Thursday, May 29, 2014

Striking lack of diversity in prehistoric birds

Date:

May 27, 2014

Source:

University of Chicago

Summary:

Birds come in astounding variety -- from hummingbirds to emus -- and behave in myriad ways: they soar the skies, swim the waters, and forage the forests. But this wasn’t always the case, according to new research.





Jeholornis, an early bird, lived during the early Cretaceous period approximately 120 million years ago. The evolution of Jeholornis and other Cretaceous birds is the subject of a new paper published in the Proceedings of the Royal Society B.
Credit: Allison Elaine Johnson

Birds come in astounding variety -- from hummingbirds to emus -- and behave in myriad ways: they soar the skies, swim the waters, and forage the forests. But this wasn't always the case, according to research by scientists at the University of Chicago and the Field Museum.



The researchers found a striking lack of diversity in the earliest known fossil bird fauna (a set of species that lived at about the same time and in the same habitat). "There were no swans, no swallows, no herons, nothing like that. They were pretty much all between a sparrow and a crow," said Jonathan Mitchell, PhD student in the Committee on Evolutionary Biology, and lead author of the new study, published May 28, 2014, in Proceedings of the Royal Society B.

The scientists examined a group of bird fossils dating back to the Cretaceous period, around 125 million years ago, relatively soon after the emergence of birds. The fossils were collected from an area in China where there was once violent volcanic activity, leading to a plethora of well-preserved fossils as intermittent eruptions periodically killed many birds. The researchers examined the diversity of species in this sample. However, because fossils indicate only the physical characteristics of the birds, understanding the diversity in how the birds behaved required significant scientific legwork.

To tease out the ecological roles played by the prehistoric birds, the researchers used modern-day birds to build a statistical technique that could relate the physical characteristics of a bird to its diet, behavior and habitat. Long legs might be associated with birds that wade through water, for instance, and the shape of the beak might hint at what the bird ate. For this purpose, the scientists painstakingly measured 1,400 modern birds -- mostly from the Field Museum's collections -- and extracted the correlations between these measurements and the birds' behavior.

Toothy birds

However, the scientists still had to show that this technique, which was useful for modern birds, could be applied effectively to the distinct sample of ancient birds. "These birds are very different from modern birds -- some of them have teeth, some of them have long bony tails," said Mitchell. Therefore, it wasn't clear if the method would translate.

In order to test the method, they looked at the contents of the birds' stomachs -- the last meals they ate before their demise -- which in some cases had survived the process of fossilization. They found agreement between the method's predictions and the birds's diet, indicating that it worked for ancient birds as well.

Once they had confirmed that the method was effective for the fossil birds with food preserved in their bellies, the scientists applied their method to the full complement of the region's bird fossils. They found that these early birds were less diverse than modern birds. In particular, larger birds and water birds were lacking. "They were all pretty much the same. They were ground-dwelling or forest-dwelling little birds, mostly eating insects and seeds," said Mitchell.

Fossilization bias?

A possible confounding factor was the bias potentially introduced by the fossilization process. Some types of birds might become fossilized more often than others, artificially reducing the diversity. To examine this possibility, the scientists compared very recent bird fossils to the populations of modern-day birds. They found that the fossilized sample was less diverse, although not enough to explain the effect they had seen in the very old fossils.

Additionally, the fossils were biased towards larger birds, and birds that lived in water. That is the opposite effect from the one seen in the oldest fossils, which were mostly composed of small land-dwellers, so the scientists concluded that this bias could not be the cause of the homogeneous birds.

The scientists' research is beginning to untangle some possible reasons for this lack of diversity. One feasible explanation is that early birds were less diverse due to competition with similar groups -- such as the prehistoric flying reptiles known as pterosaurs. But the scientists used an evolutionary model to show that the paucity of ecological niches could be explained simply by the fact that birds were new to the scene, and thus hadn't had time to diversify. "It looks like they just hadn't evolved the crazy diversity of ecologies that we see in modern birds," said Mitchell.

The research was carried out through UChicago's Committee on Evolutionary Biology, an interdisciplinary graduate program, which allows for collaborative work between students at the university and outside research institutions such as the Field Museum. Peter Makovicky, associate curator of paleontology and chair of the Field Museum's department of geology, was co-author. The program, Makovicky said, is a great place for students to "really tackle these big-picture questions."

The results have implications for when and how birds originated -- a topic under some debate -- as well as for the study of evolution in general. "In a broader sense, I think that our research speaks to an understanding of how groups of organisms, which are perhaps dominant today in modern ecosystems, get to that point," Makovicky, said. Birds, for example, evolved from humble beginnings into the diverse group we know today. The early bird, therefore, may indeed have gotten the worm -- or the insect or seed -- but not much else.

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

Journal Reference:
  1. Jonathan H. Mitchell and Peter J. Makovicky. Low ecological disparity in early Cretaceous birds. Proceedings of the Royal Society B, May 28, 2014 DOI: 10.1098/rspb.2014.0608

University of Chicago. "Striking lack of diversity in prehistoric birds." ScienceDaily. ScienceDaily, 27 May 2014. <www.sciencedaily.com/releases/2014/05/140527214911.htm>.

Friday, May 23, 2014

Penguin Fossil Expert Joins Greenwich's Bruce Museum As Science Curator

Daniel Ksepka is the Bruce Museum's new Curator of Science. He begins in June.
Daniel Ksepka is the Bruce Museum's new Curator of Science. He begins in June. Photo Credit: Contributed

GREENWICH, Conn., -- Daniel Ksepka, an expert in the fossil records of penguins, will join Greenwich's Bruce Museum as its newest Curator of Science in June. 

“We are delighted that Daniel Ksepka is joining the curatorial staff at the Bruce,” says Peter C. Sutton, executive director of the Bruce Museum.  “Daniel comes to us not only with a vast body of knowledge but also with a great deal of creativity and enthusiasm.  He is already planning some exciting new science exhibitions for the Museum.” 
 
Ksepka earned his doctorate in earth and environmental sciences from Columbia University in 2007. He spent five years in residence at the American Museum of Natural History in New York, where he performed his dissertation research on the fossil record of penguins and gained broad experience in the curation and study of natural history objects, including fossils, skeletal materials, skins and geological specimens. 

"Penguins are 10 times older than humans and have been here for a very, very long time," said Ksepka, who has researched the evolution of penguins and how they came to inhabit the African continent. 
 
Because penguins have been around for 60 million years, they have an extensive fossil record, he wrote at the American Scientist. (Watch the video above as Ksepka goes into depth about how his research pieces together the evolutionary puzzle of penguins and other related bird species.)

Ksepka recently contributed to several important museum exhibitions, including the traveling Race to the End of the Earth and Mythical Beasts exhibitions at the American Museum of Natural History and the Polar Palooza special exhibition at the North Carolina Museum of Natural Sciences.

His background includes work in science education, an important aspect of the Bruce Museum’s exhibition programs. Ksepka has a long track record of collaborating with K-12 educators, including designing science content, presenting formal professional development talks for science teachers, and designing workshops for teaching special topics in geology, biology and paleontology.

Ksepka has been a featured speaker at the Nature Research Center at the North Carolina Museum of Natural Sciences, the Carnegie Museum of Natural History and the Field Museum. In addition to more than 30 formal peer-reviewed research papers, he has written articles for popular science magazines, including Scientific American, American Scientist, and Dig. Even his personal blog, “March of the Fossil Penguins,” attracts more than 50,000 visitors per year.

Ksepka joins the Bruce Museum from the National Evolutionary Synthesis Center in North Carolina, where he served as a postdoctoral researcher, and retains associate positions at the Field Museum, the Smithsonian Institution National Museum of Natural History, and the North Carolina Museum of Natural Sciences.

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Friday, May 16, 2014

Study sheds light on penguins first year far from home

Date:
May 14, 2014
Source:
PLOS
Summary:
In the first study of its kind, scientists tracked penguins first year away from home and found young king penguins explored new habitat, eventually learning to find food similarly to their parents.








In the first study of its kind, scientists tracked penguins first year away from home and found young king penguins explored new habitat, eventually learning to find food similarly to their parents, according to results published May 14, 2014, in the open access journal PLOS ONE by Klemens Pütz from Antarctic Research Trust and colleagues.

Most foraging ecology studies of marine vertebrates are limited to breeding adults, although young penguins may be susceptible to increased mortality due to their inexperience. To better understand young penguin foraging behavior, scientists used satellite telemetry to track 18 king penguins in from two sites in the Southwest Atlantic for about 120 days in 2007. The two sites differed with respect to climate and proximity to the Antarctic Polar Front, a key oceanographic feature generally thought to be important for king penguin finding food.

Scientists found that young penguins undertake large-scale movements when at-sea for the first time -- ranging from a maximum distance of about 600 km to 4,000 km and averaging about 45 km per day. They also moved similarly at both locations, but more detailed analyses revealed slight differences in habitat use between the two localities. For example, juveniles from the Falkland Islands spent more time in comparatively shallow waters with low sea surface temperature, sea surface height, and chlorophyll variability. The authors suggest that in this species, juveniles eventually use similar habitat to find food as the adults, which may indicate that inexperienced king penguins develop their foraging skills progressively over time, irrespective of location.

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

Journal Reference:
  1. Klemens Pütz, Phil N. Trathan, Julieta Pedrana, Martin A. Collins, Sally Poncet, Benno Lüthi. Post-Fledging Dispersal of King Penguins (Aptenodytes patagonicus) from Two Breeding Sites in the South Atlantic. PLoS ONE, 2014; 9 (5): e97164 DOI: 10.1371/journal.pone.0097164


PLOS. "Study sheds light on penguins first year far from home." ScienceDaily. ScienceDaily, 14 May 2014. <www.sciencedaily.com/releases/2014/05/140514182707.htm>.

Thursday, May 8, 2014

Shrinking helped dinosaurs and birds to keep evolving

Date:
May 6, 2014
Source:
University of Oxford
Summary:
Although most dinosaurs went extinct 65 million years ago, one dinosaur lineage survived and lives on today as a major evolutionary success story -- the birds. A study that has 'weighed' hundreds of dinosaurs suggests that shrinking their bodies may have helped the group that became birds to continue exploiting new ecological niches throughout their evolution, and become hugely successful today.



Dinosaur phylogeny showing nodes with exceptional rates of body size evolution.
Credit: Benson RBJ, Campione NE, Carrano 
MT, Mannion PD, Sullivan C, et al. (2014) Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage. PLoS Biol 12(5): e1001853. doi:10.1371/journal.pbio.1001853









Although most dinosaurs went extinct 65 million years ago, one dinosaur lineage survived and lives on today as a major evolutionary success story -- the birds.
A study that has 'weighed' hundreds of dinosaurs suggests that shrinking their bodies may have helped the group that became birds to continue exploiting new ecological niches throughout their evolution, and become hugely successful today.

An international team, led by scientists at Oxford University and the Royal Ontario Museum, estimated the body mass of 426 dinosaur species based on the thickness of their leg bones. The team found that dinosaurs showed rapid rates of body size evolution shortly after their origins, around 220 million years ago. However, these soon slowed: only the evolutionary line leading to birds continued to change size at this rate, and continued to do so for 170 million years, producing new ecological diversity not seen in other dinosaurs.

A report of the research is published in PLOS Biology.

'Dinosaurs aren't extinct; there are about 10,000 species alive today in the form of birds. We wanted to understand the evolutionary links between this exceptional living group, and their Mesozoic relatives, including well-known extinct species like T. rex, Triceratops, and Stegosaurus,' said Dr Roger Benson of Oxford University's Department of Earth Sciences, who led the study. 'We found exceptional body mass variation in the dinosaur line leading to birds, especially in the feathered dinosaurs called maniraptorans. These include Jurassic Park's Velociraptor, birds, and a huge range of other forms, weighing anything from 15 grams to 3 tonnes, and eating meat, plants, and more omnivorous diets.'

The team believes that small body size might have been key to maintaining evolutionary potential in birds, which broke the lower body size limit of around 1 kilogram seen in other dinosaurs.
'How do you weigh a dinosaur? You can do it by measuring the thickness of its leg bones, like the femur. This is quite reliable,' said Dr Nicolás Campione, of the Uppsala University, a member of the team. 'This shows that the biggest dinosaur Argentinosaurus, at 90 tonnes, was 6 million times the weight of the smallest Mesozoic dinosaur, a sparrow-sized bird called Qiliania, weighing 15 grams. Clearly, the dinosaur body plan was extremely versatile.'

The team examined rates of body size evolution on the entire family tree of dinosaurs, sampled throughout their first 160 million years on Earth. If close relatives are fairly similar in size, then evolution was probably quite slow. But if they are very different in size, then evolution must have been fast.

'What we found was striking. Dinosaur body size evolved very rapidly in early forms, likely associated with the invasion of new ecological niches. In general, rates slowed down as these lineages continued to diversify,' said Dr David Evans at the Royal Ontario Museum, who co-devised the project. 'But it's the sustained high rates of evolution in the feathered maniraptoran dinosaur lineage that led to birds -- the second great evolutionary radiation of dinosaurs.'

The evolutionary line leading to birds kept experimenting with different, often radically smaller, body sizes -- enabling new body 'designs' and adaptations to arise more rapidly than among larger dinosaurs. Other dinosaur groups failed to do this, got locked in to narrow ecological niches, and ultimately went extinct. This suggest that important living groups such as birds might result from sustained, rapid evolutionary rates over timescales of hundreds of millions of years, which could not be observed without fossils.

'The fact that dinosaurs evolved to huge sizes is iconic,' said team member Dr Matthew Carrano of the Smithsonian Institution's National Museum of Natural History. 'And yet we've understood very little about how size was related to their overall evolutionary history. This makes it clear that evolving different sizes was important to the success of dinosaurs.'

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

Journal Reference:
  1. Roger B. J. Benson, Nicolás E. Campione, Matthew T. Carrano, Philip D. Mannion, Corwin Sullivan, Paul Upchurch, David C. Evans. Rates of Dinosaur Body Mass Evolution Indicate 170 Million Years of Sustained Ecological Innovation on the Avian Stem Lineage. PLoS Biology, 2014; 12 (5): e1001853 DOI: 10.1371/journal.pbio.1001853


University of Oxford. "Shrinking helped dinosaurs and birds to keep evolving." ScienceDaily. ScienceDaily, 6 May 2014. <www.sciencedaily.com/releases/2014/05/140506190736.htm>.

Tuesday, May 6, 2014

How much ammonia does a penguin emit?


A study conducted by researchers at the UPM and in the UK has estimated the ammonia rate that a penguin colony emits in the atmosphere and its direct effects on the ecosystem.
The researcher Mark Theobald, from the research group of Pollution of Agricultural Systems by Agricultural Practices of the Universidad Politécnica de Madrid (UPM), has conducted a study in collaboration with UK scientists about a colony of 39,000 Adélie penguins from Antarctica. The results obtained show that penguins emit 43 kg of ammonia every day which is a similar rate to the emissions of a poultry farm with half a million birds.

Penguins, like all living beings, emit ammonia in the atmosphere. In the case of penguins, part of the ingested nitrogen from eating fish is emitted in the air in form of ammonia (NH3). In fact, large penguin colonies can emit more NH3 than massive livestock farms, but with the difference that the first group lives in less altered pristine ecosystems. This situation allows researchers to analyze the physicochemical processes of NH3 emissions and their ulterior spreading in near ecosystems. All this is studied in an onsite lab.

The NH3 that travels in the air stream from penguin colonies to sensitive ecosystems leaves behind an excess of nitrogen. It would be something similar to adding fertilizers to these ecosystems which could cause irreparable damage. In the case of penguins, this problem is related to a natural situation, but it is quite similar to factory farms that emit NH3 close to sensitive ecosystems.

The first thing to understand the mentioned physicochemical processes is to measure the NH3 produced by penguins. Researchers have indeed measured the NH3 concentration in several areas around the colony in order to estimate later the amount of NH3 emitted by animals using dispersion models that simulate air movements in the atmosphere. These types of models are usually used to predict impacts of air pollution through gas flow simulation or particles from a resource to a receiver (person or ecosystem). However, the same models can predict emissions from a data concentration measured at a particular location (inverse modeling).

By using this methodology, scientists were able to estimate that a penguin colony releases 43 kg of NH3 in the atmosphere every day, which is a similar figure to the emissions produced by half a million chickens in a massive livestock farm.

To know the amount of NH3 produced by the penguin colonies, the first step is to study what amount of NH3 released by these animals can begin to affect nearby ecosystems. This study will also allow researchers to learn about the response of these sensitive systems to air pollution, such as the contamination directly associated to NH3 emissions.


THEOBALD, MR; CRITTENDEN, PD; TANG, YS; SUTTON, MA. “The application of inverse-dispersion and gradient methods to estimate ammonia emissions from a penguin colony”. Atmospheric Environment 81: 320-329. DOI: 10.1016/j.atmosenv.2013.09.009. December 2013.

source 

Distinct avian influenza viruses found in Antarctic penguins

10 hours ago
Distinct avian influenza viruses found in Antarctic penguins
Aeron Hurt with a penguin. Credit: Aeron Hurt, WHO Collaborating Centre for Reference and Research on Influenza in Melbourne, Australia.
An international team of researchers has, for the first time, identified an avian influenza virus in a group of Adélie penguins from Antarctica. The virus, found to be unlike any other circulating avian flu, is described in a study published this week in mBio, the online open-access journal of the American Society for Microbiology.

While other research groups have taken blood samples from penguins before and detected influenza antibodies, no one had detected actual live influenza virus in penguins or other birds in Antarctica previously, says study author and Associate Professor Aeron Hurt, PhD, a senior research scientist at the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne, Australia.
For the study, Hurt and colleagues collected swabs from the windpipes and posterior openings of 301 Adélie penguins, and blood from 270 of those penguins, from two locations on the Antarctic Peninsula: Admiralty Bay and Rada Covadonga. The samples were collected during January and February 2013.

Using a laboratory technique called real-time reverse transcription-PCR, the researchers found (AIV) genetic material in eight (2.7%) samples, six from adult penguins and two from chicks. Seven of the samples were from Rada Covadonga. The researchers were able to culture four of these viruses, demonstrating that live infectious virus was present. On further analysis of the samples, the researchers found all viruses were H11N2 influenza viruses that were highly similar to each other.

But when the researchers compared the full genome sequences of four of the collected viruses to all available animal and human sequences in public databases, "we found that this virus was unlike anything else detected in the world," says Hurt. "When we drew phylogenetic trees to show the evolutionary relationships of the virus, all of the genes were highly distinct from contemporary AIVs circulating in other continents in either the Northern or Southern Hemisphere."
Four of the gene segments were most closely related to North American avian lineage viruses from the 1960s to 1980s. Two genes showed a distant relationship to a large number of South American AIVs from Chile, Argentina and Brazil. Using a molecular clock to incorporate the evolutionary rate of each AIV gene segment, the researchers estimated that the virus has been evolving for the past 49 to 80 years without anyone knowing about it. Whether this evolution has occurred exclusively in Antarctica is currently unknown, Hurt says.

Additional experiments found that 16% of penguins (43 of 270) had influenza A antibodies in their blood, and that the newly identified virus is likely to be exclusive to birds, as it did not readily infect a group of ferrets used as a test to see if the virus could infect mammals.

While the virus did not cause illness in the , the study shows that " viruses can get down to Antarctica and be maintained in penguin populations," Hurt says. "It raises a lot of unanswered questions," including how often AIVs are being introduced into Antarctica, whether it is possible for highly pathogenic AIVs to be transferred there, what animals or ecosystems are maintaining the , and whether the are being cryopreserved during the winters.

Journal reference: mBio search and more info website
Provided by American Society for Microbiology search and more info




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