Temperature and respiratory function in ectothermic vertebrates

Pulmonary ventilation is adjusted to maintain balance between O2 demands and CO2 elimination, which is essential for acid–base status in land ectothermic vertebrates. Rising temperatures cause increases in O2 consumption (Q10 effect) and decreases in the O2 affinity of hemoglobin (a rightward shift in the oxygen–hemoglobin dissociation curve). These changes in air-breathing ectotherms are not proportional, i.e., the increased ventilation is relatively smaller than the change in metabolic rate. Therefore, the ratio between ventilation and metabolic rate is reduced, and consequently blood pH changes inversely with temperature. The combination of high temperatures and hypoxia exposure results in an amplified increase of ventilation, which may be explained by the balance between increased O2-demand and decreased O2-supply as well as increased O2-chemoreceptors sensitivity. High temperature also increases pulmonary diffusing capacity. Global warming is expected to have significant impacts on the world’s climate, with temperature changes affecting living organisms, in relation to their physiology and distribution. These physiological mechanisms and their capacity to respond appropriately to temperature illustrate the complexity of the relationship between ambient temperature and the respiratory function in ectothermic vertebrates, which are particularly susceptible to change in their environment.

► Respiratory function is affected by temperature changes in amphibians, reptiles and lungfish.
► Blood gases, central chemoreception, hypoxic ventilatory responses and diffusing capacity are among the affected variables.
► Respiratory responses to temperature are essential for adapting in a new thermal condition.
► Climate changes may impact on vertebrates’ life.