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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
Along the vines of the Vineyard.
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.
...
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#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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