Tom Oliver, the lead author of the study and an ecological modeler at the Center for Ecology & Hydrology in Oxfordshire, United Kingdom, cites the green-veined white butterflies as being just one of the species with a low probability of surviving into 2050.
Dr. Oliver worked in collaboration with colleagues from CEH, the charity Butterfly Conservation, Natural England, and the University of Exeter. The research group identified six species of drought-sensitive butterflies that included the ringlet, speckled wood, large skipper, large white, small white and green-veined white, as having a low probability of survival into the 2050s.
Butterflies are among the most well-studied groups of species because of their excellent records of year-to-year abundance, although, as the team says, there are other drought-sensitive groups that would be similarly affected.
In studying 28 species of butterflies and how they reacted to the UK’s extreme drought in 1995, the driest summer on record since 1776, the team found the only ones to show dramatic declines were the six species named.
Dr Oliver adds, “We consider the average response across Great Britain. Losses are likely to be more severe in drier areas with more intensive land use, whilst wetter areas with less fragmented habitat will provide refugia. We assume that butterflies won’t have time to evolve to become more drought-tolerant, because their populations are already small, and evolution would need to be very rapid. The study looked at butterflies, but the conclusions are potentially valid for other species such as birds, beetles, moths and dragonflies.”
Oliver also pointed out that while butterflies thrive in warm summer weather, their larvae cannot withstand sweltering conditions, and dry, hard soil doesn’t help the plants that play host to butterflies to survive. Using computer modeling, the research team studied the six drought-sensitive species over a period of four years in different types of habitat.
Habitats included grasslands, hay meadows, woodlands, historic sites, bogs, wetlands and heather moorlands, tracking the six species within a 1.9 mile (3 kilometers) radius. The results of the study were not surprising. Butterflies with good habitat easily rebounded from the drought, where as those butterflies in areas where habitat loss was evident, often because of human activity, felt the effects of the drought more intensely, and had a harder time rebuilding their populations.
“The butterflies are unlikely to evolve in small ways, or ‘microevolve,’ over a very short time frame to increase their drought tolerance, because their populations are small and their bodies are physiologically limited in how they can adapt to drought,” the researchers said in their paper.
The researchers recommend better land management to prevent habitat loss in these drought-sensitive species of butterflies, as well as other species affected by changing climate. They also warn that the only way to avoid widespread extinctions is to reduce CO2 emission levels along with land management measures.
The above study was published in the journal Nature Climate Change on August 10, 2015, under the title: “Interacting effects of climate change and habitat fragmentation on drought-sensitive butterflies.”
