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Archive for the 'ZSL' Category

Calculated Risks:
Foraging and Predator Avoidance in Rodents

By Claire Asher, on 3 October 2014

Finding food is one of the most important tasks for any animal – most animal activity is focused on this job. But finding food usually involves some risks – leaving the safety of your burrow or nest to go out into a dangerous world full of predators, disease and natural hazards. Animals should therefore be expected to minimise these risks as much as possible – foraging at safer times of day, especially when there’s lots of food around anyway. This hypothesis is known as the “risk allocation hypothesis”, but it has rarely been tested in wild animals. Recent research from ZSL academic Dr Marcus Rowcliffe showed that the behaviour of the Central America agouti certainly seems to follow this pattern, and highlights the amazing plasticity of animal behaviour.

Central American Agouti
(Dasyprocta punctata)

Foraging, although essential, is always a compromise between finding food and avoiding being eaten by a predator. The aim of the game is to eat as much as you can whilst avoiding being eaten yourself, in order to live long enough and grow large enough to reproduce. Since finding food is one of the most important things an animal has to do, foraging behaviour has been subject to strong natural selection.

The risk allocation hypothesis predicts that prey species should focus their foraging effort at times of day that pose the least risk. So, if your main predator is active during the day, you best forage at night and vice versa. There ought to be some flexibility in this system too, though – if food in your habitat is plentiful, it should be easy to find enough to fill you and there is little need to take any additional risks. Conversely, if food is pretty scarce, you may be forced to take more risks than usual by foraging for longer or at more dangerous times of day.

In a recent study, academics from the Institute of Zoology, London, in collaboration with colleagues around the world, investigated this trade off between food and predator avoidance in the Central American Agouti (Dasyprocta punctata). The agouti’s biggest problem in life is the Ocelot (Leopardus pardalis), who primarily feed on agoutis. Using radio telemetry and camera trapping, the researchers investigated activity patterns of agouti living in areas with lots of Astrocaryum fruits, and those living in areas with less. They were able to generate an enormous dataset – over 30,000 camera trap records of agoutis, with a further 50 individuals radio collared and tracked!

Ocelots are highly nocturnal, and across nearly 500 camera trap observations, Ocelots were almost exclusively observed at night. During this time, agoutis were under a great deal of risk – the predation risk from Ocelots was estimated to be four orders of magnitude higher between dusk and dawn than during daylight hours. The foraging activity of agouties mirrored this – activity was highest during the day, with peaks first thing in the morning and again later in the afternoon. Most interestingly, these patterns differed for agoutis that lived in habitats with abundant fruit and habitats where fruit was sparse. When food availability was high, agoutis took fewer risks, leaving their burrows later in the morning and coming home again earlier at the end of the day. Overall their activity levels were lower, presumably because they didn’t need to forage for as long to find all the food they needed.

The results of this study support the risk allocation hypothesis, and show that animals are able to make complex calculations about risks and benefits based upon environmental conditions and alter their behaviour so as to minimise risks and maximise benefits. Only when food availability is high can agoutis afford to have a lie-in and avoid any ocelots returning home late.

Original Article:

() Animal Behaviour

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This research was made possible by funding from the National Science Foundation (NSF) and the Netherlands Foundation for Scientific Research

The Importance of Size in the Evolution of Complexity in Ants

By Claire Asher, on 16 September 2014

Ants are amongst the most abundant and successful species on Earth. They live in complex, cooperative societies, construct elaborate homes and exhibit many of the hallmarks of our own society. Some ants farm crops, others tend livestock. Many species have a major impact on the ecosystems they live in, dispersing seeds, consuming huge quantities of plant matter and predating other insect species. One of the major reasons for their enormous success is thought to be the impressive division of labour they exhibit. Theory suggests that, during the evolution of ants, increases in colony size drove increases in the complexity of their division of labour. However, there have been few previous attempts to test the hypothesis. A recent paper by GEE’s Professor Kate Jones and Phd student Henry Ferguson-Gow tested this hypothesis across the Attine ants, a large neotropical group including the famous leaf-cutter ants.

Ants, along with other social insects such as some bees, wasps and termites, are eusocial. This means that reproduction in their societies is dominated by just one or a few queens, while most of the colony members never reproduce, but instead perform other important tasks such as foraging, nest construction and defence. This system initially puzzled evolutionary biologists, because it poses the question, “how do non-reproductive workers pass on their genes?”. More specifically, “how can genes evolve to generate different morphology and behaviour in workers if they never reproduce and pass those genes on?”. This question was resolved in the 1960s, when W.D. Hamilton proposed the concepts of inclusive fitness and kin selection. He pointed out that although members of the non-reproductive worker caste do not directly pass on their genes, they are helping to ensure the survival of their siblings. Closely related individuals, such as siblings, share a large percentage of their genetic information, so by helping relatives, you are indirectly passing on your genes. Inclusive fitness is a measure of the total reproductive success of an individual, including direct fitness (gained by producing your own offspring) and indirect fitness (gained by helping relatives to reproduce). Kin selection, a form of natural selection, can therefore favour genes that cause sterility in the worker caste through it’s positive effects on the reproductive success of relatives.

When eusociality first began to evolve, colonies were probably small and although the worker caste likely refrained from reproduction most of the time, they weren’t completely sterile. In small colonies, keeping your reproductive options open makes a lot of sense – if the queen dies you may have a good chance of taking over the colony and reproducing yourself. Through evolutionary time, however, colony size increased in some lineages, and it is thought this may have driven increasing specialisation and commitment of individuals to their queen and worker roles. As colony size increases, your chances for gaining any kind of direct fitness start to decrease very rapidly. As a worker it’s a much better bet to do what you can to maximise your indirect fitness benefits in large colonies, and this can be achieved by becoming increasingly specialised for your particular role. Increases in division of labour, for example, as individuals specialise more in particular tasks, may lead to increase colony efficiency and success. In turn, this may allow for the evolution of larger colonies, resulting in a positive feedback loop whereby increases in colony size lead to increases in division of labour which lead to increases in colony size, and so on. This force may have lead to the evolution of ant species with enormous colonies – over a million workers can be found in some leaf-cutter colonies!

GEE Researchers Professor Kate Jones and Henry Ferguson-Gow, along with colleagues at the University of East Anglia and the University of Bristol, produced a phylogenetic tree for the Attine Ants (a group containing over 250 species), and mapped social and environmental data onto this tree in order to test for the effects of colony size and environment on the evolution of more sophisticated division of labour. The Attini are a good group of ants to test this hypothesis in, as they show large variation in colony size and the extent of morphological divergence between the queen and worker caste.

They collected published data on social traits (colony size, worker size, queen size) and environmental conditions (daytime temperature, seasonality in temperature and precipitation) for over 600 observations of populations for 57 species of Attine ant, including every single Attine genus. Using supertree methods, they constructed a phylogeny for the attine ants, which enabled them to control for evolutionary relationships and to estimate the speed at which evolutionary changes occurred.

Colony size ranged from 16 to 6 million individuals, with the largest colonies exhibited by the fungus growing leaf-cutter ants Atta and Acromyrmex. The authors found that increases in colony size through evolution are strongly associated with increases in both worker size variation (representing division of labour within the worker caste) and queen worker dimorphism (representing reproductive division of labour). Colony size showed a positve correlation with variation in size within the worker caste, and a weaker, but positive correlation with queen-worker dimorphism. Environmental factors such as temperature, rainfall and seasonality did not have any effect on colony size, indicating that climate and other environmental variables have not been an important factor in driving the evolution of increased colony size.

This study finds strong support for the size-complexity hypothesis, which suggests that during the evolution of eusociality, increases in colony size both drove and were driven by increases in division of labour and in specialisation of the queen and worker castes to their respective roles. This pattern may have also occurred during other major transitions in evolution, such as the evolution of multicellularity, which shares many similarities with the evolution of eusociality (e.g closely related group members, division of labour). The relationship between group size and complexity may therefore have been a crucial force in the evolution of complex life, and in the major evolutionary innovations that have generated the diversity of life we see today.

Original Article:

() Science

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This research was made possible by funding from the Natural Environment Research Council (NERC).

Finding a Place to Call Home:
Translocation and the Plight of the Hihi

By Claire Asher, on 16 May 2014

Climate change alters how climate is distributed both geographically and temporally. Over the coming decades, for species sensitive to climatic variables, it may become a case of ‘relocate or die’ – those species that are not able to shift their populations from old, unsuitable habitat into newly emerging suitable habitat, in line with climate change, will likely go extinct. Conservationists can provide a helping hand to species in this position, however – translocation programs aim to establish populations in appropriate habitat when the species is unlikely to reach it on their own. Determining whether translocations are likely to be necessary in the future, what populations to move and where to move them are complex questions to answer, however. Recent work by researchers at the Institute of Zoology (part of the Center for Ecology and Evolution and affiliated with UCL’s GEE department) developed a framework for understanding species’ relationships with climate and identifying potential translocation sites which will provide suitable habitat through future climate change. For one of New Zealand’s endemic birds, the Hihi, translocation to sites further south may be it’s best chance of long-term survival.

Hihi, endangered bird endemic to New Zealand

The climate is changing. Changes in temperature, rainfall and seasonality are occurring globally, and we are already measuring the effects on wildlife. Often, conditions are shifting geographically, and many species will find that their current range no longer overlaps with any suitable habitat (human land-use change isn’t helping!). In these cases, some species will be able to shift their ranges to account for this, but many species will be unable to do change quickly enough to keep up and instead face extinction. Humans can intervene here by moving endangered species to more suitable habitat, but translocation is expensive and it is crucial to select the new location carefully if the population is to have a chance of succeeding. IoZ researchers set out to develop a statistical framework for determining suitable translocation habitat, using one of New Zealands most endearing but endangered endemics, the Hihi (Notiomystis cincta), to test the framework.

The population of Hihis in Tiritiri Mantangi island offers a special opportunity to study the direct effects of climate change without other variables such as food ability confounding the results. This is because they have been provided supplementary food for nearly two decades. Using data on the reproductive success of females in this population, combined with climate data, Dr Aliénor Chauvenet and Dr Nathalie Pettorelli from the Institute of Zoology, along with colleagues at Imperial College London and Massey University in New Zealand, were able to show that Hihi populations are effected by the climate even when food availability is removed from the equation.

Next, using mathematical modelling, the authors tried to predict the future of Hihi populations, using different simulated changes in climate based upon the variables that were found to be most important in influencing current Hihi populations on Tiritiri Mantangi. Changes in temperature, as well as increases in climate variability had a significant influence on the survival of simulated Hihi populations. The final step was to again use mathematical modelling to predict and map suitable Hihi habitat both now, and in the future. Again, this modelling showed that current Hihi populations are most strongly influenced by temperature, a key variable in determining habitat suitability, with rainfall as another important influence.

Looking forward, under models of predicted future climate change, suitable Hihi habitat is expected to move south. The north of New Zealand, which currently offers highly suitable habitat, is predicted to become almost entirely unsuitable over the next few decades. The most successful reintroduced population of Hihis, as well as the largest and last remaining natural Hihi population both stand to lose suitable habitat by 2050. New suitable habitat is expected to emerge in the southern end of the North Island, as well as the northern part of the South Island, where historically conditions have not been suitable for Hihis.

Because Hihis show population declines as temperatures warm even when we control for food availability, even careful management of existing population may prove ineffective under future climate change. Instead, translocation may provide the only solution to guarantee the long-term survival of the Hihi in New Zealand. Although translocations traditionally perform the role of reintroduction – returning a species to part of it’s historical range – future plans for endangered species like the Hihi need to take climate change into consideration. We should opt for ‘assisted colonisation’ – introducing populations to new habitat that is likely to persist (and perhaps even become more suitable) through future climate change. In this way we can attempt to ‘future-proof’ our conservation efforts and hopefully ensure the survival of many species which might otherwise go extinct as the climate changes.

Original Article:

() Journal of Applied Ecology

This research was made possible by funding from AXA Research and Research Councils UK .

GEE Science Uncovered

By Claire Asher, on 7 October 2013

On Friday 27th September, scientists in 300 cities across Europe got together with the public for a variety of activities and events to celebrate European Researcher’s Night 2013. In London, the Natural History Museum kept their doors open late for ‘Science Uncovered’ – an evening of special exhibitions, stalls and activities, engaging the public with researchers from universities and academic organisations across the capital.

Together with researchers from the Natural History Museum and UCL’s Department of Geography, academics from GEE displayed some of their work and chatted to the public about environmental change. GEE staff and students including Professor Georgina Mace, Dr Sarah Whitmee, Claire Asher and Stuart Nattrass, along with Sara Contu from the PREDICTS Project and Robin Freeman from ZSL, chatted to members of the public about their thoughts on environmental change and biodiversity loss.

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We are now becoming increasingly aware of the rapid climatic changes that are taking place globally, and with the release last week of the latest IPCC report, the climate has been a major talking point. Environmental change, including climate and land-use, will influence both us and the biodiversity with which we share our planet. Some animals may be able to adapt to climatic changes, but these will act in combination with human activities and land-use to influence which species persist and which perish.

PREDICTS Game NHMAs part of the GEE Environmental Change Stall, in collaboration with the PREDICTS Project, and ZSL, Claire Asher and Robin Freeman developed a game to test the public’s perceptions of present and future environmental change and biodiversity loss. Participants were asked to make a guess about future environmental change under two scenarios – a low-emissions scenario in which land-use decisions are based primarily on the agricultural value of the land, and a high-emissions scenario in which emissions pricing influenced land-use decisions. Predicted levels of global biodiversity were estimated up to 2100 using the PREDICTS model and well recognised scenarios of climatic warming and land-use change. The game proved very popular, with nearly 50 players during the night, competing to achieve the best score.

DSC06144 copyThe answer was not as simple as many of our players might have expected. Because climate does not act alone to influence species extinctions, land-use and other aspects of each scenario also played a major role. In the high-emissions scenario, emissions pricing (an attempt to minimise further warming) encouraged the preservation of primary forest, mitigating some of the negative effects of climate change on biodiversity. Meanwhile, in the low-emissions scenario, continued loss of primary forest in favour of agricultural land, particularly for the production of biofuels, meant that biodiversity suffered more than we might have thought from climate warming alone. Our decisions about emissions, land-use and conservation policies will have a far-reaching effect on global biodiversity.

The Future of Biodiversity game will be available to play online soon!

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Award-Winning Bat Conservation

By Claire Asher, on 16 September 2013

This year’s Vincent Weir Scientific award for bat conservation biology has been awarded to GEE’s Charlotte Walters for her PhD work on the iBatsID tool.

The Vincent Weir Scientific Award is an annual award given to a UK-based student for their outstanding contribution to the conservation biology of Bats. It is awarded by the Bat Conservation Trust (BCT), a national organisation devoted to the conservation of bats and their habitats within the UK. Charlotte Walters, who recently completed her PhD with the Zoological Society of London (ZSL), University College London (UCL), University of Kent and BCT, has been awarded the prize for her contribution to bat conservation and particularly her work for the Indicator Bats Program (iBats).

iBats is a partnership between ZSL and BCT, aiming to monitor global changes in bat biodiversity and provide valuable data for policy makers and conservation groups. They provide training and equipment to projects monitoring bat biodiversity to ensure standardised methodology which will enable global comparisons. They have also developed a number of free tools for iPhone and Android which enable fast, simple and efficient detection and identification of bats, and Charlotte’s iBatsID program is a key part of this.

Myotis bechsteini
Image Credit: Gilles San Martin, used under creative commons licence.

During her PhD, Charlotte developed the iBatsID tool, an automatic tool for acoustic identification of European bat ecolocation calls. The tool is able to identify 34 different species of bat based on their calls alone, and is enabling scientists to achieve consistent monitoring of bat populations across Europe. The tool uses ensembles of artificial neural networks to classify bat echolocation calls and identify which species or group the call belongs to. Dr Karen Haysom (Director of Science, BCT) says “New tools and techniques to assist monitoring help us find out more about these fascinating and vulnerable creatures, [and] Charlotte particularly impressed the judges with the innovation and technical quality of her research”.

Eptesicus nilssonii

Bats are ecologically important, playing a key role as predators and seed dispersers. They are also very sensitive to human activities, and are useful as ‘indicator species’ for monitoring biodiversity patterns in general. In Europe, all 52 species of Bat are protected by law as part of the “Agreement on the Conservation of Populations of European Bats“. However, being nocturnal and generally small, they are difficult to detect visually or by trapping. Recording bat calls can allow researchers to survey difficult habitats and gain a clearer picture of what bat species are present and in what numbers. But a standardised statistical method for identifying the species of bat based upon it’s call was needed. This has previously been difficult to achieve, but the recent publication of a global library of bat calls, EchoBank, enabled this type of large-scale identification project to be attempted.

Bat calls vary between species and have been shaped by natural selection relating to species’ ecology. However, calls also vary between individuals within a species according to sex, age, habitat and geographical location, and social environment. Bats also vary their calls depending on what they’re doing – calls are longer when a bat is searching for prey and become shorter as it narrows in on it’s target. So, identifying a species by it’s call is a little more complex than one might expect. Charlotte developed an artificial neural network which was trained on calls of known species and can then be used to identify new calls recorded in the field.

Example of an Artificial Neural Network
Image by Chrislb, used under creative commons licence.

Artificial neural networks are computer models inspired by the central nervous system of animals. They are represented as an interconnected set of ‘neurons’, each of which makes simple calculations which together generate complex behaviour. Artificial neural networks are ‘trained’ first and this training determines the simple algorithms performed by each neuron. The trained network can then be used on real data. In the case of iBats, this involves training the network using calls for which the bat species is known, and the finished neural network can then be used to estimate which species an unknown recorded call belongs to. ANNs are a form of computer learning, and will improve in their accuracy with training – the network of neurons is able to ‘learn’ from it’s mistakes and refine the algorithm to improve classification. This method proved to be highly accurate; 98% of calls from 34 species can be accurately classified into a ‘call-type’ group, and 84% can be classified to species-level.

The iBatsID tool is freely available online, enabling researchers to utilise a standardised methodology for identifying bat species across Europe. This will facilitate large-scale comparative studies and will be particularly useful for studying European bats that have a large geographical range or are migratory. This data will be important for making conservation decisions for the future, and is therefore crucial for bat conservation but also for biodiversity monitoring in general, as bats can provide an accurate assessment of the health of entire biological communities.

Original Article:

() Journal of Applied Ecology

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This research was made possible by funding from the Natural Environment Research Council (NERC) and the Bat Conservation Trust

Summer Science Events

By Claire Asher, on 17 July 2013

July has been an exciting month for science shows – The Royal Society Summer Exhibition ran from the 2nd to the 7th at Carlton House in London, and on Friday 5th July, Soapbox Science took to the south bank for it’s third annual event celebrating women in science.

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Technology for Nature. Dr Robin Freeman (UCL, ZSL) demonstrates Mataki technology

At this year’s Royal Society Summer Exhibition, Technology for Nature, a joint project between UCL, Imperial College London, Microsoft Research and the Zoological Society of London, held a successful stall demonstrating a number of applications of technology to ecology and conservation. A particular highlight was the demo for Mataki, a new tracking technology which can detect behavioural information as well as locational information from a small tracking device attached to an animals back. This technology is being used to monitor the movement and foraging behaviour of sea birds. Professor Kate Jones and Dr Robin Freeman were amongst demonstrators during the week, talking to the public.

“We have a pressing need to better assess the behaviour, distribution and status of many species, and new technologies provide new ways to achieve this. From recording the dynamic behaviour of animals in the wild, to better assessments of distribution and diversity – within the Technology for Nature unit we’re developing and using new technological innovations to understand the natural world on which we rely.”
– Dr Robin Freeman (UCL CoMPLEX, Zoological Society of London)

Now in its 10th year, the Royal Society Summer Science Exhibition is an annual event showcasing cutting-edge research from around the UK. Each year, teams of scientists congregate in London hoping to demonstrate and communicate their science to the public, to students and fellow scientists, to policy-makers and the media. With interactive demonstrations, along with evening events and talks, the Royal Society Summer Science exhibition is a highlight of the year. This year, 24 Universities were selected to bring their scientific innovations to the exhibition, covering topics as diverse as dark matter, glacial melting, antibiotics and ecological monitoring. UCL’s Technology for Nature, in collaboration with Imperial College, ZSL and Microsoft Research, demonstrated three of their innovative projects aiming to apply technological advances to ecological problems.

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One of the highlights of the Technology for Nature stand was the Mataki demonstration, that had members of the public step into the shoes (wings?) of seabirds to test out the revolutionary technology that can not only track animals, but also monitor behaviour. The small, light weight, economical tracking device produces data that enables different types of flight and foraging behaviour to be identified.

Robin Freeman, a research fellow in UCL’s CoMPLEX and head of the Indicators and Assessments unit at ZSL, helped develop the technology: “The Mataki platform provides an open, low-cost tool that researchers can use to record animal movement and behaviour in the wild. By providing a powerful tracking technology in a small, low-cost package, I hope that more researchers are able to gather the rich data that we need to understand the changing behaviour of animals in the wild.”

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Professor Kate Jones (UCL, ZSL) and Dr Robin Freeman (UCL, ZSL) engage with the public to demonstrate Technology for Nature

Professor Kate Jones, from UCL’s Center for Biodiversity and Environment Research, has been working on a number of projects aimed at improving the ease of detecting and identifying bats, and utilising crowd-sourcing as a means to tackle large data sets generated by such technology.

“Developing easily accessible tools with which to identify wild species is critical to engage more people with the natural world and to monitor any changes. Imagine a world where you could hold up your smartphone when you hear a bird call and it would identify the species – like a Shazam app for biodiversity. We are still a way from that point yet but we are progressing with such tools for bats where the first stage is to develop an online tool that can identify bat echolocation calls. We are now developing that into a smartphone application”
– Professor Kate Jones (UCL CBER)

Find out more about the Technology for Nature project.

Soapbox Science

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Julie Dunne (Bristol University)
talking about the history of dairy
consumption.

As the long awaited summer finally arrived in London, so did 12 of the UK’s top female scientists, ready to communicate their science to the public in one of London’s most unusual science events – Soapbox science. Here, scientists are challenged to enthuse, entertain and educate a diverse audience about their research, without the aid of powerpoint slides and scientific jargon. Armed with nothing more than a few props, a Soapbox and a lot of enthusiasm, this years inspiring female scientists were challenged to explain their research to the public.

Soapbox science is a collaboration between the Zoological society of London and L’Oréal-UNESCO For Women in Science, which aims to highlight the struggles faced by women pursuing a career in science and challenge the public’s view of women in science. Soapbox science was created by Dr Seirian Sumner and Dr Nathalie Pettorelli, hoping to inspire a new generation of female scientists.

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Professor Laura Piddock talks about antibiotic resistance, and Dr Emily Cross demonstrates how the human brain perceives complex movement.

Co-organiser, Dr Nathalie Pettorelli (Zoological Society of London) says: “Now in its fourth year, Soapbox Science is a platform to showcase the most eminent female scientists in the UK, and to highlight some very serious issues that we have witnessed as mid-career scientists: the disappearance of our female peers”. Dr Seirian Sumner (Bristol University) adds “Through events like Soapbox Science and our Campaign for Change, we want to actively bring women of all career stages together and promote that women can have a career in science”.

This year’s Soapbox scientists covered topics ranging from gut bacteria to the neuroscience of dance, from computing to antibiotics. Find out more about Soapbox Science

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Soapbox Science in Gabriels Wharf. Dr Zoe Schnepp (University of Birmingham) explains superconducting seaweed and green nanotechnology.