Do dragonflies give birth to live young?

Heliocypha perforataSomething strange seems to be happening in one particular species of damselfly, the common blue jewel Rhinocypha perforata (pictured right). Or at least it has been caught on video for the first time… Aside from being a particularly attractive species of damselfly found in China, Thailand, Laos, Malaysia and Vietnam, the common blue jewel seems to adopt a rather unusual form of reproduction (for an insect, at least). Read More »

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The impact of environmental warming on Odonata – a review [paper summary]

This is part of a series of short lay summaries that describe the technical publications I have authored.  This paper, entitled “The impact of environmental warming on Odonata – a review”, was published in the International Journal of Odonatology in 2012. You can find this paper online at the publisher, or on Figshare.

Background: Odonata (dragonflies and damselflies) are thought to have evolved in the tropics and possess a number of adaptations that allow them to exist at higher latitudes.  This makes them interesting to investigate in the context of climate change, since these adaptations might facilitate a response to increasing temperatures.

What we did: This paper is a review of the literature looking at the ecology and evolution of Odonata in the context of climate change.  A number of areas are discussed including distributional changes, phenological shifts, evolutionary responses, the effects of drought and the physiological effects of temperature.

Importance: A large amount of work has been carried out on the influence of temperature on the biology of Odonata over the past 50-60 years.  This has come from a variety of loosely-related fields and our review brings this together to provide an overview of the state-of-play concerning our understanding of the topic.


Image credit: Patricia H Schuette, CC BY-NC-ND 2.0, http://bit.ly/1BO5i4r

Computer models can predict where rare species might be found

Background:  Species distribution models (SDMs) have been used for a number of different purposes. This approach involves the mapping of species distributions (like the map shown on the right, for the citrine forktail damselfly) onto environmental variables to evaluate the contributions of those variables to determining the species range. This knowledge can then be use to predicted where the species will be in the future under climate change. However, another way in which they can be used is to predict in which areas the species has not been found but could potentially exist.

What we did: My study applied SDMs to this latter problem, predicting where 176 species of North American dragonflies and damselflies occur based on the patchy recording that is currently available.  The models fitted reasonably well, which isn’t surprising given the reliance of dragonflies and damselflies on warm, dry weather for their adult stage.  This highlighted areas for which the models predicted species presence but where those species had not been recorded.  I also demonstrated that the patterns of diversity found in North America were consistent with those found in Europe.

Importance: This kind of study can be used to predict where rare or endangered species may have gone undiscovered as well as directing limited conservation efforts towards areas that are likely to have high diversities of animals or plants but have not been properly explored. We can also look for regions that have been under-surveyed and where resources need to be focused.


This is part of a series of short lay summaries that describe the technical publications I have authored.  This paper, entitled “Predicting the distributions of under-recorded Odonata using species distribution models”, was published in the journal Insect Conservation and Diversity in 2012. You can find this paper online at the publisher, or on Figshare.

Image credit: L. B. Tettenborn, CC BY-SA 3.0, http://bit.ly/XHiqce

Less common species tend to have more parasites

Background:  Parasites and the individuals that they attack (called “hosts”) often have a long evolutionary history of interaction. This history often plays-out as an “arms race” where the parasite finds a new way of attacking the host and the host then evolves a defence against that attack, followed by subsequent evolution by the parasite. Not only this, but species of parasites (such as the aquatic mites and protozoa that I work on) that exploit many host species can differentially affect those different hosts. In this study, we were interested in how parasitic protozoa affect closely related damselfly species that differed in their distributions.

What we did: Julia Mlynarek, a PhD student at Carleton University, collected a large number of damselflies from a number of sites around eastern Ontario. The species were grouped into pairs so that we could compare between species from the same genus.  She dissected these to find the number of protozoa (like the one shown above) in guts of each animal. We found that species with smaller geographical distributions tended to have more protozoan parasites than closely related species with larger distributions.

Importance: Explaining how parasites affect their hosts is a big question spanning ecology and evolutionary biology. These results suggest that there might be a combined effect of (i) shared parasites due to evolutionary history, and (ii) varying resistance due to different exposure across geographical ranges.


This is part of a series of short lay summaries that describe the technical publications I have authored.  This paper, entitled “Higher gregarine parasitism often in sibling species of host damselflies with smaller geographical distributions”, was published in the journal Ecological Entomology in 2012. You can find this paper online at the publisher, or on Figshare.

Image credit: Christophe Laumer, CC BY 2.0, http://bit.ly/1rrvyzt

Study design and mark recapture estimates of dispersal [paper summary]

This is part of a series of short lay summaries that describe the technical publications I have authored.  This paper, entitled “Study design and mark recapture estimates of dispersal: A case study with the endangered damselfly Coenagrion mercuriale”, was published in the Journal of Insect Conservation in 2012. You can find this paper online at the publisher, or on Figshare.

9303167014_cdbcb32d61_zBackground:  I have long been interested by movement of animals in the landscape and whether or not this can be accurately quantified in the field.  One of the major issues associated with these field studies (such as mark-release-recapture studies, in which animals are marked with a unique tag then recaptured at a later time) is that you cannot detect dispersal distances that are greater than the size of the study area that you are using.  For example, people have been marking damselflies for decades to try to measure how far they fly.  However, if you only look for them 500m from where you first found them, you won’t find them flying any further than that.

What we did: This study used a large mark-release-recapture dataset and investigated the effect that expanding a study area has on the maximum dispersal distance detected.  We found that the original study (on the endangered southern damselfly, Coenagrion mercuriale) was at a scale sufficient to estimate the maximum distance that the insect is able to fly, around 2km.

Importance: This endangered species has very specific habitat requirements (water meadows and shallow ditch systems) which mean that it has a long distance to move between these rare areas.


Image credit: Paul Ritchie, CC BY-NC-ND 2.0, http://bit.ly/1sZpjCC