There have been a great many legends describing early attempts at flight, with perhaps the most famous being that of Daedalus and his son Icarus. Daedalus created the Labyrinth on Crete for King Minos and the king imprisoned Daedalus in a tower so that he could not spread the knowledge of labyrinth-building to other kingdoms. Daedalus escapes with Icarus, but Icarus flies too close to the sun causing the wax holding his feathers melts and he falls into the sea and drowns. Daedalus, meanwhile, reaches Sicily (750km away). Ovid’s description of the myth states that Daedalus “…flexed each [feather] into a gentle curve, so that they imitated real bird’s wings”, and so this is clearly a calculated (if legendary) attempt to mimic bird flight.Read More »
I’m delighted to announce a suite of additional PhD projects in the School of Biology at the University of Leeds (scheme details are here). These are in addition to the dozen or so competitively-funded projects through our NERC DTP, so please do check there as well if you are interested. Most titles are indicative of the broad research area, but there will usually be a great deal of flexibility in the nature of the project depending on the interests of the student. The deadline for all projects is Thursday 29th January 2015, and applicants will need to have submitted a research degree application form (see our “How to apply” page) and be in receipt of a student ID number prior to application for the scheme. Briefly, the titles are:
The Evolution of Plant Form
Marine microbial processes and interactions
Improving piglet survival and subsequent performance
Managing soil plant processes to enhance the sustainable intensification of agriculture
Emerging Infectious Diseases
Continental trends in, and drivers of, the spread of European aquatic invasive species
Biomimicry, biophilia, and urban design solutions
Identifying and investigating factors which improve sow performance in Irish pig herds
See the project summaries below for more details.Read More »
Something 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 »
For the two or three people who actually pay any attention to what I get up to here, you might have noticed a bit of a theme over the past couple of months: large numbers of posts (an anomaly in itself!) summarising some of my papers. I set myself the task of writing these lay summaries to try to make my work a little bit more accessible to people who might be interested in the topic but who might not have access to the paper, have the technical skills needed to interpret the findings, or who simply don’t have time to go and read a 7,000 word scientific article.
I’m pleased to say that I am (nearly) up to date now, and you can see the fruit of my labour here or click the green links labelled “lay summary” next to each of my papers on my publications page. There are 30 summaries in total, with a couple missing for the most recent papers. Trying to make research more open and accessible is a personal passion, and so I’d love to hear what you thought of this. Is it useful? Is anything still unclear? Drop a note in the comments and let me know.
Background: It is thought that all animals age: they show an increased probability of death at greater ages. However, the lifespans of many animals vary widely. What is it that determines whether or not an animal lives for one year or one hundred years? One of the key drivers is thought to be how likely you are to be killed by something else. Those animals that that are unlikely to be eaten, whether that is because they are very large (elephants), well armoured (tortoises) or poisonous (poison dart frogs), tend to evolve lower rates of ageing. After all, if you are going to live for a long time anyway, you might as well make the most of it. On the other hand, if you live precariously from day to day then there isn’t much point in investing later in life because you probably won’t get that far.
What we did: We compared lifespans of amphibians and snakes that either had a chemical defense (in amphibians) or venom (in snakes) with those that did not have those traits. We showed that (accounting for their evolutionary history) poisonous amphibians had a significantly longer lifespan than non-poisonous amphibians, but there was no difference in venomous and non-venomous snakes.
Importance: This study has two major implications. The first is that it is vital to incorporate evolutionary history into these sorts of analyses. We had built our study on the findings of an earlier piece of work (which did not account for evolutionary history) that suggested that the snakes also showed a longer lifespan when they were venomous, but our results refute that earlier finding. Second, our findings offer yet more evidence for an offensive role for the origins of snake venom, which has been suggested in other recent studies.
This is part of a series of short lay summaries that describe the technical publications I have authored. This paper, entitled “Species with a chemical defense, but not chemical offense, live longer”, was published in the Journal of Evolutionary Biology in 2013. You can find this paper at the publisher or for free at Figshare.
Background: As well as publishing in ecology and evolutionary biology, I am also interested in how that publishing industry works. There is a clear need to disseminate information as widely as possible in order to accelerate the rate of testing of new theories and discovery of new information. However, some publishing models (and some publishing companies) hide scientific research away so that most people do not have access to that work. Self-archiving is a way for researchers to make available certain forms of their research without breaking copyright (which is almost always handed over to the publishers).
What I did: I reviewed some of the literature on the benefits of self-archiving, in terms of the access to the general public and what has become known as the “open access advantage”: papers that are more openly available are cited more. I also show that over half of all ecology and evolution papers could have been archived in a format that was almost identical to their final, finished format without breaking copyright. I then highlight key methods that researchers can use to self-archive their work: publishing through institutional repositories, third party websites, or self-creation of online portfolios using online tools.
Importance: Self-archiving has the potential to open up research (often funded by taxpayers) to a far wider audience, and this is an important step towards making research more accessible to the general public.
This is part of a series of short lay summaries that describe the technical publications I have authored. This paper, entitled ““Going green”: self-archiving as a means for dissemination of research output in ecology and evolution”, was published in the journal Ideas in Ecology and Evolution in 2013. You can find this paper for free at the publisher.
Background: There are a number of ways in which animals and plants attempt to defend themselves from predators. Sometimes they look or sound like something that they are not, such as another animal or plant that is venomous, in a process known as “mimicry”. Other times, rather than attempting to deceive a predator after being seen, the animal or plant might try to hide altogether. This second defensive strategy, known as “camouflage”, can take a number of forms. One of the most interesting forms of camouflage is “disruptive colouration” which involves breaking up the edge of an animal to make it harder to detect.
What we did: Rich Webster is a PhD student at Carleton University who applied a novel approach to the question of how disruptive colouration helps to hide animals. He used eye-tracking technology with humans as predators searching for digital moths on pictures of trees. With this approach he was able to see where people were looking and how long it really took them to find the “moth”. Importantly, he could also tell how many times they looked at the moth without actually seeing it. We were able to show that the length of time taken to find a target and the number of times that the target was missed were both significantly higher when the moth had a larger number of patches on the edge of its wings.
Importance: Mottled colouration has been observed in many species, but until now we have not had a clear description of the mechanism by which this form of defensive colouration acts. Our results provide that first insight into how and why predators sometimes fail to find prey which are camouflaged in this way.
This is part of a series of short lay summaries that describe the technical publications I have authored. This paper, entitled “Disruptive camouflage impairs object recognition”, was published in the journal Biology Letters in 2013. You can find this paper at the publisher or archived at Figshare.
Image credit: All images are by Rich Webster, and used with permission.
Background: A large number of species are expanding their ranges in response to climate change. This is also true in the damselflies, where the small red-eyed damselfly (Erythromma viridulum) has recently (around 1998) crossed the sea from France to England. Since then, the species has moved hundreds of kilometres north in an unprecedented range expansion (at least as far as European dragonflies and damselflies are concerned). What is less clear is what impact this expansion has had on the species. Are the newly-founded populations the same as those that are resident in France? Can we trace the arrival and expansion of the species through genetic techniques?
What we did: Simon Keat was a PhD student at the University of Liverpool who was lucky enough to be just beginning his PhD when the small red-eyed damselfly first established in the UK. Simon surveyed a number of populations around Europe and in the UK, collecting animals to measure them and extract DNA. With the body size measurements we showed that animals tend to show a strong relationship with latitude: populations further north were much larger and this held for both the older populations in France, Belgium and Germany as well as the newer populations in the UK. Looking at the genetics, we had expected to see declining genetic diversity further north, as a small number of individuals led the charge up the country. However, instead of a decline in diversity in the UK we saw an almost complete lack of genetic pattern. This suggests that the animals were moving in such great numbers that there was not the time for any local patterns to develop.
Importance: Range expansions have important consequences for many aspects of human life: agricultural pests shift and threaten crops, diseases and their vectors shift and threaten human health, and endangered species shift and potentially move out of protected areas. We have shown that during this particular range expansion there has been negligible change in genetic structure but that newly-invaded areas contain relatively large damselflies. Since damselflies are voracious predators, this could have substantial implications of local ecosystems.
This is part of a series of short lay summaries that describe the technical publications I have authored. This paper, entitled “Bergmann’s rule is maintained during a rapid range expansion in a damselfly”, was published in the journal Global Change Biology in 2014. You can find this paper at the publisher or archived at figshare.
Background: 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.
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.