Water availability and environmental temperature correlate with geographic variation in water balance in common lizards

Abstract

Water conservation strategies are well documented in species living in water-limited environments, but physiological adaptations to water availability in temperate climate environments are still relatively overlooked. Yet, temperate species are facing more frequent and intense droughts as a result of climate change. Here, we examined variation in field hydration state (plasma osmolality) and standardized evaporative water loss rate (SEWL) of adult male and pregnant female common lizards (Zootoca vivipara) from 13 natural populations with contrasting air temperature, air humidity, and access to water. We found different patterns of geographic variation between sexes. Overall, males were more dehydrated (i.e. higher osmolality) than pregnant females, which likely comes from differences in field behaviour and water intake since the rate of SEWL was similar between sexes. Plasma osmolality and SEWL rate were positively correlated with environmental temperature in males, while plasma osmolality in pregnant females did not correlate with environmental conditions, reproductive stage or reproductive effort. The SEWL rate was significantly lower in populations without access to free standing water, suggesting that lizards can adapt or adjust physiology to cope with habitat dryness. Environmental humidity did not explain variation in water balance. We suggest that geographic variation in water balance physiology and behaviour should be taken account to better understand species range limits and sensitivity to climate change.

Water restriction induces behavioral fight but impairs thermoregulation in a dry‐skinned ectotherm

“…Interestingly, behavioral adjustments were not efficient enough to counter physiological dehydration since lizards in this study suffered from a slight increase in plasma osmolality and decrease in body mass change as in earlier laboratory experiments (Dupoué et al 2018). The range of measured changes in plasma osmolality in this study indicates a mild physiological dehydration (Dupoué et al 2018), and plasma osmolality levels of water-restricted individuals were high compared to baseline levels recorded in a range of natural populations with contrasted access to water (Dupoué et al 2017). In addition, we found gradual changes in behavioral responses of lizards in this experiment, which suggests that they are mostly driven by changes in water balance instead of a direct response to water availability per se.…”

“…In this study, we used a laboratory experiment to quantify the behavioral responses to a chronic water restriction and acute heat stress in the European common lizard Zootoca vivipara . This cold‐adapted species inhabits mesic environment and is tightly dependent on humid conditions in the wild (Lorenzon et al , Massot et al , Dupoué et al ). In previous studies, we have shown that common lizards exposed to dry soil conditions invest more in exploration behaviors (Rozen‐Rechels et al ), and juvenile lizards living in dry habitats disperse more from their natal home range (Massot et al ), whereas sub‐adults reduce their locomotor activity during a chronic water restriction (Lorenzon et al ).…”

Water availability and temperature induce changes in oxidative status during pregnancy in a viviparous lizard

“…We first investigated how oxidative status relates to reproduction and environmental conditions in natural populations using a ‘cross‐sectional study’. We compared variation in oxidative status among pregnant females and adult males from 12 natural populations distributed across a gradient of air temperature and water availability (permanent in humid peat bogs vs. periodic in dry meadows, Dupoué, Rutschmann, Le Galliard, Miles, et al, ; Dupoué, Rutschmann, et al, ). We subsequently examined the effects of water restriction on oxidative status in pregnant females and adult males, and reproductive effort in females using an ‘experimental study’.…”

“…We induced a two‐week period of water restriction during pregnancy, a protocol known to trigger hydric costs of reproduction and mother–offspring conflict for water (Dupoué, Le Galliard, et al, ). An important aspect of the studied populations is that all adult females engage in reproduction so that we cannot quantify the cost of pregnancy (Dupoué, Rutschmann, Le Galliard, Miles, et al, ). That is, reproductive female Z. vivipara commit energy to a litter prior to fertilization.…”

Reduction in baseline corticosterone secretion correlates with climate warming and drying across wild lizard populations

“…In this study, we examined the variation in baseline plasma corticosterone (the primary GCs in birds and reptiles) across 14 populations of the European common lizard (Zootoca vivipara) distributed across an altitudinal gradient. Our study populations occupy habitats that differ in thermal microclimates and access to free-standing water (Dupoué, Rutschmann, Le Galliard, Miles, et al, 2017;Rutschmann et al, 2016), and are distributed along an extinction risk gradient including rapidly declining populations at the lowest altitudes and steady populations at mountaintops (Chamaillé-Jammes, Massot, Aragon, & Clobert, 2006;Sinervo et al, 2010). So far, population extinction has been directly related to warmer conditions in lowland populations although the proximate mechanisms remain unknown (Bestion, Teyssier, Richard, Clobert, & Cote, 2015).…”