Is reproduction of male eastern rock sengis (Elephantulus myurus) from southern Africa affected by photoperiod?

Abstract

Many mammals use the change in day-length to time physiological and behavioural activities on a seasonal basis. Particularly mammals from temperate regions use photoperiod to regulate reproductive functions; however, information on the role of photoperiod in small mammals from the tropics and sub-tropics is scarce. We studied the response of the reproductive system of male eastern rock sengis (Elephantulus myurus) from southern Africa to photoperiods of differing length. Elephantulus myurus breeds seasonally during the spring and summer months of the southern hemisphere despite its subtropical distribution. It is one of only three sengi species known to breed seasonally. Fourteen male E. myurus were subjected to either long-day (LD; 16L:8D) or short-day (SD; 8L:16D) photoperiods and the photoperiodic effects on the testes, testosterone concentration and body mass were examined. Testicular volume and mass, seminiferous tubule diameter as well as body mass were not significantly different between LD and SD conditions. However, plasma testosterone concentration was significantly lower in males on LD compared to SD photoperiods. Male E. myurus may not use photoperiod as a cue to control seasonal reproductive changes. Other environmental factors such as temperature, rainfall, food abundance or social factors are possibly influencing seasonal reproduction in this species.