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Why insects are marvels of engineering

From Department of Zoology. Published on Jul 03, 2015.

Women’s faces get redder at ovulation, but human eyes can’t pick up on it

By fpjl2 from University of Cambridge - Department of Zoology. Published on Jun 30, 2015.

Previous studies have shown that men find female faces more attractive when the women are ovulating, but the visual clues that allow this are unclear. Now, new research investigating whether it might be to do with subtle changes in skin colour has shown that women’s faces do increase in redness during ovulation, but the levels of change are just under the detectable range of the human eye.

Researchers say this may mean that facial redness in females was once an involuntary signal for optimal fertility, but has since been “dampened” by evolution as it is more beneficial for females to hide or control outward signs of peak fertility.

Involuntarily signalling ovulation can prevent longer-term investment from males. In primate species that advertise ovulation, males only express sexual interest in females when they appear to be fertile. In humans, ovulation is less conspicuous and sexual behaviour is not restricted to the period of peak fertility.       

The research, published today in the open-access journal PLOS ONE, is the most complete objective study of female faces during the ovulatory cycle, say researchers. Twenty-two women were photographed without make-up at the same time every working day for at least one month in the same environment and using a scientific camera modified to more accurately capture colour (usually used for studying camouflage in wildlife).

A computer programme was designed to select an identical patch of cheek from each photograph. The participants also self-tested for hormone changes at key times dictated by the research team’s “period maths”.        

A surge in luteinising hormone told researchers that ovulation would occur in roughly the next 24 hours, so they knew which photographs were taken when the women were most fertile. The team converted the imagery into red/green/blue (RGB) values to measure colour levels and changes.

They found that redness varied significantly across the ovulatory cycle, peaking at ovulation and remaining high during the latter stages of the cycle after oestrogen levels have fallen. Skin redness then dips considerably once menstruation begins. The research suggests facial redness closely maps fluctuations in body temperature during the cycle.

However, when running the results through models of human visual perception, the average difference in redness was 0.6 units. A change of 2.2 units are needed to be detectable to the naked human eye.

“Women don’t advertise ovulation, but they do seem to leak information about it, as studies have shown they are seen as more attractive by men when ovulating,” said Dr Hannah Rowland, from the University of Cambridge’s Zoology Department, who led the study with Dr Robert Burriss, a psychologist from Northumbria University.   

“We had thought facial skin colour might be an outward signal for ovulation, as it is in other primates, but this study shows facial redness is not what men are picking up on - although it could be a small piece of a much larger puzzle,” she said.

Primates, including humans, are attracted to red, say the study’s authors. Women may subconsciously augment the naturally-occurring facial redness during ovulation through make-up such as blusher or red clothing, they say.

“As far back as the 1970s, scientists were speculating that involuntary signals of fertility such as skin colour changes might be replaced with voluntary signals, such as clothing and behaviour,” said Burriss. “Some species of primate advertise their fertility through changes in the colour of their faces. Even if humans once advertised ovulation in this way, it appears that we don’t anymore.”

It may be that, during ovulation, women have a greater propensity for blushing when around men they find attractive, say the researchers. “Other research has shown that when women are in the fertile phase of their cycle they are more flirtatious and their pupils dilate more readily, but only when they are thinking about or interacting with attractive men,” said Burriss. “We will need to do more research to find out if skin redness changes in the same way”.

Rowland and Burriss first conceived of the experiment seven years ago, but it wasn’t until Rowland arrived at Cambridge that they were able to do the research, thanks to the University’s collegiate system. “We were able to recruit undergraduates in a number of colleges and photograph the women just before they had dinner in the college hall every evening. The collegiate routines and networks were vital to collecting data with such regularity,” said Rowland.

Past research shows men find female faces more attractive at peak fertility. A new study shows an increased redness of women’s face skin at the most fertile point of ovulatory cycle, but just under the threshold for detectability, ruling out skin colouration as a driver of the attractiveness effect.

Women don’t advertise ovulation, but they do seem to leak information about it
Hannah Rowland

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Emeritus Professor Sir Pat Bateson awarded the ZSL Frink Medal 2014

From Department of Zoology. Published on Jun 25, 2015.

Richard Preece and Roz Wade on 'Wildlife Wednesday'

From Department of Zoology. Published on Jun 18, 2015.

Prof. Simon Laughlin publishes new book on brain design

From Department of Zoology. Published on Jun 15, 2015.

Nick Davies appears on 'Springwatch'

From Department of Zoology. Published on Jun 12, 2015.

Janet Moore Prize for Supervising in Zoology

From Department of Zoology. Published on Jun 12, 2015.

Cuckoos mimic 'harmless' species as a disguise to infiltrate host nests

By fpjl2 from University of Cambridge - Department of Zoology. Published on Jun 10, 2015.

Brood parasites are reproductive cheats that evolve ways of duping other birds into raising their young. Examples such as mimicry of host eggs, chicks and fledglings by brood parasitic eggs, chicks and fledglings are amongst the most iconic examples of animal deception in nature.

New research shows that adult brood parasitic female cuckoo finches have evolved plumage colours and patterns to mimic a harmless and abundant species, such as southern red bishops, to deceive possible host birds and reduce the risk of being attacked when approaching host nests to lay their eggs.

Researchers say this is the first time that "wolf in sheep's clothing" mimicry has been shown to exist in any adult bird.

While other brood parasites watch the movements of their host victims by hiding in nearby foliage, the openness of the African savannahs mean that mimicking a plentiful and nontoxic species might be the best way cuckoo finches have of sneaking up on host nests without raising the alarm.

However, the researchers found that the most common victim of the cuckoo finch, the tawny-flanked prinia, has evolved an awareness of the cuckoo finch's disguise and takes no chances - acting with equal aggression towards a female cuckoo finch and bishop alike.

Prinias attacked female cuckoo finches and female bishops equally, and increased the rate of egg rejection after seeing either a female cuckoo finch or female bishop near the nest. Egg rejection involves physically removing the parasitic egg from their nest, allowing them to salvage the majority of their reproductive effort.

At the study site in Zambia, the researchers found a consistently high rate of parasitism by cuckoos among the prinia population, with almost a fifth of all prinia eggs hatching as fledgling cuckoo finches. Cuckoo finches usually remove at least one egg on parasitism, and their hatchlings will out-compete all the host's young.

Researchers say these rates of parasitism might explain the willingness of prinias to attack anything that looks like a dangerous female cuckoo finch and reject more eggs when the risk of parasitism is high. But, the cost of this strategy can be high: during the researchers' experiments, some of the eggs rejected by prinia were their own, triggered by nothing more than a harmless bishop bird that resembles the mimetic cuckoo finch.

"Our findings suggest that female cuckoo finches are aggressive mimics of female bishops, and that prinia hosts have responded to this successful deception with generalised defences against cuckoo finches and harmless bishops alike. This suggests these prinias have decided that it's best to 'play it safe' when the risk of parasitism is high because they can't distinguish between the two species" said Dr William Feeney from Cambridge University's Department of Zoology, who led the research.

"While other brood-parasite species monitor host behaviour from concealed perches in nearby trees, cuckoo finches must seek host nests in open grasslands and savannahs. In such exposed circumstances, resembling an abundant and harmless model may allow female cuckoo finches to remain unnoticed when monitoring hosts nests at a medium range," he said.

The research is published today in the journal Proceedings of the Royal Society B.

To investigate the cuckoo finch's disguise, the research team conducted plumage and pattern analysis using cuckoo skins from the Natural History Museum in Tring. They compared plumage to the cuckoo finches closest evolutionary relatives (Vidua finches), as well as with the skins of similar-looking birds (bishops) that share the same habitat.

In both human and bird visual systems, they found that the plumage of a female cuckoo finch is far closer to the bishops and other species in the weaver family than to those of its closest relative, the Vidua finches.

The researchers also investigated the reaction of prinia breeding pairs to models of female cuckoo finches and bishop birds, as well as the males of both species.

While prinias had very little reaction to the males, the female cuckoo finch and the harmless female bishop bird both received similarly high levels of alarm calls and group attacks from the prinia, known as 'mobbing'.

The researchers then did a final experiment where they presented a male bishop, female bishop and female cuckoo finch and then placed a fake egg in their nest. They found that after seeing the harmful female cuckoo finch or harmless (but similar-looking) female bishop, they increased their rate off egg rejection compared to when they saw a male bishop near their nest.

Added Feeney: "This study is interesting as it's the first time anyone has quantitatively tested for 'wolf in sheep's clothing' mimicry in any adult bird, and also suggests that this type of mimicry is used by brood parasites to deceive hosts at all stages of their nesting cycle."

First time ‘wolf in sheep’s clothing’ mimicry has been seen in birds. Host birds have evolved a general counter-strategy in which they defend against all birds with the mimicked plumage - cuckoos and harmless species alike.

It's the first time anyone has quantitatively tested for 'wolf in sheep's clothing' mimicry in any adult bird
William Feeney
Cuckoo finch on the left and a bishop bird on the right

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All Museum creatures great and small

From Department of Zoology. Published on Jun 09, 2015.

Birds ‘cry hawk’ to give offspring chance to escape predators

By fpjl2 from University of Cambridge - Department of Zoology. Published on Jun 03, 2015.

New research has found that the 6 gram brown thornbill mimics the hawk alarm calls of neighbouring species to scare a nest predator by convincing it that a much bigger and scarier predator – the brown goshawk – is on its way.

Currawongs, which raid the nests and hunt the chicks of thornbills, are also prey to goshawks. Although currawongs normally benefit from listening in on hawk alarm calls of other species, thornbills exploit this and turn it against them.

As well as issuing their own hawk alarm call, thornbills mimic those of the local species to create the impression of an impending hawk attack, which in turn distracts the pied currawong - a predator 40 times larger than the thornbill - providing thornbill nestlings with an opportunity to escape.

While animals often mimic dangerous or toxic species to deter predators, the thornbill is a surprising example of a species mimicking another harmless species to trick a predator.

The research, conducted by scientists at the University of Cambridge and the Australian National University (ANU), is published today in the journal Proceedings of the Royal Society B.   

“The enormous size difference between a tiny thornbill and a 0.5kg goshawk might make it difficult for thornbills to mimic hawk vocalisations accurately, limiting them to mimicking the chorus of hawk alarm calls given by small local species instead,” said Jessica McLachlan, a PhD student from Cambridge’s Department of Zoology, who co-authored the study.

“As hawks are silent when hunting, the alarm calls of local species may be the only sound that warns of a hawk’s presence,” she said. 

The researchers studied the thornbills and currawongs living in and around the Australian National Botanic Gardens in Canberra. They devised a series of experiments in which they placed stuffed currawongs in front of thornbill nests to test when thornbills use such trickery, followed by experiments testing how currawongs respond to the calls of thornbills.

They found that thornbills used their own and mimicked hawk alarm calls when their nests are under attack. They also found that currawongs delayed attacks for twice as long when mimetic and non-mimetic alarm calls were played together as opposed to non-mimetic calls played alone.

“Distracting a currawong attacking the nest could give older thornbill nestlings a chance to escape and hide in the surrounding vegetation,” said Dr Branislav Igic from ANU, who led the study.

“It’s perhaps the thornbills best nest defence in this circumstance because physical attacks on the much larger currawong are hopeless,” Igic said.

Inset image: Pied currawong. Credit: Jessica McLachlan

Surprising finding shows that thornbills simulate a ‘chorus of alarm’ to distract predators by convincing them something scarier is on its way.

As hawks are silent when hunting, the alarm calls of local species may be the only sound that warns of a hawk’s presence
Jessica McLachlan
Brown thornbill

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A is for Albatross

By amb206 from University of Cambridge - Department of Zoology. Published on Jun 01, 2015.

In June 1910 Dr Edward Wilson set sail from Cardiff to Antarctica on board the Terra Nova as the Chief of the Scientific Staff on the British Antarctic Expedition led by Captain Scott. On 1 November the following year a group from the Terra Nova set out from Cape Evans across the ice with the intention of reaching the South Pole. The venture ended in tragedy. The members of the British expedition perished on their return from the pole having discovered that the Norwegians had got there first.

Wilson was a talented artist as well as a doctor. He began drawing as a child and throughout his life he made meticulous sketches and watercolours of the natural world.

After his death, his final sketchbook was retrieved from the tent where he and his companions spent their last days. His watercolours were returned from the Cape Evans hut where they had been produced.

Artworks made by Wilson on both the Discovery Expedition of 1901 and the Terra Nova Expedition are testimony to the spirit of discovery and the splendour of the Antarctic.

The Scott Polar Research Institute (SPRI) is fortunate in holding around 1,900 of Wilson’s drawings and sketches, the majority of them given to SPRI by his wife Oriana. Nineteen of these artworks depict the albatross – several species of which Wilson shows both in close-up studies and soaring above the ocean.

Mrs Heather Lane, former Keeper of the Polar Museum, says: "Wilson is undoubtedly one of the greatest artists of the heroic age of polar exploration. He was one of Scott’s closest friends and on expeditions the person to whom others looked for stability.

"As an artist he was self-taught yet he captured with stunning accuracy both the anatomical structure and the fragile beauty of living things. He was particularly fascinated by birds."

The wandering albatross has the largest wingspan (up to 12 foot) of any bird. Its flight is so efficient that it expends as little energy soaring on currents of air (a type of flight known as 'dynamic soaring') as it does sitting on its nest. In all, there are 22 species of albatross, most of them living in the southern oceans. The majority are under threat, chiefly from longline fishing. Attracted by the bait, the birds become entangled by the hooks and drown.  Estimates put the annual death toll at 100,000 birds.

PhD candidate Tommy Clay (Department of Zoology) is contributing to a British Antarctic Survey (BAS) programme that is creating a detailed picture of their migratory movements. The research is made possible by lightweight battery-powered devices capable of tracking the birds’ movements over multiple years.

Albatrosses pair for life: Wanderers raise at most one chick every two years. They spend a whole year incubating their one egg and looking after the chick. Once the chick is independent, its parents enjoy a recovery period before they breed again, returning to the same breeding spots on remote islands in the southern ocean.

"Until relatively recently, very little has been known about the pattern of albatross movements across their lifespans, which can be more than 60 years. We’re beginning to build up a picture of what individual birds do and why they do it. We now know that in the inter-breeding period, the birds cover huge distances. One Grey-headed albatross, for example, circumnavigated the southern hemisphere in just 46 days," says Clay.

"Albatrosses are regarded as sentinel species for the health of the marine environment. Albatrosses are scavengers – they follow ships and eat the debris thrown into the water. In the North Pacific, dead birds are found with plastic in their stomachs, showing just how widespread – and destructive – is our impact on the oceans."

The long association between the albatross and the seafarer was cemented in 1798 with the publication of Samuel Taylor Coleridge’s epic Rime of the Ancient Mariner. In the poem, which was dismissed by early critics as an extravagant cock-and-bull story, the eponymous mariner shoots an albatross in a seemingly motiveless act of cruelty.

When the ship is becalmed (Day after day, day after day,/We stuck, nor breath nor motion; /As idle as a painted ship/ Upon a painted ocean), the dead albatross is hung around the mariner’s neck by his shipmates.

The poem was famously illustrated by Gustav Doré in the 1870s and became one of the most quoted ballads in the English language. Images of the crew dying of thirst out at sea (Water, water, every where,/And all the boards did shrink;/ Water, water, every where,/ Nor any drop to drink) and the dead bird hanging around a man’s neck became embedded in the public imagination.

In the 1930s, albatross entered the Oxford English Dictionary as a word to describe an unshakeable burden.

“The indeterminacy of the mariner’s crime makes the story compelling: we don’t know what makes him pick up his crossbow and shoot a bird that the crew has befriended. Some scholars have read the poem as a Christian narrative in which evil is punished by God. Others, more recently, have argued for an environmental context in which mankind is punished for an attack on the natural world,” says Professor Heather Glen of the Faculty of English.

“Or possibly – and this is in keeping with the poem’s deliberately archaic ballad form – Coleridge is suggesting that the shooting of the albatross is a violation of a much more ancient tradition of welcome to the stranger. In the note with which he headed the poem in 1800 edition of Lyrical Ballads, Coleridge announces that it will portray ‘how the Ancient Mariner cruelly, and in contempt of the laws of hospitality, killed a sea-bird; and how he was followed by many and strange judgements’.”

For a short time, Coleridge was a student at Jesus College, Cambridge, where he described himself as ‘a library-cormorant’ greedily devouring as many books as he could. The device of the albatross was suggested to him by his close friend William Wordsworth during a walking holiday. Wordsworth had been reading George Shelvocke’s Voyage Round the World (1726) in which an albatross is shot. Both Cambridge University Library and SPRI have early editions of the book.

Next in the Cambridge Animal Alphabet: B is for an animal that roamed Cambridgeshire 120,000 years ago, provided sport for the inhabitants of Madingley Hall, and became a friend to one eccentric poet at Trinity College.

Inset images: Diomedea melanophrys. Discovery 1901. Black browed albatross, by Edward Adrian Wilson. (Scott Polar Research Institute); Wandering albatross. (Robert Paterson, British Antarctic Survey); Gustav Doré's illustration from Rime of the Ancient Mariner by Samuel Taylor Coleridge. (Cambridge University Library).

The Cambridge Animal Alphabet series celebrates Cambridge's connections with animals through literature, art, science and society. Here, A is for Albatross – in sketches retrieved from Antarctica, research into migratory patterns, and Coleridge’s famous ballad.

In the inter-breeding period, the birds cover huge distances. One Grey-headed albatross circumnavigated the southern hemisphere in just 46 days
Tommy Clay
Head of an albatross caught on Sep. 22 1901 by Edward Adrian Wilson

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Henry Disney paper chosen as Science Editor's Choice

From Department of Zoology. Published on May 18, 2015.

What research would enhance business sustainability?

By sc604 from University of Cambridge - Department of Zoology. Published on May 15, 2015.

The natural world is already in peril, yet demand for water, food and energy are set to rise further as the global population grows and climate change takes hold. Increased demand for one of these will alter the availability of the others. Businesses sit at the heart of this ‘nexus’ of interactions, both depending on and impacting on the environment. What academic research could help make their operations more sustainable?

Working with leading researchers from the Departments of Geography and Zoology, the Cambridge Institute for Sustainability Leadership’s (CISL) Nexus2020 project is bringing together ideas from the 6,000 alumni of our executive education programmes, business people, academics, policy-makers and members of the general public.

The project is part of the Nexus Network, an extensive network coordinated by CISL, the University of Sussex and the University of East Anglia, and supported by the Economic and Social Research Council. With its considerable outreach across business, academia and government, CISL encourages conversation and stimulates the research that is most helpful to companies.

We want to know what you think are the most important questions around business practice that, if answered by 2020, could help companies manage their dependencies and impacts upon food, energy, water and the environment.

How can we meet future needs for food, energy and water without degrading our natural environment and putting companies out of business? Can we meet increasing demand for energy without making climate change worse? How do we produce enough food and energy with less water? These are the types of questions we are looking for.

In September, we will bring together leading members of the academic and business communities to rank the submissions and identify the most important questions for research. We’ll present these at the Nexus Network annual conference in November, by which point research will be underway. 

The process of gathering questions and prioritising research needs is not new: Cambridge’s Bill Sutherland identified the 100 ecological questions of high policy relevance in the UK in 2006. More recently a project led by Jules Pretty looked at the top 100 questions of importance to the future of global agriculture, and Lynn Dicks has replicated this process to look at the conservation of wild insect pollinators and the UK food system. These ranking exercises are extremely valuable and have had consequences for high-level policy, including Defra’s National Pollinator Strategy. These approaches also encouraged scientists to come together to develop workshops and led to the identification of initial priorities for programmes such as the UK’s Global Food Security Research Programme.

With the UN’s 2014 report highlighting that one-fifth of the world’s aquifers are being overexploited, how do ensure that corporate actions are alleviating water-related stresses? How do we communicate the urgency of sustainable farming methods when 10 million hectares of arable land are being eroded or degraded every year?

Whether your question is around policy, business education, rights, science, finance, or best practice, take part in this project - we want to know what you think.

A new project led by the Cambridge Institute for Sustainability Leadership is looking at how academic research can help make businesses more sustainable. Dr Jonathan Green, one of the project leads, is looking to the public to ask the questions that may form the basis of future research, and help businesses reduce their impact on the environment.

How can we meet future needs for food, energy and water without degrading our natural environment and putting companies out of business?
Jonathan Green
Tar sands, Alberta

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Baboons prefer to spend time with others of the same age, status and even personality

By sc604 from University of Cambridge - Department of Zoology. Published on May 13, 2015.

New research shows that chacma baboons within a troop spend more of their time with baboons that have similar characteristics to themselves: associating with those of a similar age, dominance rank and even personality type such as boldness. This is known as homophily, or ‘love of the same’.

A team of researchers led by the University of Cambridge and international conservation charity the Zoological Society of London says that this may act as a barrier to the transfer of new social information to the wider troop, as previous research done by the team shows baboons of a certain age and personality type – the younger, bolder animals – are more likely to be information ‘generators’: those who solve new foraging problems.    

Given that information generators spend much of their time in the company of similar baboons, researchers say there is a risk that acquired information may end up exclusively confined to other information generators, thus decreasing the likelihood of new knowledge being disseminated to the wider troop.

Research teams tracked the same two baboon troops from dawn until dusk across Namibia’s Tsaobis Nature Park over several months each year between 2009-2014 to observe patterns of behaviour. The study is the first to monitor baboon social network structures over such a timescale and is published today in the journal Royal Society Open Science.    

“Within these big troop networks over time social preferences are generally dictated by age, rank, personality and so on,” said Dr Alecia Carter, from the University of Cambridge’s Department of Zoology, first author of the study. “This happens in humans all the time; we hang out with people who have the same income, religion, education etc. Essentially, it’s the same in baboons.”

To test for the personality traits of ‘boldness’ – essentially an assertive curiosity – the researchers planted unfamiliar foods on the edge of paths commonly used by baboon troops. These stimuli included hard-boiled eggs and small bread rolls dyed red or green. The research team then measured the time spent on investigating the new foodstuff, and whether they ate it, to determine a scale of boldness for members of the baboon troops.

“Our analysis is the first to suggest that bolder and shyer baboons are more likely to associate with others that share this personality trait,” said Dr Guy Cowlishaw from the Zoological Society of London, senior author of the study. “Previous studies in other animals – from chimps to guppies – suggests that time spent in the company of those with similar personalities could promote cooperation among individuals.

“Why baboons should demonstrate homophily for boldness is unclear, but it could be a heritable trait, and the patterns we’re seeing reflect family associations.”    

Perhaps surprisingly, says Carter, gender was not a particular obstacle to social interaction, with females preferring to groom males. This is, in part, due to the obvious sexual engagements for breeding, but also as a tactic on the part of females to curry favour with particular males for the sake of their offspring.

“Chacma baboon males will often commit infanticide, killing the babies of rivals. Female baboons try and get around this by being as promiscuous as possible to confuse the paternal identity – so males find it harder to tell if they are killing a rival’s offspring or their own,” added Dr Carter.

“They will also try and form bonds with particular males in the hope that they will protect their offspring and let the babies forage in good places with them – although males tend to be fairly lazy when it comes to this; it’s up to the babies to follow the males to good food.” 

Latest research shows that, within large troops, baboons spend more time grooming those with similar dominance rank and boldness to themselves. Preferring such grooming partners may prevent new skills and knowledge being transmitted around the wider troop, say researchers.

This happens in humans all the time; we hang out with people who have the same income, religion, education etc. Essentially, it’s the same in baboons
Alecia Carter

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Fish born in larger groups develop more social skills and a different brain structure

By fpjl2 from University of Cambridge - Department of Zoology. Published on May 07, 2015.

A new study shows that cichlid fish reared in larger social groups from birth display a greater and more extensive range of social interactions, which continues into the later life of the fish. Researchers say this indicates the fish develop more attuned social behaviour as a result of early environments.

The researchers also found that those fish raised in a more complex social environment have a different brain structure to those who experienced fewer group members in early life. If fish experienced the complex social environment for 2 month they had a larger hypothalamus: the area that contains most of the brain nodes of the ‘social behaviour network’. They also had a larger ‘optic tectum’, which processes visual stimuli and could be related to the need to process more visual stimuli in larger groups, say researchers.   

The brains of fish with enhanced social skills were not bigger overall than those reared in small groups; however, the ‘architecture’ within the brain was different.    

“Our data suggests that, during development, relative brain parts change their size in response to environmental cues without affecting overall brain size: increasing certain parts forces others to decrease concurrently. These ‘plastic’ adjustments of brain architecture were still present long after the early stages of social interaction,” said study author Dr Stefan Fischer, from Cambridge University’s Department of Zoology.

“Social animals need to develop social skills, which regulate social interactions, aggression and hierarchy formations within groups. Such skills are difficult and costly to develop, and only beneficial if the early social environment predicts a high number of social interactions continues to be critically important later in life,” he said.

For the study, published this week in the journal The American Naturalist, researchers used the Neolamprologus pulcher (N. Pulcher) breed of cichlid, primarily found in Lake Tanganyika - the great African freshwater lake that feeds into the Congo River.   

N. Pulcher lives in family groups with up to 25 individuals, with one breeder pair and several helpers participating in territory defence and raising of offspring - known as ‘cooperative breeding’. To test for social skills, the researchers reared juvenile fish over two months with either three or nine adult group members, and observed all social behaviours at key experimental points.

These interactions included ‘lateral display’ - when one fish interrupts another by displaying their body side-on, sometimes as a mating ritual - as well as ramming, tail quivering, and ‘mouth fighting’: a social display in which fish lock mouths to challenge each other over everything from food to mates.

Six month after this test phase, individual fish brains were measured to investigate the long term consequences of early group size on brain morphology, revealing differences in brain architecture.

The researchers say that one of the effects on social behaviour in larger groups might be the perception of environmental risk. “In the wild, larger social groups of N. Pulcher represent a low-risk environment with enhanced juvenile survival. Being part of a larger, safer group may increase the motivation of juveniles to interact socially with siblings, enhancing the opportunities to acquire social skills,” said Fischer.

As perhaps with any social creature, Fischer points out that higher social competence and the ability to conform to social hierarchies may well stand the cichlids in good stead in later life:

“Group size for these fish stays relatively stable across the years, they have delayed dispersal. Remaining in a larger group means a better chance of survival. Fish reared in large groups showed more submissive and less aggressive behaviour to big fish in the group, social behaviour which greatly enhances the survival chances of smaller fish.”

Fischer added: “In highly social animals, such as cooperative breeders, almost all activities involve social interactions, where individuals need to adequately respond to social partners. In larger groups, these interactions are more common and individuals developing sophisticated social skills during childhood might highly benefit from them later in life.”

New research on a highly social fish shows that those reared in larger social groups from the earliest stage of life develop increased social skills and a brain shape, or ‘neuroplasticity’, which lingers into the later life of the fish.

Fish reared in large groups showed more submissive and less aggressive behaviour to big fish in the group, social behaviour which greatly enhances the survival chances of smaller fish
Stefan Fischer
Neolamprologus pulcher (N. Pulcher) breed of cichlid fish used in the study

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Legs give moths a flying start

From Department of Zoology. Published on May 01, 2015.

The Arup Building is renamed The David Attenborough Building

From Department of Zoology. Published on Apr 22, 2015.

Wendy Gu wins first place in BSCB BSDB Student Poster prize competition

From Department of Zoology. Published on Apr 15, 2015.

Red Noses in Zoology

From Department of Zoology. Published on Mar 25, 2015.

Colour-morphing reef fish is a 'wolf in sheep's clothing'

By fpjl2 from University of Cambridge - Department of Zoology. Published on Mar 19, 2015.

A new study has shown that the dottyback, a small predatory reef fish, can change the colour of its body to imitate a variety of other reef fish species, allowing the dottyback to sneak up undetected and eat their young.

The dottyback also uses its colour-changing abilities to hide from larger predators by colour-matching to the background of its habitat - disappearing into the scenery.

The research, published today in the journal Current Biology, reveals a sophisticated new example of 'mimicry': disguising as a different species to gain evolutionary advantage.

While using mimicry to hunt or hide from other species is commonplace in nature - from cuckoos to butterflies - scientists point out that if the same physical deception is encountered too frequently, species on the receiving end become more vigilant and develop tactics to mitigate the mimics.

The dottyback, however, is able to colour-morph depending on the particular colour of the surrounding species it is currently hunting: different types of damselfish being a popular target.

Scientists say that this flexibility of physical mimicry makes it much harder for the dottyback's prey to develop detection strategies and avoid getting eaten.

"By changing colour to imitate local damselfish communities, dottybacks are able to overcome the predator avoidance behaviour in the juvenile fish they hunt," said Dr William Feeney, co-author of the study from the University of Cambridge's Department of Zoology.

"The dottyback behaviour is comparable to the 'wolf in sheep's clothing' scenario from Aesop's Fables, where distinguishing the predator from the harmless 'flock' becomes increasingly difficult when they look alike - allowing the dottyback to creep up on unsuspecting juvenile damselfish," Feeney said.

Dottybacks are generally solitary and highly territorial predators of around eight centimetres in length, commonly found in Indo-Pacific coral reefs.

While dottybacks can vary their colouration from pink to grey, the researchers focused on two colour 'morphs' - yellow and brown - that both occur on the reefs surrounding Lizard Island, off the coast of north-east Australia. This is because the area has populations of both yellow and brown damselfish, and habitat consisting of live coral and dead coral 'rubble'.

The scientists built their own simulated reef outcrops comprising both live coral and rubble, and stocked them with either yellow or brown damselfish. When released into reefs with damselfish of the opposite colour, scientists found the dottybacks would change from yellow to brown or vice versa over the course of approximately two weeks.

Anatomical study of dottyback skin cells revealed that while the level of 'chromatophores' - pigment-containing cells that reflect light - remain constant, the ratio of yellow pigment cells to black pigment cells shifts to move the dottyback from yellow to brown or back again.

The team conducted lab experiments with adult and juvenile damselfish to test whether this colour change affects dottyback hunting success. They found that once the dottyback matched the colour of the damselfish, they were up to three times more successful at capturing juvenile damselfish.

The scientists also found that the dottyback use their colour-morphing powers to blend into the coral of their habitats to hide from their own predators, such as the coral trout - a predator they share with damselfish, who have also adapted to match the colour of their environment.

The scientists measured the strike rates of coral trout when exposed to images of different colours of dottyback against different habitats. The coral trout had trouble picking out the fish when the colour matched the habitat.

"While the dottybacks change colour to aggressively mimic damselfish, they may also gain a secondary benefit: a reduced risk of being eaten themselves. Damselfish have evolved to blend into their environment, so, by imitating the damselfish, they also colour-match the habitat - making it harder for coral trout to see them," said Feeney.

"This is the first time that an animal has been found to be able to morph between different guises in order to deceive different species, making the dottyback a pretty crafty little fish"

Inset image: dottyback eyeing up damselfish prey, credit Christopher E Mirbach

The dottyback changes its colour to match surrounding damselfish species, enabling it to counter the defences of its damselfish prey by disguising itself as a harmless part of their community, then swoop in to hunt their young.

This is the first time that an animal has been found to be able to morph between different guises in order to deceive different species, making the dottyback a pretty crafty little fish
William Feeney
Brown Vs Yellow Dottyback

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Fossil skull sheds new light on transition from water to land

By fpjl2 from University of Cambridge - Department of Zoology. Published on Mar 16, 2015.

A new 3D reconstruction of skull of one of the earliest four-footed vertebrate – which differs from earlier 2D reconstructions – suggests such creatures, which lived their lives primarily in shallow water environments, were more like modern crocodiles than previously thought.

The researchers applied high-resolution X-ray computed tomography (CT) scanning to several specimens of Acanthostega gunnari, one of the ‘four-footed’ vertebrates known as tetrapods which invaded the land during one of the great evolutionary transitions in Earth’s history, 380-360 million years ago. Tetrapods evolved from lobe-finned fishes and display a number of adaptations to help them survive on land. 

An iconic fossil species, Acanthostega gunnari is crucial for understanding the anatomy and ecology of the earliest tetrapods.  However, after hundreds of millions of years in the ground fossils are often damaged and deformed.  No single specimen of Acanthostega preserves a skull that is complete and three-dimensional which has limited scientists’ understanding of how this key animal fed and breathed – until now.

Researchers from Cambridge and Bristol University used specialist software to ‘digitally prepared’ a number of Acanthostega specimens from East Greenland, stripping away layers of rock to reveal the underlying bones.  

They uncovered a number of bones deep within the skull, including some that had never before been seen or described, resulting in a detailed anatomical description of the Acanthostega skull. 

Once all of the bones and teeth were digitally separated from each other, cracks were repaired and missing elements duplicated.  Bones could then be manipulated individually in 3D space.  Using information from other specimens, the bones were fitted together like puzzle pieces to produce the first 3D reconstruction of the skull of Acanthostega, with surprising results.

Co-author Dr Laura Porro, formerly of Cambridge’s Department of Zoology and Bristol’s School of Earth Sciences (now at the Royal Veterinary College) said: “Because early tetrapods skulls are often ‘pancaked’ during the fossilization process, these animals are usually reconstructed having very flat heads.  Our new reconstruction suggests the skull of Acanthostega was taller and somewhat narrower than previously interpreted, more similar to the skull of a modern crocodile.”

The researchers also found clues to how Acanthostega fed.  The size and distribution of its teeth and the shape of contacts between individual bones of the skull (called sutures) suggest Acanthostega may have initially seized prey at the front of its jaws using its large front teeth and hook-shaped lower jaw.

The team say that these new analyses provide fresh clues about the evolution of the jaws and feeding system as the earliest animals with limbs and digits began to conquer the land.

The researchers plan to apply these methods to other flattened fossils of the earliest tetrapods to better understand how these early animals modified their bones and teeth to meet the challenges of living on land.

“This work is the first stage of a study towards understanding how the earliest tetrapods fed, and that might lead us to what they fed on, and give further clues as to when and how they started to feed on land,” said co-author Professor Jennifer Clack from Cambridge’s Zoology Department.

Digital models of the original fossils and the 3D reconstruction are also useful in scientific research and education.  They can be accessed by researchers around the world, without risking damage to fragile original fossils and without scientists having to travel thousands of miles to see original specimens. Furthermore, digital models and 3D printouts can be easily and safely handled by students taking courses and by the public during outreach events. The study is published recently in the journal PLOS ONE.

Adapted from a Bristol University press release.

Inset image: 3D model showing the complete skull on top with ‘exploded’ views of the upper and lower jaws below.

The first 3D reconstruction of the skull of a 360 million-year-old near-ancestor of land vertebrates has been created by scientists.

This work is the first stage of a study towards understanding how the earliest tetrapods fed, and that might lead us to what they fed on
Jennifer Clack
Left: 3D model with the jaws open; the individual bones are colour-coded to show the boundaries between them. Right: Original fossil skull of Acanthostega gunnari

The text in this work is licensed under a Creative Commons Licence. If you use this content on your site please link back to this page. For image rights, please see the credits associated with each individual image.


MPhil student wins bursary

From Department of Zoology. Published on Mar 09, 2015.

Nick Davies’ new book, Cuckoo: Cheating By Nature

From Department of Zoology. Published on Mar 06, 2015.

Baby mantises harness mid-air ‘spin’ during jumps for precision landings

By fpjl2 from University of Cambridge - Department of Zoology. Published on Mar 05, 2015.

The smaller you are, the harder it is not to spin out of control when you jump. Miniscule errors in propulsive force relative to the centre of mass results in most jumping insects – such as fleas, leafhoppers and grasshoppers – spinning uncontrollably when they jump.

Until now, scientists worked under the hypothesis that such insects can’t control this, and spin unpredictably with frequent crash landings.

But new high-speed video analysis of the jumps of wingless, baby praying mantises has revealed a technique which actually harnesses the spinning motion, enabling them to jump with accuracy at the same time as repositioning their body mid-air to match the intended target – all in under a tenth of a second.

Researchers used a thin black rod distant from the platform on which the mantises sat as a target for them to jump at.

During the jumps, the insects rotated their legs and abdomen simultaneously yet in varying directions – shifting clockwise and anti-clockwise rotations between these body parts in mid-air – to control the angular momentum, or ‘spin’. This allowed them to shift their body in the air to align themselves precisely with the target on which they chose to land.

And the mantises did all of this at phenomenal speed. An entire jump, from take-off to landing, lasted around 80 milliseconds – literally faster than the blink of a human eye.

At first, scientists believed the mantis had simply evolved a way to mitigate the natural spin that occurs when such small insects jump at speed.

On closer inspection, however, they realised the mantis is in fact deliberately injecting controlled spin into the jump at the point of take-off, then manipulating this angular momentum while airborne through intricate rotations of its extremities in order to reposition the body in mid-air, so that it grasps the target with extreme precision.

For the study, published today in the journal Current Biology, the researchers analysed a total of 381 slowed-down videos of 58 young mantises jumping to the target, allowing them to work out the intricate mechanics used to land the right way up and on target virtually every time.  

“We had assumed spin was bad, but we were wrong – juvenile mantises deliberately create spin and harness it in mid-air to rotate their bodies to land on a target,” said study author Professor Malcolm Burrows from Cambridge University’s Department of Zoology, who conducted the research with Dr Gregory Sutton from Bristol University.

“As far as we can tell, these insects are controlling every step of the jump. There is no uncontrolled step followed by compensation, which is what we initially thought,” he said.

In fact, when the researchers moved the target closer, the mantises spun themselves twice as fast to ensure they got their bodies parallel with the target when they grasped it. 

For Sutton, the study is similar to accountancy, only with distribution of momentum instead of money. “The mantis gives itself an amount of angular momentum at take-off and then distributes this momentum while in mid-air: a certain amount in the front leg at one point; a certain amount in the abdomen at another – which both stabilise the body and shift its orientation, allowing it to reach the target at the right angle to grab on,” he said.

The researchers tested what would happen if they restricted the ability of the mantis to harness and spread the ‘spin’ to its extremities during a jump. To do this, they glued the segments of the abdomen together, expecting the mantis to spin out of control.

Intriguingly, the accuracy of the jump wasn’t impeded. The mantises still reached the target, but couldn’t rotate their bodies into the correct position – so crashed headlong into it and bounced off again.

The next big question for the researchers is to understand how the mantis achieves its mid-air acrobatics at such extraordinary speeds. “We can see the mantis performs a scanning movement with its head before a jump. Is it predicting everything in advance or does it make corrections at lightning speed as it goes through the jump? We don’t know the answer between these extreme possibilities,” said Burrows.
Sutton added: “We now have a good understanding of the physics and biomechanics of these precise aerial acrobatics. But because the movements are so quick, we need to understand the role the brain is playing in their control once the movements are underway.”

Sutton believes that the field of robotics could learn lessons from the juvenile mantis. “For small robots, flying is energetically expensive, and walking is slow. Jumping makes sense – but controlling the spin in jumping robots is an almost intractable problem. The juvenile mantis is a natural example of a mechanical set-up that could solve this,” he said.

Professor Malcolm Burrows and Dr Gregory Sutton

High-speed videos reveal that, unlike other jumping insects, the juvenile praying mantis does not spin out of control when airborne. In fact, it both creates and controls angular momentum at extraordinary speeds to orient its body for precise landings.

As far as we can tell, these insects are controlling every step of the jump
Malcolm Burrows
A juvenile praying mantis

The text in this work is licensed under a Creative Commons Licence. If you use this content on your site please link back to this page. For image rights, please see the credits associated with each individual image.


Museum of Zoology plans boosted

From Department of Zoology. Published on Mar 02, 2015.

Congratulations to Nick Crumpton and Robert Brocklehurst

From Department of Zoology. Published on Feb 26, 2015.

Museum of Zoology on BBC Look East

From Department of Zoology. Published on Feb 20, 2015.

Ants prefer to pick on ants their own size

From Department of Zoology. Published on Feb 11, 2015.

Graduate student discovers new species of dragonfly in Sabah, Malaysian Borneo

From Department of Zoology. Published on Jan 30, 2015.

Zoology staff feature on TV and radio

From Department of Zoology. Published on Jan 26, 2015.

'Going for Gold' with Professor Tom Welton

From Department of Zoology. Published on Jan 21, 2015.

Cambridge Biotomography Centre officially open

From Department of Zoology. Published on Jan 20, 2015.

Julian Jacobs wins Employee Recognition Award

From Department of Zoology. Published on Dec 22, 2014.

The Janet Moore Prize for supervising in Zoology

From Department of Zoology. Published on Nov 24, 2014.

Croonian Lecture awarded to Prof Nick Davies

From Department of Zoology. Published on Aug 04, 2014.

Professor Ron Laskey awarded CRUK Lifetime Achievement Prize

From Department of Zoology. Published on Jul 22, 2014.

Professor Jenny Clack awarded Honorary Doctor of Science Degree

From Department of Zoology. Published on Jul 10, 2014.