Cyprus's endemic mouse and the house mouse differ in jaw and molar shape, 3D study finds

A paper by Morgane Dubied, Emilie A. Hardouin, George P. Mitsainas and Sabrina Renaud, published online on 30 September in the Journal of Anatomy, compares the lower jaws and molars of two mice that share Cyprus: the endemic Cyprus mouse, Mus cypriacus, and the introduced house mouse, Mus musculus domesticus. The team used 3D geometric morphometrics, a statistical method for measuring shape.

The two species look alike and are occasionally found in the same spot. According to the authors, the house mouse depends on food from people, while the Cyprus mouse eats a broader, wilder diet. The team measured how the species differ, how shape changes with size and how molars wear down with age, and tested which measures best record ancestry, ecological specialisation and growth. They conclude that small differences of form can register adaptation at a fine scale, separately for each species.

The study works on living animals. The same family of methods has been applied to excavated mouse bones: at the Ayios Tychonas-Klimonas village in the Limassol district, dated to about 10,800 years ago, it identified the house mouse among 41 mouse teeth and bones, distinct from the endemic species, which has probably lived on the island since the Middle Pleistocene [1, p. 3]. That mouse arrived with the island's first farming settlers, along with dogs and cats; a 2023 review by Jean-Denis Vigne and colleagues suggests the cats were probably brought to keep rodents down [1, p. 3].