- South Asia is home to 24 different species of bulbuls, a family of songbirds for which a new genetic analysis shows an evolutionary history dating back to the archipelago of Southeast Asia to Africa and the islands of South Asia. ‘Indian Ocean.
- In every region where birds are present, climatic and environmental factors have shaped their evolution, leaving some species in India with more similarities to their Southeast Asian cousins ââthan to their Southeast Asian counterparts. .
- This diversification in the bulbul family tree did not stop after their displacement from Southeast Asia to South Asia, and in fact continued as they dispersed across the Middle East and Africa, as well as “from island to island” in Madagascar and the Mascarenes. .
COLOMBO – The rich diversity of bulbuls in South Asia can be traced back to the Sundaland region of Southeast Asia, to the islands that today make up Indonesia and Malaysia, according to a new study.
Bulbuls, the Pycnonotidae family of fruit-eating songbirds, number more than 150 species in Asia and Africa, including 24 in South Asia, half of which are endemic to the region. Genetic analysis now shows that these South Asian bulbuls find their origins in Sundaland, coming from several waves of colonization that crossed mainland Southeast Asia to reach the Indian subcontinent.
“When the genetic identities of these bulbuls are placed on the global bulbul evolution tree, they fit in different places suggesting that these species occupied South Asia at different times,” said Ashish Jha, author principal of the new study and researcher in the laboratory. for the conservation of endangered species in Hyderabad, India.
Jha and his colleagues compared the genetics of South Asian bulbuls primarily with their Asian cousins ââto recreate an evolutionary tree and map other factors to study their phylogeny, or how they developed over time. time. Data for some South Asian endemic bulbuls were lacking in the existing global bulbul phylogeny. The team therefore used the genetic data available and supplemented them with genetic data from endemic species from India and Sri Lanka.
The researchers placed particular emphasis on the roots of the region’s endemic bulbul species, which evolved in response to specific climatic and environmental conditions.
âOnce the entire Indian peninsula was covered with humid and humid forest, but about 12 million years ago, in the post-Miocene era, it started to dry up,â Jha told Mongabay. “This rapid aridification has restricted the region’s rainforests primarily to high elevations, allowing the bulbul members that have isolated themselves in these locations to evolve as distinct species.”
Molecular dating shows that the oldest bulbul in South Asia is the striated bulbul (Striated pycnonotus) and mountain bulbul (Ixos mcclellandii) of the Himalayas, and the yellow-throated bulbul (P. xantholaemus), and the white-browed bulbul (P. luteolus) from peninsular India, which diverged at the end of the Miocene (11.63 to 5.33 million years ago). Bulbuls endemic to the Western Ghats in India diverged from their sister species during the Pliocene, approximately 5.33 to 2.58 million years ago.
The oldest endemic species of the peninsular region are the yellow-throated bulbul from the Deccan region of India and the yellow-eared bulbul from Sri Lanka (P. penicillatus). âThese two species do not have closely related sister taxa, so they are unique in the evolutionary tree,â Jha said.
The African connection
The study also established that South Asian bulbuls belonging to the Pycnone genus colonized Africa in the Pliocene, crossing the Arabian Peninsula and the Middle East, while those of the Hypsipetus The genus “jumped from island to island” as far as Madagascar and the Mascarene Islands at the beginning of the Pleistocene, about 2.58 million to 12,000 years ago.
Today there are two Hypsipetus species in South Asia: the black bulbul (Hypsipetes leucocephalus) in the Himalayas, and the square-tailed bulbul (H. ganeesa) found in the Western Ghats and Sri Lanka.
âMany would assume that the Himalayan species is a sister species to the Western Ghats and the Sri Lankan square-tailed bulbul, but it is actually related to the Philippine bulbul. [H. philippinus], while the square-tailed bulbul was found to be closely related to the Madagascan bulbul [H. madagascariensis]Jha told Mongabay.
“These variations within the bulbul family make it a very good model for understanding local and regional diversity while studying the long-term impacts associated with climate and geological changes over time for species,” said the co -author of the study Sampath Seneviratne from the University of Colombo.
For example, in Sri Lanka, the yellow-eared bulbul is probably the most common bird in the central highlands, present even in home gardens and urban areas. But at altitudes below 1,200 meters (4,000 feet), they simply disappear. Likewise, the square-tailed bulbul is very common in tropical rainforests and sometimes found in home gardens, but is absent in areas without rainforest. In contrast, the most common bird in Sri Lanka is the red-vented bulbul (P. cafer), which nestles on apartment balconies and is comfortable in an urban setting.
Numerous recent scientific publications have examined how rapid aridification and other environmental factors that occurred millions of years ago contributed to the colonization and evolution of biodiversity in South Asia today. ‘hui.
“It is interesting to study how different groups of animals respond to historical climate and environmental changes,” Seneviratne said, “because it helps to understand what will happen in the future, if similar changes occur.”
Jha, A., Seneviratne, S., Prayag, HS and Vasudevan, K. (2021). Phylogeny identifies multiple Miocene colonization and aridification events as drivers of the diversification of South Asian bulbuls (Passeriformes: Pycnonotidae). Diversity and evolution of organisms, 21(4), 783-794. doi: 10.1007 / s13127-021-00506-y
Banner image of a square-tailed bulbul (Hypsipetes ganesa) found in the Western Ghats of India and Sri Lanka, which has sister species in the African islands of Madagascar. Image courtesy of Erich Joseph.