Regulation of reproduction in female common mole-rats (Cryptomys hottentotus hottentotus): the effects of breeding season and reproductive status

The effects of breeding season and reproductive status on female reproducti on were investigated in the common mole-rat, Cryptomys hottentotus hottento tus, a co operatively breeding rodent that exhibits seasonal breeding and a reproductive: division of labour. Body mass, reproductive tract morphometr ics, ovarian histology and plasma testosterone concentrations were studied in 80 females from 42 wild-caught colonies. Although the birth of offspring is restricted to the summer, qualitative analysis of ovarian histology rev ealed that females retained reproductive function during the winter non-bre eding period. Seasonal differences were found in ovarian morphometrics and testosterone concentrations and are probably associated with the occurrence of pregnancy in reproductive females during the breeding period. The conti nuance of reproductive function during the non-breeding period in female co mmon mole-rats parallels the situation in males, and is believed to be impo rtant in dispersal in C. h. hottentotus. The nonbreeding period coincides w ith the period of maximal dispersal opportunities in the winter rainfall ar eas inhabited by the common mole-rat. Reproductive activation in dispersing animals may aid intersexual recognition, assist pair-bond formation and th ereby facilitate independent reproduction. Reproductive and non-reproductiv e females exhibited a similar degree of reproductive function, and as for s eason, the only clear-cut status-related differences were associated with t he occurrence of pregnancy in reproductive females. This absence of a physi ologically well-defined suppression of reproduction in female common mole-r ats is similar to the situation in males. Incest taboos between philopatric siblings may negate the need for a rigorous suppression of reproduction in subordinate colony members of this obligate out-breeder.