The brown argus butterfly has responded to climate change by evolving a narrrower diet.

New research suggests brown argus butterfly has lost ability to use its main host plant, rockrose.

Research by the University of Bristol has revealed that a UK butterfly species responds to climate change by evolving a narrower diet.

In response to climate change, the brown argus butterfly has been able to spread rapidly north in the UK by evolving to use only the widespread wild geranium. However, new research suggests that by doing so, it has lost the ability to use its main host plant, rockrose.

The authors of the study, Dr James Buckley and Dr Jon Brindle, explain:  "Our research on the brown argus butterfly shows that rapid evolutionary change in a species’ diet is important for responding to recent climate change. Adaptations like this that alter how species interact may be crucial for many other organisms to survive in a changing world.”

The researchers stress that although fast evolutionary responses can allow for the rapid population of new areas, it could result in the loss of variation in ecologically important traits, such as dietary preferences. Such loss of variation could compromise the ability of species to adapt to future climate change.

Unlike the brown argus, many butterflies already have restricted diets. This means that they could be unable to rapidly adapt to climate change and therefore be condemned to extinction in increasingly fragmented habitat.

Using shopping baskets as cages, the researchers transported female butterflies between habitats across the UK, and counted the number of eggs they laid on larval food plants in different areas.

Butterflies from long-established areas in the south laid eggs on two plants: the locally common rockrose and wild geranium.  In contrast, females from recently colonised populations further north only laid eggs on the widespread geranium and not rockrose.  

The University of Bristol say that these results show the importance of conducting experiments in natural habitats as well as in laboratory environments to identify how organisms will adapt to ongoing climate change.

The paper, 'Loss of adaptive variation during evolutionary responses to climate change'  was published in Ecology Letters.

Image (C) Rosenzweig