Climate-driven range shifts of a rare specialist bee, Macropis nuda (Melittidae), and its host plant, Lysimachia ciliata (Primulaceae)

Earth's climate is on track to surpass the proposed mean global temperature change limit of 1.5ºC above pre-industrial levels, threatening to disrupt ecosystems globally. Yet, studies on temperate bee response to climate change are limited, with most studies of non- Apis bees focusing on the eusocial genus Bombus . Here, we assess the response of a rare habitat and host plant specialist bee, Macropis nuda , to projected climate change scenarios. We use species distribution models of M. nuda and its host plant, Lysimachia ciliata , trained on publicly available occurrence records, to evaluate bee distribution and habitat suitability changes under four climate change scenarios. We find that the bee and host plant distributions respond synchronously to increased greenhouse gas emissions, which result in range-wide habitat suitability loss and a northward range shift. These results provide an important example of a temperate solitary bee's response to climate change and help inform conservation efforts to preserve pollinator biodiversity and pollinator-host plant relationships.