台灣授粉蜂物種分布及溫度耐受性

Abstract

近年來，全球氣候變遷已對自然生態系統造成重大衝擊，造成許多授粉蜂類如 蜜蜂（Apis spp.）、熊蜂（Bombus spp.）和其他野生授粉蜂等族群數量大幅下降。 本研究為評估氣候變遷對台灣山區授粉蜂分布與多樣性的影響，於南投縣濁水溪 流域設置 9 個海拔 500-2600 公尺之間的調查樣點，於 2021-2023 年進行為期兩年 的定期每月調查，記錄不同海拔梯度授粉蜂的物種組成與多樣性，並同時記錄授粉 蜂與開花植物之間的相關性。同時，選擇 6 種具代表性的不同海拔授粉蜂物種，利 用 MaxEnt 軟體建構物種分布模型（Species distribution model, SDM）比較當今及 2070 年的兩種氣候變遷情景（SSP2-4.5 及 SSP5-8.5）下的潛在棲地分布變化趨勢。 此外，透過溫度耐受性實驗測試不同海拔授粉蜂的高、低溫耐受極限，評估其對未 來氣溫上升的生理反應。在多樣性調查結果中，共記錄到 11 科 53 屬約 166 種授 粉蜂，以蜜蜂屬（Apis spp.）、淡脈隧蜂屬（Lasioglossum spp.）和熊蜂屬（Bombus spp.）數量最多。沿海拔高度，物種總數呈現遞減趨勢，但中海拔具較高的稀有性。 不同授粉蜂與當地 56 種植物形成複雜的授粉網絡。而在 SDM 結果中，發現低海 拔授粉蜂物種的適宜棲地面積將在未來擴大；相反，高海拔物種的棲地範圍則呈縮 減趨勢，與實驗結果的高海拔物種耐熱度較差一致。分析結果顯示氣候變遷將促使 低海拔授粉蜂向山區較高海拔區域遷移，但高山物種的分布適應力受限。本研究首 次評估氣候變遷對台灣山區授粉蜂多樣性的衝擊，可提供保育這些重要授粉者的 科學依據。未來研究可進一步探討不同授粉蜂對氣候變遷的生理調控機制，以及氣 候變遷所導致的授粉網絡變化。

In recent years, global climate change has severely impacted natural ecosystems, leading to sharp declines in populations of many pollinator bees such as the honey bee (Apis spp.), bumblebees (Bombus spp.) and other wild pollinators. This study aimed to assess the impacts of climate change on pollinator bee diversity and distribution in mountainous areas of Taiwan. The survey was conducted during 2021-2023 at nine survey sites at 500-2600 m asl along the Choshui River Basin, Nantou County. Hymenopteran pollinator species composition and diversity along the elevational gradient were estimated, and their associations with floral resources were recorded. Six representative pollinator species across elevations were selected for ecological niche modeling using MaxEnt to project potential range shifts under current and two future climate change scenarios (SSP2-4.5 and SSP5-8.5) in 2070. Furthermore, critical thermal maximum experiments were performed to evaluate the physiological resilience of different elevation bees towards future warming. The diversity survey recorded 11 families, 53 genera and 166 species, with Apis spp., Lasioglossum spp. and Bombus spp. as the dominant taxa. Total species richness decreased with increasing elevation, but rare species contributions peaked at mid elevations. Complex pollination networks between bees and 56 plant species were characterized. Species distribution model projections showed range expansions for low elevation bees, but reductions for high altitude species, consistent with poorer heat tolerance of high altitude bees from the experiments. Our findings support that climate change may drive upward elevational range shifts of lowland pollinators, but compress distributions of high altitude species due to physiological limitations. This represents the first assessment of climate change impacts on mountain pollinator diversity in Taiwan, providing a scientific basis for conserving these vital pollination service providers. Future studies could elucidate pollinator regulatory mechanisms of physiology and altered plant-pollinator interactions under climate change.