The pygmy marmoset, the world’s smallest monkey, is not a cute animal – it is actually two separate species of exceptionally cute animals.
Evolutionary biologists at the University of Salford in the UK have used genome sequencing on numerous specimens of this pygmy marmoset to study their evolutionary history. Their DNA showed that there are actually two separate species of Cebuella that diverged from one another around 2-3 million years ago – one from the north of the Amazon River, one from the south.
The study was recently published in the scientific journal Molecular Phylogenetics and Evolution.
Native to the rainforest of the western Amazon Basin, this bug-munching marmoset weighs a little over 100 grams (3.5 ounces) and is about the size of a toy figurine. German naturalist Johann Spix first described the species back in 1823, however, his work been the subject of some controversy in the marmoset-studying world.
"There has long been confusion over the taxonomy of these wonderful creatures mostly because Spix did not record in his travel diaries the exact location where he collected the type of Cebuella pygmaea in the early 1800s,” Jean Boubli, professor of tropical ecology and conservation, at Salford University, said in a statement. “That creates confusion as to which of the two recently uncovered species should keep the original name; that of the north or of the south of the Amazon.”
"The beauty of genomics means that we can now see the pygmy marmoset is a term for two species which have been evolving independently for nearly 3 million years."
So, what's the difference between these two? The case for these marmosets being two different species relied on hard genomic evidence, but you can notice some differences between the species even with the naked eye. For one, the north-of-the-river marmosets tend to be lighter, with the southerners having darker tinged striped patterns.
This new discovery could be a game changer for conservationists, it effectively means that the known population numbers have been halved overnight because the species has been suddenly split in two. Although the pygmy marmosets are species listed as "Least Concern" on the IUCN Red List of Threatened Species, recent disease epidemics have prompted primate experts at the IUCN to recommend updating that status to "Vulnerable."
Being divided by a river, or any other geographical feature, is a common way in which populations of animals can get split up and eventually evolve into two different species. One of the most interesting examples of this is chimpanzees and bonobos. These two great apes split from each other on the evolutionary tree around 2 million years ago as a direct result of the Congo River forming.