Thermoregulatory behavior and high thermal preference buffer impact of climate change in a Namib Desert lizard

Abstract

Abstract. Knowledge of the thermal ecology of a species can improve model predictions for temperatureinduced population collapse, which in light of climate change is increasingly important for species with limited distributions. Here, we use a multi-faceted approach to quantify and integrate the thermal ecology, properties of the thermal habitat, and past and present distribution of the diurnal, xeric-adapted, and active-foraging Namibian lizard Pedioplanis husabensis (Sauria: Lacertidae) to model its local extinction risk under future climate change scenarios. We asked whether climatic conditions in various regions of its range are already so extreme that local extirpations of P. husabensis have already occurred, or whether this micro-endemic species is adapted to these extreme conditions and uses behavior to mitigate the environmental challenges. To address this, we collected thermoregulation and climate data at a micro-scale level and combined it with micro-and macroclimate data across the species' range to model extinction risk. We found that P. husabensis inhabits a thermally harsh environment, but also has high thermal preference. In cooler parts of its range, individuals are capable of leaving thermally favorable conditions-based on the species' thermal preference-unused during the day, probably to maintain low metabolic rates. Furthermore, during the summer, we observed that individuals regulate at body temperatures below the species' high thermal preference to avoid body temperatures approaching the critical thermal maximum. We find that populations of this species are currently persisting even at the hottest localities within the species' geographic distribution. We found no evidence of range shifts since the 1960s despite a documented increase in air temperatures. Nevertheless, P. husabensis only has a small safety margin between the upper limit of its thermal preference and the critical thermal maximum and might undergo range reductions in the near future under even the most moderate climate change scenarios.

A test of desert shrub facilitation via radiotelemetric monitoring of a diurnal lizard

“…Although facilitation as an ecological process does not necessarily include lifetime fitness as a component (Stachowicz, 2001, Bruno et al, 2003, Michalet et al, 2011, Michalet & Pugnaire, 2016, our inference that E. californica facilitates G. sila would take on additional relevance, particularly to the potential for community structuring and the promotion of resilience in lizard populations, if the effects of E. californica facilitation on G. sila individual fitness were quantified. In the case of diurnal lizards, the link between thermal habitat quality and individual fitness has been firmly established by both theory and empirical testing (Kirchhof et al, 2018, Ortega, Mencía, & Pérez-Mellado, 2016, Vickers et al, 2016, Pontes-da-Silva et al, 2018, Camacho et al, 2018, but we believe further study on the E. californica-G. sila relationship with respect to individual fitness is warranted.…”

Smaller climatic niche shifts in invasive than non-invasive alien ant species

“…Incorporating experimental data on changes in physiology, phenology or species interactions in response to environmental changes into more mechanistic models may capture a more realistic view of the climates that can be tolerated (e.g., refs. [48][49][50] ).…”

Climate change, thermal niches, extinction risk and maternal‐effect rescue of toad‐headed lizards, Phrynocephalus, in thermal extremes of the Arabian Peninsula to the Qinghai—Tibetan Plateau

“…We average h r over months of breeding (N breed ), which as determined by sensitivity analyses, was the best predictor of observed extinctions due to climate change in Mexican Sceloporus . Typically, T e models built from PVC would be used to compute h r on a daily basis given local T max at a nearby weather station Kirchhof et al 2017), defined by periods when the average among all T e models exceeds T p (e.g. T e > T p , for the data-logger sampling rate, typically 1-2 min).…”

“…In Fig. 4e, we compare the theoretical h r curve computed from 10 microclim scenarios used by Kirchhof et al (2017) using Equations (1)-(2) with empirical h r data from PVC models for a guild of Namibian lacertid lizards occupying habitats similar to Phrynocephalus. The fit is remarkable, given the geographic distances involved.…”

“…(e) Points are empirical T e data for PVC models for 3 species of Nambian lacertids during the breeding season deployed across their ranges (4 sites each), with a black line representing the h r = f(T max -T p ). The red line reflects the fitted "theoretical" h r curve for Phrynocephalus sites using microclim data in Equations (1) and (2) (with microclim scenarios restricted to microhabitats instrumented byKirchhof et al 2017).…”