Monday, February 16, 2015

Sweet? Bitter? #Penguins Can't Tell, Research Suggests

Feb 16, 2015
                                               Wikimedia Commons/Tekken50

NEW YORK (GenomeWeb) – Penguins appear to lack taste receptor genes governing three of the five tastes, according to a genomic analysis conducted by a trio of researchers from the US and China.

The trio, led by Jianzhi Zhang at the University of Michigan, searched through the genomes of the Adélie penguin (Pygoscelis adeliae) and emperor penguin (Aptenodytes forsteri) and other birds for taste receptor genes. Penguins, they found, lacked receptors involved in perceiving sweet, bitter, and umami taste, but have retained salty and sour taste receptors, as they reported in Current Biology.

"Penguins eat fish, so you would guess that they need the umami receptor genes, but for some reason they don't have them," Michigan's Zhang said in a statement. "These findings are surprising and puzzling, and we do not have a good explanation for them. But we have a few ideas."

Zhang and his team searched for genes that encode taste receptors — sour's PKD2L1, salty's ENaC, umami's Tas1r1–Tas1r3 heterodimer, sweet's Tas1r2–Tas1r3 heterodimer, and bitter's Tas2r genes — in Adélie and emperor penguins, as well as in the little egret and a dozen or so other birds whose genomes were publicly available.

None of the birds had the Tas1r2 gene, which encodes part of the sweet taste receptor, though the researchers did find the gene in mammalian and reptile outgroups.

Tas1r3, which makes up the other part of the sweet taste receptor heterodimer as well as part of the umami taste receptor heterodimer, was also lacking in penguins. It was, the researchers noted, present in other birds.

The other half of the umami taste-specific receptor, Tas1r1, is actually a pseudogene in penguins, the researchers found, as it contains a two basepair deletion that leads to a premature stop codon.
Other penguin species shared this pseudogene, but other birds have working copies, Zhang and his team reported.

Similarly, the researchers identified three Tas2r pseudogenes in penguins while most other birds had working copies of the gene behind bitter taste. They noted, though, those three penguin pseudogenes were orthologous to the two working copies and one pseudogene version of Tas2r found in the little egret.

This, Zhang and his colleagues said, indicates that the common ancestor of all penguins lost the umami and bitter tastes, while the sweet taste was lost even earlier in the avian lineage.
The receptor gene for sour taste was present in all birds, including penguins, as were the genes encoding the subunits of the salty taste receptor, ENaC.

Zhang and his colleagues said they suspect that the penguin's ancestral stomping grounds of Antarctica might have had a role in this gene loss.

Trpm5, which is involved in transducing the sweet, umami, and bitter tastes, doesn't work well at lower temperatures. At freezing temperatures, the researchers suggested that it might not work at all, leading to the inability to taste sweet, umami, and bitter, and then to the loss of the genes linked to those tastes.



Journal Reference:
  1. Huabin Zhao, Jianwen Li, Jianzhi Zhang. Molecular evidence for the loss of three basic tastes in penguins. Current Biology, 2015; 25 (4): R141 DOI:10.1016/j.cub.2015.01.026

Tuesday, February 10, 2015

#Penguin change stuns scientists


Yellow-eyed penguin. Adult standing showing wing 'flippers'. Otago Peninsula, January 2006. Image © Craig McKenzie

Dunedin
When yellow-eyed penguins arrived in New Zealand just decades after the country's native waitaha penguin became extinct, it became one of the most rapid prehistoric animal turnovers ever found, University of Otago researchers say.

The team of researchers used carbon dating and DNA analysis of penguin remains from coastal New Zealand to establish the timing of the waitaha's extinction and the colonisation by yellow-eyed penguins from the subantarctic.

University of Otago postdoctoral research fellow Dr Nic Rawlence, who carried out the study, said the combination of ecology, archaeology and DNA in this way was new and was also being used to investigate if similar patterns exist with New Zealand sea lions, Stewart Island shags, elephant seals and fur seals.

Previous research had shown at the time of human arrival, New Zealand was inhabited by the waitaha penguin. ''Hunting and habitat change apparently caused the extinction of this unique mainland penguin, before the yellow-eyed penguin later arrived here from the subantarctic,'' Dr Rawlence said.

The new dating study showed waitaha went extinct around the same time as the giant flightless moa, within 200 years of Polynesian settlement of New Zealand - before 1500 AD. The yellow-eyed penguin then replaced the extinct penguin within about 20 to 30 years, in the early 1500s. ''It's one of the most rapid biological turnovers ever documented.''

Associate Prof Ian Smith, who was also involved in the study, said the very rapid biological shift implied a substantial change in human pressure around that time. ''Interestingly, recent archaeological studies similarly suggest that the Maori population in southern New Zealand declined around 1500 AD, and coincided with a major dietary shift.''

Dr Rawlence said if there had not been the dietary shift from large animals to fish and shellfish, yellow-eyed penguins would not have been able to fill the niche left by the waitaha. ''Yellow-eyeds would have arrived and then become extinct if there hadn't been that change.''

The near absence of the yellow-eyed penguin from the mainland before the extinction of the waitaha was similar to what happened to New Zealand's sea lions.

A University of Otago study published last year found today's sea lions replaced an extinct prehistoric New Zealand sea lion. The Marsden and Allan Wilson Centre-funded research on penguins included team members from the Universities of Auckland, Otago, Adelaide and Oslo, as well as Canterbury Museum and Te Papa.

The team's findings were published this week in the leading international journal Quaternary Science Reviews.

source

Tuesday, January 20, 2015

Climate Change Puts Picky #Penguin Eaters At Risk

By Jenna Iacurci
Jan 20, 2015 
 
penguins
Climate change is putting picky penguin eaters at risk, according to a new study. (Photo : Rachael Herman, LSU) 
 
Climate change is putting picky penguin eaters at risk, according to a new study.

Chinstrap and Gentoo penguins live in close proximity to one another in the Antarctic Peninsula, especially during the summer breeding season. So in order to peacefully co-exist and avoid competition for food resources, they evolved different feeding strategies over time. Now, however, this seems to be backfiring on one of the two species.

Named for the black stripe under their chins, Chinstrap penguin populations are decreasing while Gentoo penguins, recognized by their bright orange beaks, are actually increasing in number.

"Our data shows Gentoo penguins have a more diverse and flexible diet than Chinstrap penguins, which forage farther offshore and preferentially feed on Antarctic krill during the breeding season," lead author Michael Polito, from Louisiana State University, said in a press release.

Thanks to climate change, the Antarctic Peninsula is the fastest warming region in the Southern Hemisphere, according to the British Antarctic Survey. Over the past 50 years, the annual air temperature has risen by about 5 degrees Fahrenheit (2.8 degrees Celsius).

"For a region that for most of the year hovers around the point of freezing, a few degrees plus or minus is the difference between freezing and melting, particularly of sea ice," Polito explained.
This isn't just bad for penguins, but for the Antarctic krill that they mainly feed on, which use sea ice for protection from predators. Krill also feed on algae that grow beneath these slabs of ice, so as temperatures warm the lack of sea ice means fewer krill are around for penguin species to eat.

Based on the laws of supply and demand, there isn't enough krill to go around - especially during breeding season when penguins have to worry about feeding their chicks. So Chinstrap penguins whose diet relies on Antarctic krill find themselves in a tough spot.

On the other hand, adaptable Gentoo penguins are doing just fine, even amongst rapidly changing environmental conditions. They are flexible in their diet and breeding location, and also likely ease the transition of their chicks into adulthood by feeding them for a longer period of time.

Researchers determined the species' feeding habits by examining their stomach contents, studying the ear bones of fishes to determine if the penguins were feeding nearshore or offshore, and analyzing breast feathers from fully grown chicks to see how much krill versus fish they were fed. The results showed two very different strategies.

"These may be the reasons why Gentoo penguins in the Antarctic Peninsula are benefiting from changes in climate and their populations are increasing, but Chinstrap penguins are decreasing," Polito said.

The results are described further in the journal Marine Ecology Progress Series.

source

Friday, December 19, 2014

Antarctic tourism may pose disease threat to #penguins

  • 19 December 2014 by Penny Sarchet
A take-off in tourism could open the door to new bird diseases <i>(Image: Frans Lanting/National Geographic Creative)</i>
A take-off in tourism could open the door to new bird diseases (Image: Frans Lanting/National Geographic Creative)

For those who go, it's the trip of a lifetime – and it wouldn't be complete without a selfie with penguins. But growing tourism to the Antarctic, in combination with its warming climate, could be placing penguins at a risk of infectious diseases.

Antarctic species are believed to have weaker immune systems due to their long isolation from the world's common pathogens. Humans only started visiting Antartica roughly 200 years ago.
Antarctica is no longer a stranger to human contact: more than 37,000 people visited the continent in the 2013-14 season as part of a growing tourist industry, compared with an estimated 8000 just twenty years earlier. An additional 4400 researchers can be accommodated simultaneously in Antarctica during peak months.

"The effects of both a growing tourism industry and research presence will not be without consequences," says Wray Grimaldi of the University of Otago in Dunedin, New Zealand. "Penguins are highly susceptible to infectious diseases." She bases that on a survey by her team of penguin diseases in captivity, reaching as far back as 1947. It found reports of Salmonella, E. coli, West Nile virus and Avian pox virus infections, among others.

Widespread deaths

The team also found evidence of a number of mass penguin mortality events across the Antarctic since 1969. A number of infectious agents are implicated, including Avian pox, which killed more than 400 gentoo penguins in 2006, and caused 60 per cent mortality rates throughout another outbreak in 2008.

Grimaldi says disease agents may have arrived in Antarctica via migrating birds like skuas or giant petrels, although some pathogenic bacteria could have been introduced by humans. There isn't enough evidence to test either possibility, she says.

Yet, as the climate warms, more birds are expected to visit Antarctic regions, bringing their pathogens with them, while diseases borne by other animals could expand their ranges southwards.

But Norman Ratcliffe of the British Antarctic Survey in Cambridge, UK, says there is not a lot of evidence that wild penguin populations have been significantly affected by disease, adding that the Antarctic's tourism industry has been very active for 20 years and takes appropriate precautions.
"The tour companies are quite careful to make sure everyone cleans their boots before they go ashore," he says. "They don't allow any animal products to be taken ashore."

Warming warning

Grimaldi warns that climate change could help drive the emergence of new penguin diseases in Antarctica. Claire Christian of the Antarctic and Southern Ocean Coalition, a group of environmental NGOs, agrees.

"Climate change may result in a number of stressors that make it more difficult for penguin populations to deal with disease," she says. In addition to prompting the arrival of new pathogens or species carrying pathogens, warming temperatures could have a negative impact on food sources like krill, which might leave the penguins less able to fight off illness, she adds.

"A coordinated monitoring system needs to be in place," argues Grimaldi. "That way, responses can be directed by science." Christian agrees, but she says research alone is not enough – the countries that are signatories to the Antarctic Treaty also need to cooperate in implementing protective and precautionary measures.


Friday, December 12, 2014

Tooth loss in birds occurred about 116 million years ago

Date:
December 11, 2014
Source:
University of California - Riverside
Summary:
A question that has intrigued biologists is: Were teeth lost in the common ancestor of all living birds or convergently in two or more independent lineages of birds? A research team used the degraded remnants of tooth genes in birds to determine that teeth were lost in the common ancestor of all living birds more than 100 million years ago.











Birds are evolutionarily derived from theropod dinosaurs.
Credit: Image courtesy of University of California - Riverside




The absence of teeth or "edentulism" has evolved on multiple occasions within vertebrates including birds, turtles, and a few groups of mammals such as anteaters, baleen whales and pangolins. Where early birds are concerned, the fossil record is fragmentary. A question that has intrigued biologists is: Based on this fossil record, were teeth lost in the common ancestor of all living birds or convergently in two or more independent lineages of birds?

A research team led by biologists at the University of California, Riverside and Montclair State University, NJ, has found an answer. Using the degraded remnants of tooth genes in birds to determine when birds lost their teeth, the team reports in the Dec. 12 issue of Science that teeth were lost in the common ancestor of all living birds more than 100 million years ago.

"One of the larger lessons of our finding is that 'dead genes,' like the remnants of dead organisms that are preserved in the fossil record, have a story to tell," said Mark Springer, a professor of biology and one of the lead authors of the study along with Robert Meredith at Montclair State University who was previously a graduate student and postdoctoral researcher in Springer's laboratory. "DNA from the crypt is a powerful tool for unlocking secrets of evolutionary history."

Springer explained that edentulism and the presence of a horny beak are hallmark features of modern birds. "Ever since the discovery of the fossil bird Archaeopteryx in 1861, it has been clear that living birds are descended from toothed ancestors," he said. "However, the history of tooth loss in the ancestry of modern birds has remained elusive for more than 150 years."

All toothless/enamelless vertebrates are descended from an ancestor with enamel-capped teeth. In the case of birds, it is theropod dinosaurs. Modern birds use a horny beak instead of teeth, and part of their digestive tract to grind up and process food.

Tooth formation in vertebrates is a complicated process that involves many different genes. Of these genes, six are essential for the proper formation of dentin (DSPP) and enamel (AMTN, AMBN, ENAM, AMELX, MMP20).

The researchers examined these six genes in the genomes of 48 bird species, which represent nearly all living bird orders, for the presence of inactivating mutations that are shared by all 48 birds. The presence of such shared mutations in dentin and enamel-related genes would suggest a single loss of mineralized teeth in the common ancestor of all living birds.

Springer, Meredith, and other members of their team found that the 48 bird species share inactivating mutations in both dentin-related (DSPP) and enamel-related genes (ENAM, AMELX, AMTN, MMP20), indicating that the genetic machinery necessary for tooth formation was lost in the common ancestor of all modern birds. "The presence of several inactivating mutations that are shared by all 48 bird species suggests that the outer enamel covering of teeth was lost around ~116 million years ago," Springer said.

On the basis of fossil and molecular evidence, the researchers propose a two-step scenario whereby tooth loss and beak development evolved together in the common ancestor of all modern birds. In the first stage, tooth loss and partial beak development began on the anterior portion of both the upper and lower jaws. The second stage involved concurrent progression of tooth loss and beak development from the anterior portion of both jaws to the back of the rostrum. "We propose that this progression ultimately resulted in a complete horny beak that effectively replaced the teeth and may have contributed to the diversification of living birds," Springer said.

The research team also examined the genomes of additional toothless/enamelless vertebrates including three turtles and four mammals (pangolin, aardvark, sloth, and armadillo) for inactivating mutations in the dentin- and enamel-related genes. For comparison, the researchers looked at the genomes of mammalian taxa with enamel-capped teeth. "All edentulous vertebrate genomes that we examined are characterized by inactivating mutations in DSPP, AMBN, AMELX, AMTN, ENAM, and MMP20, rendering these genes non-functional," Springer said. "The dentin-related gene DSPP is functional in vertebrates with enamelless teeth -- sloth, aardvark, armadillo. All six genes are functional in the American alligator, a representative of Crocodylia, the closest living relatives of birds, and mammalian taxa with enamel capped teeth."

The research was supported, in part, by a grant to Springer from the National Science Foundation.
Springer and Meredith were joined in the research by Guojie Zhang at China National GeneBank, China; M. Thomas P. Gilbert at the University of Copenhagen Oster Voldgade, Denmark; and Erich D. Jarvis at Duke University Medical Center, NC.

All the scientists are coauthors with several others, including UC Riverside biologist John Gatesy, on a second paper in the same issue of Science. This paper employs the same 48 bird genomes to ask the question: "What makes a bird a bird?"

"The new bird genomes represent a major advance given that only a handful of bird genomes -- zebra finch, turkey, chicken and duck -- were previously available," Springer said.

Story Source:
The above story is based on materials provided by University of California - Riverside. The original article was written by Iqbal Pittalwala. Note: Materials may be edited for content and length.

Journal Reference:
  1. R. W. Meredith, G. Zhang, M. T. P. Gilbert, E. D. Jarvis, M. S. Springer. Evidence for a single loss of mineralized teeth in the common avian ancestor. Science, 2014; 346 (6215): 1254390 DOI: 10.1126/science.1254390


University of California - Riverside. "Tooth loss in birds occurred about 116 million years ago." ScienceDaily. ScienceDaily, 11 December 2014. <www.sciencedaily.com/releases/2014/12/141211142148.htm>.

'Big Bang' of bird evolution mapped: Genes reveal deep histories of bird origins, feathers, flight and song

 


Crocodiles are the closest living relatives of birds, sharing a common ancestor that lived around 240 million years ago and also gave rise to the dinosaurs.
Credit: Stephen J. O'Brien, Avian Phylogenomics Group

Date:
December 11, 2014
Source:
Duke University
Summary:
The first findings of the Avian Phylogenomics Consortium are being reported nearly simultaneously in 29 papers -- eight papers in a Dec. 12 special issue of Science and 21 more in Genome Biology, GigaScience and other journals. The analyses suggest some remarkable new ideas about bird evolution, including insights into vocal learning and the brain, colored plumage, sex chromosomes and the birds' relationship to dinosaurs and crocodiles.
 ______________________________________________________________________________
The genomes of modern birds tell a story of how they emerged and evolved after the mass extinction that wiped out dinosaurs and almost everything else 66 million years ago. That story is now coming to light, thanks to an ambitious international collaboration that has been underway for four years.
The first findings of the Avian Phylogenomics Consortium are being reported nearly simultaneously in 29 papers -- eight papers in a Dec. 12 special issue of Science and 21 more in Genome Biology, GigaScience and other journals.

Scientists already knew that the birds who survived the mass extinction experienced a rapid burst of evolution. But the family tree of modern birds has confused biologists for centuries and the molecular details of how birds arrived at the spectacular biodiversity of more than 10,000 species is barely known.

To resolve these fundamental questions, a consortium led by Guojie Zhang of the National Genebank at BGI in China and the University of Copenhagen, Erich D. Jarvis of Duke University and the Howard Hughes Medical Institute and M. Thomas P. Gilbert of the Natural History Museum of Denmark, has sequenced, assembled and compared full genomes of 48 bird species. The species include the crow, duck, falcon, parakeet, crane, ibis, woodpecker, eagle and others, representing all major branches of modern birds.

"BGI's strong support and four years of hard work by the entire community have enabled us to answer numerous fundamental questions to an unprecedented scale," said Guojie Zhang. "This is the largest whole genomic study across a single vertebrate class to date. The success of this project can only be achieved with the excellent collaboration of all the consortium members."

"Although an increasing number of vertebrate genomes are being released, to date no single study has deliberately targeted the full diversity of any major vertebrate group," added Tom Gilbert. "This is precisely what our consortium set out to do. Only with this scale of sampling can scientists truly begin to fully explore the genomic diversity within a full vertebrate class."

"This is an exciting moment," said neuroscientist Erich Jarvis. "Lots of fundamental questions now can be resolved with more genomic data from a broader sampling. I got into this project because of my interest in birds as a model for vocal learning and speech production in humans, and it has opened up some amazing new vistas on brain evolution."

This first round of analyses suggests some remarkable new ideas about bird evolution. The first flagship paper published in Science presents a well-resolved new family tree for birds, based on whole-genome data. The second flagship paper describes the big picture of genome evolution in birds. Six other papers in the special issue of Science describe how vocal learning may have independently evolved in a few bird groups and in the human brain's speech regions; how the sex chromosomes of birds came to be; how birds lost their teeth; how crocodile genomes evolved; ways in which singing behavior regulates genes in the brain; and a new method for phylogenic analysis with large-scale genomic data.

The Avian Phylogenomics Consortium has so far involved more than 200 scientists hailing from 80 institutions in 20 countries, including the BGI in China, the University of Copenhagen, Duke University, the University of Texas at Austin, the Smithsonian Museum, the Chinese Academy of Sciences, Louisiana State University and many others.

A Clearer Picture of the Bird Family Tree

Previous attempts to reconstruct the avian family tree using partial DNA sequencing or anatomical and behavioral traits have met with contradiction and confusion. Because modern birds split into species early and in such quick succession, they did not evolve enough distinct genetic differences at the genomic level to clearly determine their early branching order, the researchers said. To resolve the timing and relationships of modern birds, the consortium authors used whole-genome DNA sequences to infer the bird species tree.

"In the past, people have been using 10 to 20 genes to try to infer the species relationships," Jarvis said. "What we've learned from doing this whole-genome approach is that we can infer a somewhat different phylogeny [family tree] than what has been proposed in the past. We've figured out that protein-coding genes tell the wrong story for inferring the species tree. You need non-coding sequences, including the intergenic regions. The protein coding sequences, however, tell an interesting story of proteome-wide convergence among species with similar life histories."

This new tree resolves the early branches of Neoaves (new birds) and supports conclusions about some relationships that have been long-debated. For example, the findings support three independent origins of waterbirds. They also indicate that the common ancestor of core landbirds, which include songbirds, parrots, woodpeckers, owls, eagles and falcons, was an apex predator, which also gave rise to the giant terror birds that once roamed the Americas.

The whole-genome analysis dates the evolutionary expansion of Neoaves to the time of the mass extinction event 66 million years ago that killed off all dinosaurs except some birds. This contradicts the idea that Neoaves blossomed 10 to 80 million years earlier, as some recent studies suggested.

Based on this new genomic data, only a few bird lineages survived the mass extinction. They gave rise to the more than 10,000 Neoaves species that comprise 95 percent of all bird species living with us today. The freed-up ecological niches caused by the extinction event likely allowed rapid species radiation of birds in less than 15 million years, which explains much of modern bird biodiversity.

Increasingly sophisticated and more affordable genomic sequencing technologies and the advent of computational tools for reconstructing and comparing whole genomes have allowed the consortium to resolve these controversies with better clarity than ever before, the researchers say.

With about 14,000 genes per species, the size of the datasets and the complexity of analyzing them required several new approaches to computing evolutionary family trees. These were developed by computer scientists Tandy Warnow at the University of Illinois at Urbana-Champaign, Siavash Mirarab, a student at the University of Texas at Austin and Alexis Stamatakis at the Heidelburg Institute for Theoretical Studies. Their algorithms required the use of parallel processing supercomputers at the Munich Supercomputing Center (LRZ), the Texas Advanced Computing Center (TACC) and the San Diego Supercomputing center (SDSC).

"The computational challenges in estimating the avian species tree used around 300 years of CPU time, and some analyses required supercomputers with a terabyte of memory," Warnow said.

The bird project also had support from the Genome 10K Consortium of Scientists (G10K), an international science community working toward rapidly assessing genome sequences for 10,000 vertebrate species.

"The Avian Genomics Consortium has accomplished the most ambitious and successful project that the G10K Project has joined or endorsed," said G10K co-leader Stephen O'Brien, who co-authored a commentary on the bird sequencing project appearing in GigaScience.

A Genomic Perspective of Avian Evolution and Biodiversity

For all their biological intricacies, birds are surprisingly light on DNA. A study led by Zhang, Cai Li and the consortium authors found that compared to other reptile genomes, avian genomes contain fewer of the repeating sequences of DNA and lost hundreds of genes in their early evolution after birds split from other reptiles.

"Many of these genes have essential functions in humans, such as in reproduction, skeleton formation and lung systems," Zhang said. "The loss of these key genes may have a significant effect on the evolution of many distinct phenotypes of birds. This is an exciting finding, because it is quite different from what people normally think, which is that innovation is normally created by new genetic material, not the loss of it. Sometimes, less is more."

From the whole chromosome level to the order of genes, this group found that the genomic structure of birds has stayed remarkably the same among species for more than 100 million years. The rate of gene evolution across all bird species is also slower compared to mammals.

Yet some genomic regions display relatively faster evolution in species with similar lifestyles or phenotypes, such as involving vocal learning. This pattern of what is called convergent evolution may be the underlying mechanism that explains how distant bird species evolved similar phenotypes independently. Zhang said these analyses on particular gene families begin to explain how birds evolved a lighter skeleton, a distinct lung system, dietary specialties, color vision, as well as colorful feathers and other sex-related traits.

Important Lessons

The new studies have shed light on several other questions about birds, including:

How did vocal learning evolve?  Eight studies in the package examined the subject of vocal learning. According to new evidence in the two flagship papers, vocal learning evolved independently at least twice, and was associated with convergent evolution in many proteins. A Science study led by Andreas Pfenning, Alexander Hartemink, Jarvis and others at Duke, in collaboration with researchers at the Allen Institute for Brain Science in Seattle and the RIKEN Institute in Japan, found that the specialized song-learning brain circuitry of vocal learning birds (songbirds, parrots and hummingbirds) and human brain speech regions have convergent changes in the activity of more than 50 genes. Most of these genes are involved in forming neural connections. 

Osceola Whitney, Pfenning and Anne West, also of Duke, found in another Science study that singing is associated with the activation of 10 percent of the expressed genome, with diverse activation patterns in different song-learning regions of the brain, controlled by epigenetic regulation of the genome. Duke's Mukta Chakraborty and others found in a PLoS ONE study that parrots have a song system within a song system, with the surrounding song system unique to them. This might explain their greater ability to imitate human speech. In a BMC Genomics study, Morgan Wirthlin, Peter Lovell and Claudio Mello from Oregon Health & Science University found unique genes in the song-control brain regions of songbirds.

The XYZW of sex chromosomes. Just as the sex of humans is determined by the X and Y chromosomes, the sex of birds is controlled by the Z and W chromosomes. The W makes birds female, just as the Y makes humans male. Most mammals share a similar evolutionary history of the Y chromosome, which now contains many degenerated genes that no longer function and only a few active genes related to "maleness." A Science study led by Qi Zhou and Doris Bachtrog from the University of California, Berkeley, and Zhang found that half of bird species still contain substantial numbers of active genes in their W chromosomes. This challenges the classic view that the W chromosome is a "graveyard of genes" like the human Y.

This group also found that bird species are at drastically different states of sex chromosome evolution. For example, the ostrich and emu, which belong to one of the older branches of the bird family tree, have sex chromosomes resembling their ancestors. Yet some modern birds such as the chicken and zebra finch have sex chromosomes that contain few active genes. This opens a new set of questions on how the diversity of sex chromosomes may drive the diversity of sex differences in the outward appearance of various bird species. Peacocks and peahens are dramatically different; male and female crows are indistinguishable.

How did birds lose their teeth? In a Science study led by Robert Meredith from Montclair State University and Mark Springer from the University of California, Riverside, a comparison between the genomes of living bird species and those of vertebrate species that have teeth identified key mutations in the parts of the genome that code for enamel and dentin, the building blocks of teeth. The evidence suggests that five tooth-related genes were disabled within a short time period in the common ancestor of modern birds more than 100 million years ago.

What's the connection between birds and dinosaurs? Unlike mammals, birds (along with reptiles, fish and amphibians) have a large number of tiny microchromosomes. These smaller packages of gene-rich material are thought to have been present in their dinosaur ancestors. A study of genome karyotype structure in BMC Genomics analyzed whole genomes of the chicken, turkey, Peking duck, zebra finch and budgerigar. It found the chicken has the most similar overall chromosome pattern to an avian ancestor, which was thought to be a feathered dinosaur. This work was led by Darren Griffin and Michael Romanov from the University of Kent, and by Dennis Larkin and Marta Farré from the Royal Veterinary College, University of London.

Another study in Science examined birds' closest living relatives, the crocodiles. This team, led by Ed Green and Benedict Paton from the University of California, Santa Cruz, David Ray from Texas Tech University and Ed Braun from the University of Florida, found that crocodiles have one of the slowest-evolving genomes. The researchers were able to infer the genome sequence of the common ancestor of birds and crocodilians (archosaurs) and therefore all dinosaurs, including those that went extinct 66 million years ago.

Do differences in gene trees versus species trees matter? In the phylogenomics flagship study by Jarvis and others, the consortium found that no gene tree has a history exactly the same as the species tree, partly due to a process called incomplete lineage sorting. Another Science study, led by Tandy Warnow at the University of Texas and the University of Illinois, and her student Siavash Mirarab, developed a new computational approach called "statistical binning." They used this approach to show it does not matter much that the gene trees differ from the species tree because they were able to infer the first coalescent-based, genome-scale species tree, combining gene trees with similar histories to accurately infer a species tree.

Do bird genomes carry fewer virus sequences than other species? Mammalian genomes harbor a diverse set of genomic "fossils" of past viral infections called "endogenous viral elements" (EVEs). A study published in Genome Biology led by Jie Cui of Duke-NUS Graduate Medical School in Singapore, Edward Holmes of the University of Sydney and Zhang, found that bird species had 6-13 times fewer EVE infections in their past than mammals. This finding is consistent with the fact that birds have smaller genomes than mammals. It also suggests birds may either be less susceptible to viral invasions or better able to purge viral genes.

When did colorful feathers evolve? Elaborate, colorful feathers are thought to be evolutionarily advantageous, giving a male bird in a given species an edge over his competitors when it comes to mating. Zhang's flagship paper in Science, which is further analyzed by Matthew Greenwold and Roger Sawyer from the University of South Carolina in a companion study in BMC Evolutionary Biology, found that genes involved in feather coloration evolved more quickly than other genes in eight of 46 bird lineages. Waterbirds have the lowest number of beta keratin feather genes, landbirds have more than twice as many, and in domesticated pet and agricultural bird species, there are eight times more of these genes.

What happens to species facing extinction or recovering from near-extinction? Birds are like the proverbial canaries in the coal mine because of their sensitivity to environmental changes that cause extinction. In a Genome Biology study led by Shengbin Li, Cheng Cheng and Jun Yu from Xi'an Jiaotong University and Jarvis, researchers analyzed the genomes of species that have recently gone nearly extinct, including the crested ibis in Asia and the bald eagle in the Americas. They found genes that break down environmental toxins have a higher rate of mutations in these species and there is lower diversity of immune system genes in endangered species. In a recovering crested ibis population, genes involved in brain function and metabolism are evolving more rapidly. The researchers found more genomic diversity in the recovering population than was expected, giving greater hope for species conservation.

The Start of Something Bigger

This sweeping genome-level comparison of an entire class of life is being powered by frozen bird tissue samples collected over the past 30 years by museums and other institutions around the world. Samples are sent as fingernail-sized chunks of frozen flesh mostly to Duke University and University of Copenhagen for DNA separation. Most of the genome sequencing and critical initial analyses of the genomes have then been conducted by the BGI in China.

The avian genome consortium is now creating a database that will be made publicly available in the future for scientists to study the genetic basis of complex avian traits.

Setting up the pipeline for the large-scale study of whole genomes -- collecting and organizing tissue samples, extracting the DNA, analyzing its quality, sequencing and managing torrents of new data -- has been a massive undertaking. But the scientists say their work should help inform other major efforts for the comprehensive sequencing of vertebrate classes. To encourage other researchers to dig through this 'big data' and discover new patterns that were not seen in small-scale data before, the avian genome consortium has released the full dataset to the public in GigaScience, and in NCBI, ENSEMBL and CoGe databases.

Under the leadership of Dave Burt, the National Avian Research Facility at the Roslin Institute and Edinburgh University, UK, has created genome browser databases based on the ENSEMBL model for 48 species.

The full set of papers in Science and other journals can be accessed at http://www.sciencemag.org/content/346/6215/1308.

Story Source:
The above story is based on materials provided by Duke University. Note: Materials may be edited for content and length.


Duke University. "'Big Bang' of bird evolution mapped: Genes reveal deep histories of bird origins, feathers, flight and song." ScienceDaily. ScienceDaily, 11 December 2014. <www.sciencedaily.com/releases/2014/12/141211142136.htm>.

March of the penguin genomes

Date:
December 11, 2014
Source:
BioMed Central
Summary:
Two penguin genomes have been sequenced and analyzed for the first time. The study reveals insights into how these birds have been able to adapt to the cold and hostile Antarctic environment.
















Adélie penguins.
Credit: David Lambert
 

Two penguin genomes have been sequenced and analyzed for the first time in the open access, open data journal GigaScience. Timely for the holiday season, the study reveals insights into how these birds have been able to adapt to the cold and hostile Antarctic environment.

Antarctic penguins are subject to extremely low temperatures, high winds, and profound changes in daylight. They have developed complicated biological systems to regulate temperature and store energy for long-term fasting. Most studies have focused on the physiological and behavioral aspects of their biology, but an international team of researchers has now analyzed the DNA of two Antarctic penguins (Adélie and emperor) relative to other bird species, revealing the genetic basis of their adaptations and their evolutionary history in response to climate change.

Using the historical genetic record within the DNA across bird species, the researchers estimate that penguins first appeared around 60 million years ago. The study shows that the Adélie penguin population increased rapidly about 150,000 years ago when the climate became warmer, but later declined by 40% about 60,000 years ago during a cold and dry glacial period. In contrast, the emperor penguin population remained stable, suggesting that they were better adapted to glacial conditions, for example, by being able to protect their eggs from freezing temperatures and incubate them on their feet.

Cai Li, Team Lead at BGI-Shenzhen, China, said: "These different patterns in historical population change also suggest that future climate change may have impacts on the two penguin species. For example, the fact that emperor penguins didn't experience the same population boom as Adélie penguins in warm climates means that they could suffer more from global warming, and this needs to be considered in conservation efforts in Antarctica."

Both penguins were found to have expanded genes related to beta-keratins -- the proteins which make up 90% of feathers. They also had at least 13 genes responsible for a single type of beta-keratin, which is the highest number compared to all other known bird genomes. This would explain their importance in ensuring that penguin feathers are short, stiff and densely packed to minimize heat loss, remain waterproof and aid underwater flight. Likely to be responsible for penguins' thick skin, the team also identified a gene called DSG1, which is known to be involved in a human dermatological disease characterized by thick skin on the palms and soles.

Fat storage is critical for penguins to withstand the cold and survive long fasting periods -- up to four months in emperor penguins. The two penguins were found to have exploited different adaptations for lipid metabolism in the course of their evolution, which may also provide insight into their contrasting abilities for coping with climate change. The researchers found eight genes involved in lipid metabolism in the Adélie penguin, and three in the emperor penguin.

During their evolutionary history, the wings (or forelimbs) of penguins changed profoundly for wing-propelled diving in the water. The team identified 17 forelimb-related genes in the penguin genomes that had unique changes. One of the genes in particular, EVC2, showed a larger number of genetic changes compared to other birds. Mutations of EVC2 in humans cause Ellis-van Creveld syndrome, characterized by short-limb dwarfism and short ribs.

Guojie Zhang, Assistant Professor at the University of Copenhagen and Associate Director at China National GeneBank, BGI-Shenzhen, China, said: "Penguins show distinct evolution relative to other bird species. They can't fly, have specialized skin and feathers, degenerated wings, and live in a cold environment in which most other birds could not survive. Comparative genomics is a powerful tool for providing answers on the molecular basis of these evolutionary changes and how organisms deal with the conditions they are exposed to. Our study has revealed several of these secrets for the two penguins."

David Lambert, Professor of Evolutionary Biology at Griffith University, Australia, said: "Although Adélie and Emperor penguins both breed on the Antarctic continent, they do so in very different ways. By sequencing the genomes of two penguin species we have been able to compare many of the genes that are responsible for these different abilities to do the same thing -- namely to survive and breed in Antarctica. This study is particularly important because it now provides us with the opportunity to conduct large scale evolutionary studies of both species."

These papers are part of a series of reports from the Avian Phylogenomics Project that are being published in concert in multiple journals. The authors of several Science papers will unveil new genomic results related to the avian tree of life, and a number of papers are also published in BMC Genomics, BMC Evolutionary Biology and Genome Biology.

Avian Genome Collection on BioMed Central: http://www.biomedcentral.com/series/avian

Story Source:
The above story is based on materials provided by BioMed Central. Note: Materials may be edited for content and length.

Journal Reference:
  1. Cai Li, Yong Zhang, Jianwen Li, Lesheng Kong, Haofu Hu, Hailin Pan, Luohao Xu, Yuan Deng, Qiye Li, Lijun Jin, Hao Yu, Yan Chen, Binghang Liu, Linfeng Yang, Shiping Liu, Yan Zhang, Yongshan Lang, Jinquan Xia, Weiming He, Qiong Shi, Sankar Subramanian, Craig D Millar, Stephen Meader, Chris M Rands, Matthew K Fujita, Matthew J Greenwold, Todd A Castoe, David D Pollock, Wanjun Gu, Kiwoong Nam, Hans Ellegren, Simon YW Ho, David W Burt, Chris P Ponting, Erich D Jarvis, M Thomas P Gilbert, Huanming Yang, Jian Wang, David M Lambert, Jun Wang, Guojie Zhang. Two Antarctic penguin genomes reveal insights into their evolutionary history and molecular changes related to the Antarctic environment. GigaScience, 2014; 3 (1): 27 DOI: 10.1186/2047-217X-3-27


BioMed Central. "March of the penguin genomes." ScienceDaily. ScienceDaily, 11 December 2014. <www.sciencedaily.com/releases/2014/12/141211142427.htm>.

Chickens and turkeys 'closer to dinosaur ancestors' than other birds

Date:
December 11, 2014
Source:
University of Kent
Summary:
New research suggests that chickens and turkeys have experienced fewer gross genomic changes than other birds as they evolved from their dinosaur ancestor.






New research from the University of Kent suggests that chickens and turkeys have experienced fewer gross genomic changes than other birds as they evolved from their dinosaur ancestor.


Professor Darren Griffin and a team at the University's School of Biosciences have conducted research that suggests that chromosomes of the chicken and turkey lineage have undergone the fewest number of changes compared to their ancient avian ancestor, thought to be a feathered dinosaur.

The Kent research is part of a study by a consortium of leading scientists into avian or bird genomes, which tell a story of species evolution. The living descendants of dinosaurs were thought to have undergone a rapid burst of evolution after most dinosaur species were wiped out. The detailed family tree of modern birds has however confused biologists for centuries and the molecular details of how birds arrived at the spectacular biodiversity of more than 10,000 species is barely known.

Professor Griffin explained: 'Bird genomes are distinctive in that they have more tiny microchromosomes than any other vertebrate group. These small packages of gene-rich material are thought to have been present in their dinosaur ancestors.
'We found that the chicken has the most similar overall chromosome pattern to its avian dinosaur ancestor.'
The research, which formed part of a vast study carried out over the past four years by the international Avian Phylogenomics Consortium, involved the analysis of the whole genome structure of the chicken, turkey, Pekin duck, zebra finch and budgerigar.

Professor Griffin and the other leaders of the research team ¬- Kent colleague Dr Michael Romanov as well as Dr Denis Larkin and Dr Marta Farré from the Royal Veterinary College, University of London -- studied data from a total of 21 avian genomes and one reptile species. The team focused on the six best-assembled genomes to put together a karyotype -- organised profile -- of the dinosaur ancestor for each chromosome.

The researchers also found that the fastest rate of change had occurred in the zebra finch and budgerigar, consistent with more rapid speciation events in songbirds and their relatives.

Story Source:
The above story is based on materials provided by University of Kent. Note: Materials may be edited for content and length.

Journal Reference:
  1. Michael N Romanov, Marta Farré, Pamela E Lithgow, Katie E Fowler, Benjamin M Skinner, Rebecca O¿Connor, Gothami Fonseka, Niclas Backström, Yoichi Matsuda, Chizuko Nishida, Peter Houde, Erich D Jarvis, Hans Ellegren, David W Burt, Denis M Larkin, Darren K Griffin. Reconstruction of gross avian genome structure, organization and evolution suggests that the chicken lineage most closely resembles the dinosaur avian ancestor. BMC Genomics, 2014; 15 (1): 1060 DOI: 10.1186/1471-2164-15-1060

University of Kent. "Chickens and turkeys 'closer to dinosaur ancestors' than other birds." ScienceDaily. ScienceDaily, 11 December 2014. <www.sciencedaily.com/releases/2014/12/141211142612.htm>.

Saturday, December 6, 2014

Scientist found penguins will 'tolerate' people



By Western Daily Press  |  Posted: December 06, 2014
  • Dr Bernard Stonehouse, top, measuring and weighing king penguins, he said the birds think of humans as a 'different' sorts of penguins that were 'less predictable, occasionally violent, but tolerable company when sitting still and minding his own business'. Pictured below is a survey hut Stonehouse built with a colleague

  • Polar scientist Bernard Stonehouse, who studied king penguins in Antarctica, has died at the aged of 88.


    Stonehouse first went to the continent when he was 20 in 1946 and was one of a lucky few who survived three winters in the bitterly cold conditions. He worked as naval pilot, a meteorologist, dog sledder and, ultimately, a biologist.

    The Telegraph told one amazing story of his survival on its website: "On September 15, 1947, Stonehouse was on board as deputy pilot when the base's Auster aircraft took off to mark out a safe landing spot for a larger American twin-engined aircraft, which was about to undertake an extensive aerial survey.

    "On the return flight, however, bad weather forced him and his two companions to make an emergency landing on sea ice, and the aircraft turned on its back after one of its skis hit an ice hummock. "The three men emerged unscathed but were forced to pitch camp on the ice. They had only a small 'pup' (two-man) tent, one sleeping bag, one inner bag and a tin of pemmican between the three of them. After somehow surviving the first night and failing to attract the attention of a rescue aircraft with a flare, they decided to attempt to cover the 70 miles to base on foot. On the first day they travelled ten miles, but then the snow set in.

    "For the next few days they averaged only three or four miles a day, hauling their few belongings on a 'sledge' improvised from the aircraft's fuel tank, taking it in turns to use the sleeping bag and eking out the pemmican. Then they were hit by a ferocious gale which saw them huddling together in the tiny tent for three more days.

    "The gale was a mixed blessing, however, because when it abated it had scoured the sea ice and they were able to set off again. Seven days after their crash, they heard the welcome sound of an aircraft circling some miles away and decided to use their last flare to attract its attention. They were rescued by the American expedition's Norseman aircraft. "They were extremely tired and hungry, but otherwise largely unharmed."

    Born in 1926, Stonehouse, was born in Hull and trained as a pilot. During his Antarctic expeditions, he was part of the group know as the "lost 11", as they had to endure a winter at a base at Stonington Island in 1949, after a relief ship failed to reach them because of thick sea ice. When he came back to the UK, he studied zoology and geology at university in London, however, he had already made significant scientific discovery.

    The Telegraph went on to explain: "The expedition to Adelaide Island had made the exciting discovery of an emperor penguin 'rookery' on the Dion Islands, just off Adelaide's south coast. At that time, only two other such rookeries were known.

    "From early June 1949, Stonehouse, supported by two companions, spent three months on the Dion Islands, living in tents in temperatures as low as -40C, to study the penguins during the winter breeding season, about which very little was known at the time. He gained valuable data on the breeding behaviour and embryology of the animals, observing their instinctive desire to hold an egg, or indeed any object of similar size.

    "On one occasion when a Leica camera was found to be missing, the thief was spotted waddling away with a leather strap trailing between its feet. A penguin, Stonehouse concluded, thinks that a human is a penguin who is 'different, less predictable, occasionally violent, but tolerable company when he sits still and minds his own business'.

    source

    Friday, November 28, 2014

    Ancient penguin was a giant of NZ birdlife

    Jamie Morton is science reporter at the NZ Herald.


    Dr Daniel Thomas holds a thigh bone from the fossil penguin which would have stood 30cm taller than an emperor penguin today (left).
    Dr Daniel Thomas holds a thigh bone from the fossil penguin which would have stood 30cm taller than an emperor penguin today (left).
    A giant ancient penguin far taller than any species alive today has been described for the first time after its fossil remains sat for decades inside an Auckland storage shed.

    The fossilised bones of the penguin, yet to be named, were found in North Waikato in 1971, but had been largely ignored until recently rediscovered by Massey University zoologist Dr Daniel Thomas.
    The unusual features of the 28-million-year-old specimen have convinced Dr Thomas it is a new species, and the first of its kind to be discovered in the North Island.

    Dr Thomas estimates the bird would have stood at 1.3m - slightly taller than the ancient Kairuku penguin discovered in 2012, and about 30cm taller than today's largest penguin, the emperor. "I imagine an emperor would have run away scared," said Dr Thomas, when asked how the two birds would compare. It was likely the bird would have been a deep-diving penguin, like the emperor, and been preyed upon by sharks and dolphins.

    He learned about the remains shortly after returning to New Zealand from overseas and searching through old research papers. Because there was little to compare the remains against when they were discovered, the specimens were not fully classified and were eventually shelved in a Tamaki storage shed operated by the University of Auckland. "It turned out there was a raft of other specimens as well - it was a treasure trove of some really incredible stuff."

    It was when he came upon the right leg bone of the penguin - enough to immediately tell him much about the bird - that the significance of the discovery struck him. "I couldn't stop grinning, to be honest ... I was looking at this thing and thinking, how has no one worked on this for 40 years?"

    Dr Thomas had the bones 3-D-scanned and sent the prints to colleague Dr Dan Ksepka in the United States for further analysis. Features in the bones of the fossil penguin were different from any of the 50 discovered so far, and Dr Thomas and his colleagues now have only to confirm its status as a juvenile or adult before they can prepare a paper for peer review.

    The find was especially exciting for Dr Thomas as the fossil was recovered near where he grew up, and he sees potential for many more new discoveries to be made in the North Island. He is keen to hear from Waikato and King Country farmers with limestone quarries who could help with the hunt.

    3 Penguin facts


    1. An unnamed ancient penguin whose fossilised bones were recently rediscovered in an Auckland storage shed lived 28 million years ago when most of New Zealand was underwater. 2. It is likely to have stood just over 1.3m tall - slightly taller than the recently discovered ancient Kairuku penguin and 30cm taller than the largest existing penguin, the emperor.
    3. It is believed to be the first specimen of its type discovered in the North Island and raises exciting possibilities of what other wonders may lie preserved inside the North Island's hills and limestone quarries.

    source

    *******************************************************************************

    Fossil find reveals new giant penguin

    Olivia Allison, Environment/Science Reporter 
    28 November 2014
    Scientists have discovered a new species of giant penguin that lived in waters around Waikato about 27 to 28 million years ago
    Dr Daniel Thomas with  the fossil.
    Dr Daniel Thomas with the fossil.
    Photo: RNZ / Olivia Allison

    Fossils were found in the 1970s, but scientists could not say for sure if it was a new species of penguin, so they stayed in storage at Auckland University. That is, until the invention of 3D printing.
    This has allowed Massey University's Dr Daniel Thomas to scan the bones to American paleontologist Dr Daniel Ksepka. Both were then able to determine that they are "almost certain" it was a new type of giant penguin.

    The penguin was dated by taking a fragment of the rock the bones were encased in and looking at fossil plankton. Records of fossil plankton are vast, so Dr Thomas said it was easier to determine the date.

    Dr Thomas said penguin fossils become accessible as parts of the North Island that were once under water rose up over time. He could tell it was a giant penguin by comparing the thigh bone of the fossil to other penguins.

    Emperor penguins are about 1 metre tall and have a thigh bone half the size of the fossil bone. Dr Thomas said it had been compared with another fossil giant penguin also, allowing them to guess that it was about 1.3 metres tall.

    Dr Thomas said it did not appear to have any links to emperor penguins, other than the fact they were both penguins. "Because it lived so far back in time, it's not a close link - they'd be very distant relatives. Definitely not a cousin or step-cousin."

    As researchers only have one leg bone and other fragments, they could not tell what body shape the penguin had or its weight. But they could guess with near certainty that it was black and white, just like penguins today.

    Dr Thomas said it was likely the penguin would have been a deep diver, travelling offshore to find fish. He said the discovery was very big, as it was the first North Island fossil giant penguin to be discovered. "Africa has fossil humans, America has fossil dinosaurs, we have a few dinosaurs, but I like to think of New Zealand as a place with giant penguins. It feeds into the idea that New Zealand is really special."

    source

    Thursday, November 6, 2014

    Taking a deeper look at 'ancient wing'

    Date:

    November 5, 2014

    Source:

    Society of Vertebrate Paleontology

    Summary:


    In order to determine the feather color of ancient organisms such as Archaeopteryx, microscopic melanin-containing structures called melanosomes have been compared in a variety of living and fossil birds. However, might there be another explanation for the presence of these structures? This research uses scanning electron microscopy and high-sensitivity molecular techniques to respond to alternative interpretations and shed light -- and color -- on Jurassic feathers.

    The fossil feather and skeleton of the iconic dinosaur Archaeopteryx.
    Credit: Copyright Museum für Naturkunde Berlin



    Reconstructing ancient life has long required a certain degree of imagination. This is especially true when considering the coloration of long-extinct organisms. However, new methods of investigation are being incorporated into paleontology that may shed light (and color) on fossils. Research presented at the recent Society of Vertebrate Paleontology meeting shows the importance of using new imaging technologies in reconstructing the color of Archaeopteryx, one of the most famous and important fossils species.
    Ryan Carney of Brown University incorporated scanning electron microscopy in a 2012 study to identify melanosomes (melanin-containing pigment structures) in modern feathers to reconstruct the feather color of the iconic Archaeopteryx, the so-called "missing link" -- or more appropriately, evolutionary intermediate -- between non-avian dinosaurs and birds. Archaeopteryx has also been referred to as the "Mona Lisa of paleontology," a fossil taxon with great scientific, historical, and cultural importance.

    However, after Carney's original publication, there has been some recent controversy with respect to two competing papers that offer alternative interpretations. The first was that the Archaeopteryx feather was both black and white, based on the distribution of organic sulfur imaged via synchrotron. The second was that the fossilized microbodies in the feather represent bacteria instead of melanosomes, given their similarities in size and shape.

    The results of Carney's new research address these alternative interpretations and provide new insights into the Archaeopteryx feather. "The inner vane of the Archaeopteryx feather, which they claimed was white, we instead found to be packed with black melanosomes," said Carney. "This is critical because white feather color is only produced in the absence of melanosomes."

    Furthermore, Carney and his Swedish colleagues have investigated the preservation of melanosomes in a variety of other fossils, utilizing additional new analytical methods such as Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). Carney added, "We are not contending that every fossilized microbody is a melanosome. However, this new chemical method has allowed us to detect actual melanin molecules, which are associated with the melanosome-like microbodies in fossilized feathers and skin, from both terrestrial and marine environments. This integrated structural and direct chemical evidence provides the definitive proof that melanosomes can indeed be preserved in the fossil record."

    Together, this new research paints the final picture of the famous wing feather as matte black with a darker tip, coloration that would have provided structural advantages to the plumage during this early evolutionary stage of dinosaur flight.

    The application of such high-sensitivity analytical techniques is ushering in a new age of paleontological investigations. What once was artistic license, such as the appearance of ancient organisms, is now revealing itself in living color. As analytical methods in paleontology keep a pulse on technological advancements, we will continue to gain understanding of how fossil animals once lived and looked.

    Story Source:
    The above story is based on materials provided by Society of Vertebrate Paleontology. Note: Materials may be edited for content and length.


    Society of Vertebrate Paleontology. "Taking a deeper look at 'ancient wing'." ScienceDaily. ScienceDaily, 5 November 2014. <www.sciencedaily.com/releases/2014/11/141105084824.htm>.

    How the shape of eggs can help explain the evolutionary history of birds

    Date:
    November 5, 2014
    Source:
    University of Lincoln
    Summary:
    The eggs of amniotes - mammals, reptiles and birds – come in a remarkable variety of shapes and sizes. Evolutionary biologists have now addressed shape variety in terrestrial vertebrates' eggs, pinpointing morphological differences between the eggs of birds and those of their extinct relatives, the theropod dinosaurs.








    Theropod Troodon clutch.
    Credit: Charles Deeming


    The eggs of amniotes -- mammals, reptiles and birds -- come in a remarkable variety of shapes and sizes.
    Evolutionary biologists have now addressed shape variety in terrestrial vertebrates' eggs, pinpointing morphological differences between the eggs of birds and those of their extinct relatives, the theropod dinosaurs.

    Researchers from the University of Lincoln, UK, examined eggshell geometry from the transition of theropods -- a sub-order of the Saurischian dinosaurs -- into birds, based on fossil records and studies of their living species.

    The results suggest that the early birds from the Mesozoic (252 to 66 million years' ago) laid eggs that had different shapes to those of modern birds. This may suggest that egg physiology and embryonic development was different in the earliest birds and so this may have implications for how some birds survived the Cretaceous-Palaeocene extinction event that wiped out the dinosaurs.

    Their findings are published in the journal Royal Society Open Science.

    Author Dr Charles Deeming, from Lincoln's School of Life Sciences, explained: "These results indicate that egg shape can be used to distinguish between different types of egg-laying vertebrates. More importantly they suggest Mesozoic bird eggs differ significantly from modern day bird eggs, but more recently extinct Cenozoic birds do not. This suggests that the range of egg shapes in modern birds had already been attained in the Cenozoic."

    The origin of the amniotic egg (an egg which can survive out of water) is one of the key adaptations underpinning vertebrates' transition from sea to land more than 300 million years ago. Modern amniotic eggs vary considerably in shape and size and it is believed this variety may reflect the different patterns of egg formation and development in these taxa.
    Dr Deeming added: "From a biological perspective, it is self-evident that different egg shapes by birds, both past and present, might be associated with different nesting behaviours or incubation methods. However, hardly any research has been carried out on this topic and fossil data are insufficient to draw firm conclusions. We hope that future discoveries of associated fossil eggs and skeletons will help refine the general conclusions of this work."

    Dr Deeming and co-author Dr Marcello Ruta, also from the University of Lincoln, are now investigating how the highly variable amounts of yolk and albumen (egg white) in eggs of different species could be a possible determinant of bird egg shape.

    Story Source:
    The above story is based on materials provided by University of Lincoln. Note: Materials may be edited for content and length.

    Journal Reference:
    1. D. Charles Deeming and Marcello Ruta. Egg shape changes at the theropod-bird transition, and a morphometric study of amniote eggs. Royal Society Open Science, 2014 DOI: 10.1098/rsos.140311

    University of Lincoln. "How the shape of eggs can help explain the evolutionary history of birds." ScienceDaily. ScienceDaily, 5 November 2014. <www.sciencedaily.com/releases/2014/11/141105084724.htm>.