Endemic to SE Asia—the secrets of the ancestry of world-renowned dream species broad-tailed swallowtail butterfly (Agehana maraho) revealed

Endemic to SE Asia—the secrets of the ancestry of world-renowned dream species broad-tailed swallowtail butterfly (Agehana maraho) revealedThe latest issue of periodical PLoS ONE published on October 25, 2015 featured a paper entitled “Phylogeny and Historical Biogeography of Asian Pterourus Butterflies (Lepidoptera: Papilionidae): A Case of Intercontinental Dispersal from North America to East Asia,” jointly authored by Taiwan butterfly ecology and classification expert Dr. Wu Li-wei, the Experimental Forest, College of Bio-Resources and Agriculture, National Taiwan University, Professor Hsu Yu-feng, Department of Life Science, National Taiwan Normal University and Associate Professor Yen Shen-Horn, Department of Biological Sciences, National Sun Yat-sen University, with the support of the Forestry Bureau. The paper shows that the broad-tailed swallowtail butterfly (Agehana maraho) has no blood relationship with East Asian butterflies but is a descendant of butterflies that migrated from North America across the Bering Strait around 18 million years ago in the Miocene Epoch of the Tertiary Period, solving the mystery of the ancestry of Agehana maraho that has lasted for nearly 100 years. Since publication date, this discovery has drawn attention from around the world.

The Forestry Bureau stated that, among the world’s 550 species of Papilionidae butterfly there are only two species of broad-tailed swallowtail butterfly that are endemic to East Asia. They are Agehana maraho discovered in the Yangtze river basin in 1889, and Agehana maraho, collected for the first time in Datong Township, Yilan, Taiwan, in 1932. Unlike other Papilionidae butterflies, both species have hind wings with tail-like prolongation and third and fourth wing veins pierced on the posterior margin.
Agehana maraho is known as the national butterfly of Taiwan. It was entered into the new genus Agehana by Dr. Matsumura Shōnen then of Taihoku Imperial University in 1936. The species’ name maraho came from the Atayal language’s word for chief, indicating its special position amongst the butterflies of Taiwan.
With the rise of the butterfly specimen industry in Taiwan, Agehana maraho became the top target of collectors. It was listed as a protected natural monument as early as 1935 in the Law for the Preservation of Historic Spots, Scenic Beauties and Natural Monuments. In 1988, it was designated a valuable and rare species in the Cultural Heritage Preservation Act, and as an endangered species in 1989’s Wildlife Conservation Act. In 2000, the Guanwu Broad-tailed Swallowtail Major Wildlife Habitat was established in the Forestry Bureau’s Compartment 49 of Da-an River Working Circle for National Forest in Wufeng Township, Hsinchu County and Taian Township, Miaoli County. The habitat is 55,991 hectares in area and its establishment gave full protection to Agehana maraho. From this time on, the habitat saved it from the threat of extinction. 

In 1966, Liao You-lin, at the time a teacher at Shun-An Elementary School of Yilan County, for the first time found broad-tailed swallowtail (Agehana maraho) larvae that only fed on the Taiwan Sassafras. From that time, study of the biology of Agehana maraho began. In the 1990s, long-term advocates of insect conservation, Yang Ping-shih Professor Emeritus, Department of Entomology, NTU and Professor Hsu Yu-feng, Department of Life Science, NTNU led two teams that cooperated in long-term ecological survey and restoration research.

Working with the Forestry Bureau, in 2009 the research teams used mitochondrial DNA to confirm that Agehana maraho and Agehana elwesi are genetically different. In 2011 the team released a paper entitled “The Complete Mitochondrial Genome of the Near-Threatened Swallowtail, Agehana maraho (Lepidoptera: Papilionidae): Evaluating Sequence Variability and Suitable Markers for Conservation Genetic Studies.” The most distinctive structure of the Agehana mitogenome is the control region (CR; 1,270bp). This is the longest CR found so far in any lepidopteran, and it also represents the first known case of two units of macro repeats within a tandem region. The information provided more suitable markers for conservation genetic studies and the combined research of morphology, physiology and behavior studies.
Major discovery of the origin of East Asian Papilionidae butterflies.

The Forestry Bureau explained that Agehana elwesi and Agehana maraho were discovered over a century ago but due to lack of specimens, their origin and relationship to otherPapilionidae butterflies had not been fully studied and there was even a dispute for almost 70 years as to whether Agehana maraho was a separate species.
Dr. Wu Li-wei, Professor Hsu Yu-feng and Associate Professor Yen Shen-Horn have studied the origin of Papilionidae butterflies for several decades. A total of 86 species representatives within Papilionidae were sampled, and four genes (concatenated length 3,842 bp) were used to reconstruct their phylogenetic relationships and historical scenarios. Surprisingly, “Agehana” fell within the American Papilio subgenus Pterourus and not as previously suggested, phylogenetically close to the Asian Papilio subgenusChilasa. Therefore the professors formally synonymize Agehana with Pterourus. Dating and biogeographic analysis allow us to infer an intercontinental dispersal of an American ancestor of Asian Pterourus in the early Miocene, which was coincident with historical paleo-land bridge connections, resulting in the present “East Asia-America” disjunction distribution. They emphasize that species exchange between East Asia and America seems to have been a quite frequent occurrence in butterflies during the Oligocene to Miocene climatic optima.

Future research directions

The Forestry Bureau stresses that this study reveals several important aspects of future work; the first is the importance of long-term government support for basic research and field work; second is the importance of collecting specimens; without the specimens of scientific value preserved long-term in the collections of museums in Taiwan and overseas, researchers would not have been able to obtain heteromorphosis information. Thirdly, is how researchers respond to public interests and policy requirements. Only with more in-depth research can science-based design and decision making be carried out with respect to follow up environmental education, general science education and the promotion of policies by various related agencies.

Due to the similarity of appearance of Asian Pterourus butterflies, in future the Forestry Bureau will continue to work with the research teams and, with the research topic, carry out in-depth study of how, after arriving in Asia, Asian Pterourus butterflies underwent dramatic changes to wing pattern and shape under the effect of Byasa impediens and natural selection.

Reference:Wu L-W, Yen S-H, Lees DC, Lu C-C, Yang P-S, Hsu Y-F (2015) Phylogeny and Historical Biogeography of Asian Pterourus Butterflies (Lepidoptera: Papilionidae): A Case of Intercontinental Dispersal from North America to East Asia. PLoS ONE 10(10): e0140933. doi:10.1371/journal.pone.0140933 
Attachment: Agehana maraho information
Agehana maraho
  1. Chinese Name: 臺灣寬尾鳳蝶、寬尾鳳蝶、闊尾鳳蝶、大尾鳳蝶
  2. Latin name:Agehana maraho (Shiraki & Sonan, 1934)
  3. English name:Broad-tailed swallowtail, Taiwan broad-tailed swallowtail
  4. Classification: Order-Lepidoptera, Family-Papilionidae
  5. Conservation status: Endangered Species
  6. Features: Forewing length 48~65mm. Male and female have similar wing vein patterns. The body color is blackish-brown, the back of the wings is brown color and the outer of the hind wings are blackish-brown color. A large white spot detoured in area of hind wing cells and its proximity of each of the hind wings, with a red crescent-shaped pattern lining the edge of hind wings. The most distinct characteristic of is its extraordinarily broad tail, which runs through the third and fourth veins (M3 and Cu2) of its wings. There are 600 papillionidae species in the world but only Agehana elwesi with aforementioned features thus became well-known worldwide. The hind wings are not folded at the inner edge. The adult butterflies have similar patterns as genus Epicopeia and Byasa.
  7. Ecological habits: Lives in evergreen broadleaf forests and mixed evergreen and deciduous broadleaved forest where host plants grow. The butterfly stage is reached from March to September. The adult butterflies have the habit of visiting flowers. The males will go to wet areas to drink. The female lays eggs on the surface of mature leaves. After emerging from their cocoon the larvae eat the leaves of Sassafras randaiense of Family Lauraceae. Some individuals spend winter in their cocoon and no correspondence with the actual number of pupae per generation. Those that don’t hatch within the year, those that are dormant only hatch the following year.
  8. Distribution: Endemic to Taiwan; Distributed at 500-2,000 meters in elevation central and northern Taiwan and eastern Taiwan. 
  9. Problems faced: pressure from illegal catching, habitat destruction.
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