Abstract:
Photoperiodism involves the use of both absolute measures of day length and the
direction in which day length is changing as a cue for regulating seasonal changes in
physiology and behaviour so that birth and lactation coincide with optimal resource
availability, increasing offspring survival. Induced ovulation and opportunistic
breeding is often found in species that are predominantly solitary and territorial. In
this study, the photoperiodic reproductive responses of male greater red musk
shrews (Crocidura flavescens (I. Geoffroy Saint-Hilaire, 1827)) were investigated in
the laboratory. The presence of spermatozoa regardless of the light cycle, suggest
that although the shrews are photoresponsive, they may be capable of breeding
throughout the year. Significantly greater testicular volume and seminiferous tubule
diameter following exposure to a short day-light cycle suggests that these animals
may have breeding peaks that correspond to short days. The presence of epidermal
spines on the penis indicates that the shrew is likely also an induced ovulator.
Flexible breeding patterns combined with induced ovulation affords this solitary
species the greatest chance of reproductive success.
