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IntroductionApis laboriosa, the Himalayan giant honeybee, inhabits the foothills of Himalaya and neighboring mountainous regions. Here we revise its distribution in light of recent reports and discoveries, review the ecozones it inhabits, and reassess its likely distribution through species distribution modeling.MethodsWe revised the range map for A. laboriosa by mapping locality records from various sources: refereed research publications, museum specimens, records with identifiable images of bees in publicly available databases, personal observations of the authors, and photos/videos and their coordinates submitted to the authors by honey-hunters, beekeepers, and extension workers. We then used that map to determine the ecozones in which the species occurs. The geographical coordinates of the data localities were used to estimate the potential suitable areas for the bee with MaxEnt modeling.ResultsOur research filled in several previously identified gaps in the distribution of A. laboriosa: in western Nepal; mountainous regions of Myanmar, northwestern Thailand, and northern Laos; several river valleys in Xizang and Yunnan, China; and northeastern Pakistan. Over most of its range this bee species primarily occupies subtropical broadleaf forests with strong Himalayan affinities. However, in the western part of its range it extends into zones dominated by conifers. The sites where A. laboriosa has been recorded closely match the predicted range of the species. Two variables, mean temperature of the coldest quarter and temperature seasonality, contributed most (76%) to the species distribution model.DiscussionApis laboriosa has a more extensive distribution in the foothills of the Himalaya and neighboring mountainous regions than has been previously recognized. The range now extends from longitude 74.4°–105.9°E, a linear distance of 3300 km, and from latitude 19.2°N–34.8°N. We have documented nesting on tree branches in northern Vietnam. Future research is warranted on its elevational migrations along river valleys, population differentiation, and ecological role as a pollinator in the different ecological zones it inhabits.

Pollinators play an important role in ecosystems, but global climate change threatens the diversity and geographical distribution of pollinators. Bees are some of the most important pollinators and are particularly sensitive to climate change and environmental change. Apis laboriosa and Apis dorsata are two species of giant honeybees distributed in Asia, and play important roles in their ecosystems. In this study, we analyzed the key factors affecting the distribution of two species, as well as their potential suitable areas and possible co-existence regional changes under the global climate change. We collected and filtered global distribution data of A. laboriosa and A. dorsata, then used eight climatic variables and Community Climate System Model version 4 (CCSM4) to simulate their potential suitable areas for the past, present and future (using two different climate scenarios) using MaxEnt. Finally, we used ArcGIS 10.2 and ENMTools to calculate range overlap and niche overlap of the two species in order to infer areas of co-existence. Temperature-related variables had the largest contribution to the model simulation. Among these variables, temperature seasonality (Bio 4) and mean temperature of coldest quarter (Bio 11) showed the strongest influence on the distributions of two giant honeybees. Under the current climate scenario, the species overlap in Nepal and Yunnan of China, with low niche overlap index. Between the last-glacial maximum to the present both honeybees moved northwest to their present range. A. laboriosa is projected to move to the northeast and A. dorsata may move southeast. Only 6.6% of overlapping distribution is currently protected, and further work is needed to protect these key areas.

Climate change is a major factor influencing the species distribution and population diversity of living creatures. In this study, the ecological niche model (ENM) MaxEnt was used to evaluate habitat suitability and predict potential habitats of two sympatric fig species, i.e., Ficus squamosa and F. heterostyla, in the Xishuangbanna region of China. Results indicated that mean diurnal range, isothermality, cation exchange capacity (at pH 7), and temperature seasonality were key variables influencing habitat suitability for F. squamosa. However, temperature seasonality and precipitation of the driest quarter showed the greatest contributions to F. heterostyla distribution. During the current period, the habitat suitability distributions of both Ficus species were considerably higher than known occurrences. In the future, potentially suitable distribution areas for both species will reduce overall across the whole study area, although some expansion may occur by 2070. Niche overlap of suitable areas for both species was initially high and then declined in the current period and future epochs in the RCP 2.6 scenario, but increased in the RCP 8.5 scenario. In short, the responses of both Ficus species to climate change differed. Thus, specific actions such as ex situ conservation and assisted migration may be needed to conserve both species.