The Effect Of Body Mass On Reproductive Strategy And Offspring Metabolic Phenotype In Brandt’s Voles (Lasiopodomys Brandtii)

Life history theory implies that organism could make trade-offs between survive, growth andreproduction to adapt to the changes of environments and maximize their fitness. Body mass orbody fat reflects animal energy status. Body mass could affect almost all biological variables ofanimals. As a costly physiological process, reproduction was often accompanied with a processof oxidative damage. Perinatal period was critical for offspring phenotypic plasticity in animals.Numerous physiological and environmental factors could program animals’ growth andmetabolic phenotype in adult. Parental effects are the major source of offspring phenotypicplasticity. We assumed that parental body mass could affect reproductive strategies, oxidativedamage and the offspring’s metabolic phenotype. Here we verified the effect of parental bodymass on reproductive strategy and offspring’s metabolic phenotype in Brandt’s voles(Lasiopodomys brandtii) which were distributed in Inner Mongolia grassland of China. The mainresults and conclusions we obtained were as follows:1. Litter size in high body mass group (HBM) was significantly higher than that of low bodymass group (LBM), but there were no significant differences in pup mass, total pup mass at birthor weaning between the HBM and LBM groups. These results showed that the litter size at birthwas significantly affected by parental body mass of Brandt’s voles, but pup mass and total pupmass were not affected. The voles with different body mass could adjust litter size according totheir own energy status and showed different reproductive strategies.2. Body mass gain in HBM was significantly higher than that of LBM at the end of pregnancy.The energy intake during pregnancy and lactation, the pup mass and total pup mass duringlactation did not show any significant differences between the two groups. It suggested thatreproduction brought the same energy cost to the dams with different body mass.3. There were no significant differences in protein carbonyl or maleicdialdehyde (MDA)levels in serum and MDA levels in liver at weaning between the two groups. These resultsshowed that the same level of oxidative damage was produced during lactation in the dams withdifferent body mass.4. Gross energy intake and digestible energy intake of offspring in parental high body massgroup (PHBM) were significantly lower than those of parental low body mass group (PLBM).The male offspring’s resting metabolic rate (RMR) in PHBM group was significantly lower than that of PLBM group. However, there was no significant difference in nonshiveringthermogenesis (NST) between the two groups. These results indicated that parental body massaffected the metabolic phenotype of offspring in adult Brandt’s voles.5. The wet and dry masses of testes in PHBM group were significantly higher than that ofPLBM group. The mass of retroperitoneal fat and gonadal fat in PHBM group was significantlyhigher than that of PLBM group in female offspring in adult. These results indicated that parentalhigh body mass promoted reproductive development in male offspring of Brandt’s voles, and thiseffect had gender differences.Briefly, parental high body mass induced the increase in litter size at birth, but did not affectmaternal energy intake, reproductive output or oxidative damage in Brandt’s voles. Paternal highbody mass induced the decrease in energy budget and promoted reproductive development inmale offspring of Brandt’s voles. These findings contribute to our understanding of energystrategies during reproduction, trade-off between survival and reproduction, and the effects ofparental body mass on offspring fitness, and provide guidance for understanding of populationfluctuations.