The colourful world of crab camouflage

How changes in colouration and behaviour enable marine arthropods to survive in a diverse environment

Who is the hero of Professor Martin Stevens? As he told the staff and students of the university this Monday, it is the famous naturalist Alfred Russel Wallace, who inspired Professor Stevens to pursue research into camouflage and colour in nature.

“Among the numerous applications of the Darwinian theory… none have been more successful, or more interesting, than those which deal with the colours of animals and plants” (Wallace 1889).

This Monday, the School of Biological Sciences was visited by Professor Stevens, who spoke about the mechanics of camouflage and its adaptive value in nature through studies of within-species diversity and habitat matching inshore crabs and chameleon prawns.

Camouflage seems like an easy concept to grasp.

We have all heard of the rapid colour change in chameleons. However, as Professor Stevens explained, it isn’t quite that simple. Firstly, the majority of colour change in animals is continuous and gradual, unlike that of the famous chameleons and cuttlefish. Additionally, this style of camouflage (background matching) is just one of many types that animals employ to disguise themselves in their environments.

Professor Stevens elaborated on this in his case study of the common shore crab Carcinus maenas. This highly adaptable organism shows a huge variation in colours and patterns, which seems in part associated with background matching to the environment individuals are in. Both in mudflats and in rocky shores, the two differently coloured habitats we find these crabs in, the crab’s colour pattern is related to their habitat. Professor Stevens also revealed that crabs showed behavioural preferences to match to certain backgrounds as well.

Interestingly, these crabs also change appearance with age, gradually become duller and tending to lose their markings and converging on a universal dull green colour.

They seem to all adopt this generalist camouflage because while they get less mobile as they age, it might not be adaptive to keep matching the background if constantly moving; this strategy was found to be surprisingly effective, through analysis of a citizen science game at the Natural History Museum! Additionally, it was interesting to hear how individual diversity in these crabs is due to different camouflage strategies, such as disruptive colouration, and how complex markings can defeat predator search images and drive apostatic selection (i.e. rare appearances being more successful in avoiding predation).

Chameleon prawns (Hyppolyte varians) have even weirder and wonderful camouflage than the crabs, some being bright green, red, or transparent.

These creatures can change colour to match seasonal changes in substrate, although again this change takes 14-21 days; it is not quick like the chameleons! Therefore, some behavioural choices are needed to allow them to effectively camouflage in the short term. They seem to prefer seaweeds that match their body colour, and this is an effective strategy as survival rate has been shown to be higher on matched background. Parallels exist with a more exotic species in Brazil; nicknamed ‘carnival prawns’, the males can also be transparent, since they are less likely to sit on algae and are more mobile while in search of females.

Finally, Professor Stevens discussed questions for possible future study: Why do they change in colour at night? Why does light intensity affect the strength of camouflage? And, most intriguingly, can these prawns see in colour vision? To finish, the influence of anthropogenic change on these organisms was discussed in the context of how increasing water temperature and ship noise pollution might affect their camouflage abilities.

Written by Esme Hedley, Biology (BSc) and Miren Porres, Zoology (BSc)

Smart scientist studies smart butterflies

During his seminar on Monday, Dr Stephen Montgomery explained how his multi-disciplinary team tackles questions of cognitive adaptation, neuroecology and evolution in butterflies. Coming to us from the University of Cambridge, Dr Montgomery’s presentation was all the more interesting as he will be joining us in the School of Biological Sciences in September.

How does cognition relate to evolution?

This may seem like a daunting question, but Dr Montgomery has made it his career. Whilst initially working on primate brain evolution as part of his PhD, Dr Montgomery now leads a team of scientists studying ecological neurobiology in two clades of Neotropical butterflies, Ithomiini and Heliconiini. His research involves many collaborators and a range of experimental methods.

However, what Dr Montgomery described as “the main story” of his research concerns pollen feeding in Heliconius butterflies. The story begins in the 1970s when Larry Gilbert and colleagues pointed out that Heliconius butterflies were the only butterflies that collect and digest the pollen grains of Cucumis anguria. These pollen grains are the butterflies’ ‘elixir of life’, as they provide rare amino acids, which lead to greater longevity and halt senescence. However, whilst these plants are a reliable food source, they are very sparsely distributed. Gilbert thus concluded that Heliconius learned specific “trap-lines” to attain this food source. Later on, John Sivinski suggested that this enhanced ability for learning and memory is associated with an enlarged region of the insect brain, the mushroom bodies.

Dr Montgomery and his colleagues are now investigating the Heliconius mushroom bodies and their relationship to cognition and evolution.

The Montgomery team started with morphometric analyses of the Heliconius mushroom bodies and compared these to closely related Lepidoptera species. Although the data are not entirely collected yet, Dr Montgomery told us that the Heliconius mushroom bodies are “ridiculously bigger” than in other butterflies.

Whilst it is clear that Heliconius have enlarged mushroom bodies, Dr Montgomery wanted to know if this translated into different processing of sensory information. In an impressive feat of computer modelling, Dr Antoine Couto, a member of Dr Montgomery’s team, produced 3D models of Heliconius brains that suggest the presence of a relatively larger projection zone coming from the ventral lobula, which receives visual information. This would be consistent with the hypothesis that Heliconius learn these “trap-lines” with visual cues.

But Dr Montgomery was not content with a suggestion, he wished to confirm this with a large-scale behavioural experiment. Designing this experiment was challenging as Heliconius seem to only learn visual cues on a large spatial scale. Thus, Dr Montgomery and his team sought out ways to conduct comparative behavioural experiments.

This work is still ongoing, but Dr Montgomery already has pilot data coming from his PhD student Fletcher Young in Panama which explores whether enlarged mushroom bodies are associated with differences in learning performance. For example, Young is testing whether Heliconius can reverse an initial colour preference bias through conditioning training. Heliconius and other closely related butterfly species are being put through this training and after a certain amount of time, they can be assessed to test subjects had retained the information. Therefore enabling a test of whether or not enlarged mushroom bodies are associated with variation in learning and memory traits.

As previously mentioned, Dr Montgomery’s investigation of butterfly cognition is impressive by its scope of different approaches. As part of his team, Dr Francesco Cicconardi and Laura Hebberecht-Lopez are also investigating the developmental process of the Heliconius mushroom bodies. They will be undertaking a comparative developmental study of mushroom bodies across several species to identify the “turning point” which characterises Heliconius’ enhanced cognition.

The study will involve monitoring brain anatomy from larva to adult stages and analysing the corresponding transcriptomes.

Finally, Dr Montgomery expressed his wish to conclude this study by a functional characterisation of the candidate genes associated with the mushroom bodies, although he admitted that it might take them a few years until his team gets there. Nevertheless, his results so far are outstanding. I was particularly impressed with the scope of disciplines that his team unite to offer a solid and complete investigation of insect cognition, to an extent which I had never heard of before.

As usual, the seminar ended with some friendly drinks in our building’s Sky Lounge. Whilst overlooking Bristol on a sunny afternoon, Dr Montgomery expressed his excitement at the prospect of moving to our vibrant city and joining our just as vibrant academic team. I can say without a doubt that the sentiment is reciprocated.

Written by Violette Desarmeaux, Biology (MSci)

A dive into the world of dolphin communication

Dolphins are almost celebrities of the animal kingdom, globally adored for their intelligence, personality and aerial displays.

But to what extent do we know why they do what they do? Someone who tries to answer this question is Dr Stephanie King, one of the University of Bristol’s newest senior lecturers who has spent years studying these charismatic mammals. Those of us in this Monday’s seminar were treated to a fascinating look into what life is like studying bottlenose dolphin behaviour, and a sneak peak at Dr King’s new research which investigates the mechanisms behind how dolphins communicate, and the ways in which they can coordinate their behaviour.

Firstly, Dr King introduced us to the social structure of bottlenose dolphin communities.

Her research focuses on males, which congregate in groups called alliances, of either first (2-3 individuals) or second (4-14 individuals) orders. Alliances are aggregates of males, who form lifetime bonds with one another to coerce females into copulation with chosen members of the alliance. Associated behaviours have been analysed by Dr King and her colleagues during follows of the KS alliance, which habituates Shark Bay in West Australia. Currently made up of 7 males, each member can be confidently identified from characteristic nicks and cuts in the dorsal fin of each individual, acting almost like dolphin fingerprints. We were also told that alliance hierarchy is mysteriously complex: there is no linear dominance hierarchy; allied preference is not with kin; and that in fact age (mainly bonding in the juvenile period) can predict alliance formation. The adaptive value of these alliances is high, as male fitness (lifetime reproductive rate) is dependent on alliance formation and membership.

Throughout her talk, Dr King ensured the audience saw the dolphins in action, allowing us to understand and visualise exactly what the behaviours were that she was talking through.

This was done with the use of drone footage that accompanied the explanations, which included incredible birds-eye view shots of phenomenons such as the coordinated butterfly display. Other alliance behaviours explained by Dr King were those such as a ‘tangos‘ and petting.

Not only are visual behaviours important for the efficient functioning of the alliances, but so are acoustics.

‘Pop trains‘, like the name suggests, are a series of successive popping sounds which encourage females to come closer to the males. Dr King and colleagues wanted to know if these pop trains could be synchronised within the alliance. The adaptive value of this was discussed, one idea being that it could possibly encourage bonding through cooperation by promoting oxytocin release. Also posited was that highly synchronous pop trains could be a signal of a high-quality alliance.

Dr King gave the audience a first look at some unpublished research

While the ability of the dolphins to cooperate has been steadfastly proven, the question remains whether the dolphins actually understand what cooperation is; that is, do they understand that they need the exact role of their partner in doing certain tasks (Fig. 1)? Or are individuals actually responding to learned social and environmental cues? Dr King gave the audience a first look at some unpublished research that is pulling apart the possible mechanisms behind previous findings regarding these ideas. Dr King signed off the seminar with other suggested hypotheses for further study, such as whether personality influences cooperative partner choice. The seminar concluded with an animated Q&A and some lively debate, which without doubt continued afterwards in the Sky Lounge over lunch.

Figure 1: Photograph lifted from Jaakkola, Guarino, Donegan and King (2018). An aerial view of a cooperative task apparatus used to test dolphin understanding of cooperation.










Written by Esme Hedley, Biology (BSc) Year 2

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From protists to whales: predicting the future of biological systems

Complex biological systems are notoriously unpredictable, but forecasting their fate has arguably never been more important. In a recent seminar in the School of Biological Sciences, Dr. Chris Clements describes his latest research in this emerging field at the interface of ecology and conservation science.

The world is facing an unprecedented biodiversity crisis. As mankind’s ecological footprint grows ever larger, the rate of environmental change continues to accelerate. Identifying at-risk populations or ecosystems before they are irretrievably lost or damaged is becoming an increasingly important goal for conservationists, but predicting how complex biological systems will respond to evolving pressures is challenging.

One way of forecasting the future trajectory of biological systems is to use system-specific models founded on a detailed understanding of the underlying ecological processes. In practice however, scientists’ ability to do this is constrained by a scarcity of in-depth knowledge for the vast majority of ecosystems. An alternative strategy is to concentrate on inferring changes in the underlying state of the system from trends in more readily available data, such as estimates of population abundance. This approach is based on detecting statistical patterns or ‘early warning signals’, which can potentially be used to alert conservationists to the imminent danger of a sudden and catastrophic shift within an ecosystem, or the impending collapse of a population. A large part of Dr. Clements’ current research is focused on testing and extending these techniques.

“Under sustained pressure, the system will eventually reach a tipping point where it is so unstable that even tiny disruptions can trigger an abrupt change”

Dramatic shifts within ecosystems can occur when a change in conditions overwhelms the capacity of the system to return to its original state. Under sustained pressure, the system will eventually reach a tipping point where it is so unstable that even tiny disruptions can trigger an abrupt change. A classic example is the rapid transformation of pristine coral reefs due to declines in the abundance of algae-grazing marine life. While transitions to so-called ‘alternative stable states’ are often difficult to reverse, in theory, it should be possible to detect them in advance: as tipping points approach, predictable changes in statistical signals should become apparent.

Despite the potential usefulness of abundance-based early warning signals, the inherently noisy nature of population estimates can sometimes lead to unreliable predictions. Animals living in complex and inaccessible landscapes are usually elusive, and it can be tricky to estimate population sizes with confidence. One possible solution to this problem is to combine or replace abundance-based early warning signals with information on trends in key individual traits, such as body size, which can be estimated more reliably. Crucially, shifts in the distribution of body sizes within the population at-risk can be indicative of deteriorating environmental conditions, and of a population under strain.

“Dramatic shifts in the variability of body size also predicted plummeting worldwide populations of blue, fin, sei and sperm whales during the historical period of commercial whaling”

By describing his recent experiments on microcosm populations of the predatory protist Didinium nasutum, Chris showed that the collapse of stressed populations was preceded by a sharp decline in mean body size. Switching focus to an analysis of whale populations during the 20th century, Chris went on demonstrate how dramatic shifts in the variability of body size also predicted plummeting worldwide populations of blue, fin, sei and sperm whales during the historical period of commercial whaling. In both cases, trait-based early warning signals produced more accurate predictions about timing of population collapses, compared to those based on measures of abundance.

While our understanding of trait-based early warning signals is progressing rapidly, there is still much to learn about how these techniques can be applied to identify at-risk biological systems in the real world, where populations differ markedly in the rate of environmental change they are exposed to. Using both mathematical models and experimental microcosms, Chris’s research group is currently focused on tackling a range of unresolved questions in this area.

Written by Andrew Szopa-Comley, PhD student in Biological Sciences

Ageing in a social world; what can animals tell us?

A prominent voice in the field of animal behaviour, Dr Lauren Brent discusses her research into the interaction of ageing and sociality with a fascinating look at the lives of two charismatic social mammals.

Dr Lauren Brent seems to live an animal behaviourist’s dream. Not only does she travel the world studying some of the world’s most interesting animals, but she also shines a light on the physiological and evolutionary explanations behind their behaviour. This Monday students and staff were treated to a look at how age affects an individual’s engagement with the social world, and on the flipside of this, how the pace at which individuals age is affected by social processes. These two themes were neatly explored using Dr Brent’s research on the southern killer whales of British Columbia and the charismatic rhesus macaques of Cayo Santiago, Puerto Rico.

It became immediately apparent in the seminar how passionate Dr Brent is about her work and how carefully she selected the subjects for her research. Breaking the talk into two sections, she first spoke about how aged based differences in these two animal groups affect their social interactions. The killer whales were followed to see how this impacted on their collective movement, questioning whether, and if so why, older, post-reproductive females led group movement. On the other side of the world, data associated with grooming and aggressive encounters between female rhesus macaques were collected to see whether age affected the frequency and reciprocity of these social interactions.

“Southern resident killer whales are one of only five species known to undergo menopause”

Southern resident killer whales are one of only five species known to undergo menopause, and there is no sex-based dispersal in populations, with the family unit choosing to stay together for life and outbreeding. The long post-reproductive period of females (lasting any time up to fifty years) is similar to humans’ in its length, and it was unknown what influence this had on the sociality of the older females. In Dr Brent’s 2015 paper, a study of over nine years’ worth of video footage of the whales was visualised into leadership networks. This resulted in the discovery that in comparison to males, females were more likely to lead and that relative to younger females, post-reproductive female whales were the most likely leaders. To understand these results, further study was undertaken to find the situations in which the older females were more likely to lead. This research revealed that older females were more likely to lead when populations of chinook salmon (the species making up at least 85% of southern killer whale diet) were low. It was apparent then that as their age increased female whales became more important in directing the collective movement of the pod, perhaps a clear indicator that the enhanced world experience that comes with age influences how these individuals engage with their social world.

“The population of rhesus macaques on Coyo Santiago was perfect for her research because of its extensive life history records and closed gene pool”

Described by Dr Brent as ‘despotic and nepotistic’, the population of rhesus macaques on Cayo Santiago was perfect for her research because of its extensive life history records and closed gene pool. Like the killer whales, the social structure of the population was explained as being a close-knit community in which the females stay (philopatry) but where the males disperse. Habituating a predator-free, food-rich environment exposed the social pressures of group living and highlighted the aggressive, competitive nature of the macaques. To see if the age of the individuals affected the frequency and intensity of their social interactions, the exposure of females to grooming and aggressive encounters was studied. No evidence was found to show older females received less grooming than younger females, and no evidence was found that they ‘gave’ less aggression. However, it was discovered that older females gave out less grooming and received less aggression, clearly showing at some level age is affecting social engagement. Dr Brent discussed with us the questions left to answer as a result of this research; these older females were still active and engaged with the group, but what were the consequences of age in relation to this interaction which meant they were received differently by their relatives?

To analyse the interaction between ageing and sociality from the opposite direction, Dr Brent now wanted to see whether the pace at which individuals age is affected by social processes. In the macaques, it as was hypothesised that more socially integrated females lived longer. In this study, as a proxy for social integration, the number of close relatives in the troop was recorded for each of the 276 females in the study. Dr Brent revealed to us that for ‘prime-aged females between the ages of 6 and 17, every relative added decreased the probability of dying the next year by 2.3 %’. Interestingly, this was not the same for older females, where their level of social integration had no effect on their survival the next year. Again, this poses the question of why; as Dr Brent proposed, “do females have an alternative route to success?’.

The lecture was rounded off with an exclusive look at some of Dr Brent’s unpublished research and a first look at the new projects she has coming up, including investigating the possible evolutionary drivers behind sociality and ageing. The audience was also left with some questions to think about regarding the physiology behind ageing in a social world. Do all tissues age at the same pace? Are they equivalently impacted by sociality? And is this ageing the same for males and females? While ageing may be the focus of this field, it is young in its development and there are many exciting questions yet to be answered.

Written by Esme Hedley, Biology (BSc)

“Rewilding is active, controversial, exciting and happening”

One of the frontiers in the UK, Dr. Paul Jepson outlined his journey engaging with the process of rewilding, beginning in 2005, when he heard about work being undertaken in the Netherlands.

Rewilding is the process of restoring ecosystem dynamics and function at various levels; it can be condensed into the ‘3 C’s’;


  1. Securing core areas
  2. Connecting these core areas
  3. Re-introducing large carnivores

The loss of micro-habitat diversity due to the reduction of megafauna and large herbivores brings into focus the severe need to restore ecosystem function around the world on a large scale. Rewilding has been suggested as a solution to this. It aims to generate new natures that are ecologically richer than those before. As Paul said – it’s all about moving forward.

The study and application of rewilding has become much more prevalent in recent years with many articles and scientific papers being released on the subject. Despite being still in its relative infancy, there are many current cases of rewilding such as species reintroduction in the UK and the development of hybrid ecosystems in Australia.

The development of rewilding may signify a new environmental narrative in which people can readily challenge governments to take actions to change the recovery and wellness in nature to surpass previous standards. Dr. Jepson’s narrative structure of ‘Recoverable Earth’, in which recovery of the environment was the final outcome, was a refreshing notion.

Paul spoke briefly about the rewilding poster child project in Nijmegen in the Netherlands:

This project was highly successful and created a huge diversity of habitats within the small area which boosted the public opinion of the scheme. Dr Jepson also spoke about the vast socio-economic benefits of rewilding with its positive impact on property values, life quality and job opportunities in Nijmegen.

Controversies surrounding rewilding included the mention of the starvation of large herbivores that were reintroduced into the Oostvaarderplassen nature reserve and the consequent public outrage in the Netherlands. Paul spoke about ‘kept wild’ animals in rewilding schemes as wild animals under management by humans (as is the norm in Southern Africa) being the most viable way to tackle current restrictions faced by domesticated animal laws; such the legal requirement to remove a carcass of a domestic animal within 3 days of death. This restricts the processes associated with carcass and scavenger ecology, which in turn restricts trophic expansion within the rewilding environment. De-domestication policies are being thought up that will enable rewilding schemes to have maximum success in trophic expansion through carcasses of ‘kept wild’ animals being reintroduced into food chains.

The seminar was closed with some thoughts on the future of rewilding. Paul spoke about the exciting future projects that rewilding has to offer and the likelihood that they will interlink with advances in technologies within the ever-expanding areas of biological sciences.

Written by Nina Blampied (year 2 Zoology BSc)

Professor Tracy Lawson talks about the effects of fluctuating light on photosynthesis and stomatal behaviour

This Monday Professor Tracy Lawson from the University of Essex talked to students and academic staff in Bristol about her last findings in the survey of stomata behaviour as a response to different environmental stimuli.

This Monday, Professor Tracy Lawson from the School of Biological Sciences of the University of Essex talked to students and academic staff of the LSB in Bristol about her last findings in the survey of stomatal behaviour as a response to different environmental stimuli. During the last 6 years, she and the members of her lab have been working on stomata, water assimilation rates and CO2 gain, the speed of response of stomata in different light conditions, and the importance of studying this topic according to current and future global environmental conditions such as increases in temperatures worldwide, more food production using less land, changing rainfall patterns and lack of water sources for demanding irrigation crops.

During the first part of her talk, Professor Lawson talked about how different plants have different patterns of stomatal behaviour and how these respond differently according to plant phenotype and environmental conditions. Just to mention an example, rice can get a maximum carbon assimilation rate of 95% in only 10 minutes in comparison to Ginkgo biloba that takes one hour to reach a similar rate.

To know more about how plants respond to light fluctuations and climate, Professor Lawson mimicked natural fluctuations in light over a diurnal period to examine the effect on the photosynthetic processes and growth of Arabidopsis (Arabidopsis thaliana). She compared the plant’s behaviour under square wave light and fluctuating light conditions. Under the first treatment, plants responded with thicker leaves, more photosynthetic efficiency, better leaf structure and more proteins associated with electron transport. Plants under the second treatment produced thinner leaves, lower light absorption and slower growth. Under both conditions, plants maintained similar photosynthetic rates.

However, these results highlight that there is a negative feedback control of photosynthesis resulting in a decrease of diurnal carbon assimilation under fluctuating light conditions and that plants under square wave light fail as predictors of performance under realistic light regimes.

The following part of her talk was about the impact of dynamic growth light on stomatal acclimation and behaviour. Professor Lawson assessed the impact of growth light regime on stomatal acclimation and gas exchange growing Arabidopsis plants in three different lighting regimes:

  1. with the same average daily intensity,
  2. fluctuating with a fixed pattern of light, fluctuating with a randomized pattern of light (sinusoidal), and non-fluctuating (square wave).

With this experiment she and her research team demonstrated that gs (stomatal conductance to water vapour) acclimation is influenced by pattern and intensity of light, modifying the stomatal kinetics at different times of the day and resulting in differences in the rapidity and magnitude of the gs response. They quantified the response to a signal that uncouples variation in CO2 assimilation and gs over most of the diurnal period. This can be translated as 25% water loss during the day without CO2 assimilation. The gs response can be characterized by a Gaussian element when incorporated into the Ball-Berry model to predict the gs in a dynamic environment.

Professor Lawson concluded that acclimation of gs to light could be an important strategy for maintaining carbon fixation and overall plant water status and should be considered to infer responses of crops under field conditions.

Written by Carlos Gracida Juarez (Biological Sciences PhD)

Research Seminar with Professor Eric Morgan

What killed over 200,000 saiga antelopes in Kazakhstan in 2015 and should it change how we think of wildlife disease?

As a species that inhabits vast regions of the Kazakhstan steppe and maintains one of the most magnificent migratory patterns in the world, it is no wonder that the mass mortality event of 2015 that killed over 200,000 saiga antelope became a global cause for concern.

In his seminar, Eric Morgan, a Professor at the School of Biological Sciences at Queen’s University Belfast, outlined the scientific response to such a mass mortality event, placing particular emphasis on the challenges he and his research team faced in the identification of the causal agent.

Saiga antelope, distinct due to their bulbous nose, roam the planes of Kazakhstan, migrating vast distances from winter to summer to aid survival in harsh environmental conditions. Once abundant, the species has experienced a series of population crashes since the collapse of communism due to a corresponding crash in livestock numbers, resulting in an increase in hunting.

Due to their complex migratory patterns, the saiga antelope is difficult to conserve, therefore mobile nature reserves were constructed by local authorities in response to their decline. This resulted in significant population growth, making the initiative “a great conservation success story”, as described by Eric.

However, the story doesn’t end there. In 2015 Richard Kock, Professor of wildlife health and emerging diseases at the Royal Veterinary College in London, discovered a vast graveyard of saiga antelope that had aggregated in central Kazakhstan to calve.

As a keystone species, this mass mortality event attracted a flurry of media attention and demanded urgent answers as to what had caused so many saiga antelope to die over a minute timescale. A meeting hosted by the UN resulted in the construction of a core research team, of which Eric Morgan was a key member.

Having never seen anything of this nature before, Eric went on to explain some of the atypical features of the scene that stumped researchers, such as even spacing of carcases, indicating an almost synchronised death of antelopes at the time of calving. Additionally, dead calves were found with their stomachs full, which is unusual as orphaned calves typically die of starvation. Therefore, this indicated to the research team that whatever had killed the adults had been passed to the offspring during feeding.

Symptoms included weakness, diarrhoea, respiratory difficulties and internal haemorrhages. Eric described the project as uncomfortable and difficult to be involved in not only due to the tragedy but due to the lack of time to respond, stating that “it was so up in the air”. The research team, therefore, were denied the time to generate and develop full hypotheses, finding themselves testing hunches, not factors. A working hypothesis table was constructed, detailing circumstantial causes rated from high to low probability. This table can be found supplementary to Eric’s paper.

The team ruled out many bacteria and viruses along with heavy metals as causal factors. A laugh was shared as Eric displayed a picture of his arm covered in mosquitoes, explaining how he had to let day-feeding mosquitoes land on him so that they could be picked off and sampled to rule out a vector-borne disease.

Finally, a diagnosis of Pasturella multocida was made, again puzzling the research team in that the bacteria is very common in the tonsils of carrier animals, so why doesn’t it cause a mortality every year? A factor within the saiga population must have been changing for bacteria carried in the tonsils to suddenly begin to invade the rest of the body. So far, further research does not show any differences between bacteria that breach the intestinal mucosa and that carried on the tonsils.

Eric continued by highlighting other interacting factors that may form additional pieces of the puzzle such as climate and parasite invasion. Climatic data at the time of past die-offs was collected and a principal component analysis developed. It was concluded that past die-offs had climatic factors in common, such as above 80% humidity and greater precipitation. Eric described this as a ‘climatic

signature’ but, highlighted that the link is weak as it is difficult to associate something out of the ordinary, a mass mortality event, with a variable factor such as climate.
But how do parasites enter the picture? “Humble gut-worms” stated Eric. Parasites invade the intestinal mucosa having dramatic effects on protein metabolism, and the effects may be accelerated during pregnancy. During late pregnancy and early-lactation, the mother directs proteins towards the developing calve, therefore is immunosuppressed and subsequently more vulnerable to bacterial infection.

Eric concluded by stating the team have only got so far in making definitive conclusions and that research is still ongoing. He commented that he is very pleased to have been involved in “a real conundrum” and described the experience as “most satisfying”.
It is possible that nothing can be done to prevent mass mortality events like this from affecting the saiga antelopes in the future. Therefore, research must focus on ways to develop populations large enough to “survive the hit”. However, it is important to acknowledge that this is relevant beyond the saiga system. Climate change is having a profound effect on host susceptibility and virulence. Adaptation to new conditions may be possible however room for manoeuvre is required. Eric stated “Leave parasites alone as they are part of the natural system? Maybe we cannot think like that anymore”.

The lecture was rounded off with a couple of questions, with one audience member enquiring as to whether the research team sought to treat any of the antelopes to try and increase the population back up to a sustainable level. Eric replied by stating “there is no time to intervene in something of this scale and would you want to?” He explained that the knee-jerk reaction may be to start feeding the saiga population hay and pasture, but that may lead to population aggregation around the food source and disease spread. “You have to think very carefully before you intervene in natural systems”.

Written by Beth Harris (year 3 Biology MSci)