Abstract:
In deserts where unpredictable rainfall arises and a large variation in temperature occurs, this poses
severe energetic and water related constraints on reproduction in small mammals and makes the use of
photoperiod as cue for reproduction unreliable. In the present study, the gonad morphometrics, gonadal
histology and endocrine profiles of the Arabian spiny mouse (Acomys dimidiatus) were studied over 12
consecutive months in a field population from western Saudi Arabia in an attempt to assess the seasonality
of reproduction and gain insights into the environmental cues that may trigger reproduction in
this species. Although sperm was present throughout the year, most reproductive parameters exhibited a
seasonal pattern with a minimum in winter in both sexes and pregnancies were observed from spring to
autumn. Whereas testes volume, the number of corpora lutea and progesterone levels were correlated
with temperature, all other reproductive parameters were correlated with rainfall. Thus, it appears that
A. dimidiatus ceases to breed during winter and uses rainfall as an environmental cue to initiate
reproduction in the study area. However, the species appears to have the ability to reproduce throughout
the year, if favourable conditions arise.
