Collagen sequence reveals evolutionary history of extinct 'island-shrews' - Nesophontes

With great satisfaction, I announce the publication of our paper on the extinct Greater Antillean endemic: Nesophontes. As you may have read from posts in this blog, the genus Nesophontes is a group of shrew-like mammals for which several species have been identified on the islands of Cuba, Cayman, Hispaniola, and Puerto Rico, but not The Bahamas or Jamaica. Each island had its own exclusive forms. These unique varieties to each island are called endemics. 

Original specimen from which Nesophontes was described: N. edithae (AMNH 14174). 

The genus Nesophontes is grouped within the mammal order Eulipotyphla. This is a group of basal placental mammals that are considered ancestrally associated to the Solenodon of Cuba and Hispaniola. Also, to other North American extinct shrew-like micromammals, but surprisingly not to the African tenrecs despite their physical similarity.  Nesophontes was small, likely venomous, nocturnal, and could tunnel underground. At least eight species are currently recognized: three in Cuba (N. major, N. micrus and N. longirostris); three in Hispaniola (N. paramicrus, N. hypomicrus, and N. zamicrus); one in Puerto Rico (N. edithae) and one in Cayman (N. hemicingulus). However, the identification, naming, and evolutionary history of this diverse group has been somewhat controversial. 

Solenodon paradoxus from Hispaniola. Plate from Allen's (1910) monograph on the species. 

We designed our study to help unravel especially the issue of evolution and species limits. Our paper, formally accepted in the journal Molecular Biology and Evolution this past march, provides the following abstract: 

“Ancient biomolecule analyses are proving increasingly useful in the study of evolutionary patterns, including extinct organisms. Proteomic sequencing techniques complement genomic approaches, having the potential to examine lineages further back in time than achievable using ancient DNA, given the less stringent preservation requirements. In this study, we demonstrate the ability to use collagen sequence analyses via proteomics to provide species delimitation as a foundation for informing evolutionary patterns. We uncover biogeographic information of an enigmatic and recently extinct lineage of Nesophontes across their range on the Caribbean islands. First, evolutionary relationships reconstructed from collagen sequences reaffirm the affinity of Nesophontes and Solenodon as sister taxa within Solenodonota. This relationship helps lay the foundation for testing geographical isolation hypotheses across islands within the Greater Antilles, including movement from Cuba towards Hispaniola. Second, our results are consistent with Cuba having just two species of Nesophontes (N. micrus and N. major) that exhibit intrapopulation morphological variation. Finally, analysis of the recently described species from the Cayman Islands (N. hemicingulus) indicates that it is a closer relative to the Cuban species, N. major rather than N. micrus as previously speculated. Our proteomic sequencing improves our understanding of the origin, evolution, and distribution of this extinct mammal lineage, particularly with respect to approximate timing of speciation. Such knowledge is vital for this biodiversity hotspot, where the magnitude of recent extinctions may obscure true estimates of species richness in the past.”

I take this opportunity to extend my gratitude and thanks to the whole team, for pushing through with persistence for nearly a decade. And to all the friends and colleagues that helped along the way. 

Stay tuned for more details on our findings and these peculiar mammals ahead. 

Recommended Citation

Buckley, Mike; Virginia L. Harvey; Joha Orihuela; Alexis M. Mychajliw; J. Keating; J. N. Almonte Milan; C. Lawless; A. T. Chamberlain; V. M. Egerton; and Phillip L. Manning (2020). Collagen sequence analysis reveals evolutionary history of extinct West Indies Nesophontes ('island-shrews'). Molecular Biology and Evolution: https://doi.org/10.1093/molbev/msaa137

Nesophontes: The Discovery of the first Greater Antillean Island Slayer

Nesophontes are a small group of shrew-like mammals with a very primitive past that reaches as far back as the Cretaceous - when the dinosaurs roamed this planet. We owe its discovery to Harold H. Anthony, one of the most proliferous pioneers of Caribbean vertebrate paleontology.

Original illustration of the type description of Nesophontes edithae H. E. Anthony 1916

The genus Nesophontes is today grouped within the Eulipotyphla order. This is a group of basal placental mammals that are today considered ancestrally associated to Solenodon and other North American extinct shrew-like micromammals, but surprisingly, not to the African tenrecs.  They were small, likely venomous, nocturnal and semi-fossorial mammals endemic to the Great Antilles, where they had a widespread distribution, with the interesting exception of The Bahamas and Jamaica.


Solenodon paradoxus from Hispaniola at the Mammalogy collection of the AMNH

By 1915, H. E. Anthony had a hint of the existence of Nesophontes from fossils found in the island of Puerto Rico. Dr. Franz Boas, the German-American father of modern anthropology, had sent material from his expedition in Puerto Rico to the American Museum of Natural History in New York City (AMNH) that same year. Anthony worked as a paleontologist there, and from Boas's material he extracted the first incomplete specimens of Nesophontes. But these were not enough to describe a new species.

Left: Franz Boas, German American Anthropologist, circa 1916. Right: Harold H. Anthony, circa 1930s.

In fact, it was Dr. Anthony's wife, Edith I. Anthony, who on July 19, 1916, discovered the first undoubtable evidence of the existence of this peculiar mammal in Cueva Clara, near Morovis, Puerto Rico. Anthony, in honor of its wife, named the type species Nesophontes edithae.

Type specimen of Nesophontes edithae AMNH 14174, collected by Mrs. Anthony in 1916

The study of Nesophontes is forever tied to the efforts of Anthony, the discovery of his wife and the material sent by Franz Boas. Gerritt S. Miller and Glover M. Allen, in addition, played a role too in the further discovery and study of these peculiar extinct mammals. In 1919, Anthony described a new species, Nesophontes longirostris, this time from a cave deposit in Daiquiri, southeastern Cuba.

H. E. Anthony would continue to work for the AMNH until the 1960's as one of the museum's most respected mammalogists, paleontologists, and curators.

Please stay tuned for an upcoming post on Solendon!