Bite force in the strictly subterranean rodent family of African mole-rats (Bathyergidae): the role of digging mode, social organisation, and ecology

Bite force is an ecologically relevant performance trait that has been
measured to better understand the adaptations to diet and habitat use.
Moreover, bite force is relevant in understanding reproductive success, as
well as inter- and intraspecific competition. African mole-rats
(Bathyergidae, Rodentia) are a unique clade of mammals that use different
digging strategies, show different types of social organisation, and occur
in ecologically diverse savannah habitats in Sub-Saharan Africa. Whereas
previous studies have suggested these animals have exceptionally high bite
forces, the ecological and other proximate and ultimate drivers of
variation in bite force in the group remain unstudied. In the present
study we measured in vivo bite force of 394 adult specimens from ten
African mole-rat species including all genera within the family. Our
results show that in African mole-rats digging mode is a major driver of
variation in bite force, with chisel-tooth diggers being stronger biters
than scratch-diggers. Moreover, species living in habitats characterised
by low and irregular precipitation patterns and in soils with a high
content of coarse particles have a higher bite force than species
occupying habitats with a regular rainfall pattern and fine soil types.
This suggests that bite force in bathyergids has evolved in concert with
rainfall and soil characteristics of different savannah habitats, which
have contributed to the successful radiation of these subterranean mammals
across sub-Saharan Africa.