Bite force is a simple trait indicating an animal's performance related to foraging, social dominance, and defence, all of which influence individual reproductive success. We examine the effect of breeding status on bite force in four social species of Fukomys, a genus of subterranean African rodents (Bathyergidae). These species are cooperative breeders, where reproduction is limited typically to a breeding pair. We collected in vivo bite force data, head width, and upper incisors width from 404 individuals from 75 families and tested whether breeders exhibit stronger bite force. We reveal that breeding males of all four species outperform non-breeders, with bite force in non-breeding males and females being 12% and 22% lower, respectively. In contrast, breeding females underperform relative to other categories, with bite force approximately 31% lower than in breeding males, and many are reluctant to bite. Head width and upper incisors width corroborate these findings. We propose that breeding males require a stronger bite force because of repeated competition with non-related males that may try to enter the family. In contrast, there is much less competition for the breeding position among females, as females rarely intrude into established families.

Centre for Invasion Biology Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa

Département Adaptations du Vivant UMR 7179 MECADEV C N R S M N H N Paris France

Department of Biology and Environmental Science Centre for Ecology and Evolution in Microbial Model Systems Linnaeus University Kalmar Sweden

Department of General Zoology Faculty of Biology University of Duisburg Essen Essen Germany

Department of Zoology Faculty of Science University of South Bohemia České Budějovice Czech Republic

Institute of Vertebrate Biology Czech Academy of Sciences Brno Czech Republic

Kalahari Research Centre Kuruman River Reserve Van Zylsrus South Africa

Mammal Research Institute Department of Zoology and Entomology University of Pretoria Pretoria South Africa

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Palanza, P., Mainardi, D., Brain, P. F. & Parmigiani, S. Male and female competitive strategies of wild house mice pairs ( DOI

Packer, C. & Pusey, A. E. Adaptations of female lions to infanticide by incoming males.

Clutton-Brock, T. H. et al. Intrasexual competition and sexual selection in cooperative mammals. PubMed DOI

Emlen, S. T. Predicting family dynamics in social vertebrates. in

Sharp, S. P. & Clutton-Brock, T. H. Competition, breeding success and ageing rates in female meerkats: competition and senescence in meerkats. PubMed DOI

Krebs, J. R. & Davies, N. B. Fighting and assessment. in

Husak, J. F., Kristopher Lappin, A., Fox, S. F. & Lemos-Espinal, J. A. Bite-force performance predicts dominance in male venerable collared lizards (

Lailvaux, S. P., Herrel, A., VanHooydonck, B., Meyers, J. J. & Irschick, D. J. Performance capacity, fighting tactics and the evolution of life–stage male morphs in the green anole lizard ( PubMed DOI PMC

Anderson, R. A., Mcbrayer, L. D. & Herrel, A. Bite force in vertebrates: opportunities and caveats for use of a nonpareil whole-animal performance measure. DOI

Herrel, A., De Smet, A., Aguirre, L. F. & Aerts, P. Morphological and mechanical determinants of bite force in bats: Do muscles matter?. PubMed DOI

van der Meijden, A., González-Gómez, J. C., Pulido-Osorio, M. D. & Herrel, A. Measurement of voluntary bite forces in large carnivores using a semi-automated reward-driven system. PubMed DOI

Aguirre, L. F., Herrel, A., Van Damme, R. & MatThysen, E. The implications of food hardness for diet in bats. DOI

Christiansen, P. & Wroe, S. Bite forces and evolutionary adaptations to feeding ecology in carnivores. PubMed DOI

Maestri, R., Patterson, B. D., Fornel, R., Monteiro, L. R. & De Freitas, T. R. O. Diet, bite force and skull morphology in the generalist rodent morphotype. PubMed DOI

Santana, S. E., Dumont, E. R. & Davis, J. L. Mechanics of bite force production and its relationship to diet in bats. DOI

Verwaijen, D., Van Damme, R. & Herrel, A. Relationships between head size, bite force, prey handling efficiency and diet in two sympatric lacertid lizards. DOI

Gowan, T. A., Mcbrayer, L. D. & Rostal, D. C. Seasonal variation in testosterone and performance in males of a non-territorial lizard species. PubMed DOI

Husak, J. F., Lappin, A. K. & Van Den Bussche, R. A. The fitness advantage of a high-performance weapon. DOI

Lappin, A. K. & Husak, J. F. Weapon performance, not size, determines mating success and potential reproductive output in the collared lizard ( PubMed DOI

Zablocki-Thomas, P., Lailvaux, S., Aujard, F., Pouydebat, E. & Herrel, A. Maternal and genetic correlations between morphology and physical performance traits in a small captive primate, DOI

Herrel, A. et al. Do adult phenotypes reflect selection on juvenile performance? A comparative study on performance and morphology in lizards. PubMed DOI

Begall, S., Burda, H. & Šumbera, R.

Bennett, N. C. & Faulkes, C. G.

Rodrigues, H. G., Šumbera, R., Hautier, L. & Herrel, A. Digging up convergence in fossorial rodents: insights into burrowing activity and morpho-functional specializations of the masticatory apparatus. in

Kraus, A. et al. Bite force in the strictly subterranean rodent family of African mole-rats (Bathyergidae): the role of digging mode, social organization and ecology. DOI

Hite, N. J. et al. The better to eat you with: bite force in the naked mole-rat ( PubMed DOI PMC

van Daele, P. A. A. G., Herrel, A. & Adriaens, D. Biting performance in teeth-digging African mole-rats ( PubMed DOI

Gomes Rodrigues, H. & Damette, M. Incipient morphological specializations associated with fossorial life in the skull of ground squirrels (Sciuridae, Rodentia). PubMed DOI PMC

Hildebrand, M. Digging of Quadrupeds. in

Burda, H., Honeycutt, R. L., Begall, S., Locker-Grutjen, O. & Scharff, A. Are naked and common mole-rats eusocial and if so, why?. DOI

Bishop, J. M., Jarvis, J. U. M., Spinks, A. C., Bennett, N. C. & O’Ryan, C. Molecular insight into patterns of colony composition and paternity in the common mole-rat PubMed DOI

Braude, S. Dispersal and new colony formation in wild naked mole-rats: evidence against inbreeding as the system of mating. DOI

Braude, S., Hess, J. & Ingram, C. Inter-colony invasion between wild naked mole-rat colonies. DOI

Burland, T. M., Bennett, N. C., Jarvis, J. U. M. & Faulkes, C. G. Colony structure and parentage in wild colonies of co-operatively breeding Damaraland mole-rats suggest incest avoidance alone may not maintain reproductive skew. PubMed DOI

Mynhardt, S., Harris-Barnes, L., Bloomer, P. & Bennett, N. C. Spatial population genetic structure and colony dynamics in Damaraland mole-rats ( PubMed DOI PMC

Patzenhauerová, H., Šklíba, J., Bryja, J. & Šumbera, R. Parentage analysis of Ansell’s mole-rat family groups indicates a high reproductive skew despite relatively relaxed ecological constraints on dispersal. PubMed DOI

Monadjem, A., Taylor, P. J., Denys, C. & Cotterill, F. P. D.

Thorley, J., Bensch, H. M., Finn, K., Clutton-Brock, T. & Zöttl, M. Damaraland mole-rats do not rely on helpers for reproduction or survival. PubMed DOI PMC

Young, A. J. & Bennett, N. C. Intra-sexual selection in cooperative mammals and birds: why are females not bigger and better armed? PubMed DOI PMC

Zöttl, M., Thorley, J., Gaynor, D., Bennett, N. C. & Clutton-Brock, T. Variation in growth of Damaraland mole-rats is explained by competition rather than by functional specialization for different tasks. PubMed DOI PMC

Caspar, K. R., Müller, J. & Begall, S. Effects of sex and breeding status on skull morphology in cooperatively breeding Ansell’s mole-rats and an appraisal of sexual dimorphism in the Bathyergidae. DOI

Thorley, J., Katlein, N., Goddard, K., Zöttl, M. & Clutton-Brock, T. Reproduction triggers adaptive increases in body size in female mole-rats. PubMed DOI PMC

Young, A. J. & Bennett, N. C. Morphological divergence of breeders and helpers in wild Damaraland mole-rat societies. PubMed DOI

Freeman, P. W. & Lemen, C. A. A simple morphological predictor of bite force in rodents. DOI

McIntosh, A. F. & Cox, P. G. Functional implications of craniomandibular morphology in African mole-rats (Rodentia: Bathyergidae). DOI

Bennett, N. C. Behaviour and social organization in a colony of the Damaraland mole-rat DOI

Francioli, Y., Thorley, J., Finn, K., Clutton-Brock, T. & Zöttl, M. Breeders are less active foragers than non-breeders in wild Damaraland mole-rats. PubMed DOI PMC

Houslay, T. M., Vullioud, P., Zöttl, M. & Clutton-Brock, T. H. Benefits of cooperation in captive Damaraland mole-rats. DOI

Lövy, M., Šklíba, J. & Šumbera, R. Spatial and temporal activity patterns of the free-living giant mole-rat ( PubMed DOI PMC

Šklíba, J., Lövy, M., Burda, H. & Šumbera, R. Variability of space-use patterns in a free living eusocial rodent, Ansell’s mole-rat indicates age-based rather than caste polyethism. PubMed DOI PMC

Wroe, S., McHenry, C. & Thomason, J. Bite club: comparative bite force in big biting mammals and the prediction of predatory behaviour in fossil taxa. PubMed DOI PMC

Deeming, D. C., Harrison, S. L. & Sutton, G. P. Inter-relationships among body mass, jaw musculature and bite force in birds. DOI

Herrel, A., Mcbrayer, L. D. & Larson, P. M. Functional basis for sexual differences in bite force in the lizard DOI

Rebol, E. J. & Anderson, D. J. Sex-specific aging in bite force in a wild vertebrate. PubMed DOI

Thomas, P. et al. Sexual dimorphism in bite force in the grey mouse lemur. DOI

Becerra, F., Echeverría, A., Vassallo, A. I. & Casinos, A. Bite force and jaw biomechanics in the subterranean rodent Talas tuco-tuco ( DOI

Herrel, A., Spithoven, L., Van Damme, R. & De Vree, F. Sexual dimorphism of head size in DOI

Kay, R. F., Plavcan, J. M., Glander, K. E. & Wright, P. C. Sexual selection and canine dimorphism in new world monkeys. PubMed DOI

Morris, J. S. & Brandt, E. K. Specialization for aggression in sexually dimorphic skeletal morphology in grey wolves ( PubMed DOI PMC

Russell, A. F., Carlson, A. A., McIlrath, G. M., Jordan, N. R. & Clutton-Brock, T. Adaptive size modification by dominant female meerkats. PubMed DOI

Magalhães, A. R., Damasceno, E. M. & Astúa, D. Bite force sexual dimorphism in Canidae (Mammalia: Carnivora): Relations between diet, sociality and bite force intersexual differences.

Jarvis, J. U. M. & Bennett, N. C. Eusociality has evolved independently in two genera of bathyergid mole-rats—but occurs in no other subterranean mammal. DOI

Šumbera, R. et al. Burrow architecture, family composition and habitat characteristics of the largest social African mole-rat: The giant mole-rat constructs really giant burrow systems. DOI

Torrents-Ticó, M., Bennett, N. C., Jarvis, J. U. M. & Zöttl, M. Sex differences in timing and context of dispersal in Damaraland mole-rats ( DOI

van Daele, P. A. A. G., Desmet, N., Šumbera, R. & Adriaens, D. Work behaviour and biting performance in the cooperative breeding Micklem’s mole-rat DOI

Rotics, S., Bensch, H. M., Resheff, Y. S., Clutton-Brock, T. & Zöttl, M. Workload distribution in wild Damaraland mole-rat groups. PubMed DOI PMC

Johnston, R. A. et al. Morphological and genomic shifts in mole-rat ‘queens’ increase fecundity but reduce skeletal integrity. PubMed DOI PMC

Jarvis, J. U. M., O’Riain, M. J. & McDaid, E. Growth and factors affecting body size in naked mole-rats. in

Lacey, E. A. & Sherman, P. W. Social organization of naked mole-rat colonies: Evidence for divisions of labor. in

Speakman, J. R. The physiological costs of reproduction in small mammals. PubMed DOI PMC

Dammann, P., Šumbera, R., Massmann, C., Scherag, A. & Burda, H. Extended longevity of reproductives appears to be common in Fukomys mole-rats (Rodentia, Bathyergidae). PubMed DOI PMC

Wallace, E. D. & Bennett, N. C. The colony structure and social organization of the giant Zambian mole-rat, DOI

Dammann, P. & Burda, H. Sexual activity and reproduction delay ageing in a mammal. PubMed DOI

Begall, S., Bottermann, L. & Caspar, K. R. Self-domestication underground? Testing for social and morphological correlates of animal personality in cooperatively-breeding Ansell’s mole-rats ( DOI

Burda, H. Individual recognition and incest avoidance in eusocial common mole-rats rather than reproductive suppression by parents. PubMed DOI

Sharp, S. P. & Clutton-Brock, T. H. Reluctant challengers: why do subordinate female meerkats rarely displace their dominant mothers? DOI

Cooney, R. Colony defense in Damaraland mole-rats, DOI

Jacobs, D. S., Reid, S. & Kuiper, S. Out-breeding behaviour and xenophobia in the damaraland mole-rat, DOI

Hazell, R. W. A., Bennett, N. C., Jarvis, J. U. M. & Griffin, M. Adult dispersal in the co-operatively breeding Damaraland mole-rat ( DOI

Griffin, A. S. et al. A genetic analysis of breeding success in the cooperative meerkat ( DOI

Nelson-Flower, M. J., Hockey, P. A. R., O’Ryan, C. & Ridley, A. R. Inbreeding avoidance mechanisms: Dispersal dynamics in cooperatively breeding southern pied babblers. PubMed DOI

Šumbera, R. Thermal biology of a strictly subterranean mammalian family, the African mole-rats (Bathyergidae, Rodentia) - a review. PubMed DOI

Patzenhauerová, H., Šklíba, J., Bryja, J. & Šumbera, R. Parentage analysis of A nsell’s mole-rat family groups indicates a high reproductive skew despite relatively relaxed ecological constraints on dispersal. PubMed DOI

Šumbera, R. et al. The biology of an isolated Mashona mole-rat population from southern Malawi, with implications for the diversity and biogeography of the genus Fukomys. DOI

van Daele, P. A. A. G., Verheyen, E., Brunain, M. & Adriaens, D. Cytochrome PubMed DOI

Borges, L. R. et al. The role of soil features in shaping the bite force and related skull and mandible morphology in the subterranean rodents of genus DOI

Ginot, S., Herrel, A., Claude, J. & Hautier, L. Skull size and biomechanics are good estimators of in vivo bite force in murid rodents. PubMed DOI

R Core Team.

Bürkner, P. Bayesian item response modeling in R with brms and Stan. DOI

Neal, R. MCMC using Hamiltonian dynamics. In

Vehtari, A., Gelman, A., Simpson, D., Carpenter, B. & Bürkner, P.-C. Rank-normalization, folding, and localization: an improved Rˆ for assessing convergence of MCMC (with discussion). DOI

Gelman, A., Hwang, J. & Vehtari, A. Understanding predictive information criteria for Bayesian models. DOI

Vehtari, A., Simpson, D., Gelman, A., Yao, Y. & Gabry, J. Pareto smoothed importance sampling.

Vehtari, A., Gelman, A. & Gabry, J. Practical Bayesian model evaluation using leave-one-out cross-validation and WAIC. DOI

Burnham, K. P. & Anderson, D. R.

Gabry, J., Simpson, D., Vehtari, A., Betancourt, M. & Gelman, A. Visualization in Bayesian workflow. DOI

Lenth, R. emmeans: estimated marginal means, aka least-squares means.

Šumbera, R. et al. Breeding males, but not females, of