Male dragonflies in hotter climates have less success in mating, study finds

Scientists fear the climate crisis could harm dragonflies’ reproduction, reports Lamiat Sabin

Female dragonflies identify potential mates by pigment on the males’ wings (Getty)

Male dragonflies in warm climates have evolved to keep cooler but have less success in mating, according to a new study.

Many male dragonflies have patches of dark pigmentation on their wings that they use to court female dragonflies and intimidate their rivals.

But the pigmentation can increase the body heat of dragonflies by as much as 2C, and this extra warmth could cause them to overheat in already warm climates.

Scientists found that male dragonflies nearly always adapted to warmer temperatures by evolving with less wing pigmentation.

They say they are concerned the climate crisis could further harm dragonflies’ ability to mate.

The scientists observed thousands of the insects to gauge whether additional heat might have forced them to evolve with different amounts of pigment in their wings depending on the climates in which they live.

Evolutionary ecologist Michael Moore, who led the study at Washington University in St Louis, said: “Given that our planet is expected to continue warming, our results suggest that dragonfly males may eventually need to adapt to global climate change by evolving less wing coloration.

“Unlike the males, dragonfly females are not showing any major shifts in how their wing colouration is changing with the current climate.

“We don’t yet know why males and females are so different, but this does show that we shouldn’t assume that the sexes will adapt to climate change in the same way.”

Rapid changes to breeding colouration could reduce a species’ ability to “identify the correct mate”, and that female dragonflies may no longer recognise males of their own species, he also said.

For this study, which will be published this week in the Proceedings of the National Academy of Sciences, the scientists created a database of hundreds of different dragonfly species using field guides and “citizen-scientist” observations to examine wing ornamentation of dragonflies and the climate variables in their locations.

The researchers also directly measured the amount of wing pigmentation on individual dragonflies from almost 3,000 observations, from the biodiversity social network iNaturalist, in a focused group of 10 selected species.

For dragonflies in each species, the scientists evaluated how populations differed in the warm and cool parts of their geographic ranges.