Ectothermic animals, including reptiles, amphibians, and most invertebrates, cannot generate enough metabolic heat to regulate their internal temperature. Instead, they depend on external heat sources to reach the body temperatures needed to sustain their physiological and ecological processes. Species fall along a continuum between two extremes: thermoconformers, whose body temperature closely tracks their immediate surroundings, and thermoregulators, which actively maintain body temperature within a narrower preferred range by exploiting spatial and temporal thermal variation through behavior. Distinguishing between these strategies is fundamental to understanding a species’ thermal ecology and its potential vulnerability to climate change.

Lizards draw on several distinct physical pathways to gather heat. Solar radiation in the ultraviolet, visible, and shortwave-infrared spectra is generally the primary heat source for diurnal lizards, transferred by radiation. Substrate temperature, the temperature of the soil, rock, sand, or leaf litter in direct contact with the animal, transfers heat by conduction. Air temperature influences body temperature mainly through convective exchange. Lizards that raise body temperature primarily by basking in sunlight are classified as heliotherms, whereas those relying mainly on conductive exchange with warm substrates are thigmotherms. Many species combine both strategies, and wind can further modify heat balance by enhancing convective heat loss when body temperature exceeds air temperature.

Because these heat sources vary at very fine spatial scales, macroclimatic data such as weather-station air temperatures or gridded climate surfaces are often poor proxies for the temperatures ectotherms actually experience. Vegetation cover, rock crevices, orientation, slope, and substrate type create fine-scale thermal mosaics that provide opportunities for behavioral thermoregulation. By selecting favorable microhabitats, lizards can maintain body temperature near their preferred range even when macroclimatic conditions would predict otherwise, a phenomenon known as the Bogert effect, in which behavioral buffering of the thermal environment may slow the pace of physiological evolution and mask a species’ climatic vulnerability.

The Anatolian rock lizard is a small diurnal lacertid endemic to western Anatolia, distributed from north of the Büyük Menderes River to Bursa and extending eastward into Central Anatolia at elevations up to roughly 1,600 meters. The species typically inhabits rocky areas with dense vegetation and proximity to moisture, and is frequently found under stones at ambient temperatures of 25 to 30 degrees Celsius. Previous work reported a preferred body temperature of approximately 34.5 degrees Celsius in adults, but data on how individuals in natural populations integrate solar radiation, substrate temperature, air temperature, and wind at the microhabitat scale remained scarce. Bioclimatic modeling predicts a northward contraction of suitable habitat for the genus under future climate scenarios, making the question urgent.

To address this gap, researchers conducted field surveys on Mount Spil between April and October 2025, capturing 125 lizards and measuring cloacal body temperature within ten seconds of capture using a fast-response thermocouple, alongside simultaneous measurements of surface temperature, air temperature one centimeter above the ground, solar radiation with a pyranometer, and wind speed at the lizard’s own height. Of these, 89 individuals had complete records and were retained for statistical analysis. Sex was determined in the field, and adults were distinguished from juveniles by snout-vent length.

The results were striking. Mean field body temperature was 32.32 plus or minus 4.53 degrees Celsius, significantly higher than both mean surface temperature of 30.6 degrees and mean air temperature of 28.1 degrees, confirming that the population behaves as an active thermoregulator rather than a passive thermoconformer. Multiple regression analysis showed that surface temperature and solar radiation were the strongest positive predictors of body temperature, with air temperature also significant, while wind speed was not significant at the conventional threshold. The full model explained 67.4 percent of the variance in body temperature, and a reduced model containing only surface temperature and solar radiation still accounted for 60.2 percent of the variance, underscoring how tightly body temperature is coupled to the radiative-thermal environment.

Principal component analysis added a compelling layer to the story. Two components jointly explained approximately 76 percent of the total variance. The first axis represented a combined thermal-radiative gradient with high loadings from body temperature, surface temperature, solar radiation, and air temperature. The second axis was dominated almost entirely by wind speed, contributing 91.96 percent to that component, and was essentially orthogonal to the first. This statistical decoupling suggests that the lizards buffer convective cooling through strategic microhabitat selection, such as using rock crevices and the base of vegetation, effectively neutralizing wind as a determinant of their thermal balance while managing heat gain primarily through solar radiation and substrate temperature.

The study also uncovered a surprising sex difference. Despite the absence of detectable differences in body size between adult males and females, females maintained significantly higher field body temperatures than males, 33.59 versus 31.44 degrees Celsius, with a moderate effect size. Neither snout-vent length nor body mass predicted field body temperature in adults, making a thermal inertia explanation unlikely. The researchers suggest that sex-specific differences in thermoregulatory behavior or microhabitat use, possibly linked to the elevated thermoregulatory demands of vitellogenesis and gestation, warrant further investigation.

The broader implications are clear. The Mount Spil population combines heliothermy with a component of thigmothermy, with solar radiation acting as the ultimate heat source, and relies on microhabitat-scale thermal heterogeneity to stabilize its thermal safety margins. As climate change reshapes thermal landscapes, the authors argue that conservation assessments should prioritize the continuity of thermal refugia and fine-scale habitat heterogeneity over macroclimatic averages. For a species whose suitable habitat is projected to contract northward, the sheltered crevice or sun-warmed rock may matter far more than any regional temperature forecast, and future work quantifying preferred and operative temperatures will be essential to refine projections of its fate under a changing climate.

Subject of Research: Thermal ecology and microhabitat thermoregulation of the Anatolian rock lizard

Article Title: Microhabitat-scale thermal determinants of body temperature in Anatololacerta anatolica from Mount Spil, Western Anatolia

Article References: Microhabitat-scale thermal determinants of body temperature in Anatololacerta anatolica from Mount Spil, Western Anatolia. (n.d.). https://doi.org/10.3897/herpetozoa.39.e188838

Image Credits: AI Generated

DOI: 10.3897/herpetozoa.39.e188838

Keywords: thermoregulation, Anatololacerta anatolica, ectotherms, microhabitat, solar radiation, Bogert effect, heliothermy, thigmothermy, climate change, lizard ecology, Mount Spil, thermal refugia

The scale of the effort was itself remarkable. India’s reefs are dispersed across vastly different oceanographic settings: the coral atolls of Lakshadweep in the Arabian Sea, the fringing and patch reefs of the Gulf of Mannar, Palk Bay and Goa on the mainland, and the islands of the Maldives-adjacent Andaman archipelago in the Bay of Bengal, including the Mahatma Gandhi Marine National Park (MGMNP). Data on mass bleaching impacts across South Asia have historically been sparse, leaving the region largely invisible in global assessments. By mobilizing a network of scientists, dive operators and trained citizen observers, the research team assembled standardized observations of bleaching and mortality across most of the subcontinent’s major reef areas during a single, globally significant thermal anomaly. The result is a rare, region-wide snapshot of how a mass bleaching event unfolds across an entire nation’s reef estate.

The study’s central metric was degree heating weeks, or DHW, the standard satellite-derived measure of accumulated heat stress that underpins global bleaching forecasting systems such as NOAA’s Coral Reef Watch. As expected, bleaching intensity generally increased with accumulated heat stress. But the strength of that relationship varied dramatically from region to region, exposing the limits of DHW as a universal predictor of reef damage. Two reefs exposed to similar thermal loads could emerge with profoundly different outcomes, a finding that echoes a growing body of evidence that global forecast models need regional and temporal calibration if they are to serve as reliable early-warning tools for reef managers.

Nowhere was this regional variability starker than in the contrast between Lakshadweep and the Mahatma Gandhi Marine National Park. Lakshadweep emerged as the hardest-hit region in the country, with up to 37 percent of coral cover bleached or dead even at intermediate levels of heat stress. The oceanic atolls, which sit in the open Arabian Sea with little local protection from sustained warming, appear to have offered their corals no thermal escape. In sharp contrast, MGMNP in the Andaman Islands recorded only 11.5 percent bleaching or mortality, despite experiencing significant heat stress. The authors attribute this striking difference to regional oceanographic processes capable of creating mesoscale thermal refugia, localized zones where currents, internal waves or other physical mechanisms buffer reefs from the worst of the heat. Previous work in the Andaman Sea has shown that large-amplitude internal waves can deliver pulses of cooler water to reef surfaces during thermal stress, and the new findings lend further weight to the idea that such hidden refugia may be decisive in determining which reefs survive the coming decades.

The taxonomic story proved equally compelling. Across all regions, the branching and plating genera Acropora, Pocillopora, Galaxea and Montipora emerged as the most affected, consistent with the canonical hierarchy of bleaching susceptibility established in reefs worldwide. These fast-growing, structurally complex corals are the architectural engineers of Indo-Pacific reefs, and their disproportionate losses carry cascading consequences for fish habitat, carbonate production and reef growth. At the other end of the spectrum, the massive and encrusting genera Pavona, Platygyra, Goniastrea and Favites were among the least affected, their thick tissues and stress-tolerant symbionts once again proving their worth under thermal duress. For reef managers, this hierarchy has long served as a rough rule of thumb for anticipating post-bleaching community composition.

But Palk Bay broke the rule in spectacular fashion. In this shallow, turbid bay on India’s southeastern coast, the study documented a near-complete reversal of canonical genus-level susceptibilities. The ordinarily vulnerable Acropora colonies showed only modest bleaching or mortality, at 13.6 percent, while the ordinarily resistant Porites colonies suffered a staggering 61.8 percent mortality. Such a reversal is rare and scientifically provocative. It suggests that local conditions in Palk Bay, possibly including prior exposure to recurrent heat stress, the presence of thermally tolerant Symbiodiniaceae symbionts such as Durusdinium, or the moderating effects of turbidity, have reshaped the thermal tolerances of its coral communities in ways that global generalizations cannot capture. It also serves as a cautionary tale: resistance traits are context-specific, and a genus that survives in one reef region may collapse in another.

The mechanistic implications reach deep into coral biology. Bleaching occurs when heat-stressed corals expel or lose the photosynthetic symbiotic algae living in their tissues, starving the coral animal of its primary energy source. Whether a coral bleaches, recovers or dies depends on an interplay of factors: the symbiont types it hosts, its history of thermal exposure, the energy reserves it carries into the event, and the physical environment surrounding it. High-frequency temperature variability, for instance, is known to reduce bleaching risk by priming coral physiological responses, while chronic local stressors can erode resilience. The Indian study’s regional contrasts, Lakshadweep’s open-ocean exposure versus MGMNP’s wave-buffered refugia, Palk Bay’s turbid, heat-conditioned waters versus the clearer reefs of the Gulf of Mannar, provide a natural experiment in how these mechanisms play out at landscape scale.

The findings arrive at a sobering moment. The fourth global bleaching event has confirmed what many reef scientists feared: that warming-driven bleaching is no longer episodic but is ushering in an era of near-annual thermal stress, with global warming tripling the persistence of marine heatwaves and intensifying them by roughly a degree Celsius. For India, the stakes are concrete. Lakshadweep’s atolls support island communities whose shorelines depend on reef-derived sediment, and studies have warned that most atolls may become increasingly uninhabitable by mid-century as sea-level rise exacerbates wave-driven flooding. The loss of up to 37 percent of coral cover in a single event, at only intermediate heat stress, signals that these reefs may have less thermal headroom than their Maldivian and Chagos neighbors, and that recovery between now and the next event is far from guaranteed.

Yet the study is not simply a eulogy. The survival of MGMNP’s reefs, the unexpected toughness of Palk Bay’s Acropora, and the resilience of massive genera across the country collectively point to genuine, mappable refugia and resistance hotspots that could anchor conservation planning. The authors argue that local oceanography and context-specific resistance patterns must be integrated into national and global assessments of bleaching impacts, rather than relying on heat-stress metrics alone. Protecting the oceanographic processes that cool reefs, identifying and safeguarding thermal refugia, and monitoring the survivors of this event as seed populations for recovery are strategies that emerge directly from the data. The study’s underlying dataset has been made openly available through Zenodo, an act of transparency that should accelerate comparative analyses across the wider Indo-Pacific.

As the ocean continues to warm, the fate of India’s reefs will depend on how quickly science can move from global averages to local realities. This nationwide collaboration has shown that the answers lie not in a single number on a satellite map, but in the interplay of currents, waves, symbionts and history that makes every reef region unique. In the ruins of Palk Bay’s Porites and the survivors of the Andaman Sea, Indian reef science has found both a warning and a roadmap.

Subject of Research: Regional and genus-specific coral bleaching responses across India's reef regions during the fourth global coral bleaching event

Article Title: Regional and genus-specific factors underpin bleaching variation across India’s corals reefs during the fourth global coral bleaching event

Article References: Pinto, W., Deshpande, K., Lobo, A. S., Jamalabad, A., Hussain, A., Paul, A., Dutta, A., Arjunwadkar, C., Patel, F. D., Thareja, H., Nangia, I., Josh, J., Goenka, K., Manikandan, B., Namboothri, N., Kuwalekar, P., Nambiar, S., Jaishankar, S., Mahesh, S., … Arthur, R. (2026). Regional and genus-specific factors underpin bleaching variation across India’s corals reefs during the fourth global coral bleaching event. Coral Reefs. https://doi.org/10.1007/s00338-026-02919-7

Image Credits: AI Generated

DOI: 10.1007/s00338-026-02919-7

Keywords: coral bleaching, fourth global bleaching event, degree heating weeks, Lakshadweep, Andaman Islands, thermal refugia, Acropora, Porites, Palk Bay, thermal stress, Indian Ocean reefs, bleaching susceptibility