Thermal ecology of the post-metamorphic Andean toad (Rhinella spinulosa) at elevation in the monte desert, Argentina.
Rhinella spinulosa is an anuran toad species distributed latitudinal and altitudinal (1200-5000m) from Peru to Argentina, inhabiting mountain valleys in the Andes. Considering the broad range of habitats where they live, it is important to understand the thermal physiological mechanisms, thermal tolerances and physiological adaptations for surviving in rigorous environments. We investigated the thermal parameters (field body temperature, selected body temperature, locomotor performance in field and laboratory conditions, and thermal extremes) during diurnal activity for a population of juvenile, post-metamorphosed toads (Rhinella spinulosa) from the Monte Desert of San Juan, Argentina. Post-metamorphic toads are active from approximately 1100-1900 (in contrast to nocturnal adult toads). Our findings show that these toads have a wide thermal tolerance range, ranging from a critical thermal maximum of 36.9°C to crystallization temperatures below 0°C. During their active period, toads always showed suboptimal thermal conditions for locomotion. Despite the suboptimal condition for the locomotion, diurnal activity is likely to confer thermal advantages, allowing them to search for food and increase digestion and growth rates. We also found that the toads are capable of super-cooling, which prevents mortality from freezing when the environmental temperatures drop below 0°C. The environmental temperatures are below zero at night, when toads are inactive and take refuge under rocks. In summary, this toad population demonstrates high thermal plasticity, as shown by a relatively high level of activity sustained over a wide range of ambient temperature (~35°C). These thermal adaptations allow this species of juvenile toads to inhabit a wide range of altitudes and latitudes.
CONICET, Instituto de Ciencias Básicas, Facultad de Filosofía Humanidades y Artes, Universidad Nacional de San Juan, Av. José Ignacio de la Roza 230 (O), San Juan CP: 5400, Argentina; Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Padre Contreras 1300, 5500 Mendoza, Argentina. Electronic address: sanabria.eduardoa@gmail.com.
Eduardo A
EA
Sanabria
Departamento de Biología, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Argentina. Electronic address: yamilnob@gmail.com.
César Y
CY
Rodríguez
Departamento de Biología, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Argentina. Electronic address: llpanambill@gmail.com.
Cristina
C
Vergara
Departamento de Biología, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Argentina. Electronic address: ema.onti@gmail.com.
Emanuel
E
Ontivero
Departamento de Biología, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Argentina. Electronic address: mari_banchig_18@hotmail.com.
Mariana
M
Banchig
Departamento de Biología, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Argentina.
Ana L
AL
Navas
Departamento de Biología, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Argentina.
Mario A
MA
Herrera-Morata
Departamento de Biología, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de San Juan, Argentina. Electronic address: quirogalb@gmail.com.
Lorena B
LB
Quiroga
D000064:Acclimatization / Q000502:physiology; D000375:Aging / Q000502:physiology; D000531:Altitude; D000818:Animals; D001118:Argentina; D001831:Body Temperature / Q000502:physiology; D002025:Bufonidae / Q000502:physiology*; D004463:Ecology; D005247:Feeding Behavior; D006813:Humidity; D007814:Larva; D008675:Metamorphosis, Biological / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology; D016019:Survival Analysis; D013696:Temperature
Critical thermal maximum; Crystallization temperature; Field body temperature; Locomotor performance; Supercooling