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Distribution patterns of the cold adapted bumblebee Bombus alpinus in the Alps and hints of an uphill shift (Insecta: Hymenoptera: Apidae)

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Climate change is threatening species and habitats. Altitudinal shifts uphill and negative population trends are commonly observed in altitude-related taxa. The bumblebee Bombus alpinus (Linnaeus, 1758) has a disjoint distribution restricted to Fennoscandia and the Alps, and is considered threatened. We studied the ecology and distribution of B. alpinus in the Alps, where the endemic subspecies Bombus alpinus helleri Dalla Torre 1882 is found, as a case-model because of its rarity, habitat, and mutual dependence with the ecosystem for pollination and resources. We developed species distribution models including both climatic and habitat variables to obtain the surface suitable for this subspecies and quantified its protected portion. Our analyses indicate that this bumblebee is restricted to the upper altitudes and has a narrow niche mainly related to the presence of glaciers, the cool temperature, a low temperature variation, and a specific range of precipitation. A strong altitudinal shift is also taking place probably due to climate change. After years of no changes in altitudinal distribution, its lowest altitudinal limit has moved up 479 m since the year 1984, while its upper altitudinal limit has remained unchanged. Over half of the suitable area in the Alps is included within protected areas, but conservation has not been planned yet. However, rare species with narrow niche, such as B. alpinus, are highly threatened by climate change. Potential short-term mitigation actions are discussed, including exchange of males between locations and integral protection of prairies in the vicinity of glaciers.
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Vol.:(0123456789)
1 3
J Insect Conserv (2017) 21:357–366
DOI 10.1007/s10841-017-9983-1
ORIGINAL PAPER
Distribution patterns ofthecold adapted bumblebee Bombus
alpinus intheAlps andhints ofanuphill shift (Insecta:
Hymenoptera: Apidae)
PaoloBiella1,2 · GiuseppeBogliani3· MaurizioCornalba4· AuloManino5·
JohannNeumayer6· MarcoPorporato5· PierreRasmont7· PietroMilanesi3,8
Received: 23 August 2016 / Accepted: 25 April 2017 / Published online: 27 April 2017
© Springer International Publishing Switzerland 2017
and resources. We developed species distribution models
including both climatic and habitat variables to obtain the
surface suitable for this subspecies and quantified its pro-
tected portion. Our analyses indicate that this bumblebee
is restricted to the upper altitudes and has a narrow niche
mainly related to the presence of glaciers, the cool tempera-
ture, a low temperature variation, and a specific range of
precipitation. A strong altitudinal shift is also taking place
probably due to climate change. After years of no changes
in altitudinal distribution, its lowest altitudinal limit has
moved up 479m since the year 1984, while its upper altitu-
dinal limit has remained unchanged. Over half of the suit-
able area in the Alps is included within protected areas,
but conservation has not been planned yet. However, rare
species with narrow niche, such as B. alpinus, are highly
threatened by climate change. Potential short-term miti-
gation actions are discussed, including exchange of males
between locations and integral protection of prairies in the
vicinity of glaciers.
Keywords Climate change· Specialist· Rare species·
Species distribution modelling· Altitudinal shift·
Conservation
Introduction
Global change is currently threatening many species
(Thomas etal. 2004). Together with land use change (Mar-
tins et al. 2014; Jha 2015), agricultural practices (Oller-
ton etal. 2014; Rundlöf et al. 2015), and new pathogens
(Smith etal. 2006; Cameron et al. 2011), climate change
affects the survival of endangered species and could even
cause extinctions (e.g. Parmesan and Yohe 2003; Thomas
et al. 2004). As pointed out by the International Panel
Abstract Climate change is threatening species and
habitats. Altitudinal shifts uphill and negative population
trends are commonly observed in altitude-related taxa. The
bumblebee Bombus alpinus (Linnaeus, 1758) has a dis-
joint distribution restricted to Fennoscandia and the Alps,
and is considered threatened. We studied the ecology and
distribution of B. alpinus in the Alps, where the endemic
subspecies Bombus alpinus helleri Dalla Torre 1882 is
found, as a case-model because of its rarity, habitat, and
mutual dependence with the ecosystem for pollination
Electronic supplementary material The online version of this
article (doi:10.1007/s10841-017-9983-1) contains supplementary
material, which is available to authorized users.
* Paolo Biella
paolo.biella@entu.cas.cz
1 Department ofZoology, Faculty ofScience, University
ofSouth Bohemia, Branišovská 31, 37005ČeskéBudějovice,
CzechRepublic
2 Biology Centre oftheAcademy ofSciences oftheCzech
Republic, v.v.i., Institute ofEntomology, Branišovská 31,
37005ČeskéBudějovice, CzechRepublic
3 Department ofEarth andEnvironmental Sciences, University
ofPavia, via Adolfo Ferrata 9, 27100Pavia, Italy
4 Department ofMathematics, University ofPavia, via Ferrata
5, 27100Pavia, Italy
5 Department ofAgricultural, Forest andFood Sciences
(DISAFA), University ofTorino, Largo Paolo Braccini 2,
10095Grugliasco, TO, Italy
6 Obergrubstraße 18, 5161Elixhausen, Austria
7 Laboratory ofZoology, Research Institute ofBiosciences,
University ofMons, Place du Parc 20, 7000Mons, Belgium
8 Swiss Ornithological Institute, Seerose 1, 6204Sempach,
Switzerland
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ContextHabitat loss threatens to exacerbate climate change impacts on pollinator communities, particularly in Mediterranean-type ecosystems where late season floral resource availability is limited by seasonal drought. While gardens have been found to supplement floral resources in water-limited urban landscapes, less is known about the role of natural habitat diversity in sustaining late season floral resources in more intact landscapes. Objectives We investigated the importance of habitat integrity and diversity for bumble bees in a water-limited ecosystem, observing bumble bee community response to seasonal drought across gradients of disturbance and soil moisture.Methods We applied hierarchical models to estimate the effects of local site conditions versus landscape scale estimates of matrix habitat on bumble bee abundance. Floral resources, soil moisture, and other environmental variables were sampled along randomly distributed belt transects. Geospatial estimates of matrix habitat were derived from terrestrial ecosystem data. Bumble bees were sampled with blue vane traps.ResultsIn the late season we found that modified wet areas supported more floral resources and bumble bee workers as compared to dry semi-natural environments. Wetlands also supported more late season floral resources and bumble bee workers, though the latter effect was not significant. Despite higher levels of late season floral resources in modified wet environments, modified matrix habitat was negatively associated, and natural matrix positively associated, with workers in June and late-flying queens in July and August. We also detected differences in bumble bee community composition in disturbed versus undisturbed environments.Conclusions Though wet modified habitats sustained the highest levels of late season floral resource availability and worker abundances in our study, bumble bee diversity and abundance were limited primarily by the availability of natural matrix habitat at the landscape scale. The conservation of natural habitat integrity and diversity can help support critical nesting and foraging habitat, and should be prioritized in efforts to foster the resilience of pollinator communities.
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Functions for species distribution modeling, calibration and evaluation, ensemble of models.
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