Standing still in running water: Lotic dragon and damselfly species less able to adapt to climate change

The study was conducted at the German Biodiversity and Climate Research Center and the Danish Centre for Macroecology, Evolution and Climate, and in cooperation with various other European research institutes.

Many dragonfly species have preferred freshwater habitats. Whereas larvae of some species are only to be found in standing (lentic) freshwater habitats such as pools, ponds and lakes, there are also species particularly adapted to running (lotic) freshwater habitats. Does the choice of habitat have consequences for the evolution of dispersal abilities and thus the potential to track climate change?" To find out we compiled data of 88 European dragonfly species and analyzed whether the observed distribution is consistent with what our models tell us about the potential distribution in Europe" says lead author Dr. Christian Hof, BiK-F, about the study design.

Habitat-stability influences dispersal abilities

Comparing the two sets of species the scientists found that lentic dragon- and damselfly species fill their potential range, i.e. the climatically suitable areas, to a higher extent than lotic species. According to the researchers, the species' different dispersal abilities are due to the lower habitat persistence of standing waters. In the long term it is more likely for pools and pond to disappear as a habitat than a stream or a river. To make up for this risk, lentic dragonfly species have evolved a higher dispersal ability.

Lentic species better able to track climate change

If lentic species are stronger dispersers than lotic species they should also be able to track climate changes more rapidly because the higher the mobility the higher the chance of a change in range. This hypothesis was proven right by comparing observed and projected distributions for 2006. Models based on datasets from 1988 over-predicted lotic species ranges in 2006 indicating that the lower dispersal abilities of lotic species hinder them from filling their climatically suitable range. The tendency for over-prediction was less pronounced for lentic species.

Generalizations for the entire species have to be revised

With a maximum velocity of up to 40 km per hour and travel distances of up to 1,000 km within a few days, dragon- and damselfly species are strong fliers and highly mobile. This has led to the assumption that they will probably survive even drastic climatic changes. "Our results regarding the different dispersal abilities of these species in relation to their habitat preference imply that generalizations for entire species groups about their ability to respond to climate change may be misleading." says Hof who conducted the study in collaboration with colleagues from the Philipps-Universität Marburg, Germany, the Center for Macroecology, Evolution and Climate, Copenhagen, Denmark and the National Museum for Natural Sciences in Madrid, Spain.