Background: When this paper was published, we had already demonstrated that ageing (an increase in the probability of dying in older individuals) was present in one species of damselfly. This was a surprise, as many biologists speculated that short-lived animals like damselflies did not live long enough in the wild to experience ageing. However, anybody who has worked with insects in the field knows that they exhibit clear signs of ageing like the tattered wings of the dragonfly shown above. Having shown that at least one species of damselfly age, it was still unclear as to whether this was the exception or the rule.
What we did: We expanded our analysis from a single species to consider all the species for which there was published data on age-related mortality which we could use to detect ageing. We found that this phenomenon was present in the vast majority of studies in which we were able to test for it. Furthermore, we were able to show that it was more apparent in territorial species where males face greater stress in having to defend their territories to obtain mates.
Importance: This study conclusively demonstrated that ageing is commonplace in dragonflies and damselflies, where once it had been proposed that no wild insect populations exhibited ageing at all. We also show a hallmark of the evolution of territoriality in the lifespans of dragonflies and damselflies.
This is part of a series of short lay summaries that describe the technical publications I have authored. This paper, entitled “A comparative analysis of senescence in adult damselflies and dragonflies”, was published in the Journal of Evolutionary Biology in 2011. You can find this paper online at the publisher, or on Figshare.
Image credit: steews4, CC BY-ND 2.0, http://bit.ly/1rrAEeW