Photoperiodic responses of four wild-trapped desert rodent species.

The purpose of this study was to examine the effect of the photoperiod on reproductive status and body and lipid masses in four Egyptian desert rodent species (Dipodillus dasyurus, Acomys cahirinus, Gerbillus andersoni, and Gerbillus pyramidum). Adult males and females were housed in long days for 11 wk. At that time, one-half of the animals were killed and the remaining animals were moved to short days (SDs) for 11 wk. Some individuals of Gerbillus andersoni and Gerbillus pyramidum had access to running wheels. Testes index and spermatogenesis, but not testis mass, were decreased in all species in SDs. In contrast, SDs did not affect female reproductive status in all species. Exercise stimulated spermatogenesis but did not affect female reproductive status. SDs increased body and lipid masses in male Acomys cahirinus, but not in other species. Collectively, these desert rodent species were responsive to day length changes, but these changes alone did not induce robust alterations in reproductive status and body and lipid masses.