Norman Pace

British species; the speckled wood (Pararge aegeria) and the gatekeeper or hedge brown (Pyronia tithonus). The researchers have looked at the patterns of genetic variation in these two species, both of which have been expanding their British distributions over the past 60 years. Both species have broadly similar dispersal ability, the researchers note, but differ in their habitat requirements. The speckled wood is confined to shady woodland with sparse grasses growing under poor light on which to lay its eggs, which is becoming an increasingly scarce habitat. In contrast, the gatekeeper inhabits a broader range of more widely occurring habitats including hedgerows, where it requires medium to tall grasses growing at the sunny base of shrubs on which to lay its eggs. The team have looked at the genetic diversity of the two species in relation to a third species, the meadow brown (Maniola jurtina), which is not currently expanding its range. Reporting in Biology Letters of the Royal Society, published online, the team have analysed several genetic polymorphisms. They found that the two expanding species at the loci studied were genetically less diverse than the meadow brown. But the researchers found a further decline in the genetic diversity at the range margin in the speckled wood, compared with similar populations of the gatekeeper. The authors believe this may be the result of more severe founder effects in the speckled wood where new habitats may be hard to find. The authors warn that this may have long-term impacts. They believe their study has shown that anthropogenic habitat loss may reduce genetic diversity during range expansion. “Given the rapidity of predicted climate warming for the future, any reduction in diversity and in species’ ability to adapt to novel environmental changes could affect their long-term persistence,” they report. Magazine R5