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Darwin’s rabbit helps to explain the fightback against myxomatosis

Cam ac uk zoology department feed - Thu, 14/02/2019 - 23:00

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Seventy years after myxomatosis decimated the rabbit populations of Australia, Britain and France, a new study led by Cambridge scientists reveals how the species has evolved genetic resistance to the disease through natural selection.

Trustees of the Natural History MuseumRabbit collections at the Natural History Museum, London.


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Butterflies are genetically wired to choose a mate that looks just like them

Cam ac uk zoology department feed - Fri, 08/02/2019 - 10:35
A team of academics from the University of Cambridge, in collaboration with the Smithsonian Tropical Research Institute in Panama, observed the courtship rituals and sequenced the DNA from nearly 300 butterflies to find out how much of the genome was responsible for their mating behaviour.   The research, published in PLOS Biology, is one of the first ever genome studies to look at butterfly behaviour and it unlocks the secrets of evolution to help explain how new species are formed. Scientists sequenced the DNA from two different species of Heliconius butterflies which live either side of the Andes mountains in Colombia. Heliconians have evolved to produce their own cyanide which makes them highly poisonous and they have distinct and brightly coloured wings which act as a warning to would-be predators.   Professor Chris Jiggins, one of the lead authors on the paper and a Fellow of St John’s College, said: “There has previously been lots of research done on finding genes for things like colour patterns on the butterfly wing, but it’s been more difficult to locate the genes that underlie changes in behaviour. What we found was surprisingly simple – three regions of the genome explain a lot of their behaviours. There’s a small region of the genome that has some very big effects.”   The male butterflies were introduced to female butterflies of two species and were scored for their levels of sexual interest directed towards each. The scientists rated each session based on the number of minutes of courtship by the male – shown by sustained hovering near or actively chasing the females.   Unlike many butterflies which use scented chemical signals to identify a mate, Heliconians use their long-range vision to locate the females, which is why it’s important each species has distinct wing markings. When a hybrid between the two species was introduced, the male would most commonly show a preference for a mate with similar markings to itself. The research showed the same area of the genome that controlled the coloration of the wings was responsible for defining a sexual preference for those same wing patterns.   Dr Richard Merrill, one of the authors of the paper, based at Ludwig-Maximilians-Universität, Munich, said: “It explains why hybrid butterflies are so rare – there is a strong genetic preference for similar partners which mostly stops inter-species breeding. This genetic structure promotes long-term evolution of new species by reducing intermixing with others.”   The paper is one of two published in PLOS Biology and funded by the European Research Council which brought together ten years of research by Professor Jiggins and his team. The second study investigated how factors including mate preference act to prevent genetic mixing between the same two species of butterfly. They discovered that despite the rarity of hybrid butterflies – as a result of their reluctance to mate with one another – a surprisingly large amount of DNA has been shared between the species through hybridisation. There has been ten times more sharing between these butterfly species than occurred between Neanderthals and humans.   Dr Simon Martin, one of the authors of the second paper, from the University of Edinburgh, explained: “Over a million years a very small number of hybrids in a generation is enough to significantly reshape the genomes of the these butterflies.”   Despite this genetic mixing, the distinct appearance and behaviours of the two species remain intact, and have not become blended. The researchers found that there are many areas of the genome that define each species, and these are maintained by natural selection, which weeds out the foreign genes. In particular, the part of the genome that defines the sex of the butterflies is protected from the effects of inter-species mating. As with the genetics that control mating behaviour, these genes enable each butterfly type to maintain its distinctiveness and help ensure long-term survival of the species. But can the findings translate into other species including humans?   Professor Jiggins said: “In terms of behaviour, humans are unique in their capacity for learning and cultural changes but our behaviour is also influenced by our genes. Studies of simpler organisms such as butterflies can shed light on how our own behaviour has evolved. Some of the patterns of gene sharing we see between the butterflies have also been documented in comparisons of the human and Neanderthal genomes, so there is another link to our own evolution.”   “Next we would like to know how novel behaviour can arise and what kind of genetic changes you need to alter behaviour. We already know that you can make different wing patterns by editing the genes. These studies suggest that potentially new behaviours could come about by putting different genes together in new combinations.”   References Martin, S et al. Recombination rate variation shapes barriers to introgression across butterfly genomes. PLOS Biology; 7 Feb 2019; DOI: 10.1371/journal.pbio.2006288 Merrill, R et al. Genetic dissection of assortative mating behavior. PLOS Biology; 7 Feb 2019; DOI: 10.1371/journal.pbio.2005902

Male butterflies have genes which give them a sexual preference for a partner with a similar appearance to themselves, according to new research.

There’s a small region of the genome that has some very big effectsChris JigginsChris JigginsHeliconius melpomene amaryllis


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The magnificent glow of fly testes

News from this site - Mon, 04/02/2019 - 16:53

γ-Tubulin Ring Complex Heterogeneity Revealed by Analysis of Mozart1 Regulating the formation of new microtubules in both space and time is critical for a wide variety of cell processes and is mediated in part by the recruitment of γ-tubulin ring complexes (γ-TuRCs) to specific microtubule organising centres (MTOCs). This...

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University of Cambridge finalist in Global Solution Search contest

News from this site - Thu, 17/01/2019 - 12:11

Researchers, including our PhD Student Emma Garnett , and staff at the University of Cambridge, have been selected as top 10 finalists in a global contest designed to identify, reward, and spotlight innovative solutions for addressing climate change. This project was selected from a pool of nearly 200 entries in Solution...

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Planar Cell Polarity Explained

News from this site - Wed, 12/12/2018 - 10:44

Cells are polarised in the plane of the sheet and this shows when they make oriented structures such as cilia or hairs. The literature in this small field is so inconclusive and complex that most are put off from reading it. Dr Peter Lawrence and Dr José Casal have written a "primer" to explain the elegant and simple...

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Living fossils from the Mediterranean here in Cambridge

News from this site - Wed, 05/12/2018 - 10:54

A new paper published today in Nature reveals for the first time the genome regulatory landscape of the only extant descendant of the ancestor to all animals with a backbone, including us, Amphioxus. Amphioxus are widely considered to be the only representative of the evolutionary transition between invertebrates and...

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Spanish Flu: a warning from history

Cam ac uk zoology department feed - Fri, 30/11/2018 - 09:22

The early origins and initial geographical starting point of the pandemic still remain a mystery but in the summer of 1918, there was a second wave of a far more virulent form of the influenza virus than anyone could have anticipated.

Soon dubbed ‘Spanish Flu’ after its effects were reported in the country’s newspapers, the virus rapidly spread across much of the globe to become one of the worst natural disasters in human history.

Doctors, nurses and volunteers were left helpless as their patients, the majority previously healthy young adults, languished and died from respiratory failure. There is now a broad consensus among experts that in just three years, Spanish Flu killed between fifty and one hundred million people. Despite this, public awareness of the disaster and the ongoing threat posed by influenza remains limited.

To mark the centenary and to highlight vital scientific research, the University of Cambridge has made a new film exploring what we have learnt about Spanish Flu, the urgent threat posed by influenza today, and how scientists are preparing for future pandemics. The film presents original photographs from the 1918 outbreak and exclusive interviews with four leading experts:

  • Dr Mary Dobson, a historian of infectious diseases 
  • Professor Derek Smith, Director of Cambridge’s Centre for Pathogen Evolution
  • Dr AJ te Velthuis, a virologist studying how RNA viruses amplify, mutate and cause disease
  • Professor Julia Gog, a mathematician of infectious diseases including influenza

One hundred years ago, celebrations marking the end of the First World War were cut short by the onslaught of a devastating disease: the 1918-19 influenza pandemic.


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified.  All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Ancient DNA analysis unlocks secrets of Ice Age tribes in the Americas

Cam ac uk zoology department feed - Fri, 09/11/2018 - 09:05

The results have been published in the journal Science as part of a wide-ranging international study, led by the University of Cambridge, which genetically analysed the DNA of a series of well-known and controversial ancient remains across North and South America.

The research also discovered clues of a puzzling Australasian genetic signal in the 10,400-year-old Lagoa Santa remains from Brazil revealing a previously unknown group of early South Americans – but the Australasian link left no genetic trace in North America.

Additionally, a legal battle over a 10,600-year-old ancient skeleton – called the ‘Spirit Cave Mummy’ – has ended after advanced DNA sequencing found it was related to a Native American tribe. The researchers were able to dismiss a longstanding theory that a group called Paleoamericans existed in North America before Native Americans. The Paleoamerican hypothesis was first proposed in the 19th century, but this new study disproves that theory.

“Spirit Cave and Lagoa Santa were very controversial because they were identified as so-called ‘Paleoamericans’ based on craniometry – it was determined that the shape of their skulls was different to current day Native Americans,” said Professor Eske Willeslev, who holds positions at the Universities of Cambridge and Copenhagen, and led the study. “Our study proves that Spirit Cave and Lagoa Santa were actually genetically closer to contemporary Native Americans than to any other ancient or contemporary group sequenced to date.”

The scientific and cultural significance of the Spirit Cave remains, which were found in 1940 in a small rocky alcove in the Great Basin Desert, was not properly understood for 50 years. The preserved remains of the man in his forties were initially believed to be between 1,500 and 2000 years old but during the 1990s new textile and hair testing dated the skeleton at 10,600 years old.

The Fallon Paiute-Shoshone Tribe, a group of Native Americans based in Nevada near Spirit Cave, claimed cultural affiliation with the skeleton and requested immediate repatriation of the remains.

Their request was refused and the tribe sued the US government, a lawsuit that pitted tribal leaders against anthropologists, who argued the remains provided invaluable insights into North America’s earliest inhabitants and should continue to be displayed in a museum.

The deadlock continued for 20 years until the tribe agreed that Professor Willeslev could carry out genome sequencing on DNA extracted from the Spirit Cave for the first time.

“I assured the tribe that my group would not do the DNA testing unless they gave permission and it was agreed that if Spirit Cave was genetically a Native American the mummy would be repatriated to the tribe,” said Professor Willeslev, who is a Fellow of St John’s College.

The team extracted DNA from the inside of the skull proving that the skeleton was an ancestor of present-day Native Americans. Spirit Cave was returned to the tribe in 2016 and there was a private reburial ceremony earlier this year. The tribe were kept informed throughout the two-year project and two members visited the lab in Copenhagen to meet the scientists and they were present when all of the DNA sampling was taken.

The genome of the Spirit Cave skeleton has wider significance because it not only settled the legal and cultural dispute between the tribe and the Government, it also helped reveal how ancient humans moved and settled across the Americas. The scientists were able to track the movement of populations from Alaska to as far south as Patagonia. They often separated from each other and took their chances travelling in small pockets of isolated groups.

Dr David Meltzer, from the Department of Anthropology, Southern Methodist University, Dallas, said: “A striking thing about the analysis of Spirit Cave and Lagoa Santa is their close genetic similarity which implies their ancestral population travelled through the continent at astonishing speed. That’s something we’ve suspected due to the archaeological findings, but it’s fascinating to have it confirmed by the genetics. These findings imply that the first peoples were highly skilled at moving rapidly across an utterly unfamiliar and empty landscape. They had a whole continent to themselves and they were travelling great distances at speed.”

The study also revealed surprising traces of Australasian ancestry in ancient South American Native Americans but no Australasian genetic link was found in North American Native Americans.

Dr Victor Moreno-Mayar, from the Centre for GeoGenetics, University of Copenhagen and first author of the study, said: “We discovered the Australasian signal was absent in Native Americans prior to the Spirit Cave and Lagoa Santa population split which means groups carrying this genetic signal were either already present in South America when Native Americans reached the region, or Australasian groups arrived later. That this signal has not been previously documented in North America implies that an earlier group possessing it had disappeared or a later arriving group passed through North America without leaving any genetic trace.”

Dr Peter de Barros Damgaard, from the Centre for GeoGenetics, University of Copenhagen, explained why scientists remain puzzled but optimistic about the Australasian ancestry signal in South America. He explained: “If we assume that the migratory route that brought this Australasian ancestry to South America went through North America, either the carriers of the genetic signal came in as a structured population and went straight to South America where they later mixed with new incoming groups, or they entered later. At the moment we cannot resolve which of these might be correct, leaving us facing extraordinary evidence of an extraordinary chapter in human history! But we will solve this puzzle.”

The population history during the millennia that followed initial settlement was far more complex than previously thought. The peopling of the Americas had been simplified as a series of north to south population splits with little to no interaction between groups after their establishment.

The new genomic analysis presented in the study has shown that around 8,000 years ago, Native Americans were on the move again, but this time from Mesoamerica into both North and South America.

Researchers found traces of this movement in the genomes of all present-day indigenous populations in South America for which genomic data is available to date.

Dr Moreno-Mayar added: “The older genomes in our study not only taught us about the first inhabitants in South America but also served as a baseline for identifying a second stream of genetic ancestry, which arrived from Mesoamerica in recent millennia and that is not evident from the archaeological record. These Mesoamerican peoples mixed with the descendants of the earliest South Americans and gave rise to most contemporary groups in the region.”

Reference: 
J. Victor
Moreno-Mayar et al. 'Early human dispersals within the Americas.' Science (2018). DOI: 10.1126/science.aav2621

Adapted from a St John's College press release.

Inset image: Skulls and other human remains from P.W. Lund's Collection from Lagoa Santa, Brazil. Kept in the Natural History Museum of Denmark. Credit: Natural History Museum of Denmark

Scientists have sequenced 15 ancient genomes spanning from Alaska to Patagonia and were able to track the movements of the first humans as they spread across the Americas at “astonishing” speed during the last Ice Age, and also how they interacted with each other in the following millennia.

Our study proves that Spirit Cave and Lagoa Santa were actually genetically closer to contemporary Native Americans than to any other ancient or contemporary group sequenced to dateEske Willeslev Linus Mørk, Magus FilmProfessor Eske Willerslev with Donna and Joey, two members of the Fallon Paiute-Shoshone tribe.


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified.  All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Mammalian Evolution, Diversity and Systematics

News from this site - Thu, 01/11/2018 - 10:08

This new volume in the Handbook of Zoology series provides up-to-date reviews of mammalian evolution, phylogenetics, and molecular biology and will be essential reading for mammalogists, zoologists and conservationists alike. The volume, edited by Frank E. Zachos, of the Natural History Museum Vienna, and our own Robert...

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