Professor Marlene Zuk discusses women and science
From Department of Zoology. Published on Dec 04, 2013.
Professor Derek Smith on global pandemics
From Department of Zoology. Published on Nov 28, 2013.Radio 4 'Frontiers' programme available now
Dr Denholm doesn't just study flies...
From Department of Zoology. Published on Nov 27, 2013.Seven of the more unusual areas of scientific research
Science lessons for MPs
From Department of Zoology. Published on Nov 22, 2013.
Research reveals details of how flu evolves to escape immunity
By sj387 from University of Cambridge - Department of Zoology. Published on Nov 21, 2013.
Scientists have identified a potential way to improve future flu vaccines after discovering that seasonal flu typically escapes immunity from vaccines with as little as a single amino acid substitution. Additionally, they found these single amino acid changes occur at only seven places on its surface – not the 130 places previously believed. The research was published today, 21 November, in the journal Science.
“This work is a major step forward in our understanding of the evolution of flu viruses, and could possibly enable us to predict that evolution. If we can do that, then we can make flu vaccines that would be even more effective than the current vaccine,” said Professor Derek Smith from the University of Cambridge, one of the two leaders of the research, together with Professor Ron Fouchier from Erasmus Medical Center in The Netherlands.
The flu vaccine works by exposing the body to parts of inactivated flu from the three major different types of flu that infect humans, prompting the immune system to develop antibodies against these viruses. When exposed to the actual flu, these antibodies can eliminate the flu virus.
However, every two or three years the outer coat of seasonal flu (made up of amino acids) evolves, preventing antibodies that would fight the older strains of flu from recognising the new strain. As a result, the new strain of virus escapes the immunity that has been acquired as a result of earlier infections or vaccinations. Because the flu virus is constantly evolving in this way, the World Health Organisation meets twice a year to determine whether the strains of flu included in the vaccine should be changed.
For this study, the researchers created viruses which had a variety of amino acid substitutions as well as different combinations of amino acid substitutions. They then tested these viruses to see which substitutions and combinations of substitutions caused new strains to develop.
They found that seasonal flu escapes immunity and develops into new strains typically by just a single amino acid substitution. Until now, it was widely believed that in order for seasonal flu to escape the immunity individuals acquire from previous infections or vaccinations, it would take at least four amino acid substitutions.
They also found that such single amino acid changes occurred at only seven places on its surface – all located near the receptor binding site (the area where the flu virus binds to and infects host cells). The location is significant because the virus would not change so close to the site unless it had to, as that area is important for the virus to conserve.
“The virus needs to conserve this, its binding site, as it uses this site to recognize the cells that it infects in our throats,” said Bjorn Koel, from Erasmus Medical Center in The Netherlands and lead author of the paper.
Seasonal flu is responsible for half a million deaths and many more hospitalizations and severe illnesses worldwide every year.
Study shows that seasonal flu escapes immunity with single amino acid substitutions.
The Professors’ Award for Outstanding Contribution
From Department of Zoology. Published on Nov 20, 2013.Ian Goldstone and Matt Lowe are joint winners of this year’s Award for Outstanding Contribution. They were presented with the awards at the Newcomers’ Party on Thursday 14th November. This annual award is to recognise and reward a member of staff who has gone that extra mile for the Department in the last year.
Prize-winning work published in Developmental Cell Nov 11th 2013
From Department of Zoology. Published on Nov 12, 2013.Tip cells act as dynamic cellular anchors in the morphogenesis of looped renal tubules in Drosophila by Helen Weavers and Helen Skaer.
Winners of the Graduate Poster Competition!
From Department of Zoology. Published on Oct 24, 2013.
Cuckoos impersonate hawks by matching their 'outfits'
By fpjl2 from University of Cambridge - Department of Zoology. Published on Oct 17, 2013.
New research shows that cuckoos have striped or “barred” feathers that resemble local birds of prey, such as sparrowhawks, that may be used to frighten birds into briefly fleeing their nest in order to lay their parasitic eggs.
By using the latest digital image analysis techniques, and accounting for “bird vision” - by converting images to the spectral sensitivity of birds - researchers have been able to show for the first time that the barred patterns on a cuckoo’s breast may allow it to impersonate dangerous birds of prey. This might enable cuckoos to frighten other avian hosts into leaving their nests exposed.
The latest findings, published today in the journal Animal Behaviour, expand the cuckoo’s arsenal of evolutionary deceptions, which include egg mimicry and chick mimicry that allow it to trick other birds into incubating its eggs.
Importantly, the study shows that a wide variety of cuckoos have adapted different plumage patterns depending on the area they inhabit so that they match a local bird of prey species.
While scientists have previously looked at links in plumage patterns between the common cuckoo and Eurasian sparrowhawk, the new research shows that this type of impersonation of a more dangerous animal – called ‘Batesian mimicry’ – may be far more widespread in cuckoos. In addition, the dangerous bird of prey that cuckoos resemble goes beyond sparrowhawks to include such raptors as bazas and harrier-hawks - depending on the species prevalent in the cuckoo’s neighbourhood.
“There is no benefit in looking like a dangerous species your target is not familiar with,” said lead researcher Thanh-Lan Gluckman from Cambridge’s Department of Zoology.
“We first established similarity in plumage pattern attributes between cuckoos and raptor species, and then showed that cuckoos look nothing like species from a different geographical area.”
The cuckoos also use their crafty ‘hawk impression’ to allow them to fly ‘under the radar’, undetected as they scope out potential nests in which to deposit their parasitic eggs.
“The barring on their plumage helps cuckoos conceal themselves while searching for potential nests, then when they approach, the host of the nest may mistake a cuckoo for a raptor coming to get them – giving them unfettered access to lay eggs,” Gluckman said.
While previous studies have focused on Batesian mimicry in the common cuckoo and Eurasian sparrowhawk, this is the first time that the plumage patterns of cuckoos have been analysed using digital image analysis techniques. The study suggests that this form of mimicry may be widespread among many cuckoo species, and that they may be mimicking a variety of different types of birds of prey.
The researchers were surprised to find no pattern matching between cuckoos and raptors that live in different geographical areas, showing that the visual similarity is highly localised to species in the immediate vicinity.
“These findings underscore the importance of using digital image analysis to objectively quantify plumage patterning in mimicry – it is important not to make assumptions about even simple patterns such as these,” added Gluckman.
“We hope this encourages other researchers to examine the function of barred plumage in parasitic cuckoos and raptors the world over.”
Another interesting finding is that of the African cuckoo-hawk, a raptor so named because of its visual resemblance to cuckoos. This study objectively shows that the naming was an apt one, given that a local cuckoo matched the African cuckoo-hawk in all of the pattern attributes measured.
One of the earliest observers of the cuckoos’ invasive guile was Ancient Greek philosopher Aristotle, who noted some 2,300 years ago that it “lays its eggs in the nest of smaller birds”.
Evolutionary trick allows cuckoos to ‘mimic’ the plumage of birds of prey, and may be used to scare mothers from their nests so that cuckoos can lay their eggs. Mimicry in cuckoos may be more much more widespread than previously thought.
Amazonia at a crossroads
By sj387 from University of Cambridge - Department of Zoology. Published on Oct 17, 2013.
The numbers associated with the Amazon are truly staggering. It encompasses nine countries; contains at least a tenth of the known species in the world; provides a home and resources to 31 million people; stores the equivalent amount of carbon to a decade of human-induced emissions for the entire planet; and discharges a fifth of the world’s fresh water.
However, rapid social and ecological change, borne on the back of deforestation, harvesting of natural resources and a changing climate, has left the future of the world’s largest remaining tropical forest uncertain – Amazonia, today, is “standing at a crossroads”, as Dr Toby Gardner describes.
He points to the existence of tough trade-offs that underpin the region’s challenges: “The demand for land and natural resources is driven by the development needs of one of the world’s largest emerging economies, as well as by the insatiable global food and commodities market. Understanding what management practices can best achieve both economic development and environmental conservation is central to addressing this challenge and shepherding the creation of a more sustainable Amazon.”
Gardner leads a new research programme that is motivated by helping to solve this dilemma – the Sustainable Amazon Network – alongside colleagues at Lancaster University, the Goeldi Museum in Belém (Brazil) and the Brazilian Agricultural Research Corporation (Embrapa), with funding from the Brazilian and UK governments and The Nature Conservancy, among others.
The Network’s 100-strong group of researchers and students from over 30 institutions are working with conservation organisations, farmers and government officials. Their approach is to assemble an evidence base on the sustainability challenges and ecological consequences associated with land uses and management strategies, and to use this to test the effectiveness and risks of alternative policy choices facing local people and regional governments.
At the heart of the research is an appreciation of the complex array of interactions and feedbacks that characterise the changing face of Amazonia. The project takes as its ‘laboratory’ two regions of the eastern Amazon: Paragominas, a region infamous for lawlessness, violence, land grabbing, illegal sawmills and rampant forest clearance until the 1990s; and Santarém-Belterra, once a centre of pre-Colombian civilisation, with a long history of farming and now home to smallholder farms and larger agricultural enterprises.
What makes the project distinct from many other research initiatives is the collection of matched data from the same network of landholdings on changes in both the ecological and the socio-economic characteristics of different land and forest use systems. The team’s survey design has enabled information to be collected across the full wealth spectrum, from the poorest to the richest farmers, while allowing comparisons at multiple spatial scales – between different farms, catchments and regions.
The result is one of the most comprehensive field assessments ever undertaken in the tropics. Critical issues that are being addressed include the identification of potential threshold effects of deforestation on the degradation of ecological systems, and the identification of strategies at both farm and municipality scales that can effectively reconcile conservation and development goals.
“In addition, one of the longer term implications of any initiative like this is the fact that a large group of students and researchers, many of whom are Brazilian, have been exposed to new ideas and new ways of thinking about sustainability problems, and this, perhaps above anything else, will be the most valuable legacy of our project,” added Gardner.
Can the world’s largest tropical forest biome be transformed into a sustainable ecological system? “There is a short window of opportunity and there is potential for recovery,” said Gardner. “But we cannot afford to be complacent.”
The Amazon rainforest faces an uncertain future – one that an international research network hopes to help steer towards sustainability.
Infanticide linked to wet-nursing in meerkats
By lw355 from University of Cambridge - Department of Zoology. Published on Oct 08, 2013.
Subordinate female meerkats who try to breed often lose their offspring to infanticide by the dominant female or are evicted from the group. These recently bereaved or ostracised mothers may then become wet-nurses for the dominant female, an activity that may be a form of “rent” that allows them to remain in the community.
Wet-nursing another mother’s offspring – called allolactation – occurs across a variety of mammals and is thought to provide survival benefits to the nursed offspring and to the mother of the pups. However, little has been definitively known of why the females who provide the wet-nurse service do so.
Now, in the most comprehensive study conducted to date, researchers studying a meerkat population in the Kalahari region of South Africa have identified factors that influence why females might wet-nurse.
The findings, published today in Animal Behaviour, show that females are more likely to allolactate if they have recently lost litters or have returned to the group following eviction.
“Breeding opportunities are monopolised by a single behaviourally dominant female in meerkat groups,” explains Kirsty MacLeod, who carried out the research at the University of Cambridge’s Department of Zoology with Professor Tim Clutton-Brock, and Dr Johanna Nielsen at the University of Edinburgh. The Kalahari Meerkat Project is run jointly by the University of Cambridge and the University of Zurich.
“She maintains this position through suppressing breeding attempts by other females – either through evicting them or killing their pups – and these subordinate females are then also more likely to wet-nurse the dominant female’s pups. This suggests to us that infanticide by the dominant female might have two evolutionary advantages for her – she reduces competition for care for her own pups, and is more likely to secure allolactation for her litter.
“Wet-nursing by formerly evicted meerkats may be a way of ‘paying rent’ to be allowed back into the group without receiving further aggression,” she adds. Helping as payment of ‘rent’ has been suggested in bird species in which helpers receive greater benefits from remaining in their territories owing to a lack of opportunity to attract a mate from elsewhere, but has previously been suggested in only one other mammal – the naked mole rat.
The research was carried out over a 15-year period, with 40 social groups of meerkats being observed. The researchers created a long-term database and recorded, among other life-history details, pregnancies and lactation periods. Because most pup nursing occurs below ground, females were identified as producing milk through the presence of suckle marks and the attachment of sand to damp nipples.
“Now that we have a clearer idea of which females are more likely to invest energy in this highly cooperative behaviour,” says MacLeod, “our next step is to figure out what benefits each party is getting from this. We know that lactation is costly, so it’s likely that if additional females also provide milk, those costs should go down. We’ll know that soon.
“These results, however, hint at what the benefits might be for subordinate allolactators. Because subordinate females were more likely to allolactate if they are related to the litter’s mother, this suggests that they may gain an indirect benefit from the activity. Evictees from the group suffer considerable stress, weight loss and reduced survival. If contributing to the maternal cares of another’s offspring allowed renewed access to the social group, or to remain in the group once following infanticide, there would be an incentive to ‘pay-to-stay’.”
Inset image: Kirsty MacLeod searches in vain for meerkats
Mothers who lose their pups to infanticide by the dominant female in a meerkat group often then provide the dominant female with a wet-nurse service, say researchers who have carried out the most comprehensive study of wet-nursing in a single species to date.
Time for plan bee
By lw355 from University of Cambridge - Department of Zoology. Published on Oct 03, 2013.
By carrying pollen from one plant to another, bees and other insects contribute to plant reproduction in almost 90% of our wild plants, and around 30% of our crops depend on them. But, as zoologist Dr Lynn Dicks explained, their future is under threat: “There has been a massive decline in some groups of insect pollinators. The number of bumblebee species in the UK dropped by around 30% between the 1950s and 1980s, and numbers of many large moth species in the UK have halved since the late 1960s.”
Most scientists agree that pollinator declines are caused by the interaction of various factors including habitat change, the consequent loss of flowers and nest sites, agricultural chemicals, disease and possibly climate change.
“There’s also an increasing acknowledgement of the important role pollinators play in food production,” added Dicks. “Some fruit crops are completely dependent on pollinators, and for others pollination results in better quality fruit.”
Dicks holds a Natural Environment Research Council (NERC) three-year Knowledge Exchange Fellowship. Her work on pollinator conservation has brought together key players to identify knowledge gaps and to devise collaborative projects to address them. Twenty large businesses, including Waitrose and Heineken, joined forces with representatives from government agencies, nature conservation agencies including Natural England and Buglife, and scientists.
Framed in terms of a business interest, pollinator conservation has moved rapidly up the political and business agendas. A consortium of UK research funders has recently invested £10 million under the Insect Pollinators Initiative to identify and mitigate the main threats. “All the food companies with a dependence on fruit production are thinking about these sustainability issues now,” said Dicks. “Heineken, which makes Bulmers cider, uses about 30% of the UK apple crop, and apple yields are between 40% and 90% lower without pollinators, depending on the variety. Around 90% of the UK blackcurrant crop goes into Ribena, and without pollination blackcurrant yields drop by 10–40%.”
“We looked at the knowledge available from academia, the private sector and government,” said Dicks. Breaking down the issue into the status of pollinators, threats, and what could be done about these, the first round of discussions generated 246 ‘big’ questions. From this, a set of 35 priorities were chosen for investigation.
“The highest priority was to understand the basic underlying ecology of the insects – how important the diversity of pollinators is to delivering a reliable pollination service,”she added. Other priorities were to understand the relative contributions of wild and managed pollinators to crop yield, and the sub-lethal effects of chemicals on wild pollinators. The next stage of the project is to address some of the top 15 knowledge needs through new research.
The work formed the pilot for a wider NERC-funded Knowledge Exchange Programme on Sustainable Food Production by the Universities of Cambridge, Bangor, Lancaster, Leeds and Reading and the Plymouth Marine Laboratory. Aiming to enhance the use of science in making UK food production systems more environmentally sustainable, the Programme has developed a web‐based database of scientific evidence (www.nercsustainablefood.com), so that all sectors with an interest in sustainable food production can access knowledge.
“In many cases, the scientists in our project already knew about the issues and had the solutions, but the people who needed to know weren’t aware of this knowledge,” said Dicks. The priority knowledge needs identified by this work will structure ongoing efforts to make science accessible to practitioners, and will help to guide future science policy and funding.
“Bringing scientists together with the business community at the start of the process is a radically different way of working,” said Dicks’ collaborator Bill Sutherland, Miriam Rothschild Professor of Conservation Biology in the Department of Zoology. “This approach could apply to almost any academic field. We want to fundamentally change the way that conservation policy and practice works. This project is about pollinators, but if the knowledge exchange process works, we can start looking at the bigger picture.”
Inset: Dr Lynn Dicks and Prof Bill Sutherland
Insect pollinators provide a service worth an estimated £430 million to food, farming and retail sectors in the UK. How can we protect them, and enhance the sustainability of the UK food production system?
Connecting science and society: much more than a problem of communication
By lw355 from University of Cambridge - Department of Zoology. Published on Oct 03, 2013.
We live in an era where there is a greater demand for applied sciences than ever before. Funding agencies and governments require more and more attention to be paid to ensuring that a given research project will have “impact”. The UK government has taken a bold and – in my opinion – laudable step to include measures of how much “impact” has been achieved by research as part of its five-year assessment of research excellence in universities. However, ensuring that applied research can deliver tangible and beneficial contributions to achieving society’s goals – whether in delivering improvements in human development and health, or in overcoming the challenges that face humanity in an era of unprecedented environmental and climatic change – remains a perpetually elusive and frustrating enterprise.
Scientists often bemoan the fact that politicians and other groups of influential people do not listen to what they have to say. It is easy to feel that if only we knew how to get the message across better, write better press releases, give interviews on the radio and television and write letters to newspapers then people would pay more attention, and positive changes would ensue.
There is little doubt that all this is true and, as a rule, scientists are generally a reclusive bunch, preferring to continue focusing on what they are good at than trying to repackage their painstaking work into accessible language and digestible sound bites. It is also unreasonable to think that scientists could and should do this on their own, and universities and research institutions could greatly enhance the impact of the work done by their scientists if they employed more than the typical handful of communications experts.
However, achieving a closer integration of science and society to leverage changes in government policy and the behaviour of individuals goes far beyond the trials and tribulations of just “getting our message across”. Sending all newly appointed researchers on media training courses would doubtless be a useful investment but it would do little to revolutionise the effectiveness and impact of science. Much more fundamental changes are needed to embed not only the outcomes, but also the process of science more deeply within the institutions and communities of people who actually have the ability to use new information and understanding to foster positive change.
A common message I hear from decision makers in government, the private sector and civil society at all levels is that, no matter how well they communicate their ideas, scientists are often not addressing the right questions in the first place. Or that they are only addressing a subset of what is in fact a much broader problem – the appreciation of which is rarely made explicit. I am inclined to agree.
A lot more can be done to critically appraise the way in which limited human resources and funding is apportioned to address competing priorities and complementary research needs. Central to this challenge is the need to be much more explicit about the underlying motivations and context of a specific research contribution, how it relates to existing knowledge and work being done in other disciplines, and the extent to which it is able to help guide real changes on the ground. In being more systematic in our appraisal of different stages in the process of acquiring knowledge to tackle a specific problem we can be more honest about contextualising specific contributions, understand the opportunities and limitations that they represent and minimise what are often fruitless and counterproductive debates.
For example, in the fields of conservation and sustainability science where I work, it is not enough to simply quantify and understand processes of environmental degradation (the focus of work by many ecologists, and much of my own research career to date). For this understanding to lead to actual changes in policy and implementation, additional work is needed to understand the opportunities that exist to confront such problems in the form of practical policy and management interventions, the conditions and risks associated with implementing any such interventions, and the barriers that may undermine their effectiveness in the long-term.
All of these stages require dedicated research attention, and the ability of science to support any process of transition towards greater sustainability depends upon a careful integration and contextualisation of findings from across different disciplines, all working under a shared appreciation of the problems facing a given region. It may be the case that more research is not needed in a given area – perhaps, for instance, we already understand enough about the environmental damage caused by illegal timber logging, and instead what is more urgently needed is a deeper understanding of the kinds of institutions and blend of regulations and incentives that can support more sustainable and equitable approaches to forest management.
Ultimately, however, even the most integrated approach to studying the linked problems and solutions facing the management of environmental resources (or any other problem) in a given region will likely have very little impact if the people who are intended to benefit from, or be influenced by, the work are not intimately involved in the research process itself. Evidence on its own is not enough.
Researchers label such kinds of participatory approaches – where scientists, decision makers and affected people all have a stake in the priorities, design and execution of research – as transdisciplinarity. Yet, despite considerable theoretical interest, genuine examples of where this has been achieved in practice are depressingly thin on the ground. To scientists and decision makers who have tried, this will come as no surprise as it is invariably an incredibly difficult and largely thankless endeavour.
Overcoming these problems and making such approaches more mainstream requires a step-change in the incentive structure of universities such that early and persistent engagement by researchers in decision-making processes is encouraged, recognised and rewarded. It also requires researchers to have access to opportunities that can foster the development of a research environment that is more intimately embedded in the community it is trying to support, such as through reciprocal secondments of research and policy experts, capacity-building programs and a much greater investment in strategic and operational modes of individual research groups. It remains to be seen whether the current changes in the culture of research funding and evaluation will be sufficient to achieve this.
Dr Toby Gardner is in the Department of Zoology.
As the deadline fast approaches for higher education institutions to submit the evidence on which the quality of their research will be assessed, Dr Toby Gardner asks how applied research can best deliver tangible contributions to achieving society’s goals.
Why Museum of Zoology in Cambridge dismantled 70ft whale skeleton
From Department of Zoology. Published on Oct 01, 2013.Cambridge News slideshow of the whale being dismantled
Dr Howard Baylis and Dr Maria Giannakou - Alzheimers Research Trust Research Grant
From Department of Zoology. Published on Sep 16, 2013.Ageing-specific changes in a Drosophila Alzheimer's model
Functioning ‘mechanical gears’ seen in nature for the first time
By fpjl2 from University of Cambridge - Department of Zoology. Published on Sep 12, 2013.
The juvenile Issus - a plant-hopping insect found in gardens across Europe - has hind-leg joints with curved cog-like strips of opposing ‘teeth’ that intermesh, rotating like mechanical gears to synchronise the animal’s legs when it launches into a jump.
The finding demonstrates that gear mechanisms previously thought to be solely man-made have an evolutionary precedent. Scientists say this is the “first observation of mechanical gearing in a biological structure”.
Through a combination of anatomical analysis and high-speed video capture of normal Issus movements, scientists from the University of Cambridge have been able to reveal these functioning natural gears for the first time. The findings are reported in the latest issue of the journal Science.
The gears in the Issus hind-leg bear remarkable engineering resemblance to those found on every bicycle and inside every car gear-box.
Each gear tooth has a rounded corner at the point it connects to the gear strip; a feature identical to man-made gears such as bike gears – essentially a shock-absorbing mechanism to stop teeth from shearing off.
The gear teeth on the opposing hind-legs lock together like those in a car gear-box, ensuring almost complete synchronicity in leg movement - the legs always move within 30 ‘microseconds’ of each other, with one microsecond equal to a millionth of a second.
This is critical for the powerful jumps that are this insect’s primary mode of transport, as even miniscule discrepancies in synchronisation between the velocities of its legs at the point of propulsion would result in “yaw rotation” - causing the Issus to spin hopelessly out of control.
“This precise synchronisation would be impossible to achieve through a nervous system, as neural impulses would take far too long for the extraordinarily tight coordination required,” said lead author Professor Malcolm Burrows, from Cambridge’s Department of Zoology.
“By developing mechanical gears, the Issus can just send nerve signals to its muscles to produce roughly the same amount of force - then if one leg starts to propel the jump the gears will interlock, creating absolute synchronicity.
“In Issus, the skeleton is used to solve a complex problem that the brain and nervous system can’t,” said Burrows. “This emphasises the importance of considering the properties of the skeleton in how movement is produced.”
"We usually think of gears as something that we see in human designed machinery, but we've found that that is only because we didn't look hard enough,” added co-author Gregory Sutton, now at the University of Bristol.
“These gears are not designed; they are evolved - representing high speed and precision machinery evolved for synchronisation in the animal world.”
Interestingly, the mechanistic gears are only found in the insect’s juvenile – or ‘nymph’ – stages, and are lost in the final transition to adulthood. These transitions, called ‘molts’, are when animals cast off rigid skin at key points in their development in order to grow.
It’s not yet known why the Issus loses its hind-leg gears on reaching adulthood. The scientists point out that a problem with any gear system is that if one tooth on the gear breaks, the effectiveness of the whole mechanism is damaged. While gear-teeth breakage in nymphs could be repaired in the next molt, any damage in adulthood remains permanent.
It may also be down to the larger size of adults and consequently their ‘trochantera’ – the insect equivalent of the femur or thigh bones. The bigger adult trochantera might allow them to create enough friction to power the enormous leaps from leaf to leaf without the need for intermeshing gear teeth to drive it, say the scientists.
Each gear strip in the juvenile Issus was around 400 micrometres long and had between 10 to 12 teeth, with both sides of the gear in each leg containing the same number – giving a gearing ratio of 1:1.
Unlike man-made gears, each gear tooth is asymmetrical and curved towards the point where the cogs interlock – as man-made gears need a symmetric shape to work in both rotational directions, whereas the Issus gears are only powering one way to launch the animal forward.
While there are examples of apparently ornamental cogs in the animal kingdom - such as on the shell of the cog wheel turtle or the back of the wheel bug - gears with a functional role either remain elusive or have been rendered defunct by evolution.
The Issus is the first example of a natural cog mechanism with an observable function, say the scientists.
Inset image: an Issus nymph
For more information, please contact firstname.lastname@example.org
Previously believed to be only man-made, a natural example of a functioning gear mechanism has been discovered in a common insect - showing that evolution developed interlocking cogs long before we did.
Honeyguide birds destroy own species’ eggs to eliminate competition
By gm349 from University of Cambridge - Department of Zoology. Published on Aug 21, 2013.
Like cuckoos, honeyguides are parasitic birds that lay their eggs in other birds' nests and dupe them into raising their young. Now scientists reveal that, unlike in cuckoos, the resemblance between honeyguide eggs and those of their bee-eater bird hosts hasn't evolved to trick hosts into accepting the imposter egg as one of their own. Rather, it appears to have evolved to trick other honeyguides who would otherwise destroy the eggs because of fierce competition for host nests. The new research is published today, 21 August, in the journal Biology Letters.
Honeyguides are intriguingly odd birds that are best-known for their unique, mutually beneficial relationship with humans. Honeyguides love to eat beeswax. To obtain it, they guide human honey-hunters to bees' nests. In return for showing the humans the bees, the honeyguide gains access to the otherwise dangerous and impenetrable nest and its sought-after wax.
But these African birds also have a dark side. They are unusually vicious parasites whose imposter chicks stab the chicks of their host birds (often little bee-eaters) to death as soon as they hatch in order to eliminate competition for the host parents' care. The newly published research has shown that this fight for monopoly of the nest also extends to other honeyguides in a battle conducted deep underground in the nest burrows that bee-eaters dig into the roofs of Aardvark holes.
The researchers' curiosity was piqued by their earlier finding that like cuckoo eggs, honeyguide eggs resemble those of each of their several host species. Instead of mimicking their colour, however, they mimic their size (as colour is irrelevant in the dark interior of the deep holes in which hosts breed). For example, honeyguides parasitising little bee-eaters lay smaller eggs in their nests than do honeyguides parasitising larger hosts. Many classic studies have shown that comparable mimicry in cuckoo eggs has evolved to reduce rejection by choosy hosts that eject mismatched eggs from their nests.
Dr Claire Spottiswoode from the University of Cambridge’s Department of Zoology, who carried out the research, said: “I assumed honeyguide egg mimicry had evolved just like cuckoo mimicry, so was bowled over and baffled when little bee-eaters turned out to be pretty dim. When I played the honeyguide and experimentally parasitised their nests, the bee-eaters blithely incubated eggs even much larger than their own. So I was quite wrong, and mimicry probably hasn't evolved to dupe bee-eaters.
“It was only when some of my experiments were parasitised by real honeyguides, and my experimental eggs were pecked to pieces, that the penny dropped – perhaps they need to look like bee-eaters or else other honeyguides will get rid of them, to avoid suffering the same grisly fate that they impose upon their hosts.”
A second experiment supported this hypothesis: again the researchers placed a larger foreign egg in bee-eaters nests, but then waited for a real honeyguide to come along and lay her own egg. When this happened they counted the number of puncture holes the female honeyguide made in each egg in the clutch. This revealed that laying honeyguides punctured the larger foreign egg more heavily than host eggs, lest it be another honeyguide's egg and kill their own chick should it hatch first. Evolution should then favour honeyguide females that lay eggs resembling those of bee-eaters and thereby avoid being detected and destroyed by a competing honeyguide.
The suggestion that mimicry might evolve because parasites benefit from concealing their eggs from one another was first made by Cambridge scientists Nick Davies and Michael Brooke 25 years ago, but this study is the first to show that it probably happens in the wild. Honeyguide parasitism on little bee-eaters is very common and about a third of parasitised nests contain eggs laid by two or more honeyguide females, resulting in especially strong parasitic competition.
Dr Spottiswoode said: “Under these circumstances it makes good sense that honeyguides have a lot to gain from tricking other honeyguides. But we still don't know why bee-eaters parents themselves are so undiscriminating, especially when they pay such high costs of being conned – all your offspring hacked to death, and over a month wasted raising the wrong chick!"
The research was funded by The Royal Society and the DST/NRF Centre of Excellence at Percy FitzPatrick Institute, University of Cape Town. It forms part of a wider research programme investigating coevolution between parasitic birds and their hosts in Zambia led by Dr Claire Spottiswoode, who adds "My colleagues and I are very lucky to be helped by a wonderful team of local field assistants who find all the nests we study, and in this case dug many holes into rock-hard soil to reach bee-eater nests and carry out these experiments!"
Scientists believe behaviour drives evolution of egg size similar to hosts.
Dr Claire Spottiswoode - European Commission FP7 MC International Incoming Fellowship
From Department of Zoology. Published on Aug 07, 2013.HONEYGUIDE IMMUNITY - The evolution of immune defences in avian brood parasites and their hosts
Dr Nicola Lewis - Defence Threat Reduction Agency Research Grant
From Department of Zoology. Published on Aug 07, 2013.Ecology and evolution of avian influenza virus (AIV) in wild birds in Georgia and the establishment of the population genetics structure of a host species
Dr Judith Fonville - MRC Fellowship
From Department of Zoology. Published on Aug 07, 2013.Quantifying pandemic risk caused by within-host evolution of influenza A/H5N1 viruses
Dr Torsten Krude - BBSRC Research Grant
From Department of Zoology. Published on Aug 07, 2013.Purification and characterisation of a novel dominant initiation factor for chromosomal DNA replication
Professor Bill Sutherland - The Nature Conservancy Research Grant
From Department of Zoology. Published on Aug 07, 2013.Quantifying and mapping mangrove ecosystem services
Dr Lynn Dicks - NERC Fellowship
From Department of Zoology. Published on Aug 06, 2013.Supporting ecosystem services on commercial farms: using evidence to inform land management decision
Dr Chris Jiggins - BBSRC Research Grant
From Department of Zoology. Published on Aug 06, 2013.Building a genome analytic resource for the lepidopteran community
Professor Rufus Johnstone - Leverhulme Trust Research Grant
From Department of Zoology. Published on Aug 06, 2013.Adaptive modeling of human infant growth
Dr Claire Spottiswoode - Leverhulme Trust Research Grant
From Department of Zoology. Published on Aug 06, 2013.The role of phenotypic plasticity in driving a remarkable adaptive radiation
Dr Rose Thorogood - Society In Science Research Grant
From Department of Zoology. Published on Aug 05, 2013.
Dr Claire Spottiswoode - BBSRC Fellowship
From Department of Zoology. Published on Aug 02, 2013.Species interactions and the evolution of biological diversity: visual signalling in antagonistic and mutalistic coevoltuion
Dr Berthold Hedwig - BBSRC Research Grant
From Department of Zoology. Published on Aug 02, 2013.RESUBMISSION: Neural processing underlying auditory pattern recognition in an insect brain
Professor Bill Amos - Isaac Newton Trust Research Grant
From Department of Zoology. Published on Aug 02, 2013.How Cows are Evolving to Pass the Standard Test of Tuberculosis
Professor Jenny Clack - Isaac Newton Trust Research Grant
From Department of Zoology. Published on Aug 02, 2013.Purchase of a Unique Collection of Fossil Material from an Important New Site
Professor Nick Davies - Isaac Newton Trust Research Grant
From Department of Zoology. Published on Aug 02, 2013.Forewarned is Forearmed: Using Information to Beat Brood Parasites
Dr Rob Asher - Isaac Newton Trust Travel Grant
From Department of Zoology. Published on Aug 02, 2013.Development and Palaentology of Southern Placental Mammals
Dr Chris Jiggins - European Commission FP7 MC International Outgoing Fellowship
From Department of Zoology. Published on Aug 02, 2013.BxMxE— The interaction between a butterfly, its microbiome and the environment
Professor Bill Sutherland - European Commission FP7 MC Intra European Fellowship
From Department of Zoology. Published on Aug 02, 2013.PRESERVATION—Predictive ecology of global species extinction risk for conservation - Tatsuya Amano
Dr Rose Thorogood - NERC Fellowship
From Department of Zoology. Published on Aug 02, 2013.Landscapes of information: how information use affects ecological communities
Quest for missing sculpture
From Department of Zoology. Published on Aug 02, 2013.
Academic Promotions 2013
From Department of Zoology. Published on Aug 02, 2013.Many congratulations to five members of the Department who have received awards in this year's Academic Promotions exercise, to take effect from 1 October 2013:
Recent Postgraduate Awards
From Department of Zoology. Published on Aug 02, 2013.
From Department of Zoology. Published on Aug 01, 2013.Professor Jenny Clack awarded Glasgow Geological Society's T. Neville George medal; Dr Henry Disney awarded Honorary Membership to the Freshwater Biological Association
Professor Jenny Clack to receive Doctor of Science honorary degree from University of Chicago
From Department of Zoology. Published on Aug 01, 2013.
Mangroves could survive sea-level rise if protected
By tdk25 from University of Cambridge - Department of Zoology. Published on Jul 31, 2013.
Mangroves, which provide a natural coastal defence to communities around the world, may be able to withstand a future rise in sea levels far more than previously thought, scientists have found.
Their report should serve to allay fears that many mangrove areas could be lost in the coming decades as sea levels go up because of global warming.
It comes, however, with a cautionary note: The authors, who have carried out a rare and detailed survey of how mangroves adapt to their environment, also argue that it is vital that they are managed and conserved so that they can continue to provide this protection.
The survey warns that human activity on land – such as the damming up of rivers or the felling of trees to create shrimp ponds – is currently a far greater threat to many mangrove habitats than the effects of climate change on sea level.
Mangroves – trees and shrubs which grow in saltwater, coastal environments – play a critical role in protecting thousands of shoreline communities in tropical and subtropical regions from floods, storms, and other hazards.
Their densely-packed, overground root systems can absorb wave energy and reduce the velocity of a sudden surge of water. In the 2004 tsunami, for example, mangroves were sometimes the difference between life and death for people whose homes lay in the path of the giant waves which crashed into shorelines around South Asia.
For some time, scientists have been concerned that if sea levels rise as predicted, they will kill off mangroves – removing these natural coastal defences at the very time they are expected to be needed most.
The new study suggests that this is far less likely than previously thought, however. Dr Anna McIvor, from the University of Cambridge, and the report’s lead author, said: “Although we can expect some mangrove areas to be lost as sea levels rise, many of them appear to be able to withstand it.”
“In fact, changes to mangrove habitats through human activity are likely to pose a bigger threat to these coastal defences than sea level rise as it stands. Our research has enabled us to find out more about how mangroves continue to flourish in spite of a rise in sea levels – but that information should be used as the basis for better management of these important ecosystems.”
The study was carried out by a team from The Nature Conservancy, Wetlands International, and the Cambridge Coastal Research Unit (based in the University’s Department of Geography). The researchers examined both recent reports looking at surface elevation in mangrove areas, and the historical reasons why mangroves have, in some places, persisted for thousands of years.
They found that the height of the soil surface in mangrove areas is often “surprisingly dynamic”, and in some cases appears to be building up at rates of between one and 10 millimetres every year. The global mean sea level rise is currently 3mm per year, meaning that many mangrove areas build up soil at a rate which keeps pace with the sea.
There are several reasons for this, but chief among them appear to be the ability of mangroves to trap sediment as it is carried down to them by rivers, and the work of their roots beneath the surface. “Mangroves provide much of the organic sediment matter that makes up the soil, their complex roots help to bind and trap the sediments on the soil surface, while the unseen growth of roots beneath helps to build up the soil from below,” McIvor said.
Despite this resistance to changes in sea level, however, the report cautions that the future stability of mangroves is by no means guaranteed. “Threshold rates of sea level rise are likely to exist, beyond which mangrove surfaces are no longer able to keep up,” the authors point out.
Perhaps more urgently, in some regions human activities like agriculture and construction are being authorised regardless of their impact on the ecosystems which enable mangroves to thrive.
In some countries, for example, rivers which play a vital role by carrying sediment to the mangrove areas so that the soil can be built up are being dammed or diverted. Another common threat is aquaculture: in Indonesia, and other South Asian countries, mangroves are often cut down without restriction to make way for shrimp ponds.
The report also warns that mangroves may need room to expand landward, especially where conditions are such that sea level rise may still be a threat to their growth. Communities which rely on them for coastal defence need to leave space to ensure that this can happen, the authors advise.
Dr Mark Spalding, from The Nature Conservancy and the Department of Zoology, University of Cambridge, said: “This report shows that well-managed mangroves in many places will continue to support and safeguard many vulnerable communities as sea levels rise. We still have lots to learn about them, but the sensible, precautionary approach is to look after them and restore them as a critical first line of defence.”
The full report can be downloaded at: http://coastalresilience.org/science/mangroves/surface-elevation-and-sea...
For more information about this story, please contact Tom Kirk, Tel: 01223 332300, email@example.com
Human activity is currently a bigger threat to mangroves, and the natural defences they provide against storm surges and other coastal disasters, than rising sea levels, according to a new study.
Part II Zoology student wins first round of University Challenge
From Department of Zoology. Published on Jul 30, 2013.Students representing Trinity College did battle with Christ Church Oxford on University Challenge last night, winning a place in the second round.
Monogamy evolved as a mating strategy
By gm349 from University of Cambridge - Department of Zoology. Published on Jul 29, 2013.
Social monogamy, where one breeding female and one breeding male are closely associated with each other over several breeding seasons, appears to have evolved as a mating strategy, new research reveals. It was previously suspected that social monogamy resulted from a need for extra parental care by the father.
The comparative study, by University of Cambridge researchers Dieter Lukas and Tim Clutton-Brock, shows that the ancestral system for all mammalian groups is of females living in separate ranges with males defending overlapping territories, and that monogamy evolved where males were unable to monopolise and defend multiple females. The research is published in the journal Science.
For the study, the researchers classified all 2500 mammalian species for which information exists as either solitary, socially monogamous or group-living (several breeding females share a common range and either eat or sleep together). They showed that nine per cent of mammals are socially monogamous, including a few rodents, a number of primates, and some carnivores, like jackals, wolves, and meerkats.
Previously, it had been suggested that monogamy evolved as a result of selection for paternal support in raising offspring (for example, if the female alone could not provide enough food or adequately defend the young). This study shows that paternal care usually evolved after monogamy was already present.
This advance in understanding was, says Lukas of Cambridge's Department of Zoology, due to the volume of information they collected and the availability of genetic information that allowed the researchers to determine the sequence in which different traits evolved.
"Up until now, there have been different ideas about how social monogamy in mammals evolved," says Lukas. "With this study we were able to test all these different hypotheses at once. Paternal care evolves after monogamy is present, and seems to be a consequence rather than a cause of the evolution of monogamy. It appears to occur in about half of all socially monogamous species, and once it does evolve, it provides a clear benefit to the female."
They found convincing support for the hypothesis that monogamy arose as a mating strategy where males could not defend access to more than one female. Monogamy is associated with low density of females, low levels of home-range overlap, and indirectly, with their diets. The study showed that monogamy evolves in species that rely on high quality but patchily distributed food sources, such as meat and fruit. In contrast, in herbivores, which rely on more abundant resources, social monogamy is rare.
"Where females are widely dispersed," says Clutton-Brock, "the best strategy for a male is to stick with one female, defend her, and make sure that he sires all her offspring. In short, a male's best strategy is to be monogamous."
The analysis did not include humans, and the researchers are sceptical that these results tell us much about the evolution of human breeding systems.
Clutton-Brock adds: "It is debatable whether humans should be classified as monogamous. Because all the African apes are polygamous and group living, it is likely that the common ancestor of hominids was also polygamous. One possibility is that the shift to monogamy in humans may be the result in the change of dietary patterns that reduce female density, and another is that slow development of juveniles required extended care by both sexes. However, reliance by humans on cultural adaptations means that it is difficult to extrapolate from ecological relationships in other animals."
For more information about this story, please contact: Genevieve Maul, Office of Communications, University of Cambridge. Email: Genevieve.Maul@admin.cam.ac.uk; Tel: 01223 765542.
New research indicates that social monogamy evolved as a result of competition for females.
Nick Crumpton co-authors children's book
From Department of Zoology. Published on Jul 29, 2013.A new children's activity book co-authored by the Department's Nick Crumpton has been published by Flying Eye books.
Cuckoo named after Professor Nick Davies
From Department of Zoology. Published on Jul 12, 2013.Professor Nick Davies has had a cuckoo named after him as part of the British Trust for Ornithology's cuckoo tracking project.
Demise of large animals such as woolly mammoth and giant sloths caused by both man and climate change
From Department of Zoology. Published on Jul 04, 2013.Past waves of extinctions, which removed some of the world's largest animals, were caused by both people and climate change, according to new research from the members of the Department.
The remarkable notebook of a 19th-century naturalist
From Department of Zoology. Published on Jul 04, 2013.A notebook recording the fauna of Cambridgeshire observed and collected by the Reverend Leonard Jenyns between 1820 and 1849 has been published in full for the first time. A significant naturalist in his own right, Jenyns turned down the offer of a place on HMS Beagle, recommending instead a younger colleague, Charles Darwin.
Crop Expansion and Conservation Priorities in Tropical Countries
From Department of Zoology. Published on Jul 04, 2013.
Reassembling the backbone of life using a particle accelerator
From Department of Zoology. Published on Jul 04, 2013.Research published in the journal Nature documents, for the first time, the intricate three-dimensional structure of the backbone in the earliest four-legged animals (tetrapods).
New Undergraduate Certificate in Evolutionary Biology
From Department of Zoology. Published on Jul 04, 2013.Institute of Continuing Education offers new year-long, part-time Undergraduate Certificate in Evolutionary Biology
Library Pinterest boards launched
From Department of Zoology. Published on Jul 04, 2013.
Part II Zoology Open Day
From Department of Zoology. Published on Jul 04, 2013.
Our ancient ancestors
From Department of Zoology. Published on Jul 04, 2013.