Some hoverflies look like stinging wasps and bees – some even act the part!

Picture1Background: Animals and plants can benefit by resembling other species. For example, some plants have spots that look like ants to deter herbivores, cuckoos look like hawks to frighten smaller birds from their nests, and harmless snakes have striped bodies that resemble highly venomous species. However, there are other modes of resemblance: animals and plants can smell, sound or act like another species in addition to (or instead of) having visual resemblance. However, we don’t know much about how different types of mimicry interact in the wild.

What we did: Heather Penney, a MSc student at Carleton University, collected individuals from 57 species of hoverfly. Hoverflies are famous for having some examples of very close visual mimicry of stinging wasps and bees, but in some species this mimicry is “imperfect”. It is also known that hoverflies can exhibit behaviours that are characteristic of wasps and bees, and so Heather tried to elicit these responses from each of the species that she caught. She found that only 6 out of 57 species exhibited behavioural mimicry, and that these species belonged to only two genera (i.e. they were all closely related). Furthermore, there was some evidence that only animals that looked a lot like wasps also had behavioural mimicry.

Importance: While behavioural mimicry has been described a number of times in the wild, it is rarely surveyed using such a comprehensive approach – Heather tested every species in a community so that we know that there are a range of species that do not exhibit these behaviours. Also, we show that the behaviours are constrained to relatively few high quality visual mimics which suggests that behavioural mimicry acts to enhance morphological mimicry where that morphological mimicry already exists.

This is part of a series of short lay summaries that describe the technical publications I have authored.  This paper, entitled “The relationship between morphological and behavioral mimicry in hover flies (Diptera: Syrphidae)”, was published in the journal American Naturalist in 2014. You can find this paper on the publisher’s website or for free at Figshare.

Image credit: Photos by Brent Lamborn, used with permission.

How helpful are urban ponds for biodiversity?

pond-84855_1280Background: Urban ecosystems are becoming increasingly important as areas for biodiversity conservation, as we begin to recognise the importance of preserving natural habitat within heavily modified environments for both wildlife and human well being. Urban ponds are a key part of this network of habitats within cities, and are commonly found in parks, gardens and industrial estates. In fact, there are an estimated 2.5-3.5 million garden ponds in the UK alone, which could have an area the size of Lake Windermere!

What we did: I was invited to submit a review of the biodiversity value of urban ponds. This later expanding beyond simply describing biodiversity patterns to include the ecological processes that generate those patterns. I describe a wide-ranging set of potential negative impacts on urban pond biodiversity, including invasive species, mismanagement, pollution, and habitat destruction.  However, I also took great care to highlight the benefits of these habitats in terms of their use in controlling stormwater, their role in local aesthetics, and the way in which they provide access to nature in inner cities. These ponds can be a fantastic resource if managed well.

Importance: Research on urban water bodies has been growing, and this review highlights both the work that has been done up to now and the gaps in our current knowledge that should be filled in the future.

This is part of a series of short lay summaries that describe the technical publications I have authored.  This paper, entitled “The ecology and biodiversity of urban ponds”, was published in the journal WIREs Water in 2014. You can find this paper at the publisher’s website or for free at Figshare.

Image credit: noitulos,, Public Domain.

Damselflies change the colour of their wings when other species are around

Calopteryx maculata M (Four Mile Creek)Background:  Animals and plants have a wide range of colours, and these different colours play different roles in different species. Some species might be signalling to potential predators that they are toxic (like a wasp’s stripes), others might be trying to hide (like a moth’s speckled grey wings), and others might be trying to signal to the opposite sex that they are high quality mates (like a peacock’s train). However, while there are clear functions in principle, the relative importance of different signals might vary depending on the context within which the animal or plant finds itself.  For example, male ebony jewelwing damselflies (Calopteryx maculata) have very dark wings and this is thought to allow females of the same species to choose appropriate mates (i.e. to avoid mating with the wrong species). However, the dark pigment can also play a role in temperature regulation. Damselflies cannot generate their own heat and so rely on absorbing heat from the sun, which is helped by the dark pigment. I was interested in how the darkness of the wings varied between locations which experience different temperatures.

What I did: I wanted to collect specimens of this species for analysis from across its entire range in North America, but the range is so large (Florida to Ontario, and New York to Nebraska) that I wouldn’t have been able to travel to sufficient sites within the one season that I have available.  Instead, I asked a lot of local dragonfly enthusiasts to catch and send me specimens from their local sites. I am extremely grateful to all of them for helping, as this could not have been done without their kind volunteering of time and energy.  I ended up with a substantial dataset of animals from 49 sites across the range. The wings of the animals were clipped from the bodies and scanned using a flatbed scanner, and then the amount of pigment was calculated from the image. I showed that the amount of pigment was pretty constant across the range apart from when the species was found with a similar species: the river jewelwing damselfly (Calopteryx aequabilis). This suggests that there might be an optimal level of pigmentation that is independent of temperature, but that if females start to struggle to identify males of their own species there might be an advantage to changing the levels of pigment.

Importance: There have been a lot of local experiments on the benefits and costs of pigment in animals (including damselflies) but there have been far fewer studies that have looked at large scale patterns in pigmentation.  These sorts of studies are essential to describe biological phenomena in the field and to reveal initial patterns in nature that might indicate interesting or novel evolutionary processes.

This is part of a series of short lay summaries that describe the technical publications I have authored.  This paper, entitled “Continental variation in wing pigmentation in Calopteryx damselflies is related to the presence of heterospecifics”, was published in the journal PeerJ in 2014. You can find this paper for free at the publisher.

Image credit: That’s one of mine!

Damselfly wings change shape in harsher habitats

Background: Odonata (dragonflies and damselflies) are an ancient order of insects. By this, I mean that they have remained largely unchanged since their ancestors evolved 500 million years ago.  They have a fairly unique flight style which is a product of the configuration and use of their wings. Wing length has been used as a measure of odonate body size for many years, but wing shape has received less attention.

What we did: I was interested in whether wing shape varied with latitude in the UK.  The populations living in habitat in the UK are exposed to a range of temperatures depending on location and it might be that certain wing shapes confer advantages in certain habitats. Based on a survey of seven populations of Coenagrion puella, I compared wing shape using a method called “geometric morphometrics”.  This allowed me to look at shape independently of the size of the wing.  I found that the wing shape in the majority of populations was very similar.  All populations in the south of England were comparable, but the populations in the south of Scotland showed a progressive shift away from this “typical” wing shape until a site near Edinburgh which was significantly (if subtly) different.

Importance: Wing shape has been highly conserved throughout odonate evolution (i.e. ancient odonates are similar in shape to present-day odonates). Because even small variations between species are consistent, wing shape and patterns of wing veins have been used to identify species. My study showed that these wing shapes were not as consistent as people had previously thought and that there might be ecological or evolutionary processes that can cause significant variation.

This is part of a series of short lay summaries that describe the technical publications I have authored.  This paper, entitled “Wings of Coenagrion puella vary in shape at the northern range margin (Odonata: Coenagrionidae)”, was published in the International Journal of Odonatology in 2008. You can find this paper online at the publisher, or on Figshare.

Image credit: Lauri, CC BY-NC-SA 2.0,

Online computer programming courses

Computer programming is becoming an increasingly important part of biology (my own discipline) and a range of other subjects.  Programming allows the analysis of data, the creation of software and the building of online resources and interfaces.  There are a range of online courses that you can take to develop these skills, and use as teaching aids for students, that cover a lot of different languages with different applications:


Codeschool offers four key “paths” composed of sets of modules in different programming environments: Ruby and JavaScript (two different methods for online application building), HTML/CSS (web design), and iOS (for Apple apps).  However, they also offer “electives” alongside the main paths, looking at R (an open source programming language), Git (a method for version control in the development of programming), and Chrome Developer Tools (for apps in the Chrome browser).


Codecademy, much like Codeschool, offers a wide range of programming languages. However, all courses through Codecademy are free of charge.  The focus is on web programming using HTML, CSS and JavaScript, and application building using Ruby, APIs, and Python.  Codecademy also allows people to generate their own courses, meaning that there are many smaller sets of tutorials designed to teach specific principles.

An Example of Use
CodeSchool runs a course called “Try R“, which offers a few hours of interactive training in the R environment.  For those of you not familiar with theR language, R is an open source programming language that is mostly built around data manipulation and analysis.  The course itself loads within the website, with a simulated R environment within which the student can work.  The content covered includes: syntax, vectors, matrices, summary statistics, factors, data frames, and “working with real-world data”.  At Leeds we teach our MSc Biodiversity and Conservation students in R for a short period, but this is the kind of tool that the students can use to familiarise themselves more completely with the language.  It could also be a gentle introduction to some of the R-based MOOCs that are run by Coursera.

“Data from above” – quadcopters and thermal imaging in ecology

I’ve been interested in small-scale variation in temperature for sometime, having worked on the impacts of thermal variation on dragonflies for my PhD. However, measuring temperature is a complicated task… Where do you measure? How often? What time of day? I have been thinking about this kind of thing when I started coming across Public Lab projects that were conducting aerial surveys using balloons. That got me thinking about flying, and before you know it I’ve pinched a colleague’s quadcopter and we’re flying (cautiously) around the University of Leeds campus:

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PhD opportunities in ecology and evolution

As part of the new NERC Doctoral Training Program at the University of Leeds, I have two PhD projects to advertise that are now (as of 15th November 2013) open to applicants:

1: DragonFlight: Linking the mechanics and energetics of flight to conservation status and responses to climate change in dragonflies

dragonfly-177338_1280The DragonFlight project builds on my earlier interests in dragonfly dispersal (1), macroecology (2), and flight morphology (3).  There has quite a bit of work done on the flight of dragonflies, but much of this has taken place in the laboratory and has not considered what goes on in the field.  Similarly, there has been quite a lot of landscape-scale work done in the form of mark-recapture studies or analyses of historical records (including my own), but none of this has really tested for the traits that underlie flight ability.  This project will link detailed biomechanical measurements of dragonfly flight to our knowledge of responses to climate change (i.e. range shifts) or conservation status.

2: Teaching old beetles new tricks: applying novel genetic techniques to re-establish a classic ecological model system, Tribolium

I’m really excited about this project.  Andrew Peel, a colleague at Leeds, has been working on the evolution of beetles (and animals in general) for a while and uses Tribolium as a model system.  I have been interested in the ecology of this system for some time and this project represents us banging our brains together. In particular, there are lots of nice ways that we can incorporate Andrew’s contemporary genomic techniques (e.g. RNAi) to test for genetic drivers of ecological phenomena.  The species is also an important pest species of stored grain, making any advances potentially applicable to pest control.

Note that both of these are “competitively funded”, which means that there are more projects than we can fund.  We interview candidates for all projects and then award the best candidates the projects that they applied for.  There are more details on the website, including how to apply.  Deadline is 24th January 2014.

(1) Hassall C, Thompson DJ (2012) Study design and mark recapture estimates of dispersal: a case study with the endangered damselfly Coenagrion mercuriale. Journal of Insect Conservation, 16, 111-120.
(2) Hassall C, Thompson DJ (2010) Accounting for recorder effort in the detection of range shifts from historical data. Methods in Ecology and Evolution, 1, 343-350.
(3) Hassall C, Thompson DJ, Harvey IF (2008) Latitudinal variation in morphology in two sympatric damselfly species with contrasting range dynamics (Odonata: Coenagrionidae). European Journal of Entomology, 105, 939-944.

Communicating camouflage and mimicry: chocolate, hover flies and Teddy Roosevelt


In September I gave a Cafe Scientifique talk at the Leeds City Museum on the evolution of mimicry and camouflage.  For those of you who aren’t familiar with the concept, Cafe Scientifique offers an opportunity for scientists to give short (or long, depending on how it is run) talks on their research to a general audience and then take questions in an informal setting.  I have always been a fan of this kind of outreach, and when Clare Brown, the curator of Natural History at Leeds Museum asked if I wanted to give a talk I jumped at the opportunity.  I spent a bit of time pulling resources together for the talk and I thought I would post them here in case anybody else could find a use for them.  I have outlined the talk I gave below:Read More »

Species with a chemical defence (but not a chemical offence) live longer

Dendrobatid frogs are the classic “aposematic” species: they advertise their toxins with bright colours

I wanted to spend a post talking about a new paper that was published recently (3 May 2013) with some colleagues from Carleton University.  It is easy to see the value of tasting bad: predators try to eat you, feel sick, then leave you alone.  Even better if you have bright colours or a strong smell (called “aposematic signals”) to go along with it – that way predators can learn to avoid your colours without having to taste you a second time.  In fact, they don’t have to taste you at all if other animals of your species also have the bad taste and the bright colours.  In theory, this chemical defence should reduce deaths due to predation which means that the prey live longer.Read More »

While we wait for the open access revolution, self-archive!

I’ve just had a paper published on open access in ecology and evolution, so I thought I would let you know what it’s all about.  I wrote a few weeks ago about how you can often post more of a scientific paper online without violating copyright than you might think.  I went through a couple of journals in which I had published articles, and tried to work out what I could self-archive.  The answer was usually “quite a lot”!  Then someone in the comments popped up and mentioned the SHERPA-ROMEO website, which allows you to search for the name of the journal in which your paper has been published and then shows you the policy on self-archiving.  Well, being the data-lover that I am I decided to check out the rest of the journals in ecology and evolutionary biology (all 165 that were listed on Thomson Reuters Journal Citation Reports).  The results were pretty interesting…

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