Eusociality in Naked Mole-Rats
Biology 342 - Fall 2010
Isabel Cylinder & Quinn Amacher
What is Phylogeny?
Phylogeny is defined as "the development or evolution of a particular group of organisms“ (21). In this case, however, we will examine the phylogeny (that is, the development or evolution) of a particular behavior, specifically eusocial behavior in naked mole-rats.
Phylogeny of H. glaber
A phylogenetic tree for African mole-rats (family Bathyergidae) and one outgroup species (H. africaeaustralis). The numbers below the branches indicate branch length. This tree shows that H. glaber evolved divergently from the rest of the African mole-rats at an early stage. (10)
The naked mole-rat and the Damaraland mole-rat (Cryptomys damarensis) are currently the only eusocial vertebrates recognized (though some have argued that the entire Cryptomys genus can be considered eusocial (4)), and the behavior is believed to be the result of convergent evolution (10). There has been no conclusive evidence as to whether the common ancestor of these two eusocial species was also eusocial or if it was solitary. Initially, eusociality was believed to have evolved because of the high rate of inbreeding in H. glaber, but when C. damarensis was found to avoid inbreeding and instead favor dispersal and outbreeding, this theory was dismissed (10).
An adult female naked mole-rat. (B)