Feeding strategies of a small mammal (Phyllotis xanthopygus, Rodentia Cricetidae) at diverse altitudes in the Central Andes, Argentina

Abstract

Knowledge of feeding habits not only contributes information related to the resources that individuals need to survive and breed, but also leads to insights about the interactions between a species and its environment. The optimal foraging theory explains diet selection by several attributes of the trophic scenario such as availability, diversity, quality and predictability of food. Other models propose that digestive tract mass increases under high metabolic demands by cold, affecting food choice and intake. Thus, diet selection emerges as a behavioural trait shaped by intrinsic and extrinsic factors. The goal of our study was to determine variation in the trophic scenario among sites at different elevations, as well as variation in phenotypic traits relevant to the nutritional and energy balance in Phyllotis xanthopygus. This small rodent is widely distributed along the Andes Mountains. We assessed diet selection and digestive tract size in individuals collected at three elevations across its distribution range. Results on dietary proportion of specific trophic categories (green parts, fruits and arthropods) showed that P. xanthopygus alternates between omnivory and granivory/frugivory. Richness, diversity and quality of the available resources evidenced a relatively low-quality trophic scenario at high altitude. Nevertheless, the diets built in by animals from diverse altitudes lacked differentiation in quality or diversity. P. xanthopygus seems to behaviourally compensate environmental variation to cope with nutritional requirements, by changing diet composition and proportion of items included. The resultant uniform diet quality is consistent with the absence of variation in the gastrointestinal tract size. Considering the spatial variability and seasonality of the region, a behavioural response is probably the most convenient strategy to overcome short-term environmental heterogeneity. In a plastic species such as P. xanthopygus, behaviour is a fundamental aspect to take into account by predictive models in the forecasts of climate change effects on biological diversity.

Phylogenetic relationships among cryptic species of the Phyllotis xanthopygus complex (Rodentia, Cricetidae)

“…A plethora of cytogenetic, morphological and ecological studies are available for this taxon, contributing to our knowledge of this genus in a greater degree than perhaps any other sigmodontine (e.g. Hershkovitz, 1962; Pearson & Patton, 1976; Pizzimenti & de Salle, 1980; Walker et al., 1984; Kelt, 1994; Kramer et al., 1999; Steppan et al., 2007; Labaroni et al., 2014; Sassi et al., 2017). Despite these contributions, our understanding of the species‐level taxonomy of Phyllotis is far from being completely understood.…”

Turnover, richness difference and nestedness of rodent assemblages along the southern Andes elevation gradient

“…2015; Sassi et al . 2017), probably conditioning its presence in hot lowlands. Mid‐elevations accounted for intermediate values of temperature and precipitation leading to higher productivity and consequently higher species abundances than either high and low elevation sites (McCain 2004; Grytnes & McCain 2007; Novillo & Ojeda 2012).…”

Skull morphological evolution in Malagasy endemic Nesomyinae rodents

“…Hence, either ecological space is not partitioned by size in Nesomyinae, either size may have been driven by other ecological parameters than those tested, as diet. However, diet is highly variable in rodents [43,49], and more data on the feeding habits of Nesomyinae are needed to test it reliably.…”

“…In rodents, it has been observed that herbivores display longer tooth rows and wider skull and rostrum [61]. However, it is well known that diet is spatially and temporally variable in rodents [49]. As far as we know, most Nesomyines are known to be omnivorous and their diet vary seasonally according to available resources [43].…”