Inter‐Population Variation in Hoarding Behaviour in Degus,Octodon degus

Abstract

Although foraging comprises a set of behaviours that typically vary with resource availability and/or climatic conditions, few studies have analysed how foraging, particularly food hoarding, varies across populations inhabiting different habitats. We carried out an inter‐population study on foraging behaviour with the caviomorph rodent Octodon degus collected from two geographically separated populations in central Chile, with contrasting climates. One population was located in a mountainous zone (at 2600 m elevation) characterized by a high‐altitude climate. The other population was from a low‐altitude Mediterranean climate zone (450 m elevation). Under laboratory conditions, we measured population‐specific differences in food consumption and hoarding by recording food utilization. We also assessed whether acclimation played a role in behavioural differences, by using two different sets of animals that had been in captivity for (1) 2 wk or (2) 6 mo, under common conditions. The results showed variation in food hoarding between populations. Individuals from the low‐altitude population exclusively displayed scatter hoarding behaviour. In contrast, high‐altitude animals carried out larder hoarding combined with scatter hoarding (37.4% and 62.6% respectively). There was no intra‐population variation between degus with different acclimation periods under captivity, thus inter‐population differences in larder hoarding were maintained despite 6 mo of acclimation to a common environment. The geographic variation observed suggests that larder hoarding is favoured under harsher environmental conditions. We discuss some probable causes for this variation. The lack of effect of acclimation suggests that inter‐population differences in larder hoarding might be the result of local adaptation or, less likely, it corresponds to an ontogenetically acquired irreversible behaviour.

Ecological drivers of group living in two populations of the communally rearing rodent, Octodon degus

“…While both study areas are characterized by a Mediterranean climate with cold, wet winters and warm, dry summers (di Castri and Hajek 1976), the high altitude area at Los Molles provides degus with a potentially more stressful environment in terms of lower ambient temperature than the low altitude area at Rinconada (Quispe et al 2009). Given that no empirical data on ambient temperature were available for Los Molles, we used a multiple regression model with latitude and altitude as predictors ( R 2 =0.74, F =38.2, P <0.001; Houston and Hartley 2003; Houston 2006) and estimated that mean annual temperature for Rinconada and Los Molles were 14.0°C and 9.4°C, respectively.…”

Estación Biológica Senda Darwin: Investigación ecológica de largo plazo en la interfase ciencia-sociedad

“…Dado su extenso rango latitudinal (c. 2,800 km), las poblaciones experimentan condiciones ambientales y presiones selectivas contrastantes. En este sentido, su estudio puede contribuir a comprender las causas de cambios microevolutivos e incluso procesos de especiación o subespeciación (e.g., Foster 1999, Quispe et al 2009). Con el objeto de estudiar algunos rasgos de historia de vida del rayadito, se instalaron cajas anideras (Fig.…”

Effects of Habitat and Social Complexity on Brain Size, Brain Asymmetry and Dentate Gyrus Morphology in Two Octodontid Rodents

“…O. degus uses relatively open savannas or open scrub environments in central Chile, but more closed scrub patches and ravines in northern populations [Quispe et al, 2009;Ebensperger et al, 2012]. In these environments, O. degus excavate and use burrow systems connected aboveground by runways or trails used during foraging [Fulk, 1976;Lagos et al, 1995;Vásquez et al, 2002].…”