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202105/11
The endangered Formosan flying fox (Pteropus dasymallus formosus) is the largest bat in Taiwan, and in the past its scarcity in numbers has resulted in very little research. To establish ecological data of the endangered species native to Taiwan, the Forestry Bureau has continued to monitor flying fox populations to formulate the direction of conservation strategies. Furthermore, the Forestry Bureau has formed a research team in collaboration with Assistant Professor Chen Shiang-Fan of the National Taipei University and Assistant Professor Ko Wen-Ya of the National Yang Ming Chiao Tung University, to analyze the genetic diversity of the Formosan flying fox and the relationship with their relatives in other islands. The team found that the genetic diversity of the Formosan flying fox was low, and the inbreeding coefficient was relatively high. The results have also been published in the international academic journals Biotropica and Journal of Heredity in March of this year.
The research team used next-generation genome sequencing technology to solve the history of the population changes of the Formosan flying fox, and compared these results with that of Okinawa's Orii's flying fox (Pteropus dasymallus inopinatus). The results showed that the two subspecies had opposite fates: the Formosan flying fox population experienced a rapid decline to one-tenth of its original size in a short period of time, while the Orii's flying fox population has grown significantly, increasing approximately five-fold in recent years. However, both Taiwanese and Japanese flying foxes have low genetic diversity and a relatively high inbreeding coefficient, indicating that they are less able to adapt to changes in the environment. In view of unpredictable environmental changes or infectious diseases in the future, the flying fox populations in Taiwan and Japan are both vulnerable.
The Forestry Bureau pointed out that the Formosan flying fox was common in Green Island in the early years, but almost disappeared entirely due to over-hunting. In recent years, small, stable populations have emerged in Turtle Island and Hualien, and have once again caught people's attention. The Formosan flying fox is a subspecies of the Ryukyu flying fox, and different subspecies are distributed in different islands in the East and Southeast Asia island arcs, spanning Japan, Taiwan, and the Philippines. Flying foxes have excellent flying abilities and can migrate over long distances. Therefore, it has been speculated that the populations in different islands have frequent exchanges and may be of the same family. However, because differences in their physical appearance are very small and difficult to distinguish, researchers can only rely on genetic molecular clues to solve the mystery of the origins of flying foxes through history. In addition, genetic diversity can also reflect the evolutionary history of a population, which can be used to estimate the effective population size and assess its "health level," helping us understand the long-term survival potential of flying fox populations.
Lin Hwa-Ching, Director General of the Forestry Bureau, said: "The research and conservation of an endangered species across different countries cannot be done by a single country or individual; it requires the cooperation of many people for the work to be more comprehensive. Our endangered species research and conservation efforts have always been a race against time because we need to understand them better in order to formulate appropriate conservation policies." The research samples are becoming more and more complete with the participation of researchers from different countries, including Assistant Research Fellow Nian-Hong Jang-Liaw from the Taipei Zoo, Tokai University, University of the Ryukyus, University of Tokyo, Okinawa Zoo & Museum, Hirakawa Zoo, American Museum of Natural History, University of London, and National Museum of Natural History of the Philippines. The samples come from Green Island, Turtle Island, Gongliao, Yilan, Hualien, Japan's Iriomote Island, Ishigaki Island, Okinawa, Minami-Daito Island, and Kuchinoerabu Island, as well as Batan Island and Sabtang Island in the Philippines. The scope covers different subspecies and regions, making each sample invaluable.
The results of mitochondrial and microsatellite DNA studies also show that deep and wide straits are a natural barrier for the migration and spreading of flying foxes. Except for the Formosan flying fox and the Yaeyama flying fox (Pteropus dasymallus yayeyamae), other different subspecies have significant genetic differences. The greater the geographical distance, the greater the genetic difference. Deep straits such as the Tokara Strait and Kerama Strait in the northern, central and southern Ryukyu Islands, the Ryukyu Trench on the eastern side of the Ryukyu Islands, and the Bashi Channel on the southern side of Taiwan correspond to the distribution boundaries of different flying fox subspecies. Among them, the population composition of the Formosan flying fox may have multiple ancestral origins. The recently emerged Turtle Island colony not only has its own unique branch, but some of its individuals are even more closely related to the flying foxes on Taiwan's main island and even to the neighboring Yaeyama flying fox population.
The Forestry Bureau will continue to improve the habitat quality of the flying foxes' distribution areas and monitor the kinship of the small colonies on the island. We hope that this endangered species can leave behind its current conservation status as soon as possible and coexist with us in harmony.
Formosan Flying Fox Mini File:
The Formosan flying fox (Pteropus dasymallus formosus) is the largest bat in Taiwan, with a wingspan of up to one meter. It feeds on fruits, flowers, and young shoots. It is an important pollinator that helps disperse seeds in the forest ecosystem. Originally mainly found in Green Island, the flying fox has nearly disappeared due to over-hunting. In recent years, small stable populations have emerged in Turtle Island and Hualien. The Formosan flying fox is an endangered protected species under the Wildlife Conservation Act.
The Formosan flying fox is a subspecies of the Ryukyu flying fox, and different subspecies are distributed in different islands in the East and Southeast Asia island arcs, from the northern islands of the Ryukyu Islands, south to Taiwan, to the northern islands of the Philippines, spanning across three countries. The subspecies include Erabu flying fox, Orii's flying fox, Daito flying fox, Yaeyama flying fox, Formosan flying fox, and Philippine flying fox. Erabu flying fox and Daito flying fox are Natural Monuments of Japan.
Note: Please contact Assistant Professor Chen Shiang-Fan of the National Taipei University for more information on flying foxes.