South-East Asian Frog Research
To study reproductive variation in frogs in Singapore and Thailand
About half of the world's amphibians are threatened with extinction. There are approximately 6,000 described amphibian species, and 2000-3000 are in danger of going extinct (32% are known to be threatened and another 23% are data deficient but believed to be threatened). Since 1980, at least 122 amphibian species have gone extinct, including one entire family (Rheobatrachus) with a unique reproductive mode (gastric brooding).
This Global Amphibian Crisis is caused by a wide range of threatening factors, including habitat destruction, climate change, pollution, exploitation, introduced species, and disease.
As global warming continues, it is important to predict how species will respond. Wide-ranging species that naturally span an environmental gradient provide ideal model systems to start answering this question.
This project investigated variations in reproduction of five common Southeast Asian frog species: banana frog (Polypedates leucomystax), field frog (Fejervarya limnocharis), Asian green-back frog (Rana erythrea), dark-sided chorus frog (Microhyla heymonsi), and painted chorus frog (Microhyla butleri).
The banana frog is a foam-breeder, i.e. the species deposits its eggs in a foam mass on vegetation over ponds or swamps and the tadpoles fall into the water below or are washed out of the foam by the next rain. The green-back frog uses both permanent and temporary ponds, and the painted chorus frog is a classic temporary or ephemeral pool-breeder, which avoids the large suite of predators found in more permanent bodies of water, but with the disadvantage that the tadpoles must develop and metamorphosize quickly before the pools dry out.
The goal of the project is to determine how these species alter their reproduction (clutch size, egg size, frequency and breeding) between an aseasonal site (Singapore) where they can breed year-round, and a seasonal site (Thailand) where breeding is restricted to 5-6 months a year. The results will help making predictions about how these organisms, which are extremely sensitive to environmental change, will respond to global warming.
WAZA Conservation Project 06008 is implemented by Miss Jennifer Sheridan, University of California, San Diego, and supported by the American Society of Ichthyologists and Herpetologists and the Singapore Zoological Gardens.
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