| Artificial light is growing at an unprecedented rate with the development of urbanization,posing a threat to biodiversity.Bats are typically nocturnal animals,playing a key role in pollination,seed dispersal,pest control,and nutrient redistribution.Despite the less developed vision,most bats can perceive the wavelength of artificial light.They are prone to suffer from the disturbance from artificial light during nightly commuting and foraging,making them an ideal taxon for the study of light pollution.Previous researches have verified the adverse impacts of artificial light on bat behavior and physiology at individual and population levels.However,it remains unclear whether artificial light acts as a negative determinant of species diversity in bats.Here,we used 359 bat species belonging to 17 families to disentangle the following three questions:(1)What is the degree of light pollution around bat roost?(2)Does artificial light at night predict bat species diversity on a global scale?(3)Does artificial light at night pose a threat to bat species diversity at community level?For the first time,we assessed the level of light pollution around 2,426 underground roosts for 359 bat species in 17 families at a global scale based on field surveys and literature searches.These families contained Craseonycteridae,Natalidae,Emballonuridae,Furipteridae,Hipposideridae,Megadermatidae,Miniopteridae,Molossidae,Mormoopidae,Noctilionidae,Nycteridae,Phyllostomidae,Pteropodidae,Rhinolophidae,Rhinonycteridae,Rhinopomatidae,and Vespertilionidae.Spatial raster analysis revealed that the average artificial light level at night within 20 km of bat roosts gradually increased between 2012 and 2021.The average nighttime artificial light intensity around bat roosts reached 0.93 ± 0.035 n W/cm2/sr,which was significantly higher than the average value across the globe.The intensity of nighttime artificial light around bat roosts depended on roost type,and showed marked spatial variation in different countries.Using the dataset comprising species richness,phylogenetic diversity,nighttime artificial light level,roost type,roost latitude,roost continent,and sampling seasons for 2426 subterranean roosts,we tested the relationship between artificial light level and bat species diversity at a global level.Kruskal-Wallis test and associated post-hoc multiple comparisons indicated that both species richness and phylogenetic diversity of bats showed a remarkable variation among roost types.Natural caves harbored the highest species richness and phylogenetic diversity compared with other underground habitats.The linear mixed model revealed that bat species richness and phylogenetic diversity scaled negatively with the intensity of artificial light at night.We explored the effects of artificial light on species compositions of bat community at Touming cave from Shandong Province.This cave was inhabited by seven bat species,namely Myotis pequinius,Myotis pilosus,Myotis fimbriatus,Hypsugo alaschanicus,Tadarida insignis,Rhinolophus pusillus,and Rhinolophus ferrumequinum.We manipulated dark control and white light outside bat roost.We monitored the number of echolocation vocalizations for each species using ultrasonic recording system before,during,and after the light exposure.We found a consistent tendency of change in the number of echolocation pulses for seven bat species.The number of echolocation vocalizations per species was the highest before the presence of white light but was the lowest during white light exposure.The number of echolocation vocalizations per species exhibited a gradual increase after recovery from dark condition.In summary,these results demonstrate that the level of nighttime artificial light around bat roosts show an increasing tendency in the recent ten years,suggesting the urgency to strengthen the control of light pollution around bat habitats.Our findings indicate that artificial light level at night is a negative predictor of species richness and phylogenetic diversity among bats at the global level.Manipulation of artificial light outside bat roost also induces a shift in species compositions within a bat community.Our findings provide strong evidence that artificial light at night poses a threat to bat species diversity at both global and local levels.This study fills the current gap of light pollution research,and offers scientific basis for bat conservation and construction of ecological civilization under the scenario of global light pollution. |
