News and Information
A cockroach that jumps
Professor Malcolm Burrows and colleagues from South Africa have written a paper that shows that a newly discovered species of cockroach jumps, unlike the 4000 other cockroaches which merely scuttle around. This new cockroach, less than 10 mm long, comes from Cape Town in South Africa and lives in the fynbos alongside grasshoppers that also jump. Its jumping movements were captured with a high speed camera operating at 2000 frames per second. These images show that this cockroach propels its jumping by rapid movements of enlarged hind legs. The muscles of these legs contract well before take-off thus storing energy which is then suddenly released in the manner of a catapult. The jumps are powerful enough to propel the body forwards by nearly 50 body lengths (humans can only manage about 2 body lengths) at take-off velocities of 2.1 metres per second while experiencing an acceleration of 23 g (we would pass out at about 5 g). Jumping makes up a large proportion of their normal movement, enabling them to move swiftly and agilely between grass and sedge culms. They speculate on why this should be the only cockroach to have evolved jumping as a means of moving about rapidly.
New research has found that a protein associated with learning and memory plays an integral role in changing the behaviour of locusts from that of harmless grasshoppers into swarming pests.
Desert Locusts are a species of grasshopper that have evolved a Jekyll-and-Hyde disposition to survive in their harsh environment. In their solitary phase, they avoid other locusts and occur in very low density. When the sporadic rains arrive and food is more plentiful, their numbers increase.
However, as the rains cease the locusts are driven onto dwindling patches of vegetation. This forced proximity to other locusts causes a little-understood transformation into their 'gregarious phase': they rapidly become very mobile, actively seek the company of other locusts, and thus form huge swarms that sweep the landscape in their search for food.
The new research, led by Dr Swidbert Ott from the Department of Zoology in collaboration with the University of Leuven, explored the role of a specific signalling protein in the locusts' brain, known as Protein Kinase A, in this transition. They found that this protein, which is typically associated with learning in other animals, has been co-opted to control the transition from solitary to gregarious behaviour in locusts.
They hypothesize that the process whereby locusts 'remember' the experience of crowding and modify their behaviour resembles learning. The 'learning' protein acts as a molecular switch in a social feedback loop, because gregarious behaviour ensures that crowding is maintained. The new results indicate that the biochemical mechanism that triggers locust swarming is similar to what enables humans and other animals to respond to social change.
Dr Ott added: "Learning is when you change your behaviour in the light of new experience, and this is what a locust needs to do when it gets caught up in the crowd. What is amazing is that the parallels don't just end there, they extend to the specific proteins that bring about the behavioural changes."
Desert locusts (Schistocera gregaria) are one of the most devastating insect pests, affecting 20% of the world's land surface through periodic swarms containing billions of locusts stretching over many square kilometres. Different species of locust continue to inflict severe economic hardship on large parts of Africa and China. In November 2008, swarms six kilometres long plagued Australia.
The research will be published this week in the journal PNAS.
A complex network of fungi in the lower canopy could be one reason tropical rainforests are home to so many different types of insects, spiders and centipedes, say scientists.
They found that nearly half of these creatures – called arthropods – are largely dependent on an almost-invisible network of fungi that traps dead leaves that have fallen from the upper canopy.
When the researchers removed the fungi, both the numbers and diversity of arthropods dropped dramatically.
The findings could help conservationists figure out how to retain some level of arthropod diversity in managed landscapes like oil palm plantations, or logged forest.
The fungi branch through the lower canopy extending from the forest floor up to around 30 metres high, catching falling leaves wherever their strands go.
'These fungi are everywhere, and form a messy tangle in the forest understory. You can't really see it until you look for it. You're always looking past it, moving it out of the way as you walk through the forest,' explains Dr Jake Snaddon from the University of Oxford, lead author of the study.
This could be why, up until now, its importance was almost entirely overlooked. Scientists have an idea that the extraordinary numbers and types of arthropods in tropical rainforests is in some way connected to the biological complexity of this habitat. But exactly what contribution these fungal networks make in supporting lots of different types of insects, spiders and millipedes isn't well understood. So together with a team of researchers from the UK and Malaysia, Snaddon decided to find out. They started by analysing how leaf litter builds up in the canopy. 'Nobody had really looked at the part this system had to play before now,' Snaddon says. 'Initially when I started looking, I could see the leaf litter, but I had to look a lot harder to see the actual fungi.'
The fungus attaches itself to living vegetation, using it as a support network. When dead plant matter falls into the network, the fungus send out tiny filaments known as hyphae to grow into it and break it down. The researchers found that this network of fungi traps more leaf litter than any other known rainforest litter-trapping systems like fern mats or bromeliads. They estimate that the network traps around 260 kilograms of leaf litter per hectare, compared with around 100 kilograms per hectare caught by bromeliads. When they tried removing the network from a small section of Malaysian rainforest, the numbers of arthropods fell by 70 per cent and the variety of species dropped by nearly 60 per cent. 'These fungi play a crucial role in the maintenance of canopy diversity, making a huge contribution to the abundance of insects, spiders and a whole range of arthropods,' says Snaddon.
It seems that these litter-trapping fungi provide both food and a home for a wide variety of rainforest organisms. Not just that, but they probably provide a means of connection for creatures living far apart from each other. 'It acts like a huge network, connecting different parts of the canopy together. It's possible that arthropods use it like a superhighway to get from place to place,' says Snaddon. 'We often focus on the more showy forest species, but this study demonstrates that all species are important,' he adds. The next step will be to figure out if these networks also exist in degraded habitats such as palm oil plantations and logged areas of forest. 'They need consistently damp conditions, which you might not find in degraded areas,' Snaddon says.
The study is published in Biology Letters.
22 young European scientists have been selected for excellence in research to join the European Molecular Biology Organisation (EMBO) Young Investigator Programme and one of those Young Investigators is Dr Irene Miguel-Aliaga from the Department.
"The EMBO Young Investigators have the potential to be tomorrow's life science leaders," says Gerlind Wallon, EMBO Deputy Director and manager of the Young Investigator Programme. "They are already active contributors to science in Europe and by supporting them, EMBO wants to highlight both their work and their potential."
With 164 applications in 2011, the EMBO Young Investigator Programme is highly sought after, for its prestige and for its comprehensive array of benefits, which include networking, training, mentorship by EMBO Members and funding. The programme targets young scientists within four years of establishing their first laboratories and aims to support their promising careers.
The percentage of female scientists in this year's intake is 36% and Gerlind Wallon, who also runs EMBO Women in Science, says that EMBO welcomes the increasing number of women in senior science roles. "At EMBO, we are committed to monitoring gender balance in all our activities, developing initiatives to counteract imbalances and to raising awareness of the challenges women face as their scientific careers advance."
The future of rainforests in a changing landscape and climate
Rainforests are vanishing worldwide and their protection is of pressing concern. This special issue of Philosophical Transactions of the Royal Society outlines how human beings are shaping the future of rainforests. The focus lies on the Danum Valley Conservation Area, one of the last remaining primary forests of Malaysian Borneo and on its surrounding forest.
The issue includes the work of William Foster and members of the Insect Ecology Group in the Department of Zoology. They examine what happens to biodiversity on conversion of forest to oil palm, discuss ways of making plantations more wildlife-friendly, and plead for more detailed work on the ecosystem services provided by biodiversity within oil palm plantations. Two members of the Department of Zoology are involved in what are arguably the largest ecological field experiments ever attempted. Edgar Turner has been managing The Stability of Altered Forest Ecosystems (SAFE) project (http://www.safeproject.net), which is a long-term experimental study of the effects of landscape design on the function of ecosystems that include both forest and oil palm plantations. Jake Snaddon has contributed both to this project and to The Sabah Biodiversity Experiment (www.sabahbiodiversityexperiment.net), which is investigating the effects of tree diversity on the rainforest ecosystem.
At the start of October the Student Conference on Conservation Science (SCCS) - begun here in Zoology back in 2000 - was held for the second time in New York. The US event, hosted by the American Museum of Natural History in partnership with a consortium of east coast universities and conservation NGOs, included 400 delegates from over 30 countries.
SCCS-NY comes hot on the heels of last month's highly successful SCCS event in Bangalore. Also in its second year, the Indian conference was organised by Suhel Quader (formerly here in the Behavioural Ecology group), supported by leading Indian research institutes and NGOs, and funded in large part through a grant to Cambridge from ADM Capital Foundation. It brought together about 250 research students from across the region, who presented their work, heard from Indian and overseas plenary speakers (including Andrew Balmford), debated with politicians and journalists about the practical implementation of conservation, and got deluged by the tail-end of the south-west monsoon.
Meanwhile plans for the 13th Cambridge SCCS event - to be held here from 20 to 22 March 2012 - are well underway. The conference organizers have recently won a $500K grant from Arcadia for a five-year expansion of the conference's internship programme which enables developing country students not only to travel to the meeting but to attend a skills-based workshop afterwards and spend several weeks getting hands-on training in a university research group or NGO. The deadline for applications for talks, posters, places and bursary support is 31 October. Further details at www.sccs-cam.org.
Aboriginal Australians were first explorers
An old lock of hair has enabled researchers to sequence the genome of an Aboriginal Australian, and show that modern Aboriginal Australians are direct descendants of the first people to arrive there.
The ground-breaking study used a single lock of hair from the Duckworth Collection at the University of Cambridge. It shows that the direct ancestors of modern Aboriginal Australians began a journey of colonisation and adaptation some 70,000 years ago, more than 20,000 years before the ancestors of Europeans and Asians dispersed throughout Eurasia, demonstrating that the continent was colonised by more than one wave of people originally from Africa.
The international team working on the project was led by the University of Copenhagen, and included a UK collaboration involving researchers from Cambridge, Imperial College London and University College London. Their findings are published today in the journal, Science.
Although there is good archaeological evidence that shows humans arrived in Australia as early as 50,000 years ago, this genome study re-writes the story of their journey. It provides good evidence that Aboriginal Australians are descendants of the earliest modern explorers. This is contrary to the previous and most widely accepted theory that all modern people in Europe and Asia derive from a single, out-of-Africa migration wave into Europe, Asia and Australia.
The study derived from a lock of hair donated to the British anthropologist A.C. Haddon by an Aboriginal man from the Goldfields region of Western Australia in the early 20th century and kept by the Duckworth Laboratory at Cambridge. One hundred years later, researchers have isolated DNA from this same hair, using it to explore the genetics of the first Australians and to provide insights into how humans first dispersed across the globe.
By sequencing the genome, which was shown to have no genetic input from modern European Australians, the researchers were able to establish that the ancestors of the Aboriginal man separated from the ancestors of other human populations some 64 – 75,000 years ago. Aboriginal Australians therefore descend directly from an early human expansion some time during this period, while the ancestors of Europeans and Asians were still somewhere in Africa or the Middle East.
As a result, the study establishes Aboriginal Australians as the population outside Africa with the longest association with the land on which they live today. It has been carried out with the full endorsement of the Goldfields Land and Sea Council, the organisation that represents the Aboriginal traditional owners for the region.
Dr. Marta Mirazon Lahr, from the Leverhulme Centre for Human Evolutionary Studies, where the Duckworth Collection is based, said: "This study is a wonderful example of how new techniques can bring alive old collections, and enhance their importance. We are delighted that the likely descendants of the Australian man – today members of the Goldfields Land and Sea Council, have been such a positive part of this research."
So far, the only ancient human genomes have been obtained from hair preserved under frozen conditions. The researchers have now shown that hair preserved in much less ideal conditions can be used for genome sequencing without risk of modern human contamination that is typical in ancient bones and teeth. Through analysis of museum collections, and in collaboration with descendant groups, researchers can now study the genetic history of many indigenous populations worldwide, even where groups have recently moved about or intermingled.
The mystery of how a butterfly has changed its wing patterns to mimic neighbouring species and avoid being eaten by birds has been solved by a team of European scientists. The study is published in the journal Nature.
The greatest evolutionary thinkers, including Wallace, Bates and Darwin, have all wondered how butterflies that taste bad to birds have evolved the same patterns of warning colouration. Chris Jiggins' group, in collaboration with researchers from CNRS and University of Exeter, have shown how butterflies perform this amazing trick.
The study focused on the Amazonian species Heliconius numata, which mimics several other butterfly species at a single site in the rainforest. One population of Heliconius numata can therefore feature many distinct wing colour patterns resembling those of other butterflies, such as the Monarch's relatives Melinaea, which are unpalatable to birds. This acts as a disguise, protecting them against predators.
The researchers located and sequenced the chromosomal region responsible for the wing patterns in H. numata. The butterfly's wing-pattern variation is controlled by a single region on a single chromosome, containing several genes which control the different elements of the pattern. Known as a 'supergene', this clustering allows genetic combinations that are favoured for their mimetic resemblance to be maintained, while preventing combinations that produce non-mimetic patterns from arising. Supergenes are responsible for a wide range of what we see in nature: from the shape of primrose flowers to the colour and pattern of snail shells.
The researchers found that three versions of the same chromosome coexist in this species, each version controlling distinct wing-pattern forms. This has resulted in butterflies that look completely different from one another, despite having the same DNA.
"We were blown away by what we found", said Dr Mathieu Joron of the Muséum National d'Histoire Naturelle, who led the research. "These butterflies are the 'transformers' of the insect world. But instead of being able to turn from a car into a robot with the flick of switch, a single genetic switch allows these insects to morph into several different mimetic forms – it is amazing and the stuff of science fiction. Now we are starting to understand how this switch can have such a pervasive effect"
Professor Richard ffrench-Constant of the University of Exeter added: "This phenomenon has puzzled scientists for centuries – including Darwin himself. Indeed, it was the original observations of mimicry that helped frame the concept of natural selection. Now that we have the right tools we are able to understand the reason for this amazing transformation: by changing just one gene, the butterfly is able to fool its predators by mimicking a range of different butterflies that taste bad."
This single supergene also appears important in melanism in other species, including moths. In April 2011, a team led by Liverpool University explained in the journal Science how the Peppered Moth developed its black wings in nineteenth-century Britain's sooty industrial environment.
"This supergene region not only allows insects to mimic each other, as in Heliconius, but also to mimic the soot blackened background of the industrial revolution – it's a gene that really packs an evolutionary punch," added Professor Richard ffrench-Constant.
Separating land for nature and land for crops may be the best way to meet increased food demand with the least impact on wild species
In parts of the world still rich in biodiversity, separating natural habitats from high-yielding farmland could be a more effective way to conserve wild species than trying to grow crops and conserve nature on the same land, according to a new study published in the journal Science.
The study, by researchers in the Department of Zoology and the Royal Society for the Protection of Birds, collected information on more than 600 species in southwest Ghana and northern India, two parts of the world where demand for agricultural land is putting ever more pressure on wild species. The researchers measured crop production as well as the abundances of birds and trees in forests and in various types of farmland.
"Farmland with some retained natural vegetation had more species of birds and trees than high-yielding monocultures of oil palm, rice or wheat but produced far less food energy and profit per hectare," said lead author Dr Ben Phalan from the Department. "As well as requiring more land to produce the same amount of food, the 'wildlife-friendly' farmlands were not as wildlife-friendly as they first appeared. Compared with forest, they failed to provide good habitat for the majority of bird and tree species in either region."
The researchers discovered that, under current and future scenarios of food demand, most species would have larger total populations if farming was restricted to the smallest area feasible, while protecting as much natural forest as possible. This was true not just for rare species but for common species as well.
This strategy, called 'land sparing', uses higher yields on existing farmland to spare land for nature (in contrast with 'land sharing', which aims to conserve wild species and grow crops on the same land). Because high-yield farming produced more food from less land, it could be used as part of a strategy to protect larger tracts of natural habitats such as forest. "It would be nice to think that we could conserve species and produce lots of food, all on the same land," said study author, Dr Malvika Onial from the Zoology Department. "But our data from Ghana and India show that's not the best option for most species. To produce a given amount of food, it would be better for biodiversity to farm as productively as possible, if that allows more natural habitat to be protected or restored."
"It is critical to note that increasing crop yields would not work in isolation," said study author Professor Andrew Balmford from the Zoology Department . "Such increases need to be combined with active measures such as national parks and community reserves to protect natural habitats from conversion to farmland. Conservation policy-makers should explore new ways to link protection of natural habitats with efforts to increase food yield per unit area in sustainable ways. Food retailers could perhaps make these linkages a feature of environmentally-friendly food products."
The researchers cautioned, however, that although their findings in Ghana and India are remarkably consistent, they may not hold true everywhere. It is possible that land sparing will be a better strategy in some places and land sharing in others. They advise that further studies in representative parts of the world are needed to determine whether there is a more general pattern.
"Our study does not give uncritical support to large-scale agribusiness over small-scale farming systems," said study author Professor Rhys Green from the Royal Society for the Protection of Birds and the Zoology Department. "High-yielding organic farming and other systems such as agroforestry can be a useful component of a land sparing strategy and may offer the additional advantage of fewer adverse effects of farming from fertilisers and pesticides. But whatever the farming system, protection of natural habitats will continue to be essential for the conservation of many species."
The last ~2.6 million years, generally known as the 'Ice Age' or Quaternary period, has been characterized by several periods of extreme cold, during which ice-sheets covered much of northern Europe and North America. These relatively long 'glacial' episodes were punctuated by shorter 'interglacial' periods when temperatures reached or even exceeded present day values. These climatic changes are recorded in greatest detail in deep sea sediments and ice-cores from polar regions. The records from the land, which are most accessible to geologists and archaeologists, are far less complete and are difficult to link to these continuous records of global climatic change. In addition, most terrestrial sediments are too old to date directly using familiar methods such as radiocarbon dating.
A team of scientists, led by chemists from the BioArCh laboratories, University of York, and palaeontologists from the Department of Zoology, has developed a method of dating Ice Age sediments using fossil snail shells contained within them. The team has conducted the most comprehensive dating of the British Quaternary yet undertaken using a single method, providing analyses of 470 fossils from 71 sites. The method, known as amino acid racemization, measures the extent of protein degradation within calcareous fossils, such as mollusc shells. The technique, which was pioneered about 40 years ago, is now significantly more accurate thanks to the discovery that amino acids (the building blocks of protein) are best preserved in the opercula of certain snails. Opercula are tiny lids that close the mouths of certain species of snail when they withdraw into their shells. They are composed of a different form of lime that provides a more stable 'closed system' repository for amino acids, enabling higher resolution dating of archaeological and geological sites.
The research, published in the latest issue of Nature, details the technique developed by Dr Kirsty Penkman and Professor Matthew Collins, University of York, using fossil material largely provided by Dr Richard Preece, in the Department.
Dr Penkman said that "The amino acids preserved within calcium carbonate crystals of the opercula are essentially a protein time capsule, which provide a chronology for events within the Ice Age". The results have shed light on the timing of early human presence in Britain, establishing occupation as least ~700,000 years ago. Moreover, no archaeological site in Britain can be attributed to the Last Interglacial (~125,000 years ago), suggesting that humans were absent during that warm period. Professor Collins said "When we started this work 11 years ago, we thought it was going to be relatively straightforward to identify a good material for dating, but the first 3 years of research on shells showed that the stability of the mineral itself was vital. The tiny trapdoor of a snail proved to be the key to success."
Richard Preece said that "Fossil opercula are common in Quaternary sediments around the world, so the new technique can be used to build regional Ice Age chronologies everywhere, giving it enormous international scope". Quaternary scientists from the Universities of Durham and Birmingham and the Naturalis Museum, Leiden and The Natural History Museum, London, also contributed to the research. The analyses were funded by English Heritage, the Natural Environment Research Council (NERC) and the Wellcome Trust. The research is a contribution to the Ancient Human Occupation of Britain (AHOB) project funded by the Leverhulme Trust.
The stunning wing patterns of Heliconius butterflies have inspired biologists since the time of Darwin. In a paper published in Science, researchers from Cambridge, California, and Panama have shown that a gene called optix is responsible for painting red patterns onto Heliconius wings. This shows how a single master switch gene, previously known for its role in eye development, can regulate complicated patterns.
Brightly coloured south American butterflies often share virtually identical patterns, even between species that aren't close relatives. This mimicry was one of the earliest examples used to support Darwin's theory of natural selection. The idea is that edible butterflies benefit from similarity by fooling predators into thinking they are something bad to eat. Inedible butterflies also benefit from looking alike, because predators learn to avoid them faster when the pattern is shared among many individuals.
What has mystified biologists however, is how so much diversity has arisen in these patterns. In particular, in two related species, Heliconius melpomene and Heliconius erato, wing patterns change every few hundred kilometres across South America. And the two species change in parallel – wherever they coexist the two look identical. How can different species manage to evolve the same patterns again and again across their range? Researchers in Cambridge have previously shown that the same region of the genome is responsible for controlling similar patterns in the two species.
It now turns out that a gene previously known for its role in eye development in fruit flies also controls these red patterns. The control gene optix (a class of genes known as transcription factors) is expressed in a way that perfectly prefigures red wing patterns in a diversity of Heliconius species. In fact, optix expression is so perfectly correlated with wing pattern that it would be possible to identify the species of butterfly solely from its gene expression patterns.
This connection between eyes and wings is not a complete surprise – it has been known for some time now that the colours in many butterfly wings are generated by a class of pigments found in the eyes of all insects. So when there was an evolutionary need for bright colours, butterflies didn't invent the colours from scratch, but instead just moved them from their eyes to their wings. What is new is the discovery that it wasn't just the pigments that were transferred - the genes controlling wing patterns have undergone a similar move, from an ancestral role in eyes, to a new function in wings.
The department is delighted to offer its congratulations to Dr Rebecca Kilner, who has been awarded a Zoological Society of London Scientific Medal. It is awarded to a research scientist with no more than 15 years post-doctoral experience for distinguished work in zoology.
New research shows that international plans to pay developing countries to reduce tropical forest destruction may increase rural poverty because critical income streams to rural people have been ignored.
The team of African, US and UK scientists and economists calculate the costs to local people of conserving forests across half a million square kilometres of Tanzania, an area of rapid conversion of some of the world's biologically forest conversion coupled with intense poverty and food insecurity. The study shows that charcoal production - usually ignored in estimates of the cost of slowing deforestation - makes up one-third of the profit of converting Tanzanian forests and woodlands to agriculture.
The research suggests that slowing deforestation will be considerably more costly than reported in the influential Stern Review on the economics of climate change.
Lead-author Dr Brendan Fisher of Princeton University and World Wildlife Fund said of the research published in Nature Climate Change, "For an international payment system like the United Nations' new REDD+ Scheme (Reducing Emissions from Deforestation and forest Degradation), it must, at the very least, cover the costs of forest conservation to those that rely on tropical forests for their livelihoods."
He continued: "However, the REDD+ scheme has a potentially more intractable problem. Even if the full costs are paid, where will the area's increasing food and fuel demand be met if agriculture stops expanding? Payments may mean that deforestation could merely move to areas of tropical countries outside of the REDD+ program. This would be a serious deficiency as REDD+ is designed to reduce carbon dioxide emissions to tackle climate change."
The researchers put forward a novel approach, called Smart-REDD, to tackle these problems by first calculating the increase in crop yields on existing land and the increase in fuel-efficiency of charcoal cook-stoves that are needed to meet the demand currently met by forest destruction. Then the team computed the cost of implementing a scheme to boost crop yields, distribute high efficiency cook-stoves and monitor and protect the forests.
The cost of implementation, at US$6.50 per tonne of carbon dioxide saved, is larger than the cost to merely compensate forest users, which is US$3.90. But the sums are still considerably less than the current market price of carbon (currently around US$24 per tonne carbon dioxide in the European Trading Scheme). The team's research suggest that even a doubling of agricultural yields is possible at US$12 per tonne of carbon dioxide.
Professor Andrew Balmford, a co-author, said, "From our calculations it may be possible to link large increases in food production and food security with carbon conservation in extraordinarily biodiverse forests, and all at a pretty low cost. With governments of richer, polluting countries - like the UK - gearing up to make REDD+ payments to slow deforestation in poorer ones, we hope that results like ours can help them target their investments in ways that are both practical and cost-effective."
Co-author Professor Pantaleo Munishi of Tanzania's Sokoine University of Agriculture, added, "In Tanzania we are faced with many interrelated problems, so solutions like this - with potential to work across problems - are the ones that have the greatest chance to make a difference. This is especially important because of existing food insecurity and the strong link between agricultural expansion and forest conversion."
"The novel angle of this research was linking an understanding of the true costs of forest conservation with practical interventions which could actually decrease forest conversion in the first place. Of course, research in other areas is needed as the drivers of deforestation and interventions may be different compared to tropical Africa. But it is exciting that Smart-REDD practical interventions that meet the demand for tropically-grown commodities could make REDD+ a much-needed success story in terms of climate mitigation, biodiversity conservation and human development." said co-author on the study, Dr Simon Lewis, a forest carbon expert at the University of Leeds.
The research was a collaboration of economists (led by Dr. Fisher), conservation scientists (led by Prof. Balmford), carbon scientists (led by Dr. Lewis) and Tanzanian experts (led by Prof. Munishi) from UK, US and Tanzanian institutions funded by the Leverhulme Trust.
The Department offers its congratulations to Professor Andrew Balmford who has become the latest member of the Department to be made a Fellow of the Royal Society. Andrew's major contribution has been to tackle fundamental questions about the relationship between people and the global loss of nature - is conservation worthwhile, why is nature being lost, how much would conservation cost, and how can we achieve it efficiently? A series of innovative and well-structures studies that directly address these questions have had important implications for global conservation and for the valuation of nature. His work is characterized by detailed quantitative studies, by clever use of the data that is available and by well designed studies that effectively balance rigour with pragmatism.
New research reveals how biological arms races between cuckoos and host birds can escalate into a competition between the host evolving new, unique egg patterns (or 'signatures') and the parasite new forgeries.
Brood parasitic birds such as cuckoos lay eggs that mimic those of their hosts in an effort to trick them into accepting the alien egg and raising the cuckoo chick as one of their own. New research from the University of Cambridge has found that different bird species parasitised by the African cuckoo finch have evolved different advanced strategies to fight back.
One strategy is for every host female to lay a different type of egg, with egg colour and pattern varying greatly among nests. These egg 'signatures' make it harder for the cuckoo finch to lay accurate forgeries. Since the female cuckoo finch always lays the same type of egg throughout her lifetime, she cannot change the look of her egg to match those of different host individuals – thus her chances of laying a matching egg are exasperatingly small.
Dr Claire Spottiswoode, a Royal Society Dorothy Hodgkin Research Fellow in the Department, said: "As the cuckoo finch has become more proficient at tricking its hosts with better mimicry, hosts have evolved more and more sophisticated ways to fight back. Our field experiments in Zambia show that this biological arms race has escalated in strikingly different ways in different species. Some host species – such as the tawny-flanked prinia – have evolved defences by shifting their own egg appearance away from that of their parasite. And we see evidence of this in the evolution of an amazing diversity of prinia egg colours and patterns.
"These variations seem to act like the complicated markings on a banknote: complex colours and patterns act to make host eggs more difficult to forge by the parasite, just as watermarks act to make banknotes more difficult to forge by counterfeiters."
They also found that some cuckoo finch hosts use an alternative strategy: red-faced cisticolas lay only moderately variable eggs but are instead extremely discriminating in deciding whether an egg is their one of their own. Thanks to their excellent discrimination, these hosts can spot even a sophisticated mimic.
Dr Martin Stevens, a BBSRC David Phillips Research Fellow also in the Department, commented on this aspect of the findings: "Our experiments have shown that these different strategies are equally successful as defences against the cuckoo finch.
Moreover, one species that has done a bit of both – the rattling cisticola – appears to have beaten the cuckoo finch with this dual strategy, since it is no longer parasitised. The arms race between the cuckoo finch and its host emphasises how interactions between species can be remarkably sophisticated especially in tropical regions such as Africa, giving us beautiful examples of evolution and adaptation."
Their findings are reported in the Proceedings of the Royal Society of B.
Researchers in the Department of Zoology have a long history of studying the common cuckoo, the well-known brood parasite that lays its eggs in the nests of other species. Female cuckoos belong to different genetic races called 'gentes,' a term coined by Alfred Newton, who became the University's first Professor of Zoology in 1866. Females belonging to different races selectively target specific hosts, and they lay an egg which often matches the colour and pattern of the host's egg remarkably well. Cuckoo mimicry has fascinated researchers since the time of Darwin and Newton, but most studies on the topic have relied on human assessments, which fail to account for bird vision.
Fast forward to 2011, when modern-day members of the Department of Zoology have developed methods to obtain a bird's-eye view of the cuckoo's egg-forging ability. Mary Caswell Stoddard and Martin Stevens applied models of bird colour vision to discover how well cuckoo eggs match host eggs from a host bird's point of view. Birds have much better colour vision than humans do. They have four colour cones in their retina, while humans only have three. The additional cone in birds is sensitive to ultraviolet wavelengths, which allows birds to see a whole range of colours humans are blind to.
To measure how well each cuckoo race matches its specific hosts, the researchers compared egg colours in avian colour space. In bird colour space, all colours can be represented based on how they stimulate the four bird colour cone-types. They revealed that some cuckoo distributions prominently overlapped those of their hosts, while others remained isolated in colour space.
"We found that cuckoos achieve better colour mimicry for hosts that are good at picking out the odd egg," explained Stoddard. "If the host is not a picky egg rejecter, the cuckoo will not have evolved a sophisticated degree of colour mimicry."
The cuckoo that parasitizes the dunnock is white with brown speckles, a poor match to the immaculate blue dunnock egg. Accordingly, the background colours of the dunnock-cuckoo and dunnock are completely isolated in avian colour space. Despite the obvious colour mismatch, dunnocks readily accept foreign eggs, and are thought to be at an early stage of the coevolutionary arms race, having not yet evolved host defenses.
But other cuckoo-host pairs appear to be further along in the arms race. The cuckoo that parasitizes the red-backed shrike, which is the strongest egg rejecter, achieves the highest colour overlap: the cuckoo and host distributions are completely superimposed in colour space. "The mimicry story is much more complex and exciting when we look through bird's eyes. The high degree of colour matching in some cases, and low degree in others, is not something that we could predict from our limited human perspective," said Stoddard.
Stoddard and Stevens published their findings this week in the journal Evolution.
Zoology graduates have again done exceptionally well in various poster competitions recently.
The Graduate School of Life Sciences Poster and Images competition
Impact/Awareness Posters (new category this year) Winner: Wendy Gu - "Meet the Fruit Fly" Poster
Image Competition Third prize to Vera Hunnekuhl for her image - a high magnification capture of the developing head of a centipede. Image
Overall Best Poster Winner: Mary Caswell Stoddard for her poster "Cuckoo Forgery - Through a Bird's Eye" Poster
Departmental Seminar Day Poster Competition Winner: Kelly Seagraves for her poster on directional sensitivity of auditory processing in crickets. Poster
Student Conference on Conservation Science 2nd Prize to Tharsila Carranza for her poster on whether protected areas work in slowing the conversion of the Brazilian cerrado. Poster
Warmest congratulations to all!
Science Festival 2011
As usual the department will be contributing to the annual Cambridge Science Festival.
Dr Irene Miguel Aliaga's lab will be showcasing the work of the four labs in the basement of the department. All sessions are now fully booked but there is an audio slide show available to see on the BBC Website:
Got a burning question about something zoological? Have a mystery animal object you want identifying? Explore the kingdom of animals at the Museum of Zoology. Meet live invertebrates and discover our fantastic collection from the tiniest flies to the majestic finback whale. Learn about the incredible intelligence of some animals, the amazing size of others, and about animals you might find in the UK. Hands on activities will be running throughout the day, and zoologists will be on hand to answer your creature questions.
This event is open to all. Admission is free and there is no need to book. Children must be accompanied at all events.
Insects hold atomic clues about the type of habitats in which they live. Members of the Departments of Plant Sciences and Zoology discover an 'atmospheric imprint' in insects, revealing where they are most likely to survive should climate change alter their ecosystem
They have have discovered that insects contain atomic clues as to the habitats in which they are most able to survive. The research has important implications for predicting the effects of climate change on the insects, which make up three-quarters of the animal kingdom.
Applying a method previously only used to examine the possible effects of climate change on plants, scientists can now determine the climatic tolerances of individual insects. Their research was published today, 16 February, in the scientific journal Biology Letters.
Because insects are at constant risk of desiccation, they have a waterproof exoskeleton which protects them from dehydration. Therefore, measuring hydration levels in an insect gives little if no indication of the type of habitat they live in (for example, whether it is humid or dry). Moreover, most insects live in the undergrowth, or in the soil; in tropical rainforests the insects live many hundreds of feet up in the canopy, which makes it very difficult to observe them directly. Using the atmospheric imprint, it will now be possible to decipher the habitat preferences of individual insects no matter where they live.
By taking advantage of a unique property of the oxygen isotopes in water; namely that the isotopes behave differently during evaporation and condensation, the researchers were able to determine how much water an insect loses when it 'breathes' through holes in its outer skeleton called spiracles, providing important insight into the type of atmosphere (for example, humid like the rain forest) it could survive.
Water (H20) is made up of two types of oxygen – 18O and 16O. Because 16O is lighter, when water evaporates it leaves behind more 18O. Using cockroaches, the scientists measured the levels of the two different oxygens in the insects' circulatory fluid - called haemolymph - as well as in their outer skeleton. From this information they were able to determine how much water had evaporated and therefore identify the atmospheric conditions necessary for the insect to survive.
Insects living in a dry atmosphere have a higher concentration of 18O as a result of a greater water loss. Insects living in very humid conditions tend to lose less water and therefore have a nearly equal ratio of 16O to 18O. With this new method, researchers will be able to predict where species are most likely to survive (e.g. in Sahara-desert dry and rainforest humid), and will be able to pinpoint with great accuracy which species share the most similar niches.
"There is an urgent need for a better understanding of how global environmental change will affect threatened plants and animals," said Dr Farnon Ellwood, lead author of the paper. "If we can determine the habitat preferences of individual insects, we can use this information to predict how climate change will impact on a group representing three-quarters of the Earth's animal species."
If you thought that we know everything about how the flea jumps, think again. In 1967, Henry Bennet-Clark discovered that fleas store the energy needed to catapult themselves into the air in an elastic pad made of resilin. However, in the intervening years debate continued about exactly how fleas harness this explosive energy. Bennet-Clark and Miriam Rothschild came up with competing hypotheses, but neither had access to the high speed recording equipment that could resolve the problem. Turn the clock forward to Malcolm Burrows' lab in 2010. 'We were always very puzzled by this debate because we'd read the papers and both Henry and Miriam put a lot of evidence for their hypotheses in place and their data were consistent with each other but we couldn't understand why the debate hadn't been settled,' says Burrows' postdoc, Gregory Sutton. He adds, 'We had a serendipitous set of hedgehog fleas show up so we figured we'd take a crack at it and try to answer the question'. Filming leaping fleas with a high-speed camera, Sutton and Burrows found that fleas push off with their toes (tarsus), see a video on BBC Earth News.
'We were concerned about how difficult it would be to make the movies because we are used to filming locusts, which are much bigger than fleas,' admits Sutton, but he and Burrows realised that the fleas stayed perfectly still in the dark and only jumped when the lights went on. Focusing the camera on the stationary insects in low light, the duo successfully filmed 51 jumps from 10 animals; and this was when they got their first clue as to how the insects jump.
In the majority of the jumps, two parts of the flea's complicated leg – the tarsus (toe) and trochanter (knee) – were in contact with the ground for the take off, but in 10% of the jumps, only the tarsus (toe) touched the ground. Sutton explains that Rothschild had suggested that fleas push off with the trochanter (knee), but if 10% of the jumps didn't use the trochanter (knee) was it really necessary, or were the fleas using two mechanisms to get airborne?
Burrows and Sutton needed more evidence. Analysing the movies, the duo could see that the insects continued accelerating during take-off, even when the trochanter (knee) was no longer pushing down. And the insects that jumped without using the trochanter (knee) accelerated in exactly the same way as the insects that jumped using the trochanter (knee) and tarsus (toe). Also, when Burrows and Sutton looked at the flea's leg with scanning electron microscopy, the tibia (shin) and tarsus (toe) were equipped with gripping claws, but the trochanter (knee) was completely smooth, so it couldn't get a good grip to push off. Sutton and Burrows suspected that the insects push down through the tibia (shin) onto the tarsus (toe), as Bennet-Clark had suggested, but the team needed one more line of evidence to clinch the argument: a mathematical model that could reproduce the flea's trajectory.
Auditory mate or prey localisation is central to the lifestyle of many animals and requires precise directional hearing. In insects where the body is small compared to the sound wavelength the directional performance of auditory systems is limited due to the lack of diffraction and minute interaural time differences. Some insects, however, possess specialised microscale hearing systems with astonishing functional properties.
Recent experiments by a team from the Department have demonstrated directional hyperacuity of the hearing system in the Mediterranean field cricket Gryllus bimaculatus. Dr Stefan Schöneich and Dr Berthold Hedwig analysed the precision of acoustic orientation in female crickets walking on a highly sensitive trackball system by measuring their steering accuracy towards male calling song. The females reliably discriminated the side of acoustic stimulation, even when the sound source deviated by only 1° from the animal's length axis. Moreover, for angles of sound incidence between 1° and 6° the females precisely walked towards the sound source.
Measuring the tympanic membrane oscillations of the front leg ears with a laservibrometer revealed between 0° and 30° a linear increasing function of interaural amplitude differences with a slope of 0.4 dB/°. Auditory nerve recordings closely reflected these bilateral differences in afferent response latency and intensity that provide the physiological basis for precise auditory steering.
The data reveal the acoustic orientation of field crickets as one of the most precise among invertebrates and place it at the same level to the achievements of vertebrate directional hearing. The work was supported by The Royal Society
A leading Indian conservation expert, Dr Karithi Karanth, has visited the Department to work with a Cambridge counterpart and give a public lecture, thanks to the Cambridge Hamied Visiting Lectureship Scheme.
The Scheme has been established to stimulate exchange of ideas and academic collaboration between India and the University of Cambridge. It is named after its founder Dr Yusuf Hamied, Chairman of Cipla Ltd, India, and an alumnus of the University's Department of Chemistry and Christ's College.
Professor Andrew Balmford invited Dr Karanth to visit Cambridge in order to initiate collaboration on the collation of key data for assessing the status of India's Protected Areas (PAs). The data will focus on status, threats and management effectiveness of the country's 600+ protected areas which cover less than 4% of the total land area but support much of the country's biological diversity, including the largest populations of the world's tigers and Asiatic elephants.
Dr Krithi Karanth is Assistant Director at the Centre for Wildlife Studies (CWS) and the Visiting Fellow at the National Centre for Biological Sciences (NCBS), both in Bangalore. She is interested in interactions between protected areas and people, biodiversity patterns and species extinctions, human-wildlife conflicts, nature-based tourism and impacts of conservation interventions and policies such as resettlement. She has conducted research in India since 2001, her current research examines wildlife habitat use, land use change, tourism impacts, and human-wildlife conflicts in ten Indian wildlife reserves.
Professor Balmford commented: "India is an exceptionally important country for conservation, both in terms of both its biodiversity and its growing reputation for world-class applied research. We're extremely keen to build on the links we already have with Indian colleagues - and Dr Karanth's visit was an important part of planning those developments."
Wild red deer on the Isle of Rum, which were featured in the BBC TV series Autumnwatch, are rutting earlier in the year, a study shows.
Scientists believe the annual rutting season on the Isle of Rum could be changing because of warming spring and summer temperatures. The study shows that the rutting and calving seasons are now up to two weeks earlier on average compared with 30 years ago.
The research was based on a 38-year study of the ecology of red deer on the Isle of Rum and used annual records of breeding success in more than 3,000 individually recognisable deer. Scientists at the Universities of Cambridge and Edinburgh, who maintained the long-term research, say this provides rare evidence that warming temperatures are affecting the behaviour of British mammals.
Professor Tim Clutton-Brock from the Department, who maintained the long-term research on Rum for 35 years and initiated the project, said: "Long term studies that can track the life histories of individuals have a crucial role to play in measuring the effects of climate change because they can identify the reasons for changes in survival and breeding success. The continuation of long-term studies like the one on Rum is crucial if we want to fully understand the consequences of climate warming for wild animal populations."
Dr Dan Nussey of the University of Edinburgh's School of Biological Sciences, who took part in the study, said: "Although many kinds of plants and animals are known to be reproducing earlier, evidence that this is happening in large mammals is very unusual. However, we still do not know exactly what is causing these changes in the timing of the deer's annual cycle. Much more work is needed to understand whether similar changes are taking place in deer populations elsewhere, and what the implications of such changes will be."
Sarah Bentley, SNH operational manager in West Highland, said: "The Isle of Rum National Nature Reserve has been a key centre for wildlife research for many years, particularly in relation to deer. We are very pleased to be supporting this latest study on the island. It provides further evidence of how climate change is impacting on wildlife. There may be implications for deer and their management in future and we will continue to work with the researchers to consider these."
The research, published in the journal Global Change Biology, was funded by the Natural Environment Research Council (NERC) and supported by Scottish Natural Heritage.
The department is delighted to offer its congratulations to Professor Ron Laskey, who was awarded a CBE in the New Year's Honours list this year for his services to Science. He started his career at Oxford, followed by post-doctoral posts on the scientific staff of Imperial Cancer Research Fund and the MRC Laboratory of Molecular Biology in Cambridge. In 1983 he moved to the Charles Darwin Chair in the University of Cambridge, first in the Department of Zoology, then in the Wellcome CRC Institute and was Director of the MRC Cancer Cell Unit in the Hutchison/MRC Research Centre until his retirement in January 2010. He is a Fellow of the Royal Society, a Member of Academia Europaea, Vice President of the Academy of Medical Sciences and a former President of the British Society for Cell Biology.
Throughout most of his career, Ron Laskey’s main interest has been how cells control DNA synthesis. He has developed cell-free systems that allow these processes to be studied in a test tube, in extracts from human cells. Some of the proteins studied in this work are emerging as promising markers for the development of screening tests for the commonest cancers.
Clues about how the human gut helps regulate our appetite have come from a most unusual source – fruit fly faeces.
Researchers from the Developmental Biology group in the department are using the fruit fly to help understand aspects of human metabolism, including why pregnant women suffer from bloating and constipation, and even the link between a low calorie diet and longevity.
Although scientists have known for some time that there are as many as 500 million nerve cells in our gut, the sheer complexity that this presents means that little is known about the different types of nerve cell and their functions.
Now, researchers led by Dr Irene Miguel-Aliaga, with funding from the Wellcome Trust and the Biotechnology and Biological Sciences Research Council, have used the fruit fly, Drosophila melanogaster, to investigate the function of these intestinal neurons. The fly has simpler versions of our nervous and digestive systems, which lend it to genetic manipulation. Their findings are published today in the journal Cell Metabolism.
"We reasoned that what comes out of the gut may be able to tell us about what is going on inside," explains Dr Miguel-Aliaga. "So, we devised a method to extract information about several metabolic features from the flies' faecal deposits - which are actually rather pretty and don't smell bad. Then we turned specific neurons on and off and examined what came out."
Dr Miguel-Aliaga and colleagues found that these intestinal neurons have very important and specialised functions, such as regulating appetite or adjusting intestinal water balance during reproduction. "Our research suggests that in addition to paying attention to what we eat, which has been the focus of longevity research, we may also have to consider what our body does with the food and what goes on in our guts."