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 »

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

Damselfly sex doesn’t always produce children, and that’s a problem for evolutionary biologists!

Background:  At the core of ecology and evolutionary biology is the concept of “fitness”, broadly defined as the number of copies of an animal’s genes it manages to leave in subsequent generations. However, biologist rarely measure this genetic fitness.  Instead, we use proxies such as the number of times an animal mated or the number of eggs an animal laid. Sometimes, we use proxies that are even further removed, such as body size (under the assumption that larger females lay more eggs).

What we did: This study compared two traditional forms of fitness measurement, daily mating rate and lifetime mating success, with a genetic measure of fitness based on finding the number of offspring each individual produced in the next generation.  We monitored a single, isolated pond over two years and individually identified all damselflies of the species Coenagrion puella, the azure damselfly.  Each individual also had a genetic sample taken and we used genetic markers called “microsatellites” to identify each individual.  When we came back the next year, we did the same thing.  This species goes through one generation per year so we knew that all the animals in the second year were the offspring of those in the first.  By comparing the genetics of the potential parents with those of the potential offspring we were able to assign offspring to parents to produce a much more accurate picture of this concept of “fitness”.  Unfortunately, what we found was that our behavioural measurements did not reflect this more accurate measure of fitness.

Importance: Since the concept of fitness is so important to evolutionary biology, it is important to test the assumptions of the studies that have sought to measure it.  We have demonstrated that some of those previous studies were not using particularly reliable proxies for fitness.  However, we have provided a case study of a potential method for avoiding these problems: by directly genotyping and assigning parents to offspring in the field we can get a much clearer picture of what “fitness” really means.


This is part of a series of short lay summaries that describe the technical publications I have authored.  This paper, entitled “Field estimates of reproductive success in a model insect: behavioural surrogates are poor predictors of fitness”, was published in the journal Ecology Letters in 2011. You can find this paper online at the publisher, or on Figshare.

Image credit: One of mine, CC-BY 3.0

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