DNA analysis reveals that queen bumblebees disperse far from their birthplace before setting up home
Researchers are closer to understanding patterns of family relatedness and genetic diversity in bumblebees. The findings could help farmers, land managers and policy makers develop more effective conservation schemes for these essential pollinators.
In the new study, published today (1 July 2014) in the journal Molecular Ecology, a combination of DNA analysis and landscape mapping was used to reveal the relationships between hundreds of wild bumblebee colonies of five different species, including four common and one rare species, in an area of nearly 20 square kilometres of farmland in southern England.
The results are the first to reveal in detail the genetic relatedness between neighbouring bumblebee nests. They show that, in all five species, queens nesting near one another were unrelated or related at only a very low level.
The project was led by ecologists from the Centre for Ecology & Hydrology (CEH) working with researchers from the Zoological Society of London, University of Bristol and University of East Anglia.
Bumblebees form short-lived colonies consisting of a single queen and up to a few hundred daughter workers. At the end of the summer new queens are produced which, after mating and hibernation, go on to set up new colonies the following spring.
Lead author of the paper, Dr Stephanie Dreier from the Zoological Society of London and University of Bristol said, "Queens, not workers, are the ones that pass on their genes to the next generation. Knowing how far a queen flies from her birthplace to set up her own colony is therefore crucial for understanding how bumblebees use the landscape".
Bumblebee nests are difficult to find in the wild, which makes direct sampling of DNA from nesting queens almost impossible. Instead the researchers took tiny amounts of DNA from the daughter workers that were caught foraging in the study area.
By mapping where workers from the same colony had been sampled, and estimating the location of each nest, the research team built up a "street view map" of neighbouring colonies and tested whether or not nests located near to one another were headed by highly related queens, such as sisters or cousins.
The results suggest that sister queens emerging from the same nest must disperse far, in different directions, before founding their own nests in the spring.
Senior author Dr Claire Carvell, an ecologist at the Centre for Ecology & Hydrology said, "We knew that bumblebee queens could fly long distances, but these results show that new queens frequently disperse widely, perhaps several kilometres away from their birthplace, before starting their own nest." She added, "This suggests that populations of both common and rare species can be genetically well mixed through queen dispersal, and that managing landscapes with flower-rich habitats that are well connected at these scales remains a priority for bumblebee conservation."
The results also showed that, of the five species studied, the rare species (Bombus ruderatus) had lower genetic diversity than the four common species, and nested at lower density. Despite this, the study found no evidence that reduced numbers had led to inbreeding in this species. Dr Dreier added, "Very little is known about how genetic factors may be affecting rare and declining bumblebees. The rare bumblebee species at our study site currently has a small population size. However, management actions in place seem to be preserving its remaining genetic diversity."
The research was funded by the UK Insect Pollinators Initiative. The Insect Pollinators Initiative is a set of nine research projects funded jointly by the Biotechnology and Biological Sciences Research Council (BBSRC), the Department for Environment, Food and Rural Affairs (Defra), the Natural Environment Research Council (NERC), The Scottish Government and The Wellcome Trust, under the Living with Environmental Change Partnership.
Notes to editors
Paper reference: Dreier, S., Redhead, J.W., Warren, I., Bourke, A.F.G., Heard, M.S., Jordan, W.C., Sumner, S., Wang, J. & Carvell, C. (2014) Fine-scale spatial genetic structure of common and declining bumble bees across an agricultural landscape. Molecular Ecology. doi: 10.1111/mec.12823
Relevant bumblebee facts
- There are currently 24 bumblebee species in Britain and, while some are still widespread, many have declined over the past 50 years due to habitat loss and degradation. Declining populations, especially if they are fragmented, often have lower levels of genetic diversity, which increases their risk of extinction.
- The researchers collected DNA samples using a well-established technique that causes no harm to the bees. These samples were 'genotyped' in the laboratory to work out which bees originated from the same colony and how genetically diverse each species was.
- Bombus ruderatus is often referred to as the 'Ruderal bumblebee' or 'Large garden bumblebee', but is not often found in gardens, and seems to prefer open, rural landscapes. The species experienced serious declines in the late twentith-century but could be making a recovery on the clover-rich flower strips being sown alongside fields as part of the Government's agri-environment scheme, including those occurring within the study landscape in Buckinghamshire, UK.
The Insect Pollinators Initiative is a set of nine research projects funded jointly by the Biotechnology and Biological Sciences Research Council (BBSRC), the Department for Environment, Food and Rural Affairs (Defra), the Natural Environment Research Council (NERC), The Scottish Government and The Wellcome Trust, under the Living with Environmental Change Partnership. For further information, visit www.insectpollinatorsinitiative.net.
About the Centre for Ecology & Hydrology
The Centre for Ecology & Hydrology (CEH) is the UK's Centre of Excellence for integrated research in the land and freshwater ecosystems and their interaction with the atmosphere. CEH is part of the Natural Environment Research Council (NERC), employs more than 450 people at four major sites in England, Scotland and Wales, hosts over 150 PhD students, and has an overall budget of about £35M. CEH tackles complex environmental challenges to deliver practicable solutions so that future generations can benefit from a rich and healthy environment. www.ceh.ac.uk
NERC is the UK's main agency for funding and managing world-class research, training and knowledge exchange in the environmental sciences. It coordinates some of the world's most exciting research projects, tackling major issues such as climate change, food security, environmental influences on human health, the genetic make-up of life on earth, and much more. NERC receives around £300M a year from the government's science budget, which it uses to fund research and training in universities and its own research centres. www.nerc.ac.uk
About the Zoological Society of London
The Institute of Zoology, Zoological Society of London, is a world-renowned research centre working at the cutting edge of conservation biology, and specialising in scientific issues relevant to preserving animal species and their habitats. The Institute is the scientific research division of the Zoological Society of London (ZSL).
About University of East Anglia
The University of East Anglia (UEA) was founded in 1963 and this academic year celebrates its 50th anniversary. It has played a significant role in advancing human understanding and in 2012 the Times Higher Education ranked UEA as one of the 10 best universities in the world under 50 years of age. The university has graduated more than 100,000 students, attracted to Norwich Research Park some of Britain's key research institutes and a major University Hospital, and made a powerful cultural, social and economic impact on the region. UEA was ranked first in the Times Higher Education Student Experience Survey 2013.
About University of Bristol
The University of Bristol is consistently ranked among the leaders in UK higher education. Research-intensive and with an international reputation for quality and innovation, the University has over 18,000 students from over 100 countries, together with more than 5,000 staff. Places at Bristol are among the most highly sought after of all UK universities.
The University was founded in 1876 and was granted its Royal Charter in 1909. It was the first university in England to admit women on the same basis as men. It is located in the heart of the city from which it grew, but is now a significant player on the world stage as well as a major force in the economic, social and cultural life of Bristol and South West England. Bristol is a member of the Worldwide Universities Network and of the Russell Group of leading research-intensive universities in the UK.
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