Effects of temperature and meal size on the postprandial metabolic response of Leptodactylus latrans (Anura, Leptodactylidae)

Abstract

The postprandial increment of metabolism, often referred to as specific dynamic action (SDA), encompasses the summed costs of meal ingestion, digestion, absorption, and assimilation. Different SDA parameters, such as its magnitude, duration, and relative cost, are affected by a diverse set of environmental and physiological determinants, including meal size and body temperature. While the influence of these variables has been thoroughly examined in most ectothermic vertebrate groups, few studies have focused on the determinants and consequences of the SDA response in anuran amphibians. Thus, we examined the effects of meal size and body temperature on the SDA response of a Neotropical frog, Leptodactylus latrans, by measuring the rates of oxygen consumption of frogs while fasting and after being fed meals of different sizes at different temperatures. SDA lasted from 3 to 5 days and increased with meal size for frogs fed meals equivalent to 5-15% of their body mass. SDA cost was not affected by meal size and averaged 14.6% of the caloric content of the meal. Temperature increment was accompanied by proportional increases in metabolic rateand shorter SDA duration. The relative SDA cost averaged 14.8% of the meal caloric content at 20°C and 25°C, but increased to 23.5% at 30°C. Our results indicate that meal size imposes no physiological or energetic constraint to L. latrans feeding.Digestion at temperatures near the thermal preference of the species seems to optimize energetic return, whereas the shortening of SDA duration at higher temperatures may provide significant ecological advantages. K E Y W O R D Sanurans, digestion, energetics, meal size, postprandial metabolic increment, temperature

Metabolic responses to starvation and feeding contribute to the invasiveness of an emerging pest insect

“…Neotropical frog (Timpone et al, 2019)). Despite the higher cost of digestion (SDA) at 30°C, C. newmannii larvae also showed a higher aerobic scope (AS) at 30°C.…”

Panorama general de las adaptaciones metabólicas en el Orden Anura

“…A pesar de las adaptaciones desarrolladas para tolerar los cambios en la temperatura, se describió que diferentes especies tienen una selectividad térmica para potenciar el retorno energético, mientras que al realizar los procesos de ingestión del alimento, digestión, absorción y asimilación por encima de estas preferencias el proceso ocurre más rápido, pero con un menor rendimiento energético, como se estudió en Leptodactylus latrans (Timpone, Gavira & Andrade, 2019)…”

Effect of meal size on the postprandial metabolic response in Chinese giant salamander (Andrias davidianus) larva

“…Previous studies on SDA in amphibians have found that meal size has a significant effect on SDA (Secor & Faulkner 2002, Secor & Boehm 2006, Secor et al 2007, Timpone et al 2020. Ingesting prey of different sizes requires adjustments to the physiological processes underlying meal digestion, such as gut evacuation, and has important ecological and energetic implications (Secor & Faulkner 2002, França et al 2004, Timpone et al 2020. The SDA duration and en ergy expended on SDA in amphibians, like other ecto thermic animals, usually increase with increasing meal size (Secor & Boehm 2006, Secor et al 2007).…”

“…Intraspecific variations in SDA responses are at tri buted to differences in meal characteristics and envi-ronmental conditions (Secor et al 2007). Previous studies on SDA in amphibians have found that meal size has a significant effect on SDA (Secor & Faulkner 2002, Secor & Boehm 2006, Secor et al 2007, Timpone et al 2020. Ingesting prey of different sizes requires adjustments to the physiological processes underlying meal digestion, such as gut evacuation, and has important ecological and energetic implications (Secor & Faulkner 2002, França et al 2004, Timpone et al 2020.…”

“…The SDA duration and en ergy expended on SDA in amphibians, like other ecto thermic animals, usually increase with increasing meal size (Secor & Boehm 2006, Secor et al 2007). The peak MO 2 (MO 2peak ) may increase linearly with meal size (Secor & Faulkner 2002, Timpone et al 2020 or level off at higher meal sizes for some amphibians, such as the tiger salamander Amby stoma tigrinum tigrinum (Secor & Boehm 2006). Some studies have found that the SDA coefficient (SDA as a percentage of the ingested energy of a meal) did not change (Secor & Boehm 2006, Secor et al 2007, Timpone et al 2020 or increased with in creasing meal size (Secor & Faulkner 2002, Secor et al 2007.…”