Over the last century, climate and land-use changes have altered ecosystems, shifted species distributions toward higher latitudes and altitudes, and led to changes in species’ phenology and morphology. In this project we focus on bumblebees, crucial to the pollination of wild plants and crops, and investigate the underlying mechanisms for why some species seem to cope with global changes, while others do not.
Background
Insect pollinators are integral to ecosystem functioning through pollination of wild plants and crops. In colder climates, bumblebees are particularly important due to their large body and facultative endothermy, which enables foraging in low temperatures and adverse weather conditions [1]. A large body size also enables foraging and dispersal over greater distances, which has become increasingly important due to loss and fragmentation of nesting and foraging resources driven by agricultural land-use changes. However, a larger body size also makes bumblebees sensitive to heat waves, which are predicted to increase due to climate change. Bumblebees are hence affected by two simultaneous environmental changes which seemingly push them to adapt in opposing directions: adapt to warming by decreasing in size, and to fragmentation by increasing in size. Long-term trends in body size have only been described for a few bumblebee species [2,3]. Not surprisingly, studies have struggled to draw conclusions about the contribution of individual environmental drivers because climate change and habitat loss have occurred simultaneously in temperate regions over the past centuries [4,5]. By assessing more species, with different ecological traits and niches, our understanding of how body size contributes to adaptation and persistence of species under global change can improve.
Aims and data collection
We will (i) study how body size of bumblebee species has shifted over time (>100 years) and across latitudes in Sweden and whether it is associated with species’ capacity to persist in changing landscapes and climate, and (ii) test whether such morphological shifts are plastic or due to genetic adaptation to new conditions, by exploring genetic changes across latitudes and elevation.
We will foremost make use of existing bumblebee collections in Swedish Natural History Museums (Lund, Gothenburg and Stockholm), possibly complemented by field sampling at around 6-10 sites across the country, from lowland to mountain areas. The body size of bees will be measured as the distance between the wing plates (Inter-Tegular Distance) and samples (a mid-leg) will be taken for further genetic analyses.
It is possible to do a shorter project (30 credits) that only uses museum material and focusses on the morphological shifts, but also to do a longer project (45-60 credits) and include fieldwork to obtain contemporary samples as a comparison. Depending on your interests and skills, it is also possibility to include assessment of genetic adaptation.
Contact: Anna Persson, anna.persson@cec.lu.se, Bengt Hansson, bengt.hansson@biol.lu.se
References
- Maebe, K., et al., Bumblebee resilience to climate change, through plastic and adaptive responses. Glob. Change Biol., 2021. 27(18): p. 4223-4237.
- Nooten, S.S. and S.M. Rehan, Historical changes in bumble bee body size and range shift of declining species. Biodiv. Conserv., 2020. 29(2): p. 451-467.
- Gérard, M., et al., Shift in size of bumblebee queens over the last century. Glob. Change Biol., 2020. 26(3): p. 1185-1195.
- Kelemen, E.P. and S.M. Rehan, Opposing pressures of climate and land-use change on a native bee. Glob. Change Biol, 2021. 27: p. 1017–1026.
- Gérard, M., et al., Impact of landscape fragmentation and climate change on body size variation of bumblebees during the last century. Ecography, 2021. 44(2): p. 255-264.
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