Impact of temperature on bite force and bite endurance in the Leopard Iguana (Diplolaemus leopardinus) in the Andes Mountains

Abstract

In ectotherms, temperature exerts a strong influence on the performance of physiological and ecological traits. One approach to understand the impact of rising temperatures on animals and their ability to cope with climate change is to quantify variation in thermal-sensitive traits. Here, we examined the thermal biology, the temperature dependence and the thermal plasticity of bite force (endurance and magnitude) in Diplolaemus leopardinus, an aggressive and territorial lizard, endemic to Mendoza province, Argentina. Our results indicated that this lizard behaves like a moderate thermoregulator which uses the rocks of its environment as the main heat source. Bite endurance was not influenced by head morphometry and body temperature, whereas bite force was influenced by head length and jaw length, and exhibited thermal dependence. Before thermal acclimation treatments, the maximum bite force for D. leopardinus occured at the lowest body temperature and fell sharply with increasing body temperature. After acclimation treatments, lizards acclimated at higher temperatures exhibited greater bite force. Bite force showed phenotypic plasticity, which reveals that leopard iguanas are able to maintain (and even improve) their bite force under a rising-temperature scenario.

Could plasticity mediate highlands lizards’ resilience to climate change? A case study of the leopard iguana (Diplolaemus leopardinus) in Central Andes of Argentina

“…In this highly seasonal landscape, the leopard iguana shows a mean T b of 26.69±1.18°C and a mean T p of 30.85±0.26°C. Also, the mean operative temperature during the same period was 19.42 ±0.49°C (Vicenzi et al, 2020).…”

“…The leopard iguana Diplolaemus leopardinus (Werner 1898) (Leiosauridae), a rock-dwelling, sit-and-wait and oviparous lizard, inhabits the cold-arid Central Andes of Argentina. In these harsh environments, the leopard iguana behaves like a moderate thermoregulator, reaching T b in the field near its T p (Vicenzi et al, 2020). Individuals living in such seasonal and daily fluctuating environments require broader tolerance ranges and behavioral and physiological acclimation abilities to buffer that variation (Janzen, 1967;Bacigalupe et al, 2018;Kreiman et al, 2019).…”

Oviductal fluid counterbalances the negative effect of high temperature on sperm in an ectotherm model

“…Increase of global surface temperatures, frequent heatwaves and extreme temperature events have been predicted by the Intergovernmental Panel on Climate Change (IPCC) for the end of the century (Allen et al, 2018;Stocker et al, 2013). Global warming is affecting biodiversity, however, there is insufficient data concerning physiological and performance impacts to extreme temperatures in natural populations (Cooper et al, 2020;Vicenzi et al, 2020). Specifically, the extent to which animal reproductive traits respond to the predicted temperature increments, remains largely unexplored (Bestion et al, 2015;Dunn and Winkler, 2010;Isaac, 2009;Kingsolver et al, 2013); and reproductive sensitivity to temperature variations is better known in endotherms (Hurley et al, 2018).…”

Domestication effects on aggressiveness: Comparison of biting motivation and bite force between wild and domesticated finches

“…Furthermore, bite performance (bite force) is a useful trait related to an individual’s fitness for survival in the wild, such as for food acquisition, defence against predators, and aggressive interactions (Anderson et al, 2008; Vicenzi et al, 2020). Bite force is correlated to body size and beak depth in finches (Van der Meij and Bout, 2004; Herrel et al, 2005).…”

“…However, investment in such traits is often costly as the expression of such traits requires energy and reduces self-maintenance and the production and care of offspring (Cain and Ketterson, 2013). Furthermore, bite performance (bite force) is a useful trait related to an individual's fitness for survival in the wild, such as for food acquisition, defence against predators, and aggressive interactions (Anderson et al, 2008;Vicenzi et al, 2020). Bite force is correlated to body size and beak depth in finches (Van der Meij and Bout, 2004;Herrel et al, 2005).…”