precipitations are of less 200mm per annum. Few species are thus present in this sector.

Many species however adapted to environments drier, choosing to bury itself to support the Sècheresse, as for examples the species of the kind Cyclorana. The conditions of layings, the duration of development of eggs and the Têtard S vary according to moisture. The species in dry zone often benefit from temporary ponds to reproduce and develop in less than one month. The tadpoles of the Arenophryne rotunda are even able to develop completely in their eggs, enfouits directly in the sand dunes. At contrario, species living in very wet zones as the species of the kind Mixophyes put more than 15 month to be metamorphosed out of frog.

Systematic

The indigenous species of Australia gather into four S to which it makes add that of the Crapaud buffalo, of recent introduction, and which became invasive. The frog species of the subfamily of the Hylidae are most numerous since one counts some more than 70. They have extremely different behaviors since some are strictly arboricolous and the other digger ones. The second family many species is the subfamily of the Myobatrachidae which counts more than 100 species divided into 20 kinds. The species of this subfamily find in all the écozone Australasien, but are not mainly present in Australia. The species of the subfamilies of Microhylidae and Ranidae , very few because arrived later. They gather 20 species and 1 respectively species, whereas they are very present in the rest of the world.

See too

Fauna of Australia

Sources

Barker, J.; Grigg, G.C. ; Tyler, M.J. (1995). In Field to Australian Frogs Guides. Surrey Beatty & Sounds.

External bonds

Site on Australian frogs
List of IUCN
Australian Site on research on the frogs
Welcome to the Frogs Australia Network site of information on the Anoura of Australia, species by species

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