About This Project

500 years ago the Conquistadors accidentally introduced black rats to the Caribbean. These rats are evolving unusually fast. They look different on every island, and on large islands there are types adapted to such environments as fields, rainforests, high mountains and caves. Cave rats are most interesting because they are apparently evolving exceptional visual capability. I am conducting the first study of them to understand how rats evolve so fast and develop seemingly impossible traits.

Ask the Scientists

What is the context of this research?

In the 16th century, the Spanish conquistadors accidentally brought black rats to the West Indies. In less than 500 years, these rats have colonized all islands and all habitats, including cities, mangroves, cloud forests and limestone caves. They now look very different on every island and in every habitat, and seem to be evolving into dozens of new species. Some of these new forms have amazing new adaptations: they can drink seawater, toerate bitter cold, and see in the almost-absolute darkness of caves. This process appears to be going much faster than currently believed possible for vertebrates. What allows the rats to evolve so fast is unknown. Surprisingly, they have never been studied in detail: zoologists are usually more interested in native species and dislike introduced "pests"

What is the significance of this project?

Sympatric speciation, in which one species divides into two or more living in the same area, is largely a mystery: we don't understand how it works. We also don't really know how animals can rapidly evolve new abilities that require complex structural "upgrades".

Caribbean rats are perfect study subjects for unlocking these secrets, much better than the famous Darwin's finches of the Galapagos: the rats are adapting to many more niches, the time of their arrival is precisely known, and rat genome has been fully sequenced and well-studied.

Highly adaptable non-native species are now becoming dominant in many parts of the world, and better understanding them is critically important: it should allow us to help other species, including ourselves, to adapt to whatever the future might bring.

What are the goals of the project?

Black rats are among the few species that benefit from human modification of the planet and are capable of keeping pace with all the changes we have brought to the environment. They are "super-animals" with an exceptional ability to adapt. Why are they so successful? I'll try to find out which mechanisms (molecular, physiologic, behavioral and/or other) allow them to evolve so fast. To do this, I will:

(1) Describe which forms exist in different habitats (this is the easy part, but it has never been done before);

(2) Study their behavior, physiology and microbiome (symbiotic and parasitic microbes);

(3) Compare their genetic makeup to their ancestors in the Old World.

This knowledge will allow me to reconstruct the evolutionary history of these rats and figure out what makes them so special.