Conclusions
Bumblebees of cold environments in the main European mountains act as
sentinels and respond in a similar way to global climate change by
shrinking their distribution and shifting uphill in elevation, in spite
of having different distributions and life histories. This will likely
lead to issues such as habitat loss, reduced surfaces for acquiring
resources and finding mates. Furthermore, it is possible that future
scenarios will also contribute to the erosion of genetic diversity, as a
low genetic diversity has been found in declining bumblebees (Cameron et
al. 2011) and also in other high-elevation specialist species (Bauert et
al. 1998, Rubidge et al. 2012). This scenario challenges dramatically
any conservation effort but attention should be directed towards the
dynamic realities of species ranges.
The narrow future ranges and small refugia will lead to conservation
issues for cold-adapted bumblebees. However, conservation should take in
full consideration the dynamic realities of species ranges over time and
that refugium areas may be target of conservation priority considering
in situ and ex situ locations. Moreover, a useful tool could be updating
the country- and continental-level Red Lists in light of the results
presented in this study, and the different responses among mountain
ranges highlight the need for regional lists at smaller scales.
Furthermore, protecting and keeping high habitat quality and
microhabitat diversity in current and in refugium areas will be the
first pillar for any reasonable conservation plan. Other future
conservation actions could also integrate biogeographical and genetic
evidence in order to further tailor the design of conservation priority
areas and therefore help outlining specific measures to preserve these
species.