Thermal Ecology of Neotropical Lungless Salamanders (Amphibia: Plethodontidae): Environmental Temperatures and Behavioral Responses

Abstract

In a substrate thermal gradient in the laboratory, seven species of neotropical plethodontid salamanders exhibited distinct thermal preferences. The mean substrate temperature selected in the gradient (preferred body temperature, PBT) was affected by acclimation temperature and feeding in some species, and was negatively correlated with the elevation at which each species was collected. Regulation of the PBT was imprecise and only partially compensated for changes, in environmental temperatures. Even though tropical plethodontids are capable of thermoregulation, they may be unable to thermoregulate in the field because of limited thermal diversity in their microhabitats. Temperatures within typical salamander microhabitats such as bromeliads (Tillandsia sp.) and banana plants (Musa sp.) ranged only 2° and 3.7°C, respectively. Diverse temperatures were available nearly in each case, but would have involved exposure to direct light or dehydrating conditions. Water relations may limit thermoregulation in salamanders because hydric requirements restrict salamanders to moist microhabitats, which may have limited thermal diversity. However, in atypical field situations in which moist thermal gradients are available, some terrestrial salamanders (e.g., Thorius narisovalis) are capable of regulating their body temperatures.

Dependencia térmica de la salamandra endémica de Colombia Bolitoglossa ramosi (Caudata, Plethodontidae)

“…En el caso de las salamandras terrestres, los estudios clásicos de Bogert (1952) y Feder (1976, 1982, , han considerado las temperaturas del sustrato como equivalentes de las temperaturas corporales. Sin embargo, las temperaturas superfi ciales en los anfi bios expuestos al aire, en donde puede haber pérdida de agua de la piel por evaporación, pueden ser diferentes a las temperaturas internas (Hutchison & Dupré, 1992).…”

“…Particularmente, por ser ectotérmos, los anfi bios no tienen la capacidad de generar calor a partir de reacciones metabólicas y por esta razón la temperatura ambiental es fundamental para el incremento de su temperatura corporal (Duellman & Trueb, 1994;Randall et al, 1997), aunque limita su distribución espacial, temporal y los restringe a determinados tipos de hábitat (Spotila, 1972;Feder & Pough, 1975;Tracy, 1976;Feder, 1982;Angilletta, 2009).…”

“…Esto hace que la mayoría tengan tendencias termoconformadoras, en donde la temperatura corporal está relacionada con la temperatura del sustrato o del aire (Lambrinos & Kleier, 2003;Iturra-Cid et al, 2014), y particularmente en el caso de las salamandras, las necesidades por mantener niveles hídricos adecuados las confina a ambientes húmedos con poca diversidad térmica (Feder, 1982), por lo que la termorregulación comportamental es poco común en la mayoría de ellas .…”

Thermal effects on the dynamics and motor control of ballistic prey capture in toads: maintaining high performance at low temperature

“…The elastic recoil mechanism expands the thermal breadth over which high performance prey capture can be accomplished. This in turn may allow toads to reduce thermoregulatory behavior and thus avoid associated costs in energy expenditure or water loss (Huey, 1974;Feder, 1982). Bufo has been shown in preference experiments to thermoregulate behaviorally near a temperature that maximizes sprinting performance when hydration is not an issue but to choose lower temperatures when water is limiting, revealing a potential conflict between performance and hydration (Lillywhite et al, 1973;Tracy et al, 1993).…”

Thermal acclimation of metabolism in salamanders: Fact or artefact?

“…More rapid thermal variation is probably not encountered by plethodontid salamanders because they spend most of their time beneath rocks or logs or in burrows, where diel or day-to-day variation in temperature is usually minimal (Feder, 1982b). Yet, opportunities for behavioural thermoregulation are limited in such microhabitats and salamanders undergo seasonal variation in BT (Feder, 1982b). Ac- Animals were acclimated at 4-5°C until the very first measurement at 17.5°C on Day 0.…”