### Predicting the spatial distribution of three Astragalus species and their pollinating bumblebees in China-Himalayas

Yuhan Shi,Zongxin Ren,Xin Xu,Weijia Wang,Jie Liu,Yanhui Zhao,Hong Wang

1. Kunming Institute of Botany, Chinese Academy of Sciences
• Received:2020-07-03 Revised:2020-08-24 Online:2020-09-20 Published:2020-09-20
• Contact: Hong Wang

Abstract: For plant species relying on animal pollination for reproduction, their spatial distribution is influenced by the geographical distribution of their pollinators. Predicting the impact of future climate change on the geographical distribution of plant and its pollinator has important significance for biodiversity conservation. In this study, we conducted a field investigation of three Astragalus species and their dominant pollinating bumblebees, and we collected 543 species distribution points of Astragalus (A. camptodontus, A. pullus and A. strictus) and Bombus and 13 environmental factors from the historical database. We used MaxEnt to simulate the suitable distribution change of three Astragalus species and two pollinating bumblebees (B. friseanus and B. rufofasciatus) at near current and 2100s two greenhouse gas concentrations scenarios (ssp245 and ssp585) combined with three possible migration situations, i.e. full dispersal, no dispersal and only Bombus dispersal. Our research shows the three Astragalus species are mainly pollinated by bumblebees. The main suitable distribution of Astragalus and Bombus is Sino-Himalaya. By 2100, their suitable distribution tend to expand toward the northwest, while the distribution areas in the Southeast will decrease. When the interaction was included in the models, potential range size of three Astragalus species is reduced by 15.83%-83.98%. Under the medium concentration of greenhouse gases scenarios (ssp245), the spatial match of three Astragalus species and their pollinating bumblebees will increase, but the spatial match of A. camptodontus, A. pullus and their dominated pollinators B. friseanus will decrease under the high concentration of greenhouse gases scenarios (ssp585). If species lacked full dispersal ability or only Bombus dispersal, the spatial match of A. strictus and its dominated pollinators B. rufofasciatus will decrease. Climate change and species dispersal ability may cause spatial mismatch between the Astragalus and their pollinating bumblebees. Our simulation shows that the environmental factors affecting the distribution of Astragalus and Bombus are different, but elevation is the most important factor. Given the importance that interaction with pollinators have on the life cycle of many plant species, our study could be used to better understand the potential effects of climate change on the spatial distribution of plants and their pollinators, particularly on species that with limited geographical range.