Plasticity is employed to match environmental variability in many animal species, and consequently increases their performance under different environmental conditions. Plasticity in body mass, energy budget, behavioral patterns and gastrointestinal (GI) tract was examined in Swiss mice and striped hamsters (Cricetulus barabensis) acclimated to a stochastic food deprivation (FD) and then an ad libitum refeeding (Re). FD leaded to a significant decrease in body mass on FD days and an increase in food intake on feeding days in both animals. Larger GI tract in size was employed to meet the higher food intake in FD mice and hamsters. Unexpectedly, activity increased significantly on FD days for both animals. Carcass and fat mass decreased significantly in FD hamsters but not in FD mice. This suggested that mice compensated completely for stochastic FD by increasing food intake on feeding days, whereas hamsters by both increasing food intake and mobilizing energy deposition. After 4 weeks of Re, all of above parameters recovered to levels of controls indicating a significant plasticity in both species over a short timescale. Finally, the current study provided a support for the hypothesis that there were species specific responses of plasticity in energy budget and behavioral patterns to unpredictable changes in food availability for non-foraging mice and foraging hamsters.
"In contrast, the golden hamster (Mesocricetus auratus) (Steinlechner et al., 1983), collared lemming (Dicrostonys groenlandicus) (Nagy et al., 1995) and tree shrew (Tupaia belangeri) (Zhu et al., 2012b) had the highest body mass in winter and the lowest in summer. This suggests that there might be species-specific responses in body mass and energy metabolism to the seasonal changes—for example, metabolic rates have been reported to differ between populations or species from habitats differing in seasonal changes (Zhao and Cao, 2009). Lipometabolism plays a major role in the body weight regulation (Bartness and Wade, 1985). "
"Each animal was observed 60 times in 8 h and the percentage of time spent on each behavior was calculated from the pooled data across the 8 h of observation of each animal (% each behavior) (Speakman et al. 2001). Observations were made in the dark phase using a 30-W red light (Zhao & Cao 2009). "
[Show abstract][Hide abstract] ABSTRACT: The value of phenotypic plasticity in energy metabolism and behavioral patterns in response to variations of food availability was handled in adult male voles (Eothenomys miletus) acclimated to random food deprivation (FD) for 4 weeks. During this period, in which voles were fed ad libitum for a randomly assigned 3 days each week, changes in body mass, food intake, resting metabolic rate (RMR), non-shivering thermogenesis (NST) and serum leptin levels were measured. Behavioral observations were made to examine behavioral patterns including activity, feeding, grooming and resting behaviors. The results showed that food intake and gastrointestinal mass increased significantly, but RMR and NST decreased significantly in the FD group compared to the control group. Moreover, the FD group had a significantly higher percentage of feeding behavior and lower activity than those in control group. In addition, serum leptin levels were positively correlated with body fat mass, but showed no significant differences between FD and the control group. These results suggest that E. miletus can compensate for an unpredictable reduction of food availability by engaging in an energetic strategy related to food intake and a decrease in energy expenditure associated with RMR, NST plus general activity, together with the mobilization of body fat as well as the adjustment of the gastrointestinal tract, which consequently play an important role in adaptations to food shortage in unpredictable environments.
Italian Journal of Zoology 08/2014; 81(2):227-234. DOI:10.1080/11250003.2014.902511 · 0.79 Impact Factor
"Nutritional stresses such as food deprivation (absence of food) and food restriction (reduction in the amount of food that an animal would normally consume) are an ecological challenge faced by small herbivores (Krackow 1989; Voltura and Wunder 1998; Zhao and Cao 2009), and might also be an important challenge for meadow voles. Meadow voles live in ephemeral and transitional grasslands, where food sources are patchy and vary in quality across the territories of female conspecifics (Bergeron et al. 1990; Bergeron and Jodoin 1987; Getz 1985). "
[Show abstract][Hide abstract] ABSTRACT: For numerous species of terrestrial mammals, postpartum estrus, PPE, is a period of heightened attractivity, proceptivity, and receptivity that occurs shortly after the female delivers her litter. Many mammals mate almost exclusively during PPE. However, we know little about the behavior of PPE females and how male conspecifics behave towards them. This review focuses on the results of recent studies that tried to examine systematically the behavior of PPE female meadow voles, Microtus pennsylvanicus, and the responses of males to them. Our review is divided in five parts. First, we introduce the topic of PPE in rodents. Second, we discuss the outcome of studies showing that PPE female voles were more attractive to males, directed more proceptive behaviors towards males, and were more sexually receptive and likely to get pregnant compared to females that were not in PPE. Third, we discuss studies that examined how male voles respond and adjust their behavior when they encounter PPE females. Males increase the likelihood of mating with PPE females by recalling the reproductive state of females and the location of their nests, and by anticipating how long or when each of these females would be in PPE. Fourth, we focus in how food availability, an ecological constraint facing gestating female voles, affected their attractivity, proceptivity, and receptivity postpartum. Fifth, we revisit the benefits of seeking out and mating with PPE females and introduce the costs of doing so for both males and PPE females. We close our review with a list of questions that can be used to formulate testable hypotheses surrounding the behavior of PPE females and the responses of male conspecifics to them.
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