Spatio-temporal variability in the feeding strategy of Andean rodents: the role of ambient temperature and food availability

RUPERTO, EMMANUEL FABIÁN; MENÉNDEZ, JOSEFINA; TARABORELLI, PAULA ANDREA; DACAR, MARÍA ANA; SASSI, PAOLA LORENA

Mammal Research

Springer

Lugar: Polonia; Año: 2023 vol. 1 p. 1 - 15

2199-2401

Animals´ diets refect the morpho-physiological and behavioral responses used to obtain nutrients and energy. While optimalforaging theory predicts them in terms of food availability, the obligatory heat model (OHM) predicts them based on ambienttemperature, which afects the activity and/or size of the digestive organs, infuencing food digestibility. In the highlands ofcentral-west Argentina, rodent diversity is dominated by Phyllotis vaccarum, Abrothrix andina, Akodon oenos, and Euneomys sp. that coexist in diferent sections of their elevational ranges. Although these species´ diets are relatively fexible, it isunclear how temperature and food availability infuence their constitution. To unveil this, we explored their feeding strategies at diferent elevations (1700, 2300, and 3100 m a.s.l.) and seasons (winter and spring-summer). By examining fecalsamples, we quantifed the intake of vegetative parts of plants, seeds, and arthropods. Abrothrix andina was insectivorous at2300 m and omnivorous at 3100 m a.s.l. in line with the OHM predictions, suggesting a higher plant consumption derivedfrom an increased capacity of digestive organs, favored by lower temperatures at higher elevations. Phyllotis vaccarum washerbivorous at all elevations, independently of food supply or temperature conditions. However, the secondary food choiceoccurred in line with the OHM predictions, suggesting a certain degree of digestive adjustment to ambient temperature.Akodon oenos, which was only captured at 2300 m, was insectivorous, whereas Euneomys sp., which was only present at3100 m, was a specialist herbivore. We detected no seasonal variation in the feeding strategies of the rodents examined.Intraspecifcally, thermoregulatory demands would infuence the variation in feeding strategies at the elevational gradient,whereas nutritional requirements would explain their consistency between seasons. Interspecifcally, we found that dietdissimilarity was relatively high, mainly at high elevations and during winter, which could facilitate species coexistence.