title: Consequences of a warming climate for social organisation in sweat bees.
abstract: The progression from solitary living to caste-based sociality is commonly regarded as a major evolutionary transition. However, it has recently been shown that in some taxa, sociality may be plastic and dependent on local conditions. If sociality can be environmentally driven, the question arises as to how projected climate change will influence features of social organisation that were previously thought to be of macroevolutionary proportions. Depending on the time available in spring during which a foundress can produce worker offspring, the sweat beeHalictus rubicundusis either social or solitary. We analysed detailed foraging data in relation to climate change predictions for Great Britain to assess when and where switches from a solitary to social lifestyle may be expected. We demonstrate that worker numbers should increase throughout Great Britain under predicted climate change scenarios, and importantly, that sociality should appear in northern areas where it has never before been observed. This dramatic shift in social organisation due to climate change should lead to a bigger workforce being available for summer pollination and may contribute towards mitigating the current pollinator crisis.
  
  
  CONCLUSIONS
  The sweat beeHalictus rubicundusis socially polymorphic, expressing both solitary and social forms, and is socially plastic, capable of transitioning from solitary to social forms, depending on local environmental conditions. Here, we analyse detailed foraging data in relation to climate change predictions for Great Britain to show that worker numbers and sociality both increase under predicted climate change scenarios. Especially dramatic will be the appearance of socialH. rubicundusnests in the north of Britain, where previously only solitary forms are found. Particularly, if more taxa are found to be socially plastic, environmentally driven shifts in social organisation may help to mitigate future pollinator crises by providing more individuals for pollination.
authors.affiliation: School of Life Sciences, University of Sussex, Brighton, BN1 9QG UK ; CTU Bern, Department of Clinical Research, University of Bern, Bern, Switzerland ; Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland.
authors.forename: Roger
authors.initials: R
authors.lastname: Schürch
authors.affiliation: School of Life Sciences, University of Sussex, Brighton, BN1 9QG UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Accleton
authors.affiliation: School of Life Sciences, University of Sussex, Brighton, BN1 9QG UK.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Field
keywords: Climate change; Halictus rubicundus; Social plasticity; Social polymorphism; Sociality; Sweat bee