NEW YORK (GenomeWeb) – Researchers from the UK, Sweden, Germany, and the US have used ancient DNA to narrate the potential history of an insect-eating mammal from the Caribbean that went extinct sometime in the 16th century.
Using DNA from owl pellets from the Dominican Republic that are estimated to be 750 years old, researchers at the Natural History Museum in London, the Zoological Society of London, and elsewhere sequenced mitochondrial and nuclear DNA from Nesophontes — an extinct shrew-like creature that earned its name ('Island Murderer' in Greek) due to its insect-devouring ways.
The results, published in Molecular Biology and Evolution, indicate that Nesophontes was part of a clade that evolved some 70 million years ago and later diverged from a lineage leading to venous insect-eating animals called solenodons that still exist in the Caribbean.
At least eight suspected Nesophontes species were once found on islands such as Hispaniola, Cuba, Puerto Rico, and the Caymans. The animals became extinct in the last 500 years or so, perhaps snuffed out through competition with rats who arrived on ships from Europe.
Because Nesophontes fossils can be hard to come by in the Caribbean, the researchers focused on owl pellets. After extracting DNA from the samples, they generated more than 337 million reads on the Illumina HiSeq 2000, including 18.4 million reads that more closely resembled existing mammalian sequences by BLAST search.
The team aligned reads for the Nesophontes mitochondrial genome and for 17 nuclear genes against sequences from related insectivores. From there, it did a phylogenetic analysis using sequences for 27 related insect-eating mammals — including Solenodon paradoxus, a living representative of the Solenodontidae family from Hispaniola.
With these data, the researchers estimated that a clade containing Nesophontes and solenodon animals emerged roughly 72.8 million years ago. After apparently colonizing the Caribbean just once, the clade appears to have diversified there, they note. The team estimates that the Nesophontes and solenodon lineages split roughly 57.3 million years ago, as land masses in the area were moving and temperatures increasing.
"The demonstrated antiquity of nesophontids, a family-level lineage as old or older than diverse estimates for many extant mammal order, highlights the role of island systems as 'museums' of diversity that preserve ancient lineages as well as promoting adaptive radiation in younger clades," the authors wrote.