title: Ecological constraints drive social evolution in the African mole-rats.
abstract: The African mole-rats (family Bathyergidae) are subterranean hystricomorph rodents occurring in a variety of habitats and displaying levels of sociality which range from solitary to eusocial, making them a unique mammalian taxonomic group to test ecological influences on sociality. Here, we use an extensive DNA-based phylogeny and comparative analysis to investigate the relationship between ecology, sociality and evolution within the family. Mitochondrial cytochrome-b and 12s rRNA trees reveal that the solitary species are monophyletic when compared to the social species. The naked mole-rat (Heterocephalus glaber) is ancestral and divergent from the Damaraland mole-rat (Cryptomys damarensis), supporting previous findings that have suggested the multiple evolution of eusociality within the family. The Cryptomys genus is species-rich and contains taxa exhibiting different levels of sociality, which can be divided into two distinct clades. A total of seven independent comparisons were generated within the phylogeny, and three ecological variables were significantly correlated with social group size: geophyte density (p < 0.05), mean months per year of rainfall greater than 25 mm (p < 0.001), and the coefficient of rainfall variation (p = 0.001). These results support the food-aridity hypothesis for the evolution of highly social cooperative behaviour in the Bathyergidae, and are consistent with the current theoretical framework for skew theory.
authors.affiliation: Institute of Zoology, Zoological Society of London, UK. c.faulkes@ucl.ac.uk
authors.forename: C G
authors.initials: CG
authors.lastname: Faulkes
authors.forename: N C
authors.initials: NC
authors.lastname: Bennett
authors.forename: M W
authors.initials: MW
authors.lastname: Bruford
authors.forename: H P
authors.initials: HP
authors.lastname: O'Brien
authors.forename: G H
authors.initials: GH
authors.lastname: Aguilar
authors.forename: J U
authors.initials: JU
authors.lastname: Jarvis
mesh_terms: D017954:Africa South of the Sahara; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D003573:Cytochrome b Group / Q000235:genetics; D004272:DNA, Mitochondrial; D004463:Ecology; D006801:Humans; D019577:Mole Rats / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000235:genetics; D051381:Rats; D012919:Social Behavior
chemical_list: D003573:Cytochrome b Group; D004272:DNA, Mitochondrial; D012335:RNA, Ribosomal; C075526:RNA, ribosomal, 12S