Ecological constraints drive social evolution in the African mole-rats.
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.
Faulkes
C G
CG
Institute of Zoology, Zoological Society of London, UK. c.faulkes@ucl.ac.uk
Bennett
N C
NC
Bruford
M W
MW
O'Brien
H P
HP
Aguilar
G H
GH
Jarvis
J U
JU
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
D003573:Cytochrome b Group; D004272:DNA, Mitochondrial; D012335:RNA, Ribosomal; C075526:RNA, ribosomal, 12S