Effect of Temperature on Activity Patterns in a Small Andean Rodent: Behavioral Plasticity and Intraspecific Variation

Abstract

The activity rhythm of a species is ruled by internal signals as well as external factors. Among them, ambient temperature strongly influences the amount, duration, and distribution of an organism's activities throughout the day. The result is a pattern of activity that, between certain limits, can be flexible to deal with seasonal and spatial thermal heterogeneity. The range of behavioral plasticity increases with environmental variability and could be beneficial for a species' persistence under novel conditions. Thus, the goal of this study was to experimentally explore the behavioral plasticity in Phyllotis xanthopygus, a rodent species inhabiting an altitudinal gradient in the Central Andes Mountains of Argentina. In the laboratory, we assessed activity rate and pattern under different temperatures by comparing groups of individuals collected at different altitudes. All animals were acclimated to subsequent thermal treatments in a paired design. As expected, P. xanthophygus showed changes in activity under different temperatures, and animals from diverse altitudes were differently affected. In particular, animals from mid‐altitudes and high altitudes reduced their activity under high temperatures. Intraspecific differences across the altitudinal gradient suggest that animals from mid‐altitudes and high altitudes are less heat tolerant than those from lower sites, in spite of acclimation to equal conditions. We propose that climate ranges experienced in the field possibly promote this different response. Our results are discussed in light of recent forecasts of temperature rises in the region, which could constrain P. xanthophygus activity in space and time.

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

“…Physiological studies of P. xanthopygus , a common Andean species, that encompass a broad latitudinal and elevation range, indicate that high temperatures diminish P. xanthopgyus activity patterns and intake rates (Sassi et al . 2015; Sassi et al . 2017), probably conditioning its presence in hot lowlands.…”

Plasticity in the timing of activity in the Red-rumped Agouti, Dasyprocta leporina (Mammalia: Rodentia), in the Atlantic Forest of southeastern Brazil

“…Thus, we suggest agouti activity patterns in study areas may also be influenced by differences in the ambient temperature, especially lower temperatures at the beginning and at the end of the day in EBSL, perhaps explaining why activity is different in the mountainous region with a milder climate compared to the hotter coastal region (more than 4 o C greater on average at RNV, noting that the daily thermal amplitude may be even higher in mountainous regions). Behavioral plasticity in response to environmental heterogeneity was also recorded to the small rodent Phyllotis xanthopygus (Waterhouse, 1837), for which groups of individuals collected at different altitudinal sites showed different rate and pattern of activity under the influence of different experimental temperatures (Sassi et al 2015).…”

“…Activity patterns may be influenced by abiotic factors, such as light (photoperiod), moon cycle, temperature, precipitation and latitude, and by biotic factors, such as food availability, interactions with competitors and risk of predation (e.g. Bronson 1988, Beltran & Delibes 1994, Goldman 1999, Kenagy et al 2002, Kronfeld-Schor & Dayan 2003, Wagner et al 2008, Pita et al 2011, Suselbeek et al 2014, Sassi et al 2015. Thus, examining how organisms respond to daily and seasonal variation in the environment and plasticity in behaviors allows us to better understand patterns of community structure, species coexistence, resource partitioning and predator avoidance (Kronfeld-Schor & Dayan 2003).…”

Geographic variation in life‐history traits: factors shaping energy investment in reproduction in a highland dwelling rodent

“…Previous experiments on P. xanthopygus have reported that high temperatures in the laboratory (30°C) result in lowered activity, decreased food intake and increased body mass in non‐breeding animals (Sassi & Novillo, ; Sassi et al ., ). Likewise, we found here that F1 females’ mass increases under the 30°C treatment, but still their pups were significantly smaller than those lactating at 17°C.…”

“…Collected individuals show signs of reproductive activity only during summer months (Kelt, ). Recent investigations performed on a population occurring along the elevation gradient in the Central Andes, report high behavioral flexibility, physiological plasticity and diverse trophic interactions, facing great thermal and resource‐related variation (Sassi & Novillo, ; Sassi et al ., , ).…”