A comparative study of resting metabolic rate was conducted for the temperature range 10-37 °C for four rodent species, northern three-toed jerboa (Dipus sagitta) (body mass, Mb 79.2±6.8 g, n = 25), ...midday gerbil (Meriones meridianus) (Mb = 45.0±8.1 g, n = 10), desert hamster (Phodopus roborovskii) (Mb = 15.4±2.9 g, n = 26, and striped hamster (Cricetulus barabensis) (Mb = 24.8±4.0 g, n = 7) in the Ordos desert in summer (July), 1997. The minimum resting metabolic rates were 1.14±0.25 ml O2/g.h for three-toed jerboa, 1.35±0.3 ml O2/g.h for midday gerbil, 2.98±0.65 ml O2/g.h for desert hamster, and 2.75±0.37 ml O2/g.h for striped hamster. The thermal neutral zones (TNZ) were wide in the three desert species that was 26~37 °C in jerboa, 26~35 °C in gerbil, and 24~34 °C in desert hamster, respectively. For the non-desert species, striped hamster, it was 26~30 °C. The results do not confirm the hypothesis that desert rodents generally have lower metabolic levels than non-desert species. The high metabolic rates of these four rodent species were interpreted to be influenced by the stable availability of food resources and low environmental temperature in the Ordos Plateau. our results partly support the hypothesis that the metabolism characteristics are determined by food resources and environment temperature for animals living in arid regions.
We studied coprophagous behaviour in Brandt's vole using a solute food marker (Co-EDTA). Examination of marker concentrations in the stomach, small intestine, caecum and colon of voles killed at ...half-hour intervals after a pulse dose of Co-EDTA indicated that the marker was recycled to the stomach by coprophagy. Recycling of digesta via coprophagy enables Brandt's vole to utilise diets of higher fibre contents. This is the first evidence for coprphagy in this species.
Rodens et spatium VII Sousa, Inês Pereira de; Quartau, José Alberto; Mathias, Maria da Luz ... Web Resource
Odprti dostop
Over the decades, islands have provided a useful background for the evaluation of the consequences of isolation upon populations. Epigenetic and morphometric divergence among black rat (Rattus ...rattus) populations from Western European island (São Miguel, Terceira, Flores, Porto Santo, Berlenga, Corsica) were analysed and compared with mainland reference populations (Portugal, France, Morocco). Neither of the two approaches showed insular samples to have greater distinctiveness than those from the mainland. The overall pictures of epigenetic and morphometric similarity among populations were concordant, apparently in agreement with their probable origin from founder individuals brought by former maritime traffic. Mainland populations were more variable, but only according to morphometric characters. The adaptive and evolutionary significance of the patterns found may be related to both the period of population isolation and island area.
We examined the capacity for nonshivering thermogenesis in four rodent species residing in the Ordos Plateau of Inner Mongolia. Nonshivering thermogenesis (NST, maximum NST minus resting metabolic ...rate) was determined for northern three-toed jerboas (Dipus sagitta), midday gerbils (Meriones meridianus), desert hamsters (Phodopus roborovskii), and striped hamsters (Cricetulus barabensis) in spring (May), summer (July, and autumn (OCtober) captured in the Kubuqi desert in 1997. NST was induced by norepinephrine (NE) and measured by using the closed-circuit respirometer at 27 °C. Our results showed significant increases from summer to autumn in NST for the four species. NST capacities were 0.52±0.27 ml O2/g0.73.h (n = 7) in summer and 2.49±1.29 (n = 6) in autumn for jerboas, 1.61±0.74 (n = 6) in summer and 3.26±1.35 (n = 5) in autumn for gerbils, 3.62±0.75 (n = 5) in summer and 9.71±2.81 (n = 6) in autumn for desert hamsters, and 6.81±3.02 (n = 8) in summer and 11.23±2.77 (n = 8) in autumn for striped hamsters. These results suggest that small mammals living in the inland arid region on Ordos Plateau adapt to their extreme environment physiologically by adjusting their thermogenic capacities to cope with the dramatic seasonal temperature fluctuations.
Rodens et spatium VII Gorshkov, Yurii A; Gorshkov, Dmitry Y; Easter-Pilcher, Andrea L ... Web Resource
Odprti dostop
The main reason for reitroducing beavers (Castor fiber) to the Raifa part of the Voga-Kama National Nature Zapovednik (VKNNZ) was to utilise their habitat-changing activities - primarily the use of ...their ability to build dams - to stop the degradation of the Zapovednik hydrosystem (Gorshkov et al. 1999). Today there are seven beaver dams on the rivers that run through the Zapovednik. We studied the movements of the beavers by locating new cuts, dens, trails, dams, etc. and by radiotelemetry. We assumed that in the first phase of reintroduction the spatial structure of the beaver subpopulation consisted of four permanent and five temporary settlements. We determined the home ranges of the reintroduced beavers as being approximately seven ha, plus smaller additional patches of habitat that were used during the witner. Another object of our investigation - the feeding behaviour of reintroduced beavers - showed that the most preferred tree genera were aspen and willows, followed by alder and birch. The wolume of trees cut by beavers between autumn 1996 and spring 1999 in the Volga-kama National Nature Zapovednik was 11.69 m3
