The evidentiary basis of the currently accepted classification of living amphibians is discussed and shown not to warrant the degree of authority conferred on it by use and tradition. A new taxonomy of living amphibians is proposed to correct the deficiencies of the old one. This new taxonomy is based on the largest phylogenetic analysis of living Amphibia so far accomplished. We combined the comparative anatomical character evidence of Haas (2003) with DNA sequences from the mitochondrial transcription unit H1 (12S and 16S ribosomal RNA and tRNAValine genes, ≈ 2,400 bp of mitochondrial sequences) and the nuclear genes histone H3, rhodopsin, tyrosinase, and seven in absentia, and the large ribosomal subunit 28S (≈ 2,300 bp of nuclear sequences; ca. 1.8 million base pairs; x = 3.7 kb/terminal). The dataset includes 532 terminals sampled from 522 species representative of the global diversity of amphibians as well as seven of the closest living relatives of amphibians for outgroup comparisons. The...

https://bioone.org/journals/Bulletin-of-the-American-Museum-of-Natural-History/volume-2006/issue-297/0003-0090(2006)297[0001:TATOL]2.0.CO;2/THE-AMPHIBIAN-TREE-OF-LIFE/10.1206/0003-0090(2006)297[0001:TATOL]2.0.CO;2.pdf

The amphibian tree of life

Nearly half the world's vascular plant species and one-third of terrestrial vertebrates are endemic to 25 "hotspots" of biodiversity, each of which has at least 1500 endemic plant species. None of these hotspots have more than one-third of their pristine habitat remaining. Historically, they covered 12% of the land's sur- face, but today their intact habitat covers only 1.4% of the land. As a result of this habitat loss, we expect many of the hotspot endemics to have either become extinct or—because much of the habitat loss is recent— to be threatened with extinction. We used World Conservation Union (IUCN) Red Lists to test this expectation. Overall, between one-half and two-thirds of all threatened plants and 57% of all threatened terrestrial verte- brates are hotspot endemics. For birds and mammals, in general, predictions of extinction in the hotspots based on habitat loss match numbers of species independently judged extinct or threatened. In two classes of hotspots the match is not as close. On oceanic islands, habitat loss underestimates extinction because intro- duced species have driven extinctions beyond those caused by habitat loss on these islands. In large hotspots, conversely, habitat loss overestimates extinction, suggesting scale dependence (this effect is also apparent for plants). For reptiles, amphibians, and plants, many fewer hotspot endemics are considered threatened or ex- tinct than we would expect based on habitat loss. This mismatch is small in temperate hotspots, however, sug- gesting that many threatened endemic species in the poorly known tropical hotspots have yet to be included on the IUCN Red Lists. We then asked in which hotspots the consequences of further habitat loss (either abso- lute or given current rates of deforestation) would be most serious. Our results suggest that the Eastern Arc and Coastal Forests of Tanzania-Kenya, Philippines, and Polynesia-Micronesia can least afford to lose more habitat and that, if current deforestation rates continue, the Caribbean, Tropical Andes, Philippines, Me- soamerica, Sundaland, Indo-Burma, Madagascar, and Choco-Darien-Western Ecuador will lose the most spe- cies in the near future. Without urgent conservation intervention, we face mass extinctions in the hotspots.

Habitat Loss and Extinction in the Hotspots of Biodiversity

As the Earth warms, many species are likely to disappear, often because of changing disease dynamics. Here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. Seventeen years ago, in the mountains of Costa Rica, the Monteverde harlequin frog (Atelopus sp.) vanished along with the golden toad (Bufo periglenes). An estimated 67% of the 110 or so species of Atelopus, which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) is implicated. Analysing the timing of losses in relation to changes in sea surface and air temperatures, we conclude with ‘very high confidence’ (> 99%, following the Intergovernmental Panel on Climate Change, IPCC) that large-scale warming is a key factor in the disappearances. We propose that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium, thus encouraging outbreaks. With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable.

Widespread amphibian extinctions from epidemic disease driven by global

A s a group [reptiles] are nei t h er ‘good ’n or ‘b ad ,’ but ia re intere s ting and unu su a l , a l t h o u gh of m i n or i m port a n ce . If t h ey should all disappe a r, it wo u l d not make mu ch differen ce one way or the other ”( Zim and Smith 1953, p. 9 ) . Fortu n a tely, this op i n i on from the Golden Gu i de Series does not persist tod ay; most people have com e to recogn i ze the va lue of both reptiles and amph i bians as an i n tegral part of n a tu ral eco s ys tems and as heralds of envi ron m ental qu a l i ty (Gibbons and Stangel 1999). In recent ye a rs , as overa ll envi ron m ental aw a reness among the p u blic has incre a s ed , con cerns have come to inclu de intere s t in the eco l ogical state of reptile and amph i bian spec i e s t h em s elves and of t h eir habi t a t s . In c re a s ed aw a reness may s tem from bet ter edu c a ti on abo ut threats to bi od ivers i ty in gen era l , and to reptiles and amph i bians in parti c u l a r, a n d po s s i bly even from an innate attracti on to these taxa ( Kell ert and Wi l s on 1993). From the perspective of many nonscientists, the two vertebrate classes comprising reptiles and amphibians, collectively referred to as the herpetofauna, are interchangeable. For example,the Boy Scout merit badge pamphlet for herpetology was called simply Reptile Study from 1926 to 1993 (Conant 1972, Gibbons 1993), and major zoos (e.g., National Zoo in Washington, DC; Zoo Atlanta; and San Diego Zoo) use only the name “reptile” to refer to the facility that houses both amphibians and reptiles. Thus, public attitudes about the need for conservation of reptiles are probably linked to concern about amphibian declines and deformities (Alford and Richards 1999, Johnson et al. 1999, Sessions et al. 1999), which have been the subject of numerous, well-documented scientific studies. Because amphibians are distributed worldwide, but herpetologists who document amphibian declines are not, it is difficult to accurately assess what portion of amphibian populations are experiencing significant declines or have already disappeared. Furthermore, the means of determining a species’ conservation status is a rigorous and time-intensive process, and therefore counts of “officially” recognized endangered and threatened species are likely to grossly underestimate the actual number of imperiled s pecies (Ta ble 1). The worl dwi de amph i bian decl i n e probl em , as it has come to be known, has garnered significant attention not only among scientists but also in the popular media and in political circles.

/pdf/the-global-decline-of-reptiles-deja-vu-amphibians-594oge2sdh.pdf

The global decline of reptiles, deja’ vu amphibians

As the Earth warms, many species are likely to disappear, often because of changing disease dynamics. Here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. Seventeen years ago, in the mountains of Costa Rica, the Monteverde harlequin frog (Atelopus sp.) vanished along with the golden toad (Bufo periglenes). An estimated 67% of the 110 or so species of Atelopus, which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) is implicated. Analysing the timing of losses in relation to changes in sea surface and air temperatures, we conclude with 'very high confidence' (> 99%, following the Intergovernmental Panel on Climate Change, IPCC) that large-scale warming is a key factor in the disappearances. We propose that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium, thus encouraging outbreaks. With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable.

http://webpages.icav.up.pt/PTDC/BIA-BEC/099915/2008/9.Pounds%20et%20al%202006%20Nature.pdf

Widespread amphibian extinctions from epidemic disease driven by global warming

Objective To investigate the distribution and incidence of chytridiomycosis in eastern Australian frogs and to examine the effects of temperature on this disease.



Design A pathological survey and a transmission experiment were conducted.



Procedure Diagnostic pathology examinations were performed on free-living and captive, ill and dead amphibians collected opportunistically from eastern Australia between October 1993 and December 2000. We conducted a transmission experiment in the laboratory to investigate the effects of temperature: eight great barred frogs (Mixophyes fasciolatus) exposed to zoospores of Batrachochytrium dendrobatidis and six unexposed frogs were housed individually in each of three rooms held at 17°C, 23°C and 27°C.



Results Chytridiomycosis was the cause of death or morbidity for 133 (55.2%) of 241 free-living amphibians and for 66 (58.4%) of 113 captive amphibians. This disease occurred in 34 amphibian species, was widespread around the eastern seaboard of Australia and affected amphibians in a variety of habitats at high and low altitudes on or between the Great Dividing Range and the coast. The incidence of chytridiomycosis was higher in winter, with 53% of wild frogs from Queensland and New South Wales dying in July and August. Other diseases were much less common and were detected mostly in spring and summer. In experimental infections, lower temperatures enhanced the pathogenicity of B dendrobatidis in M fasciolatus. All 16 frogs exposed to B dendrobatidis at 17°C and 23°C died, whereas 4 of 8 frogs exposed at 27°C survived. However, the time until death for the frogs that died at 27°C was shorter than at the lower temperatures. Infections in survivors were eliminated by 98 days.



Conclusion Chytridiomycosis is a major cause of mortality in free-living and captive amphibians in Australia and mortality rate increases at lower temperatures.

Effect of season and temperature on mortality in amphibians due to chytridiomycosis

Seventeen aurein peptides are present in the secretion from the granular dorsal glands of the Green and Golden Bell Frog Litoria aurea, and 16 from the corresponding secretion of the related Southern Bell Frog L. raniformis. Ten of these peptides are common to both species. Thirteen of the aurein peptides show wide-spectrum antibiotic and anticancer activity. These peptides are named in three groups (aureins 1-3) according to their sequences. Amongst the more active peptides are aurein 1.2 (GLFDIIKKIAESF-NH2), aurein 2.2 (GLFDIVKKVVGALGSL-NH2) and aurein 3.1 (GLFDIVKKIAGHIAGSI-NH2). Both L. aurea and L. raniformis have endoproteases that deactivate the major membrane-active aurein peptides by removing residues from both the N- and C-termini of the peptides. The most abundant degradation products have two residues missing from the N-terminal end of the peptide. The solution structure of the basic peptide, aurein 1.2, has been determined by NMR spectroscopy to be an amphipathic alpha-helix with well-defined hydrophilic and hydrophobic regions. Certain of the aurein peptides (e.g. aureins 1.2 and 3.1) show anticancer activity in the NCI test regime, with LC50 values in the 10-5-10-4 M range. The aurein 1 peptides have only 13 amino-acid residues: these are the smallest antibiotic and anticancer active peptides yet reported from an anuran. The longer aurein 4 and 5 peptides, e.g. aurein 4.1 (GLIQTIKEKLKELAGGLVTGIQS-OH) and aurein 5. 1 (GLLDIVTGLLGNLIVDVLKPKTPAS-OH) show neither antibacterial nor anticancer activity.

The antibiotic and anticancer active aurein peptides from the Australian Bell Frogs Litoria aurea and Litoria raniformis the solution structure of aurein 1.2.

Michael J. Tyler

Papers

Effect of season and temperature on mortality in amphibians due to chytridiomycosis

The antibiotic and anticancer active aurein peptides from the Australian Bell Frogs Litoria aurea and Litoria raniformis the solution structure of aurein 1.2.

A novel method for the release and collection of dermal, glandular secretions from the skin of frogs.

Host-defence peptides of Australian anurans: structure, mechanism of action and evolutionary significance.

A Field Guide to Australian Frogs