Sep

17

2007
 
 

Army of one



Biological invasions can be launched from the smallest possible population

one's enoughA single, mated solitary ground-nesting bee Lasioglossum leucozonium successfully invaded North America, claim a group of York University, Toronto biologists. Writing in PLoS ONE, Amro Zayed and colleagues describe how North American populations have extraordinarily low levels of genetic variation compared with their European counterparts. Such low diversity usually means that the population is descended from a small number of ancestors, and this particular genetic bottleneck – which took place between 50 and 150 years ago – bears all the hallmarks of being about as severe as it could. The arrival of just one mated female, probably in soil used as ships’ ballast, marked the start of a continent-wide expansion. The findings undermine current theories of biological invasion, notably that success is positively linked to the size of the founder population. So conservationists, be vigilant; keep an eye out for those single aliens. Source: Zayed A, Constantin SA & Packer L (2007) Successful biological invasion despite a severe genetic load. PLoS ONE DOI: 10.1371/journal.pone.0000868

Related stories in Conservation magazine: When Worlds Collide | The Conundrum of Biological Control

Image © Pavel Lebedinsky

Filed Under Invasive species, Monitoring, Tools and technology | 

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