Variations in the Potential Suitable Habitats of Different Populations of Hippuris vulgaris, a Species with Cross-Altitude Distribution

Understanding the variations in the potential suitable habitats of different populations of the same species is crucial for targeted biodiversity conservation and ecosystem management in specific regions. For widely distributed species, the impact of climate change on the suitable habitats of different populations may vary. However, research in this area is currently insufficient. Hippuris vulgaris is an aquatic species widely distributed across the Northern Hemisphere, with an altitudinal range from 0 to 5000 m, known for its high ecological and medicinal significance. In this study, we employed a MaxEnt model to simulate the current and future suitable habitats of H. vulgaris through constructing high-altitude, low-altitude, and integrated distribution models. The results indicated that bio3 (isothermality), bio1 (annual mean temperature), and bio19 (precipitation of coldest quarter) significantly influenced the distribution of high-altitude populations of H. vulgaris, whereas in low-altitude areas, bio3, bio9 (mean temperature of driest quarter), and bio13 (precipitation of wettest month) were the main influencing factors, and for integrated distribution populations, bio1, bio13, and bio19 were the main factors. The suitable habitat area for high-altitude populations of H. vulgaris will be increased by 19.66% in the 2050s but decrease by 47.75% in the 2070s. The suitable habitat area for low-altitude populations will be increased by 99.71% in the 2050s and by 13.29% in the 2070s. Our findings showed that the key bioclimatic variables and suitable values influencing the distribution of H. vulgaris populations in high- and low-altitude regions differed, and changes in the suitable habitats for high- and low-altitude populations showed completely opposite trends under climate change, with migration directions extending towards higher altitudes and higher latitudes, respectively.