The influence of food restriction and photoperiod on reproduction in male spiny mice ( Acomys spinosissimus ): Evidence for terminal investment?

Abstract

Photoperiod and food availability often interact in the regulation of reproductive activity in seasonal environments. We tested the effects of a 10% food restriction and short-(SD) and long-day (LD) photoperiods on reproductive preparedness of male spiny mice (Acomys spinosissimus) from South Africa. Males were either fed ad libitum or a 10% restricted diet and on both food regimes, they were exposed to either a 14h light:10h dark (LD) or 10h light:14h dark (SD). Testes size, seminiferous tubule diameter and faecal androgen metabolite concentrations were significantly larger in food restricted males subjected to LD than in any of the other groups. SD photoperiods did not suppress reproductive activity, despite earlier findings, which may be explained by "spontaneous" recrudescence due to prolonged exposure to SD. The high reproductive activity observed in food restricted LD males may indicate a terminal investment strategy in male spiny mice with males investing more into reproduction in the face of reduced future survival.

Food restriction delays seasonal sexual maturation but does not increase torpor use in male bats

“…Similarly, there were no M b changes in male Daubentons' bats during intensive spermatogenesis despite a more than 2-fold increase in food intake (Encarnação and . Indeed, small mammals can use up reserves and subsequently lose mass to balance the costs of thermoregulation and spermatogenesis if they cannot increase food intake (Entwistle et al, 1998;Dietz and Hörig, 2011;Becker et al, 2013;de Bruin et al, 2018). In our study, we did not observe M b loss in the low food bats.…”

“…Thus, trade-offs between costly reproductive processes and body maintenance or thermoregulation are particularly challenging for small animals (Grinevitch et al, 1995;Willis et al, 2006). Resource limitation may further exacerbate competition between life-history traits (Boggs and Ross, 1993;Cotter et al, 2011;Chinn et al, 2018).…”