Datos de investigación
Traits associated with energy balance of small Andean rodents across an altitudinal gradient and their response to thermal acclimation
Autores:
Menéndez Sammartino, Josefina
; Sassi, Paola Lorena
; Ruperto, Emmanuel Fabián
; Taraborelli, Paula Andrea
; Sassi, Paola Lorena
; Ruperto, Emmanuel Fabián
; Taraborelli, Paula Andrea
Colaboradores:
Linares, Maria Cielo
Publicador:
Consejo Nacional de Investigaciones Científicas y Técnicas
Fecha de depósito:
15/01/2025
Fecha de creación:
2018/2023
Clasificación temática:
Resumen
The datasets contain traits associated with energy acquisition and expenditure of four species of small Andean rodents collected at different elevations in the Central Andes of Argentina. For each individual, traits were measured post-capture (within the first week after capture) and after 6 weeks of acclimation to three thermal treatments (constant room temperature of 16°C, 25°C, and 30°C, respectively). Regarding energy acquisition, we present data on daily gross dry matter and energy intake, energy digestibility, daily digestible energy intake, and food transit time. Concerning energy expenditure, we present data on resting metabolic rate at different ambient temperatures, thermal conductance, total evaporative water loss, and body mass and body temperature at the beginning and end of each metabolic trial.
Métodos
Study site: The study was carried out at two adjacent reserves, Manzano Histórico Reserve and Manzano-Portillo de Piuquenes Reserve, Mendoza Province, Argentina. There, we established three sampling sites along an altitudinal transect, running East–West, at 1700 (33°35'35.8''S ; 69°24'15.6''W), 2300 (33°36'48.4''S; 69°28'42.7''W) and 3100 (33°36'37.9''S;69°32'14.5''W) m a.s.l., separated by a linear distance of 7 and 5 km respectively.
Animal capture and experimental design: We collected 10 adult male individuals (to avoid effects of pregnancy and lactation) per species-elevation combination (total n= 70): Phyllotis vaccarum captured at 1700, 2300 and 3100 m a.s.l.; Abrothrix andina captured at 2300 and 3100 m a.s.l.; Akodon oenos captured at 2300 m a.s.l.; Euneomys sp. captured at 3100 m a.s.l. Animales were captured using Sherman traps baited with oats and peanut butter, during the austral summer months (December-March) of 2018-2022. Once in the laboratory, the animals were housed individually in 30 × 30 × 40 cm cages, provided with woodchip bedding and a plastic tube with cotton to use as a refuge. They were kept under a 12 L:12 D photoperiod at 24 ± 1°C, and provided with food and water ad libitum (standard laboratory conditions). (1) To detect the residual effect of distinct thermal conditions endured in the field, all response variables (specified below) were measured within the first week after capture (“post-capture”; Chetty, 2006; Nespolo & Rosenman, 1997). (2) To evaluate the flexibility of these traits, each animal was sequentially acclimated to three thermal treatments, following a crossover design: all individuals were first acclimated to 25°C and then half were acclimated in second place to 16°C and finally to 30°C, while the other half followed the reverse order (30°C in second place and last at 16°C; Nespolo et al, 2001). Each acclimation lasted 6 weeks, after which the response variables were measured again. Between the treatments at 16°C and 30°C animals were housed for 3 weeks at 25°C (initial conditions). Particularly for Euneomys sp., a species restricted to high altitudes (above 2800 m a.s.l. in the study region; Novillo et al., 2014), we observed a marked decrease in locomotor activity at 25°C. Therefore, we decided not to expose this species to the treatment at 30°C. To maintain the cross-over design, after initial post-capture trials, half of the Euneomys sp. individuals were first acclimated to 25°C followed by 16°C, while the other half was first acclimated to 16°C followed by 25°C.
Energy acquisition trials: To estimate food intake and digestibility, animals were provided daily with a known amount of food, and 24 hrs later the feces and remaining food were collected, dried at 60°C in a dry heat sterilizer for a week, and weighed. This procedure was performed over the course of 3 consecutive days to obtain representative estimates with sufficient resolution (Sales and Janssens, 2003, and references therein). Animals were weighed at the beginning and end of each trial. The energy content per gram of feces and food was measured using a Parr Bomb Calorimeter, and multiplied by the dry weight of samples. Daily dry matter intake (DMI) was measured as the difference between the amount of dried food offered minus the amount left per day. Daily energy intake (EI) was calculated as Qi–Qe, where Qi is the daily rate of energy in food intake and Qe is the daily rate of energy wasted in feces. Apparent energy digestibility (D) was calculated as [(Qi - Qe)/Qi] x 100% and digestible energy intake (DEI) as Qi x D (Sassi and Novillo, 2015). This method underestimates digestive efficiency because it includes the contribution of metabolic wastes, non-reabsorbed secretions of the digestive system, and microorganisms (Naya and Bozinovic, 2006). After the last day of the intake trials, individuals were fasted for 12 hs and then provided with a single pulse of carrot stained with an edible dye as a marker. Animals were given 30 min to eat the carrot and were then placed in metabolic cages where feces were collected every hour for a total period of 12 hrs. Food transit time (TT) was estimated as the time elapsed between the ingestion of the carrot and the time of the first deposition of colored feces (Martino et al., 2007). Body weight was measured at the beginning of the trial.
Metabolic trials: Metabolic rate was measured as the rate of oxygen consumption (VO2) using an open-flow respirometry system (Field Metabolic System; Sable Systems, Anderson, NV). The respirometry chamber received dry, CO2-free air as it was previously passed through CO2 and H2O absorbents (sodalime and calcium sulfate, respectively). Flow rates were set at 730 ml/min for P. vaccarum and Euneomys sp., and at 630 ml/min for A. andina and A. oenos. Excurrent air was sampled every 1 s by the FMS gas analyzers and data was recorded and analyzed using ExpeData acquisition software (Sable Systems, Anderson, NV). Oxygen consumption was calculated as (FR x 60 x (FIO2 – FEO2 ))/(1 – FIO2), where FR is the flow rate and FIO2 and FEO2 are the incurrent and excurrent O2 fractional concentrations, respectively (Lighton, 2008). Evaporative water loss was calculated as (VE x pE) – (VI x pI), where VI and pI are the incurrent air flow and absolute humidity, respectively, and VE and pE are the excurrent ones (Cavieres y Sabat, 2008). Metabolic measurements were taken at ambient temperatures (Ta) of 7°, 14°, 20°, 30°, and 36.5°C, one temperature per day on consecutive days, during the resting phase of the daily cycle of each species (Ruperto et al., 2020; Ruperto et al., 2022a; Ruperto et al., 2022b). The order in which each Ta was measured for each individual was randomized. For cool temperatures (7°C-20°C) the metabolic trials lasted 2 hs, for Ta=30°C (standard temperature within the TNZ of rodents in the body mass range of the studied species) it lasted 4 hrs (Bozinovic & Rosenman, 1988; Nespolo et al., 2003), and for Ta=36.5°C it lasted 1.5 hrs. During post-capture measurements, animals were not exposed to Ta=36.5°C. For Ta control, the respirometry chamber was placed inside a Peltier-effect cabinet and Ta was set and held constant by a PELT-5 temperature controller (Sable Systems, Anderson, NV). At the beginning and end of each trial, we recorded body mass (Mb) with an electronic balance and body temperature (Tb) by inserting a thermocouple 2 cm into the rectum. Metabolic rate (MR) at each Ta was calculated from the consecutively lowest most stable 5 min period. Total evaporative water loss (TEWL) corresponds to evaporative water loss during the selected 5-minute period of MR. Thermal conductance (C) was calculated as the slope of the MR-Ta curve under cool conditions (7°C-20°C; Bozinovic and Rosenman, 1988).
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Datos de Investigación(IADIZA)
Datos de Investigación de INST. ARG DE INVEST. DE LAS ZONAS ARIDAS
Datos de Investigación de INST. ARG DE INVEST. DE LAS ZONAS ARIDAS
Datos de Investigación(IBYME)
Datos de Investigación de INST.DE BIOLOGIA Y MEDICINA EXPERIMENTAL (I)
Datos de Investigación de INST.DE BIOLOGIA Y MEDICINA EXPERIMENTAL (I)
Datos de Investigación(SEDE CENTRAL)
Datos de Investigación de SEDE CENTRAL
Datos de Investigación de SEDE CENTRAL
Citación
Menéndez Sammartino, Josefina; Sassi, Paola Lorena; Ruperto, Emmanuel Fabián; Taraborelli, Paula Andrea; (2025): Traits associated with energy balance of small Andean rodents across an altitudinal gradient and their response to thermal acclimation. Consejo Nacional de Investigaciones Científicas y Técnicas. (dataset). http://hdl.handle.net/11336/252541
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