KU Biodiversity Institute scientists recently announced the results of an extensive study of the genetics of the tree frogs in the Philippines. Their surprising results suggest that the Asian Tree Frog (known to biologists as Polypedates leucomystax and many Filipinos as Banana Frogs, or “Palakang Saging”) has spread throughout the Philippine islands in few centuries. Their finding of genetic uniformity throughout the Philippines suggests that humans have inadvertently transported these Asian tree frogs throughout the archipelago as “hitchhikers” or “stowaways” in agricultural shipments between islands by boats, ferries, and commercial shippers.
Biodiversity Institute herpetologists, in collaboration with the Parks and Wildlife Bureau of the Department of Environment and Natural Resources and the National Museum of the Philippines, published these findings in the international journal Molecular Phylogenetics and Evolution. Their results suggest that the extraordinary Philippine tree frog species P. leucomystax has expanded its range throughout the Philippines, aided by humans and the constant inter-island trafficking of sugar cane, bananas, copra, rattan, rice and other goods.
“We know that this species is often found mixed in with shipments of agricultural products,” said Rafe Brown, curator of herpetology and leader of the team that published the recent scientific article. “It is reasonable to assume that humans, in the daily commerce of food products around the country, have contributed to the spread of the Asian tree frog throughout the Philippines.”
Meanwhile, scientists are baffled by the presence of the Asian tree frogs on nearly every island in the Philippines that has been surveyed by biologists. The species’ recent arrival on many hundreds of islands defies a natural explanation and suggests that humans must have been involved in the spread of its populations. Brown also cited a recent study by Japanese biologists who concluded that humans had brought Philippine Banana Frogs to the as far north as the rice fields of Japan.
“These findings suggest that Filipinos, in our every day comings and goings, have contributed to the expansion of Banana Frog populations throughout the country,” said T. Mundita Lim, Director of PAWB-DENR. “The results of this study reinforce the idea that humans may have a real impact on the distribution of animal life in the Philippines.”
On a more serious note, Lim emphasized that the new study by Brown and colleagues demonstrated how quickly an invasive species can spread if humans are not careful and take steps to prevent exotic species introductions. Lim cited the case of the American Cane Toad, which was introduced into the expansive sugar cane plantations on Negros a century ago in hopes that it would control insect pest species, only to become a major pest itself.
The rare Philippine flat-headed frog, Barbourula busuangensis
What do the highly celebrated Bornean lungless frogs and the rare Philippine flat-headed frogs have in common? The answer, scientists revealed this week, is tens of million years of evolutionary history and potential isolation of their ancestors on a small “raft” of islands that split from mainland Asia 30 million years ago.
The surprising findings, the result of collaboration between scientists in four countries, were announced today in the international journal PLoS ONE. Dr. David Blackburn, KU Biodiversity Institute researcher and the lead author on the findings, said that the results "reveal a very ancient origin to these enigmatic frogs and suggest a new interpretation for the origins and history of some animal species inhabiting the western islands of Philippines.”
“If our results are correct,” said scientist Arvin Diesmos, co-author on today’s paper and a curator at the National Museum of the Philippines in Manila, “the ancestors of lungless frogs may have become isolated on a small chain of islands that rifted from the Asian mainland 30 million years ago. These highly distinctive, threatened frogs may have acquired their unique characteristics during the period that they were isolated on the Palawan raft.”
The subject of the new study is the evolutionary origins of the lungless and flat-headed frogs, known to scientists as Barbourula kalimantanensis (from south-central Borneo Island) and Barbourula busuangensis (from Palawan Island in the western Philippines). The study involved scientists from the University of Kansas, the National Museum of the Philippines, the National University of Singapore, and the Bandung Institute of Technology, Indonesia. The team sequenced a large number of genes and performed molecular clock analyses to date the evolutionary origins of lungless and flat-headed frogs.
“Our findings have the potential to turn the “Palawan Paradigm” on its head, stated Rafe Brown, KU curator of herpetology and recipient of the National Science Foundation grant that funded the research. “Given our new data, we must consider the possibility that these unique amphibians survived 20 million years in the Philippines before dispersing to Borneo—and not the other way around.”
Brown also emphasized several other recent studies which, together with the new findings, emphasize the evolutionary uniqueness of the western Philippines and reject the past 150 years’ prevailing interpretation of the western Philippines as simple, unremarkable “faunal peninsula” of Borneo.
A significant new collection of photos has been added to AmphibiaWeb by the KU Biodiversity Institute's Herpetology scentists. Of the 559 photos contributed, 328 species were not previously represented by photos in AmphibiaWeb, and 108 are holotypes. AmphibiaWeb is an online system that provides access to information on amphibian declines, conservation, natural history and taxonomy. All copyrights are held by KU's Division of Herpetology.
AmphibiaWeb recognized Dave Blackburn, KU post-doctoral associate, for organizing the photo additions, Bill Duellman, curator emeritus, for contributing so many of his own photos, and curators Rafe Brown and Linda Trueb.
Through loss or modification of habitats, infectious disease and climate change, declines and extinction of amphibians are happening all around the world. Unlike other regions of the earth, there are few documented cases of discovering large die-offs of frogs in sub-Saharan Africa. Recently a team of scientists including the Biodiversity Institute's David Blackburn investigated an unusual die-off in Cameroon.
Blackburn, together with colleagues from the United States and Canada, documented the mortality event of the critically endangered Lake-Oku clawed frog (Xenopus longipes). The frog is known to only live near a small crater lake high in the mountains of the west African country. Unlike almost all other vertebrate species, this small frog is biologically unique in having twelve sets of chromosomes (instead of the two sets that people have).
The team sought to document the unexplained die-off event and attempt to determine whether this species has also fallen victim to the chytrid fungus (Batrachochytrium dendrobatidis), which is responsible for many mass mortality events elsewhere in the world.
Using both molecular and anatomical techniques, Blackburn and the team did not find presence of the fungus or the equally deadly ranavirus. Instead, the team’s analysis indicates that the animals may have been exposed to a source of skin irritation that caused large wounds which subsequently became infected.
At present, the causes of these deaths remain unclear, but the observations of the team have led to the development of a conservation action plan in collaboration with the non-government organization, Amphibian Ark.
The findings were published in the African Journal of Herpetology.
University of Kansas researchers are members of a team of international scientists who have discovered and documented a new species of monitor lizard in the Philippines that can grow up to 2 meters long.
Through the analysis of its physical features and its DNA, scientists have determined that the new species is distinct from other similar species. It spends most of its time in trees in the forests of the Northern Sierra Madre mountain range of Luzon.
Although the species had been seen as early as 2001, it was only last year that a joint KU-National Museum of the Philippines expedition to Aurora Province yielded a large, adult specimen and good DNA samples. The scientific description of the reptile has been published this week in Biology Letters, an international journal published by the Royal Society of London.
Luke Welton, a KU graduate student and one of the coauthors of the scientific description, was one of the first biologists to see a living Northern Sierra Madre Monitor Lizard in Aurora Province.
“I knew as soon as I saw the animal that it was something special,” says Welton. “I had seen specimens of the other two species of fruit-eating monitors, but neither of the other known species are nearly as spectacular as the Northern Sierra Madre Forest Monitor.”
Giant fruit-eating monitor lizards are found only in the Philippines. It is one of three giant fruit-eating monitor lizard species that are threatened by destruction of their forest habitats and, to a lesser degree, by hunting for their meat and the pet trade.
“We hope that by focusing on protection of this new monitor, conservation biologists and policy makers can work together to protect the remaining highly imperiled forests of northern Luzon” said Rafe Brown, assistant professor of biology at KU and curator of Herpetology at the KU Biodiversity Institute.
“The new species can serve as a convenient ‘Flagship Species’ for conservation, focusing the attention of the public and affording protection to many unrelated species if its habitat is preserved,” said Brown, who led the research team that discovered the new species.
Brown also said that it was extremely rare to discover a new, large vertebrate species.