Season-sex interaction induces changes in the ecophysiological traits of a lizard in a high altitude cold desert, Puna region

Habitat conservation enhances the resilience of the lizard Liolaemus cuyumhue to high summer temperatures

Habitat degradation from human activities affects essential microhabitats, threatening ecological processes like foraging, mating, locomotion, predator evasion, and competition among reptiles. We assessed how microhabitat selection and body temperature of the endangered lizard Liolaemus cuyumhue respond to differences in vegetation composition and thermal conditions between a disturbed site and an undisturbed site impacted by oil and gas activities in Argentina. During five expeditions between September 2022 and March 2023, we searched for L. cuyumhue and collected data on body temperature, substrate and air temperatures, body mass, snout-vent length, sex, and habitat characteristics. We also measured operative temperatures and assessed vegetation cover and microhabitat availability at each site. Our results showed significant differences in microhabitat characteristics and selection between sites. The undisturbed site had higher vegetation and lower operative temperatures, while the disturbed site had higher temperatures and lower vegetation, especially in summer. Lizards at the disturbed site showed higher body temperatures, suggesting stressful thermal conditions, and preferred microhabitats with lower bare ground cover. Capturing lizards in the disturbed site required more effort than in the undisturbed site. This study emphasizes the impact of habitat disturbance on the thermal environment and behavior of L. cuyumhue. Conservation efforts should prioritize maintaining and restoring vegetation to support the species' thermoregulation needs, especially under global warming.

Thermo-physiological changes and reproductive investment in a liolaemid lizard at the extreme of the slow-fast continuum

Gravid female lizards often experience reduced thermal preferences and impaired locomotor performance. These changes have been attributed to the physical burden of the clutch, but some authors have suggested that they may be due to physiological adjustments. We compared the thermal biology and locomotor performance of the lizard Liolaemus wiegmannii 1 week before and 1 week after oviposition. We found that gravid females had a thermal preference 1°C lower than that of non-gravid females. This was accompanied by a change in the thermal dependence of maximum running speed. The thermal optimum for locomotor performance was 2.6°C lower before oviposition than after. At relatively low temperatures (22 and 26°C), running speeds of females before oviposition were up to 31% higher than for females after oviposition. However, at temperatures above 26°C, females achieved similar maximum running speeds (∼1.5 m s-1) regardless of reproductive stage. The magnitude of the changes in thermal parameters and locomotor performance of L. wiegmannii females was independent of relative clutch mass (clutches weighed up to 89% of post-oviposition body mass). This suggests that the changes are not simply due to the clutch mass, but are also due to physiological adjustments. Liolaemus wiegmannii females simultaneously adjusted their own physiology in a short period in order to improve locomotor performance and allocated energy for embryonic development during late gravid stage. Our findings have implications for understanding the mechanisms underlying life histories of lizards on the fast extreme of the slow-fast continuum, where physiological exhaustion could play an important role.

The divergent effects of moderate climate warming on the gut microbiota and energetic state of cold-climate lizards from open and semi-closed microhabitats

Introduction

Understanding the physiological responses to warming temperatures is critical for evaluating the vulnerabilities of animals to climate warming. The physiological responses are increasingly affected by gut microbiota. However, the interactions between physiological responses and the gut microbiota of sympatric animals from various microhabitats in the face of climate change remain largely unknown.

Methods

To evaluate the effects of warming temperatures on animals from different microhabitats, we compared locomotor performance, metabolic rate, growth, survival, and gut microbiota of two sympatric ectothermic species (Eremias argus and Takydromus amurensis) from open and semi-closed microhabitats under present and moderate warming climate conditions, respectively.

Results and discussion

We found that locomotor performance and growth rates of snout-vent length (SVL) were enhanced in both lizard species by warming climate. Interestingly, warming temperatures enhanced resting metabolic rates (RMR) in the open-habitat lizard, E. argus, but depressed them in the semi-closed habitat lizard, T. amurensis. Reversely, the metabolism-related gut microbiota was not affected by warming in E. argus, whereas it was significantly enhanced by warming in T. amurensis, indicating a plausible compensatory effect of the gut microbiota on the metabolic regulation of T. amurensis. Furthermore, warming likely improved immunity in both lizard species by significantly reducing pathogenic bacteria while increasing probiotics. This study found that high-latitude sympatric lizards from both open and semi-closed habitats were beneficial to warming temperatures by physiological modification and regulation of the gut microbiota and highlighted the importance of integrating the physiology and gut microbiota in evaluating the vulnerability of animals to climate warming.