Signals, cues and the nature of mimicry
From Department of Zoology. Published on Feb 22, 2017.
Pilkington Teaching Prize Award 2017
From Department of Zoology. Published on Feb 17, 2017.
Deeper origin of gill evolution suggests 'active lifestyle' link in early vertebrates
By fpjl2 from University of Cambridge - Department of Zoology. Published on Feb 09, 2017.
A new study has revealed that gills originated much deeper in evolutionary history than previously believed. The findings support the idea that gills evolved before the last common ancestor of all vertebrates, helping facilitate a "lifestyle transition" from immobile filter-feeder to actively swimming predator.
The research, published today in the journal Current Biology, shows that gills develop from the same embryonic tissue in both jawed and jawless vertebrates - a lineage that split very early in our ancestral tree.
Jawed vertebrates - such as fish, birds and mammals - make up 99% of all living vertebrates, including us. Jawless vertebrates include the parasitic lamprey and scavenging hagfish: eel-like creatures that diverged from the ancestral line over 400 million years ago.
Previous work in this area involved slicing thin sections of fish embryos to chart organ growth. These "snapshots" of development led scientists to believe that gills were formed from different tissues: the internal 'endoderm' lining in jawless vertebrates, and the 'ectoderm' outer skin in the jawed.
As a result, since the mid-20th century it was thought that the ancient jawed and jawless lines evolved gills separately after they split, an example of 'convergent evolution' - where nature finds the same solution twice (such as the use of echolocation in both bats and whales, for example).
Biologists at the University of Cambridge used fluorescent labelling to stain cell membranes in skate embryos, and tracked them through the dynamic development process. Their experiment has now shown that the gills of jawed vertebrates emerge from the same internal lining cells as their jawless relatives.
The researchers say this is strong evidence that gills evolved just once, much earlier in evolutionary history - before the jawless divergence - and that the "crown ancestor" of all vertebrates was consequently a more anatomically complex creature.
The findings pull the invention of gills closer to the "active lifestyle" shift in our early ancestors: the evolution from passive filter feeders to self-propelled ocean swimmers. Scientists say that gill development may have been a catalyst or consequence of this giant physiological leap.
"These findings demonstrate a single origin of gills that likely corresponds with a key stage in vertebrate evolution: when some of our earliest relatives transitioned from filtering particles out of water pumped through static bodies to actively swimming through the oceans," says lead author Dr Andrew Gillis, a Royal Society University Research Fellow in Cambridge's Department of Zoology, and a Whitman Investigator at the Marine Biological Laboratory in Woods Hole, US.
"Gills provided vertebrates with specialist breathing organs in their head, rather than having to respire exclusively through skin all over the body. We can't say whether these early animals became more active and needed to evolve a new respiratory mechanism, or if it was gill evolution that allowed them to move faster.
"However, whether by demand or opportunity, our work suggests that the physiological innovation of gills occurred at the same time as the lifestyle transition from passive to active in some of our earliest ancestors."
While the jawed vertebrate lineage spawned the majority of vertebrate life that exists on Earth today - "evolutionarily speaking, we are all bony fish," says Gillis - lamprey and hagfish are the living remnants of a once extensive assemblage of primitively predatory jawless vertebrates.
"Lamprey are eel-like parasites that use their tooth-like organs and raspy tongue to latch onto fish and suck out the blood, while hagfish scavenge by taking bites out of dead matter," he says.
Gillis and colleagues used embryos of the little skate to track early gill development through cell tracing. The skate is a cartilaginous fish - an early-branching lineage of jawed vertebrates that includes the sharks and stingrays.
This made skate an excellent comparison point to try and infer the primitive anatomical and developmental conditions in the last common ancestor of jawed and jawless vertebrates.
The embryonic work of the Gillis laboratory neatly complements paleontological research from their Cambridge colleague Prof Simon Conway Morris, who has spent much of his career studying fossils of the Cambrian period of rapid evolution - when most major animal groups originated.
In 2014, Conway Morris was part of the team that discovered Metaspriggina: one of the oldest-known vertebrate fossils, perhaps over 500 million years old, which displayed hints of a gill structure, as well as the muscle arrangement of an active swimmer.
"Our embryological research helps us understand exactly how the gill structures in early vertebrates such as Metaspriggina relate to the gills of living forms," says Gillis.
"Embryology can tell us about the evolutionary relationship between anatomical features in living animals, while palaeontology can pinpoint precisely when these features first appear in deep time. I think that this work nicely illustrates how these two areas of research can inform one another."
Fish embryo study indicates that the last common ancestor of vertebrates was a complex animal complete with gills – overturning prior scientific understanding and complementing recent fossil finds. The work places gill evolution concurrent with shift to self-propulsion in our earliest ancestors.
Baltic hunter-gatherers adopted farming without influence of mass migration, ancient DNA suggests
By fpjl2 from University of Cambridge - Department of Zoology. Published on Feb 02, 2017.
New research indicates that Baltic hunter-gatherers were not swamped by migrations of early agriculturalists from the Middle East, as was the case for the rest of central and western Europe. Instead, these people probably acquired knowledge of farming and ceramics by sharing cultures and ideas rather than genes with outside communities.
Scientists extracted ancient DNA from a number of archaeological remains discovered in Latvia and the Ukraine, which were between 5,000 and 8,000 years old. These samples spanned the Neolithic period, which was the dawn of agriculture in Europe, when people moved from a mobile hunter-gatherer lifestyle to a settled way of life based on food production.
We know through previous research that large numbers of early farmers from the Levant (the Near East) – driven by the success of their technological innovations such as crops and pottery – had expanded to the peripheral parts of Europe by the end of the Neolithic and largely replaced hunter-gatherer populations.
However, the new study, published today in the journal Current Biology, shows that the Levantine farmers did not contribute to hunter-gatherers in the Baltic as they did in Central and Western Europe.
The research team, which includes scientists from the University of Cambridge and Trinity College Dublin, say their findings instead suggest that the Baltic hunter-gatherers learned these skills through communication and cultural exchange with outsiders.
The findings feed into debates around the ‘Neolithic package’ – the cluster of technologies such as domesticated livestock, cultivated cereals and ceramics, which revolutionised human existence across Europe during the late Stone Age.
Advances in ancient DNA work have revealed that this ‘package’ was spread through Central and Western Europe by migration and interbreeding: the Levant and later Anatolian farmers mixing with and essentially replacing the hunter-gatherers.
But the new work suggests migration was not a ‘universal driver’ across Europe for this way of life. In the Baltic region, archaeology shows that the technologies of the ‘package’ did develop – albeit less rapidly – even though the analyses show that the genetics of these populations remained the same as those of the hunter-gatherers throughout the Neolithic.
Andrea Manica, one of the study’s senior authors from the University of Cambridge, said: “Almost all ancient DNA research up to now has suggested that technologies such as agriculture spread through people migrating and settling in new areas.”
“However, in the Baltic, we find a very different picture, as there are no genetic traces of the farmers from the Levant and Anatolia who transmitted agriculture across the rest of Europe.”
“The findings suggest that indigenous hunter-gatherers adopted Neolithic ways of life through trade and contact, rather than being settled by external communities. Migrations are not the only model for technology acquisition in European prehistory.”
The researchers analysed eight ancient genomes – six from Latvia and two from Ukraine – that spanned a timeframe of three and a half thousand years (between 8,300 and 4,800 years ago). This enabled them to start plotting the genetic history of Baltic inhabitants during the Neolithic.
DNA was extracted from the petrous area of skulls that had been recovered by archaeologists from some of the region’s richest Stone Age cemeteries. The petrous, at the base of the skull, is one of the densest bones in the body, and a prime location for DNA that has suffered the least contamination over millennia.
While the sequenced genomes showed no trace of the Levant farmer influence, one of the Latvian samples did reveal genetic influence from a different external source – one that the scientists say could be a migration from the Pontic Steppe in the east. The timing (5-7,000 years ago) fits with previous research estimating the earliest Slavic languages.
Researcher Eppie Jones, from Trinity College Dublin and the University of Cambridge, was the lead author of the study. She said: “There are two major theories on the spread of Indo-European languages, the most widely spoken language family in the world. One is that they came from the Anatolia with the agriculturalists; another that they developed in the Steppes and spread at the start of the Bronze Age.
“That we see no farmer-related genetic input, yet we do find this Steppe-related component, suggests that at least the Balto-Slavic branch of the Indo-European language family originated in the Steppe grasslands of the East, which would bring later migrations of Bronze Age horse riders.”
The researchers point out that the time scales seen in Baltic archaeology are also very distinct to the rest of Europe, with a much more drawn-out and piecemeal uptake of Neolithic technologies, rather than the complete ‘package’ that arrives with migrations to take most of Europe by storm.
Andrea Manica added: “Our evidence of genetic continuity in the Baltic, coupled with the archaeological record showing a prolonged adoption of Neolithic technologies, would suggest the existence of trade networks with farming communities largely independent of interbreeding.
“It seems the hunter-gatherers of the Baltic likely acquired bits of the Neolithic package slowly over time through a ‘cultural diffusion’ of communication and trade, as there is no sign of the migratory wave that brought farming to the rest of Europe during this time.
“The Baltic hunter-gatherer genome remains remarkably untouched until the great migrations of the Bronze Age sweep in from the East.”
Ancient DNA analyses show that – unlike elsewhere in Europe – farmers from the Near East did not overtake hunter-gatherer populations in the Baltic. The findings also suggest that the Balto-Slavic branch of the Indo-European language family originated in the Steppe grasslands of the East.
Ancient DNA reveals genetic ‘continuity’ between Stone Age and modern populations in East Asia
By fpjl2 from University of Cambridge - Department of Zoology. Published on Feb 01, 2017.
Researchers working on ancient DNA extracted from human remains interred almost 8,000 years ago in a cave in the Russian Far East have found that the genetic makeup of certain modern East Asian populations closely resemble that of their hunter-gatherer ancestors.
The study, published today in the journal Science Advances, is the first to obtain nuclear genome data from ancient mainland East Asia and compare the results to modern populations.
The findings indicate that there was no major migratory interruption, or “population turnover”, for well over seven millennia. Consequently, some contemporary ethnic groups share a remarkable genetic similarity to Stone Age hunters that once roamed the same region.
The high “genetic continuity” in East Asia is in stark contrast to most of Western Europe, where sustained migrations of early farmers from the Levant overwhelmed hunter-gatherer populations. This was followed by a wave of horse riders from Central Asia during the Bronze Age. These events were likely driven by the success of emerging technologies such as agriculture and metallurgy
The new research shows that, at least for part of East Asia, the story differs – with little genetic disruption in populations since the early Neolithic period.
Despite being separated by a vast expanse of history, this has allowed an exceptional genetic proximity between the Ulchi people of the Amur Basin, near where Russia borders China and North Korea, and the ancient hunter-gatherers laid to rest in a cave close to the Ulchi’s native land.
The researchers suggest that the sheer scale of East Asia and dramatic variations in its climate may have prevented the sweeping influence of Neolithic agriculture and the accompanying migrations that replaced hunter-gatherers across much of Europe. They note that the Ulchi retained their hunter-fisher-gatherer lifestyle until recent times.
“Genetically speaking, the populations across northern East Asia have changed very little for around eight millennia,” said senior author Andrea Manica from the University of Cambridge, who conducted the work with an international team, including colleagues from Ulsan National Institute of Science and Technology in Korea, and Trinity College Dublin and University College Dublin in Ireland.
“Once we accounted for some local intermingling, the Ulchi and the ancient hunter-gatherers appeared to be almost the same population from a genetic point of view, even though there are thousands of years between them.”
The new study also provides further support for the ‘dual origin’ theory of modern Japanese populations: that they descend from a combination of hunter-gatherers and agriculturalists that eventually brought wet rice farming from southern China. A similar pattern is also found in neighbouring Koreans, who are genetically very close to Japanese.
However, Manica says that much more DNA data from Neolithic China is required to pinpoint the origin of the agriculturalists involved in this mixture.
The team from Trinity College Dublin were responsible for extracting DNA from the remains, which were found in a cave known as Devil’s Gate. Situated in a mountainous area close to the far eastern coast of Russia that faces northern Japan, the cave was first excavated by a soviet team in 1973.
Along with hundreds of stone and bone tools, the carbonised wood of a former dwelling, and woven wild grass that is one of the earliest examples of a textile, were the incomplete bodies of five humans.
If ancient DNA can be found in sufficiently preserved remains, sequencing it involves sifting through the contamination of millennia. The best samples for analysis from Devil’s Gate were obtained from the skulls of two females: one in her early twenties, the other close to fifty. The site itself dates back over 9,000 years, but the two women are estimated to have died around 7,700 years ago.
Researchers were able to glean the most from the middle-aged woman. Her DNA revealed she likely had brown eyes and thick, straight hair. She almost certainly lacked the ability to tolerate lactose, but was unlikely to have suffered from ‘alcohol flush’: the skin reaction to alcohol now common across East Asia.
While the Devil’s Gate samples show high genetic affinity to the Ulchi, fishermen from the same area who speak the Tungusic language, they are also close to other Tungusic-speaking populations in present day China, such as the Oroqen and Hezhen.
“These are ethnic groups with traditional societies and deep roots across eastern Russia and China, whose culture, language and populations are rapidly dwindling,” added lead author Veronika Siska, also from Cambridge.
“Our work suggests that these groups form a strong genetic lineage descending directly from the early Neolithic hunter-gatherers who inhabited the same region thousands of years previously.”
In contrast to Western Europeans, new research finds contemporary East Asians are genetically much closer to the ancient hunter-gatherers that lived in the same region eight thousand years previously.
Cooperation helps mammals survive in tough environments
By fpjl2 from University of Cambridge - Department of Zoology. Published on Jan 24, 2017.
Cooperatively breeding mammal species, such as meerkats and naked-mole rats, where non-breeding helpers assist breeding females in raising their offspring, are better able to cope with living in dry areas than related non-cooperative species, new research reveals.
A comparative study of mammals, by University of Cambridge researchers Dieter Lukas and Tim Clutton-Brock, shows that cooperatively breeding species occur in dry areas, yet are absent in tropical climates - even though these are the places on earth with the highest biodiversity.
Researchers have found that most cooperatively breeding mammals live in areas where it might not rain for weeks. While many have long argued that climate and social behaviour are linked, the Cambridge team say these findings provide a detailed understanding of how helping behaviour is connected to the environment individuals live in.
“Rainfall often affects food availability, and cooperatively breeding mammals appear better able to cope with the uncertainties of food availability during periods of drought,” said Lukas, from Cambridge’s Department of Zoology.
In this study, published in the journal Royal Society Open Science, the researchers mapped the global occurrence of mammalian species living in different social systems to determine how averages and variation in rainfall and temperature explain species distributions.
They found that although the presence of non-breeding adults in breeding groups is not associated with contrasts in climate, non-breeders commonly play an important role in raising the offspring of breeders in species living in dry environments.
“Long-term field studies show that helpers improve offspring survival, and our findings highlight that such cooperation is particularly important under harsh conditions,” said Clutton-Brock. Previous studies of birds show that here, too, non-breeding adults often help breeders to raise their young in species living in dry unpredictable environments.
Researchers say the activities of helpers in groups of cooperative mammals may ensure that infants and juveniles born in the group (who are usually closely related to them) are adequately fed, even when resources are scare.
In turn, non-breeders may gain future benefits from helping because it increases their chance that their group will survive adverse years, giving them a chance of inheriting the breeding position.
Groups of cooperative breeders occupy territories year-round. During droughts, mortality can be high, and only the largest groups might persist. “However, females in cooperatively breeding mammals can have very high rates of reproduction as soon as conditions are suitable. Populations can rebound, and dispersers move to fill vacant territories,” said Lukas.
By contrast, he says that many other mammals that live in arid areas are migratory, moving as resources are exhausted, such as the large ungulate herds roaming across the African savannahs.
Researchers say the new study also indicates that cooperation enables cooperative breeders to occupy a wider range of habitats than non-cooperative species which are limited to more favourable habitats.
Cooperative breeders are also twice as likely as non-cooperative mammals to occupy human-modified habitats suggesting that cooperative breeding may make it possible to colonize new environments. “Cooperative breeders may also persist in areas where changes in climate make life increasingly difficult,” said Clutton-Brock.
New research suggests that cooperative breeding makes mammal species such as meerkats better suited to dry, harsh climates.
Dr Hannah Rowland on The One Show
From Department of Zoology. Published on Jan 18, 2017.
Sir Jim Smith - knighted in 2017 New Years Honours
From Department of Zoology. Published on Jan 03, 2017.
Malcolm Burrows’ research featured on QI
From Department of Zoology. Published on Jan 03, 2017.
Professor Robert Hinde 1923-2016
From Department of Zoology. Published on Jan 03, 2017.
Languages still a major barrier to global science, new research finds
By fpjl2 from University of Cambridge - Department of Zoology. Published on Dec 29, 2016.
English is now considered the common language, or 'lingua franca', of global science. All major scientific journals seemingly publish in English, despite the fact that their pages contain research from across the globe.
However, a new study suggests that over a third of new scientific reports are published in languages other than English, which can result in these findings being overlooked - contributing to biases in our understanding.
As well as the international community missing important science, language hinders new findings getting through to practitioners in the field say researchers from the University of Cambridge.
They argue that whenever science is only published in one language, including solely in English, barriers to the transfer of knowledge are created.
The Cambridge researchers call on scientific journals to publish basic summaries of a study's key findings in multiple languages, and universities and funding bodies to encourage translations as part of their 'outreach' evaluation criteria.
"While we recognise the importance of a lingua franca, and the contribution of English to science, the scientific community should not assume that all important information is published in English," says Dr Tatsuya Amano from Cambridge's Department of Zoology.
"Language barriers continue to impede the global compilation and application of scientific knowledge."
The researchers point out an imbalance in knowledge transfer in countries where English is not the mother tongue: "much scientific knowledge that has originated there and elsewhere is available only in English and not in their local languages."
This is a particular problem in subjects where both local expertise and implementation is vital - such as environmental sciences.
As part of the study, published today in the journal PLOS Biology, those in charge of Spain's protected natural areas were surveyed. Over half the respondents identified language as an obstacle to using the latest science for habitat management.
The Cambridge team also conducted a litmus test of language use in science. They surveyed the web platform Google Scholar - one of the largest public repositories of scientific documents - in a total of 16 languages for studies relating to biodiversity conservation published during a single year, 2014.
Of the over 75,000 documents, including journal articles, books and theses, some 35.6% were not in English. Of these, the majority was in Spanish (12.6%) or Portuguese (10.3%). Simplified Chinese made up 6%, and 3% were in French.
The researchers also found thousands of newly published conservation science documents in other languages, including several hundred each in Italian, German, Japanese, Korean and Swedish.
Random sampling showed that, on average, only around half of non-English documents also included titles or abstracts in English. This means that around 13,000 documents on conservation science published in 2014 are unsearchable using English keywords.
This can result in sweeps of current scientific knowledge - known as 'systematic reviews' - being biased towards evidence published in English, say the researchers. This, in turn, may lead to over-representation of results considered positive or 'statistically significant', and these are more likely to appear in English language journals deemed 'high-impact'.
In addition, information on areas specific to countries where English is not the mother tongue can be overlooked when searching only in English.
For environmental science, this means important knowledge relating to local species, habitats and ecosystems - but also applies to diseases and medical sciences. For example, documents reporting the infection of pigs with avian flu in China initially went unnoticed by international communities, including the WHO and the UN, due to publication in Chinese-language journals.
"Scientific knowledge generated in the field by non-native English speakers is inevitably under-represented, particularly in the dominant English-language academic journals. This potentially renders local and indigenous knowledge unavailable in English," says lead author Amano.
"The real problem of language barriers in science is that few people have tried to solve it. Native English speakers tend to assume that all the important information is available in English. But this is not true, as we show in our study.
"On the other hand, non-native English speakers, like myself, tend to think carrying out research in English is the first priority, often ending up ignoring non-English science and its communication.
"I believe the scientific community needs to start seriously tackling this issue."
Amano and colleagues say that, when conducting systematic reviews or developing databases at a global scale, speakers of a wide range of languages should be included in the discussion: "at least Spanish, Portuguese, Chinese and French, which, in theory, cover the vast majority of non-English scientific documents."
The website conservationevidence.com, a repository for conservation science developed at Cambridge by some of the authors, has also established an international panel to extract the best non-English language papers, including Portuguese, Spanish and Chinese.
"Journals, funders, authors and institutions should be encouraged to supply translations of a summary of a scientific publication - regardless of the language it is originally published in," says Amano. The authors of the new study have provided a summary in Spanish, Portuguese, Chinese and French as well as Japanese.
"While outreach activities have recently been advocated in science, it is rare for such activities to involve communication across language barriers."
The researchers suggest efforts to translate should be evaluated in a similar way to other outreach activities such as public engagement, particularly if the science covers issues at a global scale or regions where English is not the mother tongue.
Adds Amano: "We should see this as an opportunity as well as a challenge. Overcoming language barriers can help us achieve less biased knowledge and enhance the application of science globally."
Over a third of new conservation science documents published annually are in non-English languages, despite assumption of English as scientific ‘lingua franca’. Researchers find examples of important science missed at international level, and practitioners struggling to access new knowledge, as a result of language barriers.
Road planning 'trade off' could boost food production while helping protect tropical forests
By fpjl2 from University of Cambridge - Department of Zoology. Published on Dec 15, 2016.
Conservation scientists have used layers of data on biodiversity, climate, transport and crop yields to construct a colour-coded mapping system that shows where new road-building projects should go to be most beneficial for food production, at the same time as being least destructive to the environment.
The hope is that this "trade-off" strategy might guide governments, investors and developers to focus on road expansions that make the most difference for current agricultural areas, rather than projects that threaten to open up significant natural habitats for conversion to farmland.
As a proof of concept, scientists applied their technique to a specific sub-region: the Greater Mekong in Southeast Asia - one of the most biologically important parts of the planet, and a place that has lost almost a third of its tropical forest since the 1970s.
They found a number of current road proposals in Vietnam, Laos, Myanmar and Cambodia have potential for massive habitat conversion with little benefit for populations and food security. They also found areas where new roads could increase food production and connectivity with limited environmental cost.
Researchers from the University of Cambridge, UK, the Kunming Institute of Botany and the World Agroforestry Centre in China say their study, published today in PLOS Biology, is an attempt to explore a more "conciliatory approach" in the hope of starting greater dialogue between developers and conservation experts.
They call on organisations such as the newly established Asian Infrastructure Investment Bank as well as Asian Development Bank to use such analyses when considering investment in future road expansion projects in the Mekong region - an area undergoing rapid development.
"It is estimated that by 2050 we will build 25 million km of new road lanes, the majority of which will be in the developing world," says Andrew Balmford, Professor of Conservation Science at Cambridge.
"Conservationists can to appear to oppose nearly all new infrastructure, while developers and their financial backers are often fairly mute on the environmental impact of their proposals. This can lead to a breakdown in communication."
"The Mekong region is home to some of the world's most valuable tropical forests. It's also a region in which a lot of roads are going to be built, and blanket opposition by the conservation community is unlikely to stop this," says Prof Jianchu Xu from the Kunming Institute of Botany in China.
"Studies like ours help pinpoint the projects we should oppose most loudly, while transparently showing the reasons why and providing alternatives where environmental costs are lower and development benefits are greater.
"Conservationists need to be active voices in infrastructure development, and I think these approaches have the potential to change the tone of the conversation."
The Greater Mekong encompasses Vietnam, Laos, Cambodia, Thailand, Myanmar and the Yunnan Province of China. It is home to around 20,000 plant species, 2000 types of land vertebrates and 850 species of freshwater fish. Much of this biodiversity is found nowhere else on the planet.
The saola, for example, is a mammal resembling a small antelope that was only discovered in 1992, and is so rare it is known as the "Asian unicorn". The region's vast forests also act as critical carbon 'sinks', absorbing greenhouse gases.
The Greater Mekong is also home to over 320 million people, and habitat loss has been accelerating. Between 1973 and 2009, an estimated 31% of the region's natural forest disappeared. Alongside this there is widespread poverty; food insecurity and malnutrition remain major challenges.
The researchers created the new framework for road planning in the Mekong by analysing various data sources: including crop yield gaps across the region, travel times between population hubs, range maps for birds and mammals, and biomass carbon stocks in soil and vegetation.
By combining this data into composite layers, the team were able to map them over the region and reduce the results to a simple green-to-purple colour scale comparing food production benefits to environmental costs.
In areas such as Myanmar's Ayeyarwady Delta, new roads could substantially boost food production through improved transport links for getting produce to market, lowering waste and increasing access to new technologies. This would come at a relatively limited environmental cost, as much of the area has been converted to agriculture, yet crop yields remain low.
However, researchers warn that planned projects in other areas with extensive forests, such as in northern Laos and western Yunnan in China, could devastate vital ecosystems with little gain for food production.
"If new roads are deployed strategically, and deliberately target already-cleared areas with poor transport connectivity, this could attract agricultural growth that might otherwise spread elsewhere," says Prof Xu.
For Balmford, this is perhaps the crux of the argument, and something he has long been vocal about: "By increasing the crop yield of current agricultural networks, there is hope that food needs can be met while containing the expansion of farming and so sparing natural habitats from destruction. The location of infrastructure, and roads in particular, will play a major role in this."
However, the researchers caution that the channeling of roads into less damaging, more rewarding areas will have to go hand-in-hand with strengthening protection for globally significant habitats such as the remaining forests of the Mekong.
Scientists hope a new approach to planning road infrastructure that could increase crop yield in the Greater Mekong region while limiting environmental destruction will open dialogues between developers and the conservation community.
Larger brain size linked to longer life in deer
By mjg209 from University of Cambridge - Department of Zoology. Published on Dec 14, 2016.
The study, published in the Royal Society Open Science journal, shows that female red deer with larger brains live longer and have more surviving offspring than those with smaller brains. Brain size is heritable and is passed down through the generations. This is the first extensive study of individual differences in brain size in wild mammals and draws on data comparing seven generations of deer.
Across species of mammals, brain size varies widely. This is thought to be a consequence of specific differences in the benefits and costs of a larger brain. Mammals with larger brains may, for example, have greater cognitive abilities that enable them to adapt better to environmental changes or they may have longer lifespans. But there may also be disadvantages: for instance, larger brains require more energy, so individuals that possess them may show reduced fertility.
The researchers, based at the University of Cambridge's Zoology Department and Edinburgh University's Institute of Evolutionary Biology, wanted to test if they could find more direct genetic or non-genetic evidence of the costs and benefits of large brain size by comparing the longevity and survival of individuals of the same species with different sized brains. Using the skulls of 1,314 wild red deer whose life histories and breeding success had been monitored in the course of a long-term study on the Isle of Rum, they found that females with larger endocranial volumes lived longer and produced more surviving offspring in the course of their lives.
Lead author Dr Corina Logan, a Gates Cambridge Scholar and Leverhulme Early Career Research Fellow in Cambridge's Department of Zoology, says: "The reasons for the association between brain size and longevity are not known, but other studies have suggested that larger brains are a consequence of the longer-lived species having longer developmental periods in which the brain can grow. These hypotheses were generated from cross-species correlations; however, testing such hypotheses requires investigations at the within-species level, which is what we did."
Dr Logan adds: "We found that some of the cross-species predictions about brain size held for female red deer, and that none of the predictions were supported in male red deer. This indicates that each sex likely experiences its own set of trade-offs with regard to brain size.”
The study also showed that females' relative endocranial volume is smaller than that of males, despite evidence of selection for larger brains in females.
"We think this is likely due to sex differences in the costs and benefits related to larger brains," adds Dr Logan. "We don’t know what kinds of trade-offs each sex might encounter, but we assume there must be variables that constrain brain size that are sex specific, which is why we see selection in females, but not males."
Professor Tim Clutton-Brock, who set up the Rum Red Deer study with Fiona Guinness in 1972 and initiated the work on brain size, points out that the reason that this kind of study has not been conducted before is that it requires long term records of a large number of individuals across multiple generations and data of this kind are still rare in wild animals.
C.J. Logan, R. Stanley, A.M. Thompson, T.H. Clutton-Brock. Endocranial volume is heritable and is associated with longevity and fitness in a wild mammal. Royal Society Open Science; 14 Dec 2016; 10.1098/rsos.160622
The size of a female animals' brain may determine whether they live longer and have more healthy offspring, according to new research led by the University of Cambridge.
Francis Crick: A Singular Approach to Scientific Discovery
From Department of Zoology. Published on Dec 06, 2016.
Nature Ecology and Evolution paper from Prof Jenny Clack and NERC consortium
From Department of Zoology. Published on Dec 06, 2016.
Congratulations to the winners of the Graduate Poster Competition 2016
From Department of Zoology. Published on Nov 22, 2016.
Profs Derek Smith and Bill Sutherland cited in Thompson Reuters Highly Cited Researchers of 2016
From Department of Zoology. Published on Nov 21, 2016.
Elephant poaching costs African economies US $25 million per year in lost tourism revenue
By fpjl2 from University of Cambridge - Department of Zoology. Published on Nov 01, 2016.
The current elephant poaching crisis costs African countries around USD $25 million annually in lost tourism revenue, according to a new study published in the journal Nature Communications. Comparing this lost revenue with the cost of halting declines in elephant populations due to poaching, the study determines that investment in elephant conservation is economically favorable across the majority of African elephants’ range.
The research, undertaken by scientists from World Wildlife Fund (WWF), the University of Vermont, and the University of Cambridge, represents the first continent-wide assessment of the economic losses that the current elephant poaching surge is inflicting on nature-based tourism economies in Africa.
“While there have always been strong moral and ethical reasons for conserving elephants, not everyone shares this viewpoint. Our research now shows that investing in elephant conservation is actually smart economic policy for many African countries,” said Dr. Robin Naidoo, lead wildlife scientist at WWF and lead author on the study.
Poachers kill between 20,000-30,000 African elephants each year for the illegal ivory trade, funded by global organized crime syndicates and fueled largely by demand in China and elsewhere in Asia. In just the past ten years, Africa’s elephants have declined by more than 20 percent.
"We know that within parks, tourism suffers when elephant poaching ramps up. This work provides a first estimate of the scale of that loss, and shows pretty convincingly that stronger conservation efforts usually make sound economic sense even when looking at just this one benefit stream," said study co-author Professor Andrew Balmford, from the University of Cambridge’s Department of Zoology.
The research shows that tourism revenue lost to the current poaching crisis exceeds the anti-poaching costs necessary to stop the decline of elephants in east, southern, and west Africa. Rates of return on elephant conservation in these regions are positive, signaling strong economic incentive for countries to protect elephant populations.
“The average rate of return on elephant conservation in east, west, and south Africa compares favorably with rates of return on investments in areas like education, food security and electricity,” said Dr. Brendan Fisher, an economist at University of Vermont’s Gund Institute for Ecological Economics. “For example, for every dollar invested in protecting elephants in East Africa, you get about $1.78 back. That's a great deal.”
However, for countries in central Africa, the study finds that elephant-based tourism cannot currently be expected to contribute substantially to elephant conservation. In these remote, forested areas where tourism levels are lower and elephants are typically more difficult to see, different mechanisms will be necessary to halt elephant declines.
Taken from a WWF press release.
New research shows investing in elephant conservation is smart economic policy for many African countries.
Alumnus Simon Keenlyside star of MetOpera's DonGiovanni wishes the Dept a Happy 150th Anniversary
From Department of Zoology. Published on Oct 26, 2016.
Eureka Moments film
From Department of Zoology. Published on Oct 26, 2016.
150th Anniversary photograph album
From Department of Zoology. Published on Oct 03, 2016.
Whale skeleton rebuilt at Cambridge University museum
From Department of Zoology. Published on Sep 29, 2016.
Unprecedented study of Aboriginal Australians points to one shared Out of Africa migration for modern humans
By tdk25 from University of Cambridge - Department of Zoology. Published on Sep 21, 2016.
The first major genomic study of Aboriginal Australians ever undertaken has confirmed that all present-day non-African populations are descended from the same single wave of migrants, who left Africa around 72,000 years ago.
Researchers sequenced the complete genetic information of 83 Aboriginal Australians, as well as 25 Papuans from New Guinea, to produce a host of significant new findings about the origins of modern human populations. Their work is published alongside several other related papers in the journal Nature.
The study, by an international team of academics, was carried out in close collaboration with elders and leaders from various Aboriginal Australian communities – some of whom are co-authors on the paper – as well as with various other organisations representing the participating groups.
Alongside the prevailing conclusion, that the overwhelming majority of the genomes of non-Africans alive today stem from one ancestral group of migrants who left Africa together, there are several other standout findings. These include:
- Compelling evidence that Aboriginal Australians are descended directly from the first people to inhabit Australia – which is still the subject of periodic political dispute.
- Evidence of an uncharacterised – and perhaps unknown – early human species which interbred with anatomically modern humans as they migrated through Asia.
- Evidence that a mysterious dispersal from the northeastern part of Australia roughly 4,000 years ago contributed to the cultural links between Aboriginal groups today. These internal migrants defined the way in which people spoke and thought, but then disappeared from most of the continent, in a manner which the researchers describe as “ghost-like”.
The study’s senior authors are from the University of Cambridge, the Wellcome Trust Sanger Institute, the Universities of Copenhagen, Bern and Griffith University Australia. Within Cambridge, members of the Leverhulme Centre for Evolutionary Studies also contributed to the research, in particular by helping to place the genetic data which the team gathered in the field within the context of wider evidence about early human population and migration patterns.
Professor Eske Willerslev, who holds posts at St John’s College, University of Cambridge, the Sanger Institute and the University of Copenhagen, initiated and led the research. He said: “The study addresses a number of fundamental questions about human evolution – how many times did we leave Africa, when was Australia populated, and what is the diversity of people in and outside Australia?”
“Technologically and politically, it has not really been possible to answer those questions until now. We found evidence that there was only really one wave of humans who gave rise to all present-day non-Africans, including Australians.”
Anatomically modern humans are known to have left Africa approximately 72,000 years ago, eventually spreading across Asia and Europe. Outside Africa, Australia has one of the longest histories of continuous human occupation, dating back about 50,000 years.
Some researchers believe that this deep history indicates that Papuans and Australians stemmed from an earlier migration than the ancestors of Eurasian peoples; others that they split from Eurasian progenitors within Africa itself, and left the continent in a separate wave.
Until the present study, however, the only genetic evidence for Aboriginal Australians, which is needed to investigate these theories, came from one tuft of hair (taken from a long-since deceased individual), and two unidentified cell lines.
The new research dramatically improves that picture. Working closely with community elders, representative organisations and the ethical board of Griffith University, Willerslev and colleagues obtained permission to sequence dozens of Aboriginal Australian genomes, using DNA extracted from saliva.
This was compared with existing genetic information about other populations. The researchers modelled the likely genetic impact of different human dispersals from Africa and towards Australia, looking for patterns that best matched the data they had acquired. Dr Marta Mirazon Lahr and Professor Robert Foley, both from the Leverhulme Centre, assisted in particular by analysing the likely correspondences between this newly-acquired genetic evidence and a wider framework of existing archaeological and anthropological evidence about early human population movements.
Dr Manjinder Sandhu, a senior author from the Sanger Institute and University of Cambridge, said: “Our results suggest that, rather than having left in a separate wave, most of the genomes of Papuans and Aboriginal Australians can be traced back to a single ‘Out of Africa’ event which led to modern worldwide populations. There may have been other migrations, but the evidence so far points to one exit event.”
The Papuan and Australian ancestors did, however, diverge early from the rest, around 58,000 years ago. By comparison, European and Asian ancestral groups only become distinct in the genetic record around 42,000 years ago.
The study then traces the Papuan and Australian groups’ progress. Around 50,000 years ago they reached “Sahul” – a prehistoric supercontinent that originally united New Guinea, Australia and Tasmania, until these regions were separated by rising sea levels approximately 10,000 years ago.
The researchers charted several further “divergences” in which various parts of the population broke off and became genetically isolated from others. Interestingly, Papuans and Aboriginal Australians appear to have diverged about 37,000 years ago – long before they became physically separated by water. The cause is unclear, but one reason may be the early flooding of the Carpentaria basin, which left Australia connected to New Guinea by a strip of land that may have been unfavourable for human habitation.
Once in Australia, the ancestors of today’s Aboriginal communities remained almost completely isolated from the rest of the world’s population until just a few thousand years ago, when they came into contact with some Asian populations, followed by European travellers in the 18th Century.
Indeed, by 31,000 years ago, most Aboriginal communities were genetically isolated from each other. This divergence was most likely caused by environmental barriers; in particular the evolution of an almost impassable central desert as the Australian continent dried out.
Assistant Professor Anna-Sapfo Malaspinas, from the Universities of Copenhagen and Bern, and a lead author, said: “The genetic diversity among Aboriginal Australians is amazing. Because the continent has been populated for such a long time, we find that groups from south-western Australia are genetically more different from north-eastern Australia, than, for example, Native Americans are from Siberians.”
Two other major findings also emerged. First, the researchers were able to reappraise traces of DNA which come from an ancient, extinct human species and are found in Aboriginal Australians. These have traditionally been attributed to encounters with Denisovans – a group known from DNA samples found in Siberia.
In fact, the new study suggests that they were from a different, as-yet uncharacterised, species. “We don’t know who these people were, but they were a distant relative of Denisovans, and the Papuan/Australian ancestors probably encountered them close to Sahul,” Willerslev said.
Finally, the research also offers an intriguing new perspective on how Aboriginal culture itself developed, raising the possibility of a mysterious, internal migration 4,000 years ago.
About 90% of Aboriginal communities today speak languages belonging to the “Pama-Nyungan” linguistic family. The study finds that all of these people are descendants of the founding population which diverged from the Papuans 37,000 years ago, then diverged further into genetically isolated communities.
This, however, throws up a long-established paradox. Language experts are adamant that Pama-Nyungan languages are much younger, dating back 4,000 years, and coinciding with the appearance of new stone technologies in the archaeological record.
Scientists have long puzzled over how – if these communities were completely isolated from each other and the rest of the world – they ended up sharing a language family that is much younger? The traditional answer has been that there was a second migration into Australia 4,000 years ago, by people speaking this language.
But the new research finds no evidence of this. Instead, the team uncovered signs of a tiny gene flow, indicating a small population movement from north-east Australia across the continent, potentially at the time the Pama-Nyungan language and new stone tool technologies appeared.
These intrepid travellers, who must have braved forbidding environmental barriers, were small in number, but had a significant, sweeping impact on the continent’s culture. Mysteriously, however, the genetic evidence for them then disappears. In short, their influential language and culture survived – but they, as a distinctive group, did not.
“It’s a really weird scenario,” Willerslev said. “A few immigrants appear in different villages and communities around Australia. They change the way people speak and think; then they disappear, like ghosts. And people just carry on living in isolation the same way they always have. This may have happened for religious or cultural reasons that we can only speculate about. But in genetic terms, we have never seen anything like it before.”
The paper, A Genomic History of Aboriginal Australia, is published in Nature. doi:10.1038/nature18299.
Inset images: Professor Eske Willerslev talking to Aboriginal elders in the Kalgoorlie area in southwestern Australia in 2012. (Photo credit: Preben Hjort, Mayday Film). / Map showing main findings from the paper. Credit: St John's College, Cambridge.
The first significant investigation into the genomics of Aboriginal Australians has uncovered several major findings about early human populations. These include evidence of a single “Out of Africa” migration event, and of a previously unidentified, “ghost-like” population spread which provided a basis for the modern Aboriginal cultural landscape.
Why mole rats are more flexible than we previously thought
By sjr81 from University of Cambridge - Department of Zoology. Published on Aug 30, 2016.
Mole rats, including the naked mole rat, live in underground colonies. The majority of rodents in the colonies are ‘workers’, with only one female (the ‘queen’) and one male responsible for breeding. All individuals cooperate by digging large underground tunnel systems to forage for food, and if a large food source is found, it is shared with the entire colony. ‘Queens’ and reproductive males remain in this role for their entire life after they have achieved this position. When a ‘queen’ dies, the strongest and largest helper is probably the prime candidate for inheriting the breeding position.
Early studies suggested that non-reproducing mole rats can be divided into non-workers, infrequent workers and frequent workers, and that most individuals stay members of distinct castes for their entire lives. Individual mole rats would focus on a particular task, such as digging, nest building or colony defence, throughout their lives.
Now, however, in a study published in Proceedings of the National Academy of Sciences, researchers from the Department of Zoology at the University of Cambridge have shown that in Damaraland mole rats, the contributions of individuals to cooperative activities change with age and that individual differences in behaviour that appeared to be a consequence of differences in caste are, in fact, age-related changes in behaviour. Whether variation in behaviour between naked mole rats is also a consequence of similar age-related changes is not known – but this seems likely.
Dr Markus Zöttl, first author of the study, explains: “In some ants, aphids and termites, individuals are born into castes that fulfil certain roles, such as soldiers or workers. Initially, everyone thought that this was only found in social invertebrates, like ants and bees, but in the eighties, the discovery of the social behaviour of mole rats challenged this view. Social mole rats were thought to be unique among vertebrates, in that they also had castes. To understand this fully, what we needed was long-term data on many mole rats over extended periods of their lives.”
To study mole rat development in more detail, a team at Cambridge led by Professor Tim Clutton-Brock from the Department of Zoology built a laboratory in the Kalahari Desert, where Damaraland mole rats are native, and established multiple colonies of mole rats in artificial tunnel systems. Over three years, they followed the lives of several hundred individuals to document how the behaviour of individuals changes as they age. All individuals were weighed and observed regularly to document their behavioural changes.
The researchers found that individual mole rats play different roles as they grow and get older. Rather than being specialists, mole rats are generalists that participate in more or fewer community duties at different stages of their lives. Instead of behaving like ants or termites, where individuals are members of a caste and specialise in doing certain activities, all mole rats are involved in a range of different activities, and their contributions to cooperative activities increases with age.
“As Damaraland mole rats do not have castes, this may mean that castes are only found in social invertebrates and have not evolved in any vertebrates,” adds Dr Zöttl. “Mole rat social organisation probably has more in common with the societies of other cooperative mammals, such as meerkats and wild dogs, than with those of social insects.”
The research was funded by European Research Council.
One of the most interesting facts about mole rats – that, as with ants and termites, individuals specialise in particular tasks throughout their lives – turns out to be wrong. Instead, a new study led by the University of Cambridge shows that individuals perform different roles at different ages and that age rather than caste membership accounts for contrasts in their behaviour.
A billion-year history of movement, from bacteria to Olympic athletes
From Department of Zoology. Published on Jul 19, 2016.
Sir Quentin Blake reveals new artwork at Cambridge's Museum of Zoology
From Department of Zoology. Published on Jul 12, 2016.
Tim Clutton-Brock's latest book 'Mammal Societies' is published
From Department of Zoology. Published on May 31, 2016.
Raising the Whale: defining zoology at Cambridge
From Department of Zoology. Published on Apr 29, 2016.
Threat of novel swine flu viruses in pigs and humans
From Department of Zoology. Published on Apr 26, 2016.
A damn close run thing (as Wellington probably did not say)
From Department of Zoology. Published on Apr 22, 2016.
Baboons queue for food - report by Alecia Carter
From Department of Zoology. Published on Apr 20, 2016.
Sir David Attenborough abseils down building bearing his name
From Department of Zoology. Published on Apr 07, 2016.
Best Student Talk prize for Syuan-Jyun Sun
From Department of Zoology. Published on Apr 04, 2016.
Crawling with Life: Flower drawings from the Henry Rogers Broughton Bequest
From Department of Zoology. Published on Apr 01, 2016.
Department of Zoology Seminar Day 2016 - winning posters
From Department of Zoology. Published on Mar 21, 2016.
David Labonte awarded ZSL Thomas Henry Huxley and Marsh Prize
From Department of Zoology. Published on Mar 16, 2016.
Peter Lawrence writes in 'Current Topics in Developmental Biology' 50th anniversary edition
From Department of Zoology. Published on Mar 08, 2016.