Editorial: Effects of urbanization and climate change on the physiology of amphibians and reptiles

Amphibians and reptiles are two of the most ecologically sensitive vertebrate groups facing unprecedented challenges in the Anthropocene. Urbanization and climate change are rapidly reshaping habitats, causing temperatures to rise, intensifying heat extremes, and increasing spatial overlap among biodiversity hotspots (Huang et al., 2019; Urban et al., 2024). As herpetofauna are ectotherms, their thermoregulation, metabolism, and physiological processes are tightly coupled to external temperature and habitat quality (Hayden Bofill and Blom, 2024; Nowakowski et al., 2018). Urban environments also impose additional stressors like artificial light at night (ALAN) (Falcón et al., 2020), anthropogenic noise (Kern and Radford, 2016; Chan et al., 2010), and chemical contaminants (Saidon et al., 2024), which can disrupt communication, predator detection, and long-term health outcomes.

Despite growing interest in the impacts of anthropogenic stressors on wildlife, the global representation of herpetofauna in physiological research remains low compared to other vertebrate groups. This limits our ability to take species-specific actions and design effective conservation strategies. This editorial highlights how urbanization and climate change interact to influence the physiology and future of amphibians and reptiles, underscoring the urgency of science-driven responses (Figure 1). The four articles collected here span reptiles and amphibians across continents and life stages, which together provide an integrated dataset to tackle some of the research gaps. The findings can be categorized into two broad themes: (1) thermal physiology and behavioral responses and (2) stress physiology and contaminant exposure.

Theme 1: thermal physiology and behavioral responses

Amphibians and reptiles both experience microhabitat changes due to urban landscape shifts. In two of the research articles, we observe how such modifications alter the thermal and behavioral responses of species. Apte et al. investigated the thermal physiology of the Mysore day gecko (Cnemaspis mysoriensis) in the major metropolitan city of Bengaluru, India. They found that human-made microhabitats had slightly higher and more variable environmental temperatures than natural microhabitats, but the geckos did not exhibit significant shifts in their thermal physiology. Instead, they relied on behavioral thermoregulation to maintain body temperatures within their preferred range. This study highlights the importance of retaining natural microhabitats in urban landscapes as the temperature range of natural microhabitats closely matches the thermal range of these species.

Monroe et al. examined the physiological and behavioral responses of the urban exploiter Gulf Coast toad (Incilius nebulifer) to urbanization and climate variation. Interestingly, populations in the warmest and least urbanized sites exhibited the highest locomotor performance, suggesting that the energetic costs of living in urban areas might have a nuanced relationship with the thermal tolerance of the species. These two studies demonstrate that multiple stressors must be studied together to accurately predict population outcomes.

Theme 2: stress physiology and contaminant exposure

Monroe et al. (discussed above) also showed that the Gulf Coast toad populations in more urbanized sites showed elevated baseline and stress-induced corticosterone release rates, faster negative feedback recovery, and higher lipid storage. Climate, on the other hand, had a non-linear relationship with these traits, with populations at both thermal extremes showing reduced corticosterone and lipid levels. The rate of glucocorticoid recovery following stress increased with urbanization but decreased with temperature, consistent with the “on-again, off-again” hypothesis of glucocorticoid regulation—whereby efficient post-stress recovery enables organisms to mount repeated stress responses without chronic physiological costs.

Ujhegyi et al. explored the hormonal and behavioral responses of young common toads (Bufo bufo) to ALAN and noise pollution. This study is also a shift from population-level responses to measuring individual consistencies in phenotypic traits. They found that while corticosterone profiles changed during ontogeny, individual consistency in stress responses was low. Interestingly, foraging rates increased under both ALAN and noise pollution, but these behavioral changes were not correlated with stress hormone levels. This decoupling suggests that phenotypic plasticity, rather than individual variation in the stress axis, may enable B. bufo to tolerate urban stressors during early life.

While the studies above focus primarily on physiological regulation, Pradhan et al. examined a distinct but equally critical axis of anthropogenic threat, chemical contamination, through an investigation of heavy metal accumulation in olive ridley sea turtles (Lepidochelys olivacea) at two mass nesting rookeries in India. As long-lived, wide-ranging reptiles occupying higher trophic positions, sea turtles are particularly susceptible to bioaccumulation of heavy metals across multiple life stages. By measuring the concentrations of nine heavy metals in adults, in utero and oviposited eggs, hatchlings, and nesting beach sand, the authors showed that contaminants move across both maternal and environmental pathways. Heavy metals in in utero eggs provided direct evidence of maternal transfer, while correlations between sand and hatchling metal concentrations suggested environmental exposure. This multistage design highlights how industrial and agricultural pollution can affect sea turtles across life stages.

Synthesis and future directions

The articles in this Research Topic show that herpetofauna responses to urbanization and climatic change are rarely uniform. Species differ in their responses through physiological adjustment, behavioral flexibility, or a combination of both. The Mysore day gecko primarily relies on behavioral adjustments while maintaining relatively conserved physiology. In contrast, the Gulf Coast toad shows population-level variation in glucocorticoid dynamics, whereas the common toad displays flexible behavior that is largely independent of hormonal state. This diversity cautions against generalizations and reinforces the need for multispecies, multiparameter approaches. Multiple stressors frequently co-occur and interact with thermal changes, sensory pollution, and chemical contamination; however, they are mostly studied individually. Life-stage dependency of responses, illustrated both by ontogenetic shifts in corticosterone profiles in common toads and by maternal contaminant transfer in olive ridley sea turtles, highlights that vulnerability assessments must span the full life cycle.

Future research should prioritize the simultaneous measurement of multiple physiological traits across environmental gradients (see Figure 1). Geographically diverse datasets (tropical, subtropical, and temperate) on herpetofaunal communities are particularly needed, given that the majority of global amphibian and reptile diversity occurs in regions that are disproportionately underrepresented in physiological research. Ultimately, insights from this Research Topic will help guide conservation interventions that consider the complex and interacting pressures now facing herpetofauna.

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Footnotes

Edited and reviewed by: Lorin Anne Neuman-Lee, Arkansas State University, United States