Evidence for habitat and climatic specialisations driving the long-term distribution trends of UK and Irish bumblebees

Casey, L M, Rebelo, H, Rotheray, E and Goulson, D (2015) Evidence for habitat and climatic specialisations driving the long-term distribution trends of UK and Irish bumblebees. Diversity and Distributions, 21 (8). pp. 864-875. ISSN 1366-9516

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Abstract

• There is widespread concern over the current state of global pollinator populations and evidence suggests that bumblebees are declining in many parts of the world. However, there is very little monitoring of pollinator populations, so the extent and patterns of decline are not well characterised.
• The most comprehensive set of bumblebee species records exists for the UK and Ireland and previous analysis of the UK data highlighted severe range contractions for a number of species by the 1980s.
• Here we use the most current dataset to quantify the extent of range change over three time periods (pre1960, 1960-80 and 1981-2012) in order to compare results with earlier studies and ascertain whether species are continuing to decline. We also investigate if species are becoming more marginal i.e. occupying areas with more extreme or specialised climatic conditions within the UK and Ireland.
• For species that have contracted or become more marginal, we predict their climatic specialisation within the UK and Ireland using Maxent models, allowing us to associate records with climatic suitability values for each time period and to investigate whether or not species are contracting towards their climatic optimum.
• We find that populations of most rare bumblebee species appear to have stabilised post-1980, while the more common species appear to have expanded in range. However, rare species tend to have become more marginal in the sites they occupy post-1980, some have contracted towards their predicted climatic optimum, and some of which also retracted towards coastal areas.
• Our results provide a mixed picture of the state of the UK and Ireland’s bumblebee fauna, and must be interpreted with caution as changing patterns of recorder effort may distort real trends. They highlight the need for future monitoring of the abundance of pollinators on both a regional and global scale.

Item Type: Article
Schools and Departments: School of Life Sciences > Evolution, Behaviour and Environment
Depositing User: David Goulson
Date Deposited: 12 Jun 2015 12:18
Last Modified: 07 Mar 2017 05:02
URI: http://sro.sussex.ac.uk/id/eprint/54232

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