Cox Lab: Research Projects

Morphological variation in red squirrel skulls

This project investigates the morphological differences in the remaining, isolated populations of red squirrels found in Great Britain. We found that squirrels with a high proportion of peanuts in their diet (e.g. at Formby in Lancashire) showed changes to the skull and jaws consistent with a lower bite force, compared to squirrels eating a harder diet of pine cone seeds or hazelnuts (e.g. in Scotland).

This research was carried out by Kim Chandler for her PhD. The results have been published in Journal of Zoology and Royal Society Open Science, and are also reported in an article for The Conversation.

Red squirrel. Photo credit: Shutterstock.

Virtual reconstructions of red squirrel skulls showing differences between North Scotland and Formby populations. Image credit: Philip Cox.

Photographs of red squirrel lower jaws showing differences between North Scotland and Formby populations. Image credit: Philip Cox.

Island gigantism

Island gigantism is the evolution phenomenon in which small mammals tend to evolve larger body size on islands. For his PhD, Jesse Hennekam investigated island gigantism in fossil dormice from Sicily, Malta and the Balearic Islands. We found that there are different pathways to becoming a giant, representing adaptations to different diets. Now, thanks to recent funding from the Leverhulme Trust, we are widening the research to study many other mammalian groups that evolved enlarged body size on Mediterranean islands (e.g. shrews, moonrats, rabbits, pikas, hamsters and mice).

Results so far have been published in Open Quaternary, Proceedings B and Evolution.

Artistic reconstruction of giant fossil dormouse, Leithia melitensis, with its extant mainland relative, Eliomys quercinus (the garden dormouse) for scale. Image credit: James Sadler.

Island dwarfism

Island dwarfism is the counterpart to island gigantism – it is the tendency of large mammals to evolve smaller body size on islands. This phenomenon is currently being investigated by PhD student George Watts in the fossil dwarf goat Myotragus, known from the Balearic Islands over the last 5 million years. Specifically, George is studying the limb bones to see how they differ in shape and in function from non-giant and non-insular relatives of Myotragus.

Domestication

The process of domestication is a potential disruptor of normal evolutionary trajectories, with artificial selection by humans replacing natural selective pressures. PhD student Atena Soltanian is researching the impact of domestication in the Caprinae, the group of ungulates containing domestic sheep and goats. He is particularly interested in how the shape and functional performance of the skull and jaws have been changed by domestication.