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The Philippines’ Mindanao is a treasure trove of reptile and amphibian diversity

  • Species identified include 49 species of lizards, 40 species of frogs, 35 species of snakes, one caecilian, one species of freshwater turtle and one crocodile.
  • Northeastern Mindanao is home to species from both mainland Mindanao and the eastern Visayas, creating a biodiversity “bulls eye.”
  • Due to the island’s complex politics and history of conflict, relatively few surveys and studies have been conducted in Mindanao.
  • Researchers hope their findings will underscore the need to protect the island’s forest ecosystems.

The Philippine Islands have long been known as a hotspot of biodiversity. Until recently, though, scientists had an incomplete understanding of the extent of reptile and amphibian diversity in Mindanao, the large and mountainous island that anchors the southern end of the archipelago. In a report appearing recently in the journal Zookeys, a team of researchers led by herpetologist Marites Sanguila of Father Saturnino Urios University announced that Mindanao is in fact an “epicenter” of southern Philippine biodiversity.

“The region’s biodiversity ‘bull’s eye’ (or epicenter, a hotspot within a hotspot), is the result of the overlap, or coming together, of 126 species,” Sanguila told Mongabay by email. The survey covered northeastern Mindano and associated islands, where species from both Mindanao Island and the eastern Visayan Islands can be found. “Added together, they make the center-of-the-center of Southern Philippine herp diversity,” she said.

Gonocephalus cf. interruptus, one of the many reptiles catalogued in Mindanao. Photograph by Rafe Brown.

A team of herpetologists and graduate students from Father Saturnino Urios University, the University of Oklahoma, the University of Kansas, the National Museum of the Philippines, Silliman University and the Philippine Department of the Environment and Natural Resources conducted surveys on four major mountains. They surveyed sites at a variety of elevations and habitat types, and at different times of the day and night. The resulting paper represents the accumulated data from many such expeditions as well as distribution records of species documented in museums around the world.

In total, they recorded around 126 species of amphibians and reptiles including 49 species of lizards, 40 species of frogs, 35 species of snakes, one caecilian (an order of limbless amphibians), one species of freshwater turtle and one crocodile. That represents 36 percent of total Philippine herpetofauna identified to date, giving it the single highest herpetological diversity of any similarly-sized region in the country currently known.

Pulchrana Gradocula, one of more than ## frogs the team surveyed. Photo by Rafe Brown.

“I think it was a surprise to see just how diverse the region is, not just in one site, but how diversity changes across this one small region of the Philippines,” Cameron Siler, a herpetologist at the University of Oklahoma, told Mongabay. “We expected a lot of new records and a lot of new discoveries to be made, but then were still surprised by how you could go from one part of northeast Mindanao to the islands just off the coast and still see completely unique habitats that are pretty close in proximity.”

Recent efforts to estimate the herpetological diversity of the Philippines have focused in the north, on the large island of Luzon, as well as central island groups. Most of the records that do exist from Mindanao are over 100 years old and were gathered by the “father of Philippine herpetology,” Edward Harrison Taylor, who spent years surveying and discovering new species on Mindanao in the early 1900s. Although these specimens provide invaluable historical records, few modern surveys have focused on the region. That may be due, in part, to the daunting nature of conducting biological research there.

Marites Sanguila, second from left, on-site in Mindanao with students and research assistants. Photo courtesy of Marites Sanguila.

“When you do survey work on Mindanao, two main issues need to be addressed; security-related and local (within site) politics,” Sanguila said. Culturally, Mindanao is incredibly complex and diverse. The island is home to some two dozen ethnolinguistic groups speaking roughly 70 languages, who often have conflicting interests over how to use the island’s rich agricultural and natural resources. Proper precautions had to be taken before researchers could go into the field, including meeting with local authorities, tribal leaders, hunters, police and military for advice.

All that hard work is now paying off. “Having [Sanguila] down there and being one of the more active biodiversity researchers in the southern Philippines is a fantastic position to develop new conservation initiatives and awareness about biodiversity,” Siler said. In 2013, Sanguila came to the University of Oklahoma on a Fulbright scholarship to study genetic sampling techniques as well as the ins and outs of building and caring for a natural history collection. It was there, in collaboration with Siler, that the ambitious project to survey the reptiles and amphibians of Mindanao was born.

Another major goal of the research was to update outdated IUCN conservation status assessments by sorting out unresolved taxonomic questions. That work, the researchers say, has just begun. Many more long-term species surveys are needed to truly understand the diversity and conservation status of the reptiles and amphibians of Mindanao. That will require using modern genetic sampling techniques as well as input from more traditional taxonomists who perform the detailed work of teasing apart species relationships. According to Sanguila, 20 percent of the species recorded require “immediate systematic revisions” before informed decisions can be made regarding their conservation status.

One of the research team’s survey sites in Mindanao. Photo courtesy of Marites Sanguila.

Sanguila also stresses the importance of conserving what is left of Mindanao’s forests, especially now that we know what a special place it is. Although much of the original forest cover in the lowlands have been lost, she believes it is critical to establish new protected areas to halt the environmentally destructive harvest of natural resources, to promote societal environmental awareness, and to allow habitats to regenerate over several decades.

Siler hopes this paper is only the beginning of a bright future for biodiversity research in the area. He plans to continue working with the University of Kansas, graduate students from the program – many of whom have started their own programs in the United States – as well as their Philippine collaborators.

“Dr. Sanguila is building a wonderful biodiversity program in the southern Philippines that we hope is going to be a thriving centerpiece for biodiversity education and training the next generation of students there to continue all of this work throughout the archipelago, Siler said. “There is so much left to be understood about our planet and the Philippines in absolutely no exception.”

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