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A little bird told me... a funny story of evolution.
#34
Biologists experimentally trigger adaptive radiation
March 5, 2019, University of Utah

[Image: 6-universityof.jpg]
The changes in color are as light as the lightest species and as dark as the darkest species in the entire genus--and this genus has been evolving for millions of years. Credit: Adapted from Bush et. al. 2019. Evo Letters
When naturalist Charles Darwin stepped onto the Galapagos Islands in 1835, he encountered a bird that sparked a revolutionary theory on how new species originate. From island to island, finches had wildly varied beak designs that reflected their varied diets. The so-called Darwin's finches are an emblem of adaptive radiation, which describes when organisms from a single lineage evolve different adaptations in response to competitors or predators.




Scientists think that adaptive radiation generates much of the biodiversity on Earth, yet most studies focus on groups that have already diversified. A new study took the opposite approach.

University of Utah biologists experimentally triggered adaptive radiation; they used host-specific parasites isolated on individual pigeon "islands." The scientists showed that descendants of a single population of feather lice adapted rapidly in response to preening, the pigeons' main defense. They found that preening drives rapid and divergent camouflage in feather lice (Columbicola columbae) transferred to different colored rock pigeons (Colombia livia). Over four years and 60 generations, the lice evolved heritable color differences that spanned the full color range of the lice genus found on 300 bird species worldwide.

"The changes in color that we saw are as light as the lightest species and as dark as the darkest species in the entire genus—and this genus has been evolving for millions of years," said Sarah Bush, associate professor in biology at the U and lead author of the paper. "The changes and selection that happens day to day are the same patterns that we see over millions of years."

This is the first study to show that the evolutionary changes that occurred within a single species (microevolution) echoed changes in color among different species that diverged millions of years ago (macroevolution).

"People have been trying to bridge micro- and macro- evolution for a long time," said Dale Clayton, professor in biology at the U and co-author of the paper. "This study actually does it. That's a big deal."

The study published online on March 5 in the journal Evolution Letters.



[Image: 7-universityof.jpg]
The biologists painted the backs of feather lice, half with black paint, and half with white paint, and put them on black, gray and white pigeons. Lice painted the 'wrong' color -- black lice on white feathers and vice versa -- were 40 …moreParasite island


Adaptive radiation is famous on archipelagos. From Hawaiian silverswords to Caribbean lizards, plant and animal lineages diversify rapidly when the ocean limits gene flow and movement between landforms. Parasites are restricted to individual host species and likely adapt and diversify like organisms restricted to islands. The host's defense seems to be the main driver of adaptive radiation in parasites, yet scientist have never tested this hypothesis experimentally.



The team worked with a host-parasite system that was uniquely easy to manipulate: rock pigeons (C. livia) and their feather lice (C. columbae). The sesame seed-sized lice are feather specialists; they never touch the bird's skin and have special gut bacteria to digest the keratin-rich down feathers. Pigeons mainly defend themselves by preening and lice hide from prying beaks by matching the color of the feathers, a strategy known as cryptic coloration.

In order to test whether preening drove the evolution of cryptic coloration, the team needed to prove that three things were happening: First, that there was a selective pressure driving the color changes. Second, that there was genetic variation for different color phenotypes. Third, that the color change needed to be heritable, passed down from parent to offspring.

Preening is a selective pressure? Genetic variation? Check!

First, the biologists showed that the birds were visually-preening the lice. They suspected this was the case—in 2010, Bush led a study that found that birds with light feathers have light-colored lice, and birds with dark feathers had dark colored lice. For the current study, the biologists began with a single population of feather lice and painted their backs with nail polish-like paint: half with black paint, and half with white paint. They then evenly distributed the lice to eight black pigeons and eight white pigeons, let the birds preen for 48-hours before counting how many black and white lice were left on the pigeons.

They found that lice painted the "wrong" color—black lice on white feathers and vice versa—were 40 percent more likely to be preened than the cryptically colored lice. They then did the same experiment but with black and white pigeons who were unable to preen by wearing harmless plastic bits on their beaks. After 48 hours, they found that the birds with impaired preening had no difference between cryptic and conspicuous lice in their feathers. This demonstrated that preening was indeed a selective pressure for lice survival.

To test whether preening selects for different colors of the lice, they infested 96 lice-free rock pigeons with unpainted lice: 32 white, 32 black and 32 grey pigeons received 25 lice each. Within each color, half of the birds preened normally while half wore the bits that impaired preening. The lice stayed on these birds over the entire course of the experiment—four years, resulting in about 60 generations of offspring. Every six months the biologists sampled the lice and took photographs to analyze the luminosity (the relative lightness or darkness) of the parasites, then put them back on the birds.

[Image: 8-universityof.jpg]
Pigeons defend themselves against lice by preening. Conspicuous lice are more likely to be picked off by prying beaks. Credit: Sydney Stringham
The luminosity of lice on white and black pigeons changed significantly relative to the color of lice on the control grey pigeons—the lice on white pigeons got dramatically lighter, while the lice on black birds got darker. By the end of the experiment, the lightest lice on white pigeons were as light as the lightest species of lice in the entire genus.

"Look at the range of colors. I mean it just went wham! The color range overlaps with other species of louse in just four years," said Clayton. "Compared to evolutionary time that's not even the bat of an eyelash."

Is the color change heritable? Check!

To test whether the color changes were heritable, Bush and the team needed to verify that the offspring of the lice were similar in color to their parents. They took lice from 12 pigeons who could preen normally and placed them on gray pigeons to reproduce. First, they needed to distinguish the parents from their offspring.

So, they gave the lice tiny haircuts. Co-lead author Scott Villa, a former postdoctoral researcher at the U who is now a postdoctoral fellow in the Department of Biology at Emory University, permanently marked the parent lice by using tiny scissors to trim miniscule bristles, called setae, off of one side of the lice. They then put the lice with these unique haircuts on 12 gray pigeons with impaired preening and waited 48 days. Then they photographed and analyzed the colors of both the parents and later the offspring, which did not have haircuts.

The luminosity of the parents was highly correlated with the luminosity of the offspring, meaning that color was heritable.

Impact lies beyond lice

Although the scientists expected that preening would eventually drive divergent camouflage in the lice, they were surprised by how rapid the changes occurred. This probably applies to other pathogens that diversify in response to host defenses, including human pathogens responding to our immune system.

"The cool thing about this project is what we're observing in terms of evolutionary response isn't unique to lice, it would apply to anything with DNA," said Bush.

The biologists are working on a second experiment in which they put feather lice on differently-sized pigeon breeds to see whether preening selects for different-sized lice. The lice may evolve divergent sizes so extreme that they are unable to mate, a significant step in the origin of a new species. Stay tuned.

[Image: 1x1.gif] Explore further: Study shows how external ecological communities can affect the coevolution of hosts and their parasites

More information: Evolution Lettersonlinelibrary.wiley.com/doi/10.1002/evl3.104 

Provided by: University of Utah


Read more at: https://phys.org/news/2019-03-biologists-experimentally-trigger.html#jCp
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With a forked tongue the snake singsss...
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#35
...
The crows were raising hell out here the other day.
I went out to see what they were after,
just in time to see about 12 crows chase a huge raven into the giant tree in the neighbors yard.
It goes up at least 75 feet with lots of huge branches everywhere.
The raven could find some rest and defensive positioning in there.
The raven was crafty.
No matter how I positioned myself to look up at him,
he would skip off to another branch and just slip out of sight.
So I stood my ground for awhile as the crows continued their loud rapid cawing.
Finally the raven had enough rest and bolted,
only to be pursued by a shit load of crows, 
that carefully but persistently tormented the raven out of town.
Crows only do that when a raven raids a nest,
or kills another crow.
...
Reply
#36
JUNE 3, 2019
Feathers came first, then birds
by University of Bristol
[Image: featherscame.jpg]Reconstruction of the studied pterosaur, with four different feather types over its head, neck, body, and wings, and a generally ginger-brown colour Credit: Reconstruction by Yuan Zhang.
New research, led by the University of Bristol, suggests that feathers arose 100 million years before birds—changing how we look at dinosaurs, birds, and pterosaurs, the flying reptiles.

It also changes our understanding of feathers themselves, their functions and their role in some of the largest events in evolution.
The new work, published today in the journal Trends in Ecology & Evolution combines new information from palaeontology and molecular developmental biology.
The key discovery came earlier in 2019, when feathers were reported in pterosaurs—if the pterosaurs really carried feathers, then it means these structures arose deep in the evolutionary tree, much deeper than at the point when birds originated.
Lead author, Professor Mike Benton, from the University of Bristol's School of Earth Sciences, said: "The oldest bird is still Archaeopteryx first found in the Late Jurassic of southern Germany in 1861, although some species from China are a little older.
"Those fossils all show a diversity of feathers—down feathers over the body and long, vaned feathers on the wings. But, since 1994, palaeontologists have been contending with the perturbing discovery, based on hundreds of amazing specimens from China, that many dinosaurs also had feathers."
Co-author, Baoyu Jiang from the University of Nanjing, added: "At first, the dinosaurs with feathers were close to the origin of birds in the evolutionary tree.
"This was not so hard to believe. So, the origin of feathers was pushed back at least to the origin of those bird-like dinosaurs, maybe 200 million years ago."
Dr. Maria McNamara, co-author from University College Cork, said: "Then, we had the good fortune to work on a new dinosaur from Russia, Kulindadromeus.
"This dinosaur showed amazingly well-preserved skin covered with scales on the legs and tail, and strange whiskery feathers all over its body.
"What surprised people was that this was a dinosaur that was as far from birds in the evolutionary tree as could be imagined. Perhaps feathers were present in the very first dinosaurs."
Danielle Dhouailly from the University of Grenoble, also a co-author, works on the development of feathers in baby birds, especially their genomic control. She said: "Modern birds like chickens often have scales on their legs or necks, and we showed these were reversals: what had once been feathers had reversed to be scales.
"In fact, we have shown that the same genome regulatory network drives the development of reptile scales, bird feathers, and mammal hairs. Feathers could have evolved very early."
Baoyu Jiang continued: "The breakthrough came when we were studying two new pterosaurs from China.
"We saw that many of their whiskers were branched. We expected single strands—monofilaments—but what we saw were tufts and down feathers. Pterosaurs had feathers."
Professor Benton added: "This drives the origin of feathers back to 250 million years ago at least.
"The point of origin of pterosaurs, dinosaurs and their relatives. The Early Triassic world then was recovering from the most devastating mass extinction ever, and life on land had come back from near-total wipe-out.
"Palaeontologists had already noted that the new reptiles walked upright instead of sprawling, that their bone structure suggested fast growth and maybe even warm-bloodedness, and the mammal ancestors probably had hair by then.
"So, the dinosaurspterosaurs and their ancestors had feathers too. Feathers then probably arose to aid this speeding up of physiology and ecology, purely for insulation. The other functions of feathers, for display and of course for flight, came much later."


[size=undefined]

Explore further
New discovery pushes origin of feathers back by 70 million years[/size]


[size=undefined]
More information: Michael J. Benton et al, The Early Origin of Feathers, Trends in Ecology & Evolution(2019). DOI: 10.1016/j.tree.2019.04.018
Provided by University of Bristol[/size]


https://phys.org/news/2019-06-feathers-birds.html
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
#37
...


Quote:"Palaeontologists had already noted that the new reptiles, 
walked upright instead of sprawling,
that their bone structure suggested fast growth,
and maybe even warm-bloodedness,
and the mammal ancestors probably had hair by then.

"So, the dinosaurs, pterosaurs and their ancestors had feathers too. 

Feathers then probably arose to aid this speeding up of physiology and ecology, 
purely for insulation Nonono 
The other functions of feathers, for display, and of course for flight, came much later Nonono


Look at all the mind conditioning from movies as recent as Jurassic Park,
training the mass public the old science on the skin and appearances of dinosaurs.

The next Jurassic Park movie will have to produce downy feathery plumage on their dinosaurs,
so that the kiddies will get the updated science.


I disagree with the last statement in the above quote:
Feathers arose in evolution  ..."purely for insulation",
and actually,
evolution also put "display" on the same fast track with insulation,
long before birds took flight. 

...
Reply
#38
Quote:"So, the dinosaurs, pterosaurs and their ancestors had feathers too. 

Feathers then probably arose to aid this speeding up of physiology and ecology, 
purely for insulation [Image: nonono.gif] 
The other functions of feathers, for display, and of course for flight, came much later [Image: nonono.gif]

Meet 'Cold Dragon of the North Winds,' the Giant Pterosaur That Once Soared Across Canadian Skies
By Mindy Weisberger - Senior Writer a day ago Animals 
Oh, Canada! A newfound pterosaur species is the country's first giant flying reptile.
[Image: fqPdfLqYRDxVXF69biyfqP-320-80.jpg]Cryodrakon boreas, a newly described species of giant pterosaur, was recently identified from fossils found in Canada.
(Image: © Illustration by David Maas)

Millions of years ago, a flying reptile as big as an airplane took flight in what is now Canada. 
Now, this enormous species of giant pterosaur — part of a group known as azhdarchids — finally has a name: [i]Cryodrakon[/i] [i]boreas, [/i]drawing from the ancient Greek words that translate to "cold dragon of the north winds." 
Fossils of [i]Cryodrakon boreas[/i] were found decades ago, and were thought to belong to another North American azhdarchid[i]Quetzalcoatlus, [/i]one of the biggest flying animals of all time. But the discovery of additional fossils in recent years told scientists that the fossils represented a newfound species, and the first new species of giant pterosaur found in Canada. 
Based on the size of one enormous neck bone thought to belong to an adult animal, the newly described pterosaur likely had a wingspan extending about 33 feet (10 meters) from tip to tip, making it comparable in size to its monstrous azhdarchid cousin [i]Quetzalcoatlus, [/i]researchers reported in a new study.

Related: Photos of Pterosaurs: Flight in the Age of Dinosaurs
All of the [i]Cryodrakon[/i] fossils came from Dinosaur Provincial Park in Alberta, and date to approximately 77 million to 74 million years ago during the Cretaceous period (145.5 million to 65.5 million years ago), according to the study.
Azhdarchids lived on all continents except Antarctica and Australia, and are known for having supersize heads, long necks, long legs and large feet, said lead study author David Hone, a senior lecturer and director of the biology program at Queen Mary University in London. But despite this group's massive size, very few fossils of the flying giants remain, Hone told Live Science in an email.
[img=602x0]https://vanilla.futurecdn.net/livescience/media/img/missing-image.svg[/img]
[Image: 4Z7igDSiiF262wasvxKcLn-650-80.jpg]
This bone is from the middle of the neck of [i]Cryodrakon boreas[/i]; the front of the bone is to the left, and it measures about 7 inches (18 centimeters) long.

(Image credit: David Hone)

Fossils are typically preserved when animal remains are buried in layers of sediment and locked away from bacteria that break down organic matter. Many of the best-preserved remains from millions of years ago belonged to animals that lived near seas or rivers, and pterosaurs at this time (including [i]Cryodrakon[/i]) mostly lived inland, Hone explained. 
"And their bones are insanely thin, so they are very rare," he added. "We're lucky we have as much good material as we do." 


What might [i]C. boreas [/i]have looked like in life? 


Paleoartist David Maas illustrated the pterosaur with a distinctive pattern of red and white that will likely be immediately recognizable to any Canadian. 

Viewed from above with its wings at full spread, the markings across [i]Cryodrakon[/i]'s back and wingtips strongly resemble the Canadian flag, down to the iconic maple leaf in the center.


Quote:I disagree with the last statement in the above quote:
Feathers arose in evolution  ..."purely for insulation",
and actually,
evolution also put "display" on the same fast track with insulation,
long before birds took flight. 


[Image: 6MPs7a9XrnKih73aRqoKXK-650-80.jpg][img=602x0]https://vanilla.futurecdn.net/livescience/media/img/missing-image.svg[/img]
(Image credit: Illustration by David Maas)
This was a "fun" artistic choice,(A.K.A. Improv -EA) as there's no fossilized evidence of the animal's colors or patterns, Hone told Live Science in the email. 


Nevertheless, "it's actually a plausible colour scheme," he added. 
"It's nothing ridiculous or impossible based on what we know about the colours of large living birds," Hone said.
The findings were published online Sept. 9 in the Journal of Vertebrate Paleontology.
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With a forked tongue the snake singsss...
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#39
MAY 14, 2019
Scientists unearth 'most bird-like' dinosaur ever found
by Patrick Galey
[Image: archaeoptery.jpg]The illustration shows the wing of Alcmonavis poeschli as it was found in the limestone slab. Alcmonavis poeschli is the second known specimen of a volant bird from the Jurassic period. Credit: Ludwig Maximilian University of Munich
Researchers in Germany have unearthed a new species of flying dinosaur that flapped its wings like a raven and could hold vital clues as to how modern-day birds evolved from their reptilian ancestors.

For more than a century and a half since its discovery in 1861, Archaeopteryx—a small feathered dinosaur around the size of a crow that lived in marshland around 150 million years ago—was widely considered to be the oldest flying bird.
Palaeontologists from Ludwig-Maximilians University (LMU) in Munich and the University of Fribourg examined rock formations in the German region of Bavaria, home to nearly all known Archaeopteryx specimens.
They came across a petrified wing, which the team initially assumed to be the same species. They soon found several differences, however.
"There are similarities, but after detailed comparisons with Archaeopteryx and other, geologically younger birds, its fossil remains suggested that we were dealing with a somewhat more derived bird," said lead study author Oliver Rauhut from LMU's Department of Earth and Environmental Sciences.
They called the new bird-like dinosaur Alcmonavis poeschli—from the old Celtic word for a nearby river and the scientist who discovered the fossil, excavation leader Roland Poeschl.
The study, published in the journal eLife sciences, said Alcmonavis poeschli was "the most bird-like bird discovered from the Jurassic".
As well as being significantly larger than Archaeopteryx, the new specimen had more notches in its wing bones that pointed to muscles which would have allowed it to actively flap its wings.
Significantly, this "flapping" trait found in Alcmonavis poeschli is present in more recent birds, but not in Archaeopteryx.
"This suggests that the diversity of birds in the late Jurassic era was greater than previously thought," Rauhut said.
The discovery is likely to fuel debate among dinosaur experts over whether birds and dinosaurs developed the ability to flap their wings from earlier gliding species.
"Its adaptation shows that the evolution of flight must have progressed relatively quickly," said Christian Foth, from the University of Fribourg, and a co-author of the research.




Explore further
The Archaeopteryx that wasn't



[b]More information:[/b] Oliver WM Rauhut et al. A non-archaeopterygid avialan theropod from the Late Jurassic of southern Germany, eLife (2019). DOI: 10.7554/eLife.43789
[b]Journal information:[/b] eLife 



https://phys.org/news/2019-05-archaeopte...mpany.html





DECEMBER 12, 2019
Experiments in evolution
[Image: dinosaur.jpg]Credit: CC0 Public Domain
A new find from Patagonia sheds light on the evolution of large predatory dinosaurs. Features of the 8-meter-long specimen from the Middle Jurassic suggest that it records a phase of rapid diversification and evolutionary experimentation.

In life, it must have been an intimidating sight. The dimensions of the newly discovered dinosaur fossil suggest that this individual was up to 8 meters long, and its skull alone measured 80 centimeters from front to back. The specimen was uncovered by the Munich paleontologist Oliver Rauhut in Patagonia, and can be assigned to the tetanurans—the most prominent group of bipedal dinosaurs, which includes such iconic representatives as Allosaurus, Tyrannosaurus and Velociraptor. This is also the group from which modern birds are derived. The new find is the most complete dinosaur skeleton yet discovered from the early phase of the Middle Jurassic, and is between 174 and 168 million years old. The specimen represents a previously unknown genus, and Rauhut and his Argentinian colleague Diego Pol have named it Asfaltovenator vialidadi. The genus name includes both Greek and Latin components (including the Latin term for hunter), while also referring to the nature of the deposits in which the fossil was found and the species name honours the road maintance of Chubut, who helped in the recovery of the specimen.
Almost the entire skull is preserved, together with the complete vertebral column including parts of the pelvis, all the bones of both anterior extremities and parts of the legs. "The fossil displays a very unusual combination of skeletal characters, which is difficult to reconcile with the currently accepted picture of the relationships between the three large groups that comprise the tetanurans—Megalosauria, Allosauria and Coelurosauria," says Rauhut, who is Professor of Palaeontology in the Department of Earth and Environmental Sciences at LMU and Senior Curator of the Bavarian State Collection for Paleontology and Geology. He and his co-author Diego Pol, who is based in the Museo Paleontológico Egidio Feruglio in Trelew (Argentina), describe the find in a paper that appears in the online journal Scientific Reports. According to the authors, A. vialidadi exhibits a diverse set of skeletal traits, which combines characters that have so far been found to be specific for various other species of dinosaurs.
The unusual mixture of morphological features displayed by A. vialidadi prompted the authors to carry out a comparative analysis with other tetanurans. They noted that around the period to which the new find can be assigned, the geographical range of this group was rapidly expanding, while the different species developed very similar sets of skeletal features.
Rauhut links the explosive evolution of the group with an episode of mass extinction that had occurred in the late stage of the Lower Jurassic, about 180 million years ago. The two researchers therefore interpret the parallel development of similar external traits in different species as an example of evolutionary experimentation during the subsequent rapid expansion and diversification of the tetanurans. The prior extinction of potential competitors will have opened up new ecological niches for the groups that survived, and the tetanurans were apparently among those that benefited.
"This is a pattern that we also observe in many other groups of animals in the aftermath of mass extinctions. It holds, for example, for the expansion and diversification of both mammals and birds following the extinction of the dinosaurs at the end of the Cretaceous 66 million years ago," says Rauhut. It could also explain why it is so difficult to unravel the phylogenetic relationships close to the origin of many highly diversified animal groups.




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A Middle Jurassic monster put in its taxonomic place



[b]More information:[/b] Oliver W. M. Rauhut et al. Probable basal allosauroid from the early Middle Jurassic Cañadón Asfalto Formation of Argentina highlights phylogenetic uncertainty in tetanuran theropod dinosaurs, Scientific Reports (2019). DOI: 10.1038/s41598-019-53672-7
[b]Journal information:[/b] Scientific Reports [/url]

Provided by [url=https://phys.org/partners/ludwig-maximilian-university-of-munich/]Ludwig Maximilian University of Munich



https://phys.org/news/2019-12-evolution.html
Along the vines of the Vineyard.
With a forked tongue the snake singsss...
Reply
#40
Anomalously, where did some species get the idea that they can fly?
Do they have such dreams?
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#41
DECEMBER 20, 2019
Evolution tunes birds to fit the bill
[Image: evolutiontun.jpg]A spectrogram showing the song of the White-plumed Honeyeater. Credit: Okinawa Institute of Science and Technology
From toucans to hummingbirds, the varying shapes and sizes of bird beaks show evolution in action.

Beaks are versatile, allowing birds to eat, regulate their temperature, and sing; these survival functions help determine beak length and size. Despite the complexity of beaks, most evolutionary studies have exclusively focused on a single function, like thermoregulation, rather than how a confluence of several functions impacts beak shape.
Using behavioral observations, morphological measurements, and mathematical analyses, researchers in the Biodiversity and Biocomplexity Unit at the Okinawa Institute of Science and Technology Graduate University (OIST), in a collaborative project with a lab in the Czech Republic, have found that beak shape is a compromise between its many functions—a valuable insight into the nuanced processes driving evolution.
In addition, beak morphology impacts the songs the birds produce, which influences these animals' mating and communication practices. The scientists' findings, published in Proceedings of the Royal Society B, may also shed light on how birds are evolving in the present day in response to increasing urbanization and climate change.
[b]Adapting to the environment[/b]
"There's something widely known in biology called Allen's rule; you tend to find animals with longer extremities in hotter regions and animals with shorter extremities in colder regions," said Dr. Nicholas Friedman, a postdoctoral researcher in the Biodiversity and Biocomplexity Unit. "Birds with really big beaks tend to live in the tropics, and those with little beaks tend to live in cold regions."
To see Allen's Rule in action, the researchers measured the average winter minimum temperatures and summer maximum temperatures endured by different species of Australian honeyeater bird. The scientists studied honeyeaters due to their morphological and geographic variety and abundance across Australia.
The scientists also studied beak evolution in relation to foraging behavior. Friedman and his colleagues used about 10,000 field observations of foraging activity in 74 species of Australian honeyeaters spread across Australia compiled by co-author Eliot Miller.
Friedman also took photographs of 525 bird specimens from a natural history museum in London. At OIST, he digitized the images to study beak morphology in detail.
Additionally, the scientists listened to hundreds of bird songs and measured their frequencies and speeds.
After obtaining this data, the researchers mapped different functions to beak curvature and depth, including nectar eaten, and the summer and winter temperatures they survived.
[b]Shaping a better understanding of evolution[/b]
Upon further analysis, the scientists found that foraging ecology had a greater effect on the shape of the beak (curved versus straight), while climate had just as much of an effect on beak size. The shape and size of a beak also influences the song that is produced—a larger beak means a slower, deeper song.
"This paper therefore connects three things: thermoregulation/Allen's Rule, foraging behavior and song behavior together through the beak. We can then better understand how this influences mating and communication behavior," said Friedman.
Friedman's findings also have valuable implications for the future. Humans have had a great impact on the environment over recent years, and Friedman is interested to study how animals will evolve in response to climate change and urbanization.
"We've already seen birds change their song in response to noise pollution, and we've seen changes in beak size and body size due to climate," said Friedman. "These birds are evolving in real time in response to climate change."




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Chillier winters, smaller beaks



[b]More information:[/b] Nicholas R. Friedman et al. Evolution of a multifunctional trait: shared effects of foraging ecology and thermoregulation on beak morphology, with consequences for song evolution, Proceedings of the Royal Society B: Biological Sciences (2019). DOI: 10.1098/rspb.2019.2474
[b]Journal information:[/b] Proceedings of the Royal Society B [/url]

Provided by [url=https://phys.org/partners/okinawa-institute-of-science-and-technology/]Okinawa Institute of Science and Technology
 




https://phys.org/news/2019-12-evolution-...-bill.html
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#42
MARCH 17, 2020
One of Darwin's evolution theories finally proved by Cambridge researcher
[Image: 5e70e7995898c.jpg]Charles Darwin's seminal book On The Origin of Species. Credit: Nordin Catic
Scientists have proved one of Charles Darwin's theories of evolution for the first time—nearly 140 years after his death.

Laura van Holstein, a Ph.D. student in Biological Anthropology at St John's College, University of Cambridge, and lead author of the research published today (March 18) in Proceedings of the Royal Society B, discovered mammal subspecies play a more important role in evolution than previously thought.
Her research could now be used to predict which species conservationists should focus on protecting to stop them becoming endangered or extinct.
A species is a group of animals that can interbreed freely amongst themselves. Some species contain subspecies—populations within a species that differ from each other by having different physical traits and their own breeding ranges. Northern giraffes have three subspecies that usually live in different locations to each other and red foxes have the most subspecies—45 known varieties—spread all over the world. Humans have no subspecies.
van Holstein said: "We are standing on the shoulders of giants. In Chapter 3 of On the Origin of Species Darwin said animal lineages with more species should also contain more 'varieties'. Subspecies is the modern definition. My research investigating the relationship between species and the variety of subspecies proves that sub-species play a critical role in long-term evolutionary dynamics and in future evolution of species. And they always have, which is what Darwin suspected when he was defining what a species actually was."

[Image: oneofdarwins.jpg]
Laura van Holstein in the Old Library at St John's College, Cambridge, with a first edition of Charles Darwin's seminal book On The Origins of Species. Credit: Nordin Catic
The anthropologist confirmed Darwin's hypothesis by looking at data gathered by naturalists over hundreds of years ¬- long before Darwin famously visited the Galapagos Islands on-board HMS Beagle. On the Origin of Species by Means of Natural Selection, was first published in 1859 after Darwin returned home from a five-year voyage of discovery. In the seminal book, Darwin argued that organisms gradually evolved through a process called 'natural selection' - often known as survival of the fittest. His pioneering work was considered highly controversial because it contradicted the Bible's account of creation.
van Holstein's research also proved that evolution happens differently in land mammals (terrestrial) and sea mammals and bats (non-terrestrial)¬ because of differences in their habitats and differences in their ability to roam freely.

van Holstein said: "We found the evolutionary relationship between mammalian species and subspecies differs depending on their habitat. Subspecies form, diversify and increase in number in a different way in non-terrestrial and terrestrial habitats, and this in turn affects how subspecies may eventually become species. For example, if a natural barrier like a mountain range gets in the way, it can separate animal groups and send them off on their own evolutionary journeys. Flying and marine mammals—such as bats and dolphins—have fewer physical barriers in their environment."
The research explored whether subspecies could be considered an early stage of speciation—the formation of a new species. van Holstein said: "The answer was yes. But evolution isn't determined by the same factors in all groups and for the first time we know why because we've looked at the strength of the relationship between species richness and subspecies richness."
The research acts as another scientific warning that the human impact on the habitat of animals will not only affect them now, but will affect their evolution in the future. This information could be used by conservationists to help them determine where to focus their efforts.

[Image: 5e70e7bccb08a.jpg]
Darwin's hypothesis that was proved by a PhD student at St John's College, Cambridge. Credit: Nordin Catic
van Holstein explained: "Evolutionary models could now use these findings to anticipate how human activity like logging and deforestation will affect evolution in the future by disrupting the habitat of species. The impact on animals will vary depending on how their ability to roam, or range, is affected. Animal subspecies tend to be ignored, but they play a pivotal role in longer term future evolution dynamics."
van Holstein is now going to look at how her findings can be used to predict the rate of speciation from endangered species and non-endangered species.
Notes to editors: What Darwin said on page 55 in 'On the Origin of Species': "From looking at species as only strongly-marked and well-defined varieties, I was led to anticipate that the species of the larger genera in each country would oftener present varieties, than the species of the smaller genera; for wherever many closely related species (i.e species of the same genus) have been formed, many varieties or incipient species ought, as a general role, to be now forming. Where many large trees grow, we expect to find saplings."
Datasets: Most of the data is from Wilson and Reeder's Mammal Species Of The World, a global collated database of mammalian taxonomy. The database contains hundreds of years' worth of work by taxonomists from all over the world. The current way of "doing" taxonomy goes all the way back to botanist Carl Linnaeus (1735), so the accumulation of knowledge is the combined work of all taxonomists since then.




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Scientists to search for relatives of extinct Galapagos tortoises



[b]More information:[/b] Terrestrial habitats decouple the relationship between species and subspecies diversification in mammals, Proceedings of the Royal Society Brspb.royalsocietypublishing.or … .1098/rspb.2019.2702
[b]Journal information:[/b] Proceedings of the Royal Society B [/url]

Provided by 
University of Cambridge

https://phys.org/news/2020-03-darwin-evo...ridge.html






MARCH 11, 2020
Discovery of smallest known mesozoic dinosaur reveals new species in bird evolution
by Scripps College
[Image: 5e68c6a9a5c70.jpg]An artistic rendering of Oculudentavis imagining what it looked like preying on an insect by HAN Zhixin. 
The discovery of a small, bird-like skull, described in an article published in Nature, reveals a new species, Oculudentavis khaungraae, that could represent the smallest known Mesozoic dinosaur in the fossil record.

While working on fossils from in northern Myanmar, Lars Schmitz, associate professor of biology at the W.M. Keck Science Department, and a team of international researchers discovered a seemingly mature skull specimen preserved in Burmese amber. The specimen's size is on par with that of the bee hummingbird, the smallest living bird.
"Amber preservation of vertebrates is rare, and this provides us a window into the world of dinosaurs at the lowest end of the body-size spectrum," Schmitz said. "Its unique anatomical features point to one of the smallest and most ancient birds ever found."
The team studied the specimen's distinct features with high-resolution synchrotron scans to determine how the skull of the Oculudentavis khaungraae differs from those of other bird-like dinosaur specimens of the era. They found that the shape and size of the eye bones suggested a diurnal lifestyle, but also revealed surprising similarities to the eyes of modern lizards. The skull also shows a unique pattern of fusion between different bone elements, as well as the presence of teeth. The researchers concluded that the specimen's tiny size and unusual form suggests a never-before-seen combination of features.

The discovery represents a specimen previously missing from the fossil record and provides new implications for understanding the evolution of birds, demonstrating the extreme miniaturization of avian body sizes early in the evolutionary process. The specimen's preservation also highlights amber deposits' potential to reveal the lowest limits of vertebrate body size.
  • A CT scan of the skull of Oculudentavis by LI Gang, Oculudentavis means eye-tooth-bird, so named for its distinctive features. Credit: Lars SchmitzA seemingly mature skull specimen preserved in Burmese amber reveals a new species, Oculudentavis khaungraae, that could represent the smallest known Mesozoic dinosaur in the fossil record. Credit: Xing LidaA CT scan of the skull of Oculudentavis by LI Gang, Oculudentavis means eye-tooth-bird, so named for its distinctive features. Credit: Lars Schmitz
  • [Image: discoveryofs.jpg]A seemingly mature skull specimen preserved in Burmese amber reveals a new species, Oculudentavis khaungraae, that could represent the smallest known Mesozoic dinosaur in the fossil record. Credit: Xing Lida
  • "No other group of living birds features species with similarly small crania in adults," Schmitz said. "This discovery shows us that we have only a small glimpse of what tiny vertebrates looked like in the age of the dinosaurs."
Explore further
Two new ancient species of cockroaches found in cave in Myanmar


[b]More information:[/b] Hummingbird-sized dinosaur from the Cretaceous period of Myanmar, Nature (2020). DOI: 10.1038/s41586-020-2068-4 , https://nature.com/articles/s41586-020-2068-4
[b]Journal information:[/b] Nature 

Provided by Scripps College

https://phys.org/news/2020-03-discovery-smallest-mesozoic-dinosaur-reveals.html

MARCH 18, 2020
Study finds bird evolution shaped by Tibetan Plateau
[Image: studyfindsbi.jpg]Credit: Matthew Wilkins
Elizabeth Scordato, an assistant professor of biological sciences, is the lead author of a study that found the evolution of barn swallows in Asia is shaped by the Tibetan Plateau.

The results, published in the journal Ecology Letters, provide the most convincing evidence yet for the long-held hypothesis that the plateau is an important factor maintaining the vast diversity of birds found in Asia.
"The formation of a species requires the cutting off of interbreeding. Once genes stop moving from one group to another, we can get a new species," said Scordato. "Our goal was to find out why two of these subspecies of swallows interbreed a lot over a huge region, but two other subspecies pairs barely interbreed despite being incredibly closely related to each other genetically and occurring in the same location."
Over three years, she and her research partners traversed Russia, a mountain range in western Mongolia, and a river valley in northern China, catching and sampling 1,288 birds from three closely related subspecies of swallows. They discovered two narrow hybrid zones– geographic regions where different subspecies of swallow came into contact with each other but showed only limited interbreeding. The narrow hybrid zones occurred in central Siberia and in western China, directly to the north of the Tibetan Plateau. They also found a region in northeastern China and eastern Siberia, far from the Plateau, where a different pair of subspecies came into contact but interbred extensively.
Because barn swallows nest only in human structures, the team traveled from village to village and town to town talking to local residents as they looked for the birds.
"We had to explain to people who we were, what we were doing and ask if we could go into their houses and catch their birds. So, the project would not have been possible without really amazing local collaborators," said Scordato.
They collected blood samples, a tail feather (to determine the carbon isotope value) and noted the color on the breast and throat, the length of tail feathers, and the length, pointedness and curvature of wings to establish which subspecies they were handling. Barn swallows migrate south for the winter, and the isotope value provides clues to where the bird might have gone.
The information from those samples provided confirmation of a migratory divide in the narrow hybrid zones: a geographic region where birds that breed in the same location during the summer fly to different locations for the winter. When the researchers looked at the carbon isotope values, they found that birds on the western side of both hybrid zones spent the winter in Africa, whereas birds to the east spent the winter in Asia. Birds with different overwintering grounds were genetically distinct from each other. By contrast, the birds in the region of east Asia with extensive interbreeding all spent the winter in similar locations in Asia.
To further determine whether different migratory routes were reducing interbreeding between subspecies, the team examined samples from mated pairs of birds across the two narrow hybrid zones. By looking at the association between color, genetics, and where the birds spent the winter, they found the most important correlation was where the birds overwinter. If the birds spent the winter in the same location, they were much more likely to pair with each other than with birds that spent the winter in different locations. While this isn't evidence that the birds actively avoid the inhospitable plateau, it does suggest that this large geographic barrier helps to keep them genetically distinct.
"Barn swallows are really sort of the perfect test case, but we think this is good evidence that the Tibetan Plateau is a general barrier that affects a lot of different bird species," said Scordato.
The study was conducted as part of a grant from the National Science Foundation to Dr. Rebecca Safran at the University of Colorado, Boulder, where Scordato was a postdoctoral researcher.




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Combining techniques provides new insight into bird migration



[b]More information:[/b] Elizabeth S. C. Scordato et al. Migratory divides coincide with reproductive barriers across replicated avian hybrid zones above the Tibetan Plateau, Ecology Letters (2019). DOI: 10.1111/ele.13420
[b]Journal information:[/b] Ecology Letters 

Provided by California State Polytechnic University

https://phys.org/news/2020-03-bird-evolu...ateau.html








MARCH 18, 2020
'Wonderchicken' fossil from the age of dinosaurs reveals origin of modern birds
[Image: wonderchicke.jpg]Artist's reconstruction of the world's oldest modern bird, Asteriornis maastrichtensis, in its original environment. 66.7 million years ago parts of Belgium were covered by a shallow sea, and conditions were similar to modern tropical beaches like The Bahamas. Asteriornis lived at the end of the Age of Dinosaurs, a time when mosasaurs (giant marine reptiles) swam in the oceans, and Tyrannosaurus rex lived on land. Asteriornis had fairly long legs and may have prowled the tropical shoreline. Credit: Phillip Krzeminski
The oldest fossil of a modern bird yet found, dating from the age of dinosaurs, has been identified by an international team of palaeontologists.

The spectacular fossil, affectionately nicknamed the 'Wonderchicken', includes a nearly complete skull, hidden inside nondescript pieces of rock, and dates from less than one million years before the asteroid impact which eliminated all large dinosaurs.
Writing in the journal Nature, the team, led by the University of Cambridge, believe the new fossil helps clarify why birds survived the mass extinction event at the end of the Cretaceous period, while the giant dinosaurs did not.
Detailed analysis of the skull shows that it combines many features common to modern chicken- and duck-like birds, suggesting that the 'Wonderchicken' is close to the last common ancestor of modern chickens and ducks. The fossil was found in a limestone quarry near the Belgian-Dutch border, making it the first modern bird from the age of dinosaurs found in the northern hemisphere.
The fossil doesn't look like much on first glance, with only a few small leg bone fragments poking out from a piece of rock the size of a deck of cards. Even those small bones attracted the researchers' interest, since bird fossils from this point in Earth's history are so rare.
Using high-resolution X-ray CT scans, the researchers peered through the rock to see what was lying beneath the surface. What they saw, just one millimetre beneath the rock, was the find of a lifetime: a nearly complete 66.7-million-year-old bird skull.
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Three-dimensional views of the skull of The Wonderchicken, Asteriornis maastrichtensis, a 66.7 million-year-old bird fossil from the end of the age of dinosaurs. It is the oldest modern bird fossil ever found. Credit: Daniel J. Field, University of Cambridge
"The moment I first saw what was beneath the rock was the most exciting moment of my scientific career," said Dr. Daniel Field from Cambridge's Department of Earth Sciences, who led the research. "This is one of the best-preserved fossil bird skulls of any age, from anywhere in the world. We almost had to pinch ourselves when we saw it, knowing that it was from such an important time in Earth's history.
"The ability to CT scan fossils, like we can at the Cambridge Biotomography Centre, has completely transformed how we study palaeontology in the 21st century."

"Finding the skull blew my mind," said co-author Juan Benito, also from Cambridge, who was CT scanning the fossils with Field when the skull was discovered. "Without these cutting-edge scans, we never would have known that we were holding the oldest modern bird skull in the world."
The skull, despite its age, is clearly recognisable as a modern bird. It combines many features common to the group that includes living chickens and ducks—a group called Galloanserae. Field describes the skull as a kind of 'mash-up' of a chicken and a duck.
"The origins of living bird diversity are shrouded in mystery—other than knowing that modern birds arose at some point towards the end of the age of dinosaurs, we have very little fossil evidence of them until after the asteroid hit," said co-author Albert Chen, a Ph.D. student based at Cambridge. "This fossil provides our earliest direct glimpse of what modern birds were like during the initial stages of their evolutionary history."
While the fossil is colloquially known as the Wonderchicken, the researchers have given it the slightly more elegant name of Asteriornis, in reference to Asteria, the Greek Titan goddess of falling stars.

[Image: 1-wonderchicke.jpg]
Three-dimensional image of the skull of the world's oldest modern bird, Asteriornis maastrichtensis. The fossil is 66.7 million years old and is close to the most recent common ancestor of duck-like birds and chicken-like birds. Credit: Daniel J. Field, University of Cambridge
"We thought it was an appropriate name for a creature that lived just before the end-Cretaceous asteroid impact," said co-author Dr. Daniel Ksepka from the Bruce Museum in Greenwich, Connecticut. "In Greek mythology, Asteria transforms herself into a quail, and we believe Asteriornis was close to the common ancestor that today includes quails, as well as chickens and ducks."
The fact that Asteriornis was found in Europe is another thing which makes it so extraordinary. "The late Cretaceous fossil record of birds from Europe is extremely sparse," said co-author Dr. John Jagt from the Natuurhistorische Museum Maastricht in the Netherlands. "The discovery of Asteriornis provides some of the first evidence that Europe was a key area in the early evolutionary history of modern birds."
"This fossil tells us that early on, at least some modern birds were fairly small-bodied, ground-dwelling birds that lived near the seashore," said Field. "Asteriornis now gives us a search image for future fossil discoveries—hopefully it ushers in a new era of fossil finds that help clarify how, when and where modern birds first evolved."
The announcement of the Wonderchicken find coincides with a new exhibit at Cambridge's Sedgwick Museum of Earth Sciences, where visitors can learn more about Asteriornis and see the fossil up close. "Dawn of the Wonderchicken" runs from 19 March to 15 June. Admission is free.
Dr. Daniel Field is funded by a UKRI Future Leaders Fellowship. He is a University Lecturer in the Department of Earth Sciences at the University of Cambridge, and a Fellow of Christ's College Cambridge.




Explore further
Discovery of smallest known mesozoic dinosaur reveals new species in bird evolution



[b]More information:[/b] Late Cretaceous neornithine from Europe illuminates the origins of crown birds, Nature (2020). DOI: 10.1038/s41586-020-2096-0 , https://nature.com/articles/s41586-020-2096-0
[b]Journal information:[/b] Nature 

Provided by [url=https://phys.org/partners/university-of-cambridge/]University of Cambridge

https://phys.org/news/2020-03-wonderchic...veals.html




[Image: 5e70e7995898c.jpg]

One of Darwin's evolution theories finally proved by Cambridge researcher
Scientists have proved one of Charles Darwin's theories of evolution for the first time—nearly 140 years after his death.

https://phys.org/news/2020-03-darwin-evo...ridge.html
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