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At first glance, the Cuban blue-headed quail dove may not seem particularly striking. With its muted brown plumage, slender beak, and a typical dove-like gait, it tends to blend into its native environment, often overshadowed by the vibrant colors of Cuba’s parrots. However, this inconspicuous bird has puzzled scientists for years regarding its origins, how it arrived on the island, and its genetic relationships to other avian species.
Recently, for the first time, researchers successfully sequenced the DNA of the blue-headed quail dove in an effort to unveil its enigmatic history. The results, however, have led to even greater confusion.
“This species has been an ornithological mystery for quite some time,” stated Jessica Oswald, a consultant at the Florida Museum of Natural History and the lead author of the study that outlines the DNA findings. “We anticipated unusual results that could shed light on the complex biogeography of the Caribbean. We did not expect to find it so evolutionarily distinct compared to other species.”
Initially, researchers believed that blue-headed quail doves were closely linked to their counterparts in Central and South America. However, careful observations revealed traits that aligned more with doves and pigeons from Australasia.
Published in the journal Biology Letters, the study concluded that neither of these initial assumptions holds true. The blue-headed quail dove does not share a close evolutionary lineage with either Australian doves or their American relatives.
“This bird is more evolutionarily unique than even the dodo,” Oswald noted. The dodo, which was also a type of dove, had at least one known relative, the Rodrigues solitaire, that is now extinct.
While the age of dove species remains uncertain, DNA analysis suggests that the blue-headed quail dove may date back as much as 50 million years. This timeframe is significant, especially in evolutionary biology, where the divergence of human and chimpanzee lineages occurred only about 5 to 6 million years ago.
Unraveling Caribbean Extinction History
Oswald conducted her research during her postdoctoral fellowship at the Florida Museum as part of a larger initiative, supported by the National Science Foundation, aimed at understanding the factors contributing to bird extinctions in the Caribbean over the last several millennia.
Since humans arrived on these islands, an estimated 12% of bird species in the Caribbean have disappeared, including a giant owl nearly four feet tall, numerous parrots, a raptor significantly larger than a bald eagle, a flightless ibis that used its wings in physical combat, and a condor with a uniquely powerful bite.
Historically, identifying the relationships of extinct Caribbean species to modern ones has been challenging due to the reliance on fossil records alone.
To address this gap, Oswald created innovative methods to extract and sequence ancient DNA from avian fossils. In a preliminary experiment with the fossil of an extinct Caribbean cave rail, she and her team identified the first known extinct Caribbean bird whose nearest relatives reside in Africa, New Guinea, and New Zealand. A subsequent study highlighted that a parrot, once widespread across the Caribbean, is now confined to the island of Hispaniola due to human activity.
While the blue-headed quail dove still exists, it faces serious threats.
“There are about 1,000 mature individuals left in Cuba. The species is at risk due to overhunting, habitat destruction, and invasive predators like cats. It is indeed on the verge of extinction,” Oswald explained.
Sequencing DNA from this elusive species has proven difficult as only a handful of specimens collected several decades ago can be found in North American museums, complicating DNA extraction using conventional techniques.
Oswald applied her newly developed DNA sequencing method to a toe pad taken from a blue-headed quail dove specimen collected in 1958 and housed at the Florida Museum. The outcome was uncertain, but after awaiting the results with anticipation, she reached out to her colleague and former doctoral advisor to share her findings.
“She called to ask if I was seated. I expected negative news, but it turned out to be the opposite,” recalled David Steadman, who served as curator of ornithology at the Florida Museum for over two decades. He acknowledged the advancements in technology that have enhanced the science of natural history.
“This example underscores the significance of museums in preserving specimens over the long term. With advancements in ancient DNA techniques, fossils, historical specimens, and even modern samples are becoming increasingly valuable for research,” he added.
The results of the DNA sequencing revealed intriguing insights. Other Caribbean doves have been identified, including an extinct species known only through archaeological remains that indicate it was part of Indigenous diets before facing extinction. However, while most Caribbean doves are believed to have originated from North or South American ancestors, the blue-headed quail dove’s origins remain ambiguous.
“This species likely represents the remnants of a once diverse lineage of birds that have existed in the Caribbean for a significant period. Cuba itself is an ancient island,” noted Steadman.
Its earlier ancestry is uncertain, suggesting it could either be the last remnant of a formerly widespread bird lineage or an unusual offshoot of existing dove species that became isolated on Cuba ages ago.
Despite its grounded behavior today, the blue-headed quail dove likely descended from ancestors that possessed strong flight capabilities, which enabled them to explore and occupy extensive territories.
“Certain bird groups are remarkable dispersers, including pigeons and doves. They can travel significant distances, especially since they often rely on fruit sources that require them to search over large areas,” remarked Oswald.
Contributors to the study include Bret Boyd from Virginia Commonwealth University, Avery Szewczak and Julie Allen from Virginia Tech, Michelle LeFebvre and Rob Guralnick from the Florida Museum of Natural History, and Brian Stucky from the University of Florida.
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