Small-winged and lighter coloured butterflies likely to be at greatest threat from climate change

Small-winged and lighter coloured butterflies likely to be at greatest threat from climate change - University of Cambridge

The family, wing length and wing colour of tropical butterflies all influence their ability to withstand rising temperatures, say a team led by ecologists at the University of Cambridge. The researchers believe this could help identify species whose survival is under threat from climate change.

Esme Ashe-Jepson conducing fieldwork in Panama, with a Juditha caucana butterfly from the Riodinidae family. Credit: Esme Ashe-Jepson

Butterflies with smaller or lighter coloured wings are likely to be ‘losers’ when it comes to climate change, with the Lycaenidae family, which contains over 6,000 species of butterflies, the majority of which live in the tropics, found to be particularly vulnerable.

Butterflies with larger or darker coloured wings are likely to fare better under increasing temperatures, but only to a point. Researchers say these butterflies could still experience dramatic declines if there were sudden heatwaves or if cool microclimates were lost through deforestation.

The results are published today in the Journal of Animal Ecology.

Butterflies rely on the sun’s warmth to give them the energy they need to function. They use ‘thermoregulation’ strategies to maintain a balanced body temperature against changing air temperatures.

Generally, strategies to keep cool involve adaptive behaviours like flying to a shady spot or angling wings away from the sun (thermal buffering). But when this is not possible or temperatures become too hot, species have to rely on physiological mechanisms such as the production of heat shock proteins to withstand high temperatures (thermal tolerance). Both of these strategies are needed to cope with climate change.

Researchers collaborated with the Smithsonian Tropical Research Institute (STRI) to study the thermal buffering and thermal tolerance strategies of tropical butterflies. They collected data from multiple habitats in Panama.

Equipped with hand-held nets, ecologists took the temperature of over 1,000 butterflies using a tiny thermometer-like probe. They compared each butterfly’s temperature to that of the surrounding air or the vegetation it was perched on. This gave a measurement of thermal buffering – the ability to maintain a steady body temperature against fluctuating air temperatures.