Water availability affects reproduction in deer mice.

Water restriction impaired sperm production in deer mice, a seasonally breeding mammal that encounters aperiodic droughts in its natural habitat throughout North America. Water-induced spermatogenic responses were sorted into three categories based upon epididymal sperm numbers: aspermic, oligospermic, and euspermic. Average gonadal mass was reduced after 10 wk of limited water consumption. Inter-individual variation in gonadal response to a simulated drought was similar to phenotypic differences in reproductive function in response to other environmental cues that direct annual reproductive cycles. Our findings suggest that water availability may act as a cue to suppress gametogenesis in deer mice independently from food, temperature, and day length.