Abstract
African mole-rats of the genus Fukomys (Northern common mole-rats) combine a monogamous mating system and pronounced sexual size dimorphism; a pattern highly untypical for mammals. At the same time, they live in cooperatively breeding groups composed of reproductive and non-reproductive members of both sexes. How and to which degree sex and breeding status influence morphofunctional characters in eusocial mole-rats is not well characterized but essential to come to a comprehensive understanding of their peculiar social system. Here, we explore patterns of morphological differentiation in skulls of Ansell’s mole-rats (Fukomys anselli) by means of multivariate analysis of linear skull measurements combined with a 2D shape analysis of cranium and mandible. Compared to females, males display larger skulls relative to body size and show an expansion of the facial portion of the cranium, while reproductive status did not have an effect on any of the traits studied. We also show that species of Fukomys mole-rats display a scaling of relative sexual body size dimorphism in compliance to Rensch’s rule, which is deemed indicative of intense male intrasexual competition. For the bathyergid family as a whole, results of scaling analyses were more ambiguous, but also indicative of Rensch’s rule conformity. In line with genetic field data, our results point to a greater role of male-male conflicts in Fukomys than is traditionally assumed and support the notion that reproductive status does not correlate with morphofunctional segregation in these unusual rodents.
Highlights
African mole-rats (Bathyergidae) are a speciose group of sub-Saharan rodents which are renowned for their superb adaptation to life underground (Gomes Rodrigues et al, 2016)
PC1 factor loadings were to a large extent evenly distributed over the measurements, excluding several measurements concerned with dental characters and the skull base, which were of specific relevance to PC2
Our study provides a comprehensive description of the welldeveloped sexual dimorphism in the skull of F. anselli, which points to a significant role of male competition in the social life of mole-rats belonging to this cooperatively-breeding genus
Summary
African mole-rats (Bathyergidae) are a speciose group of sub-Saharan rodents which are renowned for their superb adaptation to life underground (Gomes Rodrigues et al, 2016). Skull Morphology in Ansell’s Mole-Rats bathyergid genus Heterocephalus (naked mole-rat), live in cooperatively breeding groups These families typically comprise only a single breeding female in all social genera, while the number of simultaneously active reproductive males varies. In Heterocephalus as well as in Fukomys, more than six generations of pups overlap in average family groups and the majority of offspring remains with their parents and assist in provisioning their siblings instead of reproducing themselves (Burda et al, 2000; Torrents-Ticó et al, 2018) Because of this high degree of philopatry in combination with partitioning of reproductive labor and cooperative breeding, these genera have at times been characterized as eusocial mammals (Burda et al, 2000). Less is known about the mating systems of solitary genera, but morphological, genetic and behavioral evidence suggests that they are either polygynous or promiscuous (Patzenhauerová et al, 2010; Bray et al, 2012; Visser et al, 2017)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
