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The origins of an extinct shrew-like mammal whose name means the island murderer have been traced using DNA from remains found in ancient owl pellets.
A multi-national team of scientists mapped the evolutionary history of the West Indian species Nesophontes back to the dawn of mammals 70 million years ago. The study, led by the Natural History Museum, is published today in Molecular Biology and Evolution.
The insect-eating creatures survived for 70 million years in the Caribbean islands until the arrival of Europeans in the 16th century. Rats arriving as stowaways on Spanish ships likely out-competed them.
“Nesophontes was just one of around 100 Caribbean mammal species that have gone extinct in recent historical time. This work shows islands can act as museums of diversity, preserving ancient lineages of animals, but also how vulnerable these populations are to human activity”, says Professor Ian Barnes, research leader at London’s Natural History Museum.
The evolutionary tree shows that Nesophontes is a sister group of the surviving native Caribbean insectivores, the Solenodons. They parted ways more than 40 million years ago, when the northern Caribbean was formed of volcanic islands, long before the origins of the islands we see today. The combined group split off from all other living mammals over 70 million years ago, before the dinosaurs became extinct.
Obtaining DNA from tropical fossils is notoriously difficult, and the team made use of the latest developments in ancient DNA technology to conduct the study.
“Once we’d dealt with the tiny size of the bone samples, the highly degraded state of the DNA, and the lack of any similar genomes to compare to, the analysis was a piece of cake,” said Natural History Museum scientist Dr Selina Brace.
Scientists used a 750-year-old specimen to generate many thousands of base pairs of DNA sequence data. This allowed the research team to uncover its evolutionary origins and finally resolve the relationships between its closest relatives, the insectivores, a group including shrews, hedgehogs and moles.
Brace S, Thomas JA, Dalén L, Burger, MacPhee JDE, Barnes I, Turvey ST (2016) Evolutionary history of the Nesophontidae, the last unplaced Recent mammal family. Mol Biol Evol.
The advanced early access online version of the Molecular Biology and Evolution article can be found at: http://mbe.oxfordjournals.org/content/early/recent DOI:10.1093/molbev/mswX
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