As the climate changes, the areas suitable for reptiles to inhabit also shift. However, protected areas cannot simply move along with them on the map. In 2025, researchers at the National Institute of Ecology used Species Distribution Models (SDM) to predict the potential habitats of 18 native reptile species and evaluated the extent of overlap between these habitats and protected areas using the Species Protection Index (SPI). The most intriguing aspect of this study is “actual habitat can shrink even if the protection rate appears favorable”—a paradox.
30-Second Summary
- By integrating nationwide survey data, 18 reptile species had their current and future potential habitats modeled.
- The average AUC of the model 0.965 was reported as follows.
- The current SPI, based on all species, 26.74 and excluding ecosystem-disrupting species, 28.16 was as follows.
- When applying Species Conservation Targets reflecting the Korean context, the values were calculated as follows. 36.62, 38.53 Calculated values.
- In both scenarios, the SPI tended to decrease in the mid-term and rise again in the long-term; however, this does not imply a recovery in the total amount of habitat.
- The Amur racer (*Oocatochus rufodorsatus*) was a prime example of a counterintuitive case where potential habitat shrank significantly, yet the proportion overlapping with protected areas increased.
Interesting Point 1: “Good areas” on the map shift over time
Species distribution models are not tools for predicting exactly where individuals will migrate in the future. Areas with a high probability of suitability are calculated using observational data alongside environmental variables such as temperature and precipitation. The research team compared current and future potential habitats under two climate scenarios—SSP2-4.5 and SSP5-8.5—and reported an average AUC of 0.965 across the models for the 18 species.
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Interesting Point 2: Habitat can shrink even as the SPI rises
The Amur grass lizard presents the most striking case. According to the study’s data, the potential habitat area was 26,281.18 km² in 2010. Projections indicate a reduction to 4,917.11 km² by 2090 under the SSP2-4.5 scenario and to 1,724.03 km² under the SSP5-8.5 scenario. However, the proportion of habitat overlapping with protected areas increased from the current 25.58% to 36.03% and 46.97%, respectively.
This does not mean that conservation efforts succeeded and expanded the habitat. Rather, it may simply be that the proportion of remaining potential habitat located within protected areas has increased; the ratio rises as the denominator shrinks. Consequently, relying solely on the SPI could lead to an overly optimistic interpretation of the situation.
Interesting Point 3: Even among “reptiles,” lifestyles vary drastically.
Although 18 species are combined into a single index, the spatial requirements of each species differ. Their lifestyles vary widely—from long, slender grass lizards and ground-dwelling racerunners that sprint across the terrain to geckos that scale walls and structures, and snakes that may have a much wider range of movement. This is why it is necessary to create models for individual species before aggregating them into an index.
Species that utilize open terrain and environments characterized by gravel and soil—such as the Mongolian racerunner—cannot be expected to respond to climate and land-use changes in the same way as arboreal species or those that inhabit urban structures.
Geckos utilize space in a different manner. Their habit of using vertical surfaces—such as walls or artificial structures—serves as a reminder that simple temperature maps are insufficient for interpreting “habitat suitability.”
Furthermore, the research is not limited to lizards. Since snakes differ in body size, range of movement, and position within the food web, the perspective on protected area boundaries and connectivity may also need to be adjusted.
How does SPI differ from protected area coverage?
Indicators measuring the percentage of national territory designated as protected areas simply show “how much” has been designated. SPI goes a step further by assessing how well a species’ potential habitat is represented within those protected areas Target 3 of the Kunming–Montreal Global Biodiversity Framework under the Convention on Biological Diversity sets a goal to effectively conserve and manage at least 30% of land, inland waters, and marine and coastal areas by 2030; the Species Protection Index (SPI) is used as a metric to assess species representation.
In this study, the current SPI was 26.74 when including all 18 species and 28.16 when excluding ecosystem-disturbing species. Recognizing that the lower limit of international species conservation targets can be highly sensitive for countries with small land areas—such as South Korea—the research team conducted a sensitivity analysis that reflects the domestic context. The resulting figures were 36.62 and 38.53, respectively.
For ecosystem-disturbing species, a ‘high SPI’ can actually serve as a warning sign.
The research team compared the SPI values of ecosystem-disrupting species and general species separately. While the SPI for disrupting species was currently lower, future scenarios showed the gap narrowing, and in the long term, the SPI for disrupting species tended to surpass that of general species. This implies that protected areas can also serve as suitable habitats for invasive species; thus, unlike with native species, a ‘high degree of overlap with protected areas’ can actually signify a management burden.
Limitations to keep in mind when reading this study
- Species distribution model results can vary depending on the choice of algorithms, thresholds, climate models, and SSPs.
- Potential habitat does not directly equate to actual population size or reproductive success.
- Land-use changes and habitat connectivity are not fully accounted for at all levels.
- An increase in SPI does not necessarily mean an increase in total habitat area or a reduction in extinction risk.
- Policy priorities may shift depending on how importance or extinction risk is weighted for each species.
So, what needs to change?
Simply expanding protected areas to cover 30% of the land is insufficient. Factors such as elevational gradients, forest connectivity corridors, riparian corridors, and micro-refugia—which support species persistence under changing climates—must also be considered. This study provides a rationale for simultaneously examining the area Family and location of protected areas.
Is this relevant to animal keepers?
This study focuses on wild distribution and conservation policies. The temperature and precipitation variables or future projections discussed in the paper should not be directly applied to setting temperature and humidity levels for captive reptiles. For keepers, it is more appropriate to view this as natural history data that illustrates the diversity in how different species—even within the broad group of reptiles—utilize climate and spatial resources.
Related reading
- Reptile Wiki
- What Are Reptiles? — A Comprehensive Overview of Characteristics, Evolution, Classification, and Ecology
- Reptile glossary
- Reptile Species Comparison
References and Image Sources
- Shin M-S, Kim B-R, Kang S-R. 2025. Assessing a Reptile Species Protection Index for the Republic of Korea under Climate Change. Proceedings of the National Institute of Ecology of the Republic of Korea 6(S): S35–S52. DOI: 10.22920/PNIE.2025.6.Special.S35.
- Convention on Biological Diversity. Kunming–Montreal Global Biodiversity Framework Target 3. Verified: 2026-08-23.
- National Institute of Biological Resources (NIBR). Amur Grass Lizard Takydromus amurensis Red Data Book Species Information. Verified: 2026-08-23.
- Takydromus amurensis — Kim, Hyun-tae, CC BY 4.0.
- Distribution Map of *Takydromus amurensis* — Arczi325, CC BY-SA 4.0.
- Takydromus wolteri — A. C. Tatarinov, CC BY-SA 3.0.
- Eremias argus — Haplochromis, CC BY-SA 4.0.
- Gekko japonicus — おむこさん志望, CC BY 2.5.
- Elaphe dione — Vladimir Yu. Arkhipov, CC BY-SA 3.0.
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