tagged w/ natural selection
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Gizmodo...
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By Jesus Diaz
Jan 22, 2012 12:30 PM
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Evolution Is the Greatest Show On Earth—And This Video Is Pretty Cool Too
If you liked Carl Sagan's autotuned music videos celebrating the wonders of the cosmos, you will like this one celebrating the wonders of evolution too, featuring David Attenborough, Richard Dawkins and Bill Nye.
It's the latest part of the Symphony of Science, created by musician John D. Boswell.
.Gizmodo...
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By Jesus Diaz
Jan 22, 2012 12:30 PM
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Evolution Is... more
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A centuries-old religious ceremony of an indigenous people in southern Mexico has led to small evolutionary changes in a local species of fish, according to researchers from Texas A&M University.
Since before the arrival of Christopher Columbus to the New World, the Zoque people of southern Mexico would venture each year during the Easter season deep into the sulfuric cave Cueva del Azufre to implore their deities for a bountiful rain season. As part of the annual ritual, they release into the cave's waters a distinctive, leaf-bound paste made of lime and the ground-up root of the barbasco plant, a natural fish toxin. Believing the cave's fish to be gifts from their gods, they scoop up their poisoned prey to feed upon until their crops are ready to harvest.
However, a team of researchers led by Dr. Michael Tobler, an evolutionary ecologist at Oklahoma State University, and Dr. Gil Rosenthal, a biology professor at Texas A&M, has discovered that some of these fish have managed not only to develop a resistance to the plant's powerful toxin, but also to pass on their tolerant genes to their offspring, enabling them to survive in the face of otherwise certain death for their non-evolved brethren.
Their findings recently were published in the online journal Biology Letters.
Tobler has been studying the small, cave-dwelling fish species known as the Atlantic molly or Poecilia mexicana and its uncanny ability to survive in the toxic sulfur environment of Cueva del Azufre since 2004. He earned his Ph.D. from the University of Zurich in 2008 and spent the next two years as a postdoctoral research associate at Texas A&M, studying under Rosenthal and Dr. Kirk Winemiller, a professor in wildlife and fisheries science, as part of a two-year, $79,000 Swiss National Science Foundation Postdoctoral Fellowship.
After learning about the Zoque people's sacred ritual and witnessing the event firsthand in 2007, Tobler and Rosenthal decided to investigate the effects of this peculiar ceremony on the mollies and their habitat. Ironically, it was the last ceremony ever held, as the Zoques ended the practice that year due to political pressure from the government, which sought to preserve the cave as a hotbed for tourism and potential revenue.
"We wanted to do a lab experiment where we exposed fish from different parts of the creek to barbasco," Tobler says. "Some of these fish had been more exposed than others."
In March 2010, the team collected molly specimens from two different areas of the cave annually exposed to the barbasco toxin as well as from two different areas upstream, further away from the Zoque's ritual. With both groups of fish in a single tank, they then introduced the barbasco root to determine how both groups would react.
They found that the mollies annually exposed to the barbasco indeed were more resistant than the fish further upstream -- to the extent that they were able to swim in the noxious water nearly 50 percent longer. Tobler and Rosenthal's group concluded that human beings had, over time, not only affected molly population dynamics, but also inadvertently kick-started the evolutionary process of natural selection as well. Mollies able to tolerate the poisonous conditions survived and passed those traits to their offspring, resigning those that perished to their fate of serving as a ceremonial feast for the Zoque.
"The cool thing is that this ceremony has gone on a long time and that the fish responded to it evolutionarily," Tobler says. "Lots of species couldn't live with these changes. It highlights how nature is affected by human activity."
Rosenthal contends that the idea of imposing evolutionary divergence on a species at an extremely localized spatial scale is not a new concept. In fact, he says, it's been happening since the beginning of humankind and that the idea of the "noble savage" is passé.
"We tend to have this wonderful Pocahontas idea that before Europeans came in, everything was pristine and in harmony with nature and that all of the changes in our environment have been post-industrialization," he explains. "No. People have been changing the environment forever."
Moreover, Rosenthal says, once a species has become genetically adapted to human presence, it is not very easy to suddenly reverse.
Their ritual since banned, the Zoques still perform a mock ceremony each Easter season. Tobler, however, would like to see the Zoque's original ceremony resume, but in a way that is sustainable to nature as well as other cave inhabitants. The key, he and Rosenthal believe, is to find a balance between human activity and their environment. In the case of the Zoques, it may mean a few limitations on barbasco usage for their ritual, such as releasing the toxin only 50-to-60 meters into the cave rather than 100 meters.
Pending further resolution, Tobler will continue his research with the mollies at Oklahoma State, where they are housed in a special tank built to safely imitate their sulfuric living conditions in Cueva del Azufre.
"We need to understand what the impact really is on these fish rather than eliminate the ceremony completely," Tobler says. "We want to hopefully find a balance between the cultural practices of these people and the ecosystem."
http://www.sciencedaily.com/releases/2010/11/101105091811.htmA centuries-old religious ceremony of an indigenous people in southern Mexico has led... more
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This video, including comments by Richard Dawkins, documents a necropsy (an autopsy on an animal other than a human) carried out in a classroom on a giraffe. In this video, we follow the pathway of the recurrent (inferior) laryngeal nerve, an important nerve that is a branch of the Vagus nerve (tenth cranial nerve). The purpose of doing this exercise is to show that there is no so-called "intelligent designer" because the pathway of this nerve is completely illogical -- unless, of course, you accept that evolution is the reason for this nerve's convoluted pathway through the body.This video, including comments by Richard Dawkins, documents a necropsy (an autopsy on... more
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Emory University researchers have identified the first fish known to have switched from ultraviolet vision to violet vision, or the ability to see blue light. The discovery is also the first example of an animal deleting a molecule to change its visual spectrum.
Their findings on scabbardfish, linking molecular evolution to functional changes and the possible environmental factors driving them, were published Oct. 13 in the Proceedings of the National Academy of Sciences.
"This multi-dimensional approach strengthens the case for the importance of adaptive evolution," says evolutionary geneticist Shozo Yokoyama, who led the study. "Building on this framework will take studies of natural selection to the next level."
The research team included Takashi Tada, a post-doctoral fellow in biology, and Ahmet Altun, a post-doctoral fellow in biology and computational chemistry.
Vision 'like a painting'
For two decades, Yokoyama has done groundbreaking work on the adaptive evolution of vision in vertebrates. Vision serves as a good study model, since it is the simplest of the sensory systems. For example, only four genes are involved in human vision.
"It's amazing, but you can mix together this small number of genes and detect a whole color spectrum," Yokoyama says. "It's just like a painting."
The common vertebrate ancestor possessed UV vision. However, many species, including humans, have switched from UV to violet vision, or the ability to sense the blue color spectrum.
From the ocean depths
Fish provide clues for how environmental factors can lead to such vision changes, since the available light at various ocean depths is well quantified. All fish previously studied have retained UV vision, but the Emory researchers found that the scabbardfish has not. To tease out the molecular basis for this difference, they used genetic engineering, quantum chemistry and theoretical computation to compare vision proteins and pigments from scabbardfish and another species, lampfish. The results indicated that scabbardfish shifted from UV to violet vision by deleting the molecule at site 86 in the chain of amino acids in the opsin protein.
"Normally, amino acid changes cause small structure changes, but in this case, a critical amino acid was deleted," Yokoyama says.
More examples likely
"The finding implies that we can find more examples of a similar switch to violet vision in different fish lineages," he adds. "Comparing violet and UV pigments in fish living in different habitats will open an unprecedented opportunity to clarify the molecular basis of phenotypic adaptations, along with the genetics of UV and violet vision."
Scabbardfish spend much of their life at depths of 25 to 100 meters, where UV light is less intense than violet light, which could explain why they made the vision shift, Yokoyama theorizes. Lampfish also spend much of their time in deep water. But they may have retained UV vision because they feed near the surface at twilight on tiny, translucent crustaceans that are easier to see in UV light.
A framework for evolutionary biology
Last year, Yokoyama and collaborators completed a comprehensive project to track changes in the dim-light vision protein opsin in nine fish species, chameleons, dolphins and elephants, as the animals spread into new environments and diversified over time. The researchers found that adaptive changes occur by a small number of amino acid substitutions, but most substitutions do not lead to functional changes.
"Evolutionary biology is filled with arguments that are misleading, at best," Yokoyama says. "To make a strong case for the mechanisms of natural selection, you have to connect changes in specific molecules with changes in phenotypes, and then you have to connect these changes to the living environment."Emory University researchers have identified the first fish known to have switched... more
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In part one of this special Darwin Day podcast, celebrating the 200th anniversary of the birth of Darwin on February 12th, Richard Milner performs part of his one-man show about Darwin; Scientific American editor-in-chief John Rennie and Darwin descendant Matthew Chapman read from the Origin of Species; and Chapman talks about his book 40 Days and 40 Nights, about the Dover Intelligent Design trial, as well as about his efforts to get Presidential candidates to discuss science, a project called ScienceDebate.
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How are you going to celebrate Darwin Day?In part one of this special Darwin Day podcast, celebrating the 200th anniversary of... more
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Charles Darwin provided, arguably, the single greatest scientific contribution in the history of mankind yet, is misunderstood and remains a controversial figure in today's America. His life's work is worthy of celebration and at least one website has been created to that end.
February 12th will mark the 200th anniversary of his birthday and the website www.darwinday.org wants to help you find ways to take part in what should be a respected date on every one's calendar. The creator(s) offer a variety of services:
"On this website you can find all sorts of information about Charles Darwin and the Darwin Day Celebration. If you are hosting a Darwin Day event, you can post information about it on our events listing. You can also locate Darwin Day programs near you by searching our events section."
However you mark the bicentennial, be safe and have a Happy Darwin Day!Charles Darwin provided, arguably, the single greatest scientific contribution in the... more
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Americans are divided over whether humans and other living things evolved over time or have existed in their present form since the beginning of time, according to a new poll.
People on both sides of that argument think students should hear about various theories, however. Nearly two-thirds of those in a Pew Research Center poll, 64 percent, say they believe "creationism'' should be taught alongside "evolution'' -- a finding likely to spark more controversy about what is taught in the schools.
In the poll by the Pew Research Center, 42 percent of those surveyed held strict "creationist'' views that "living things have existed in their present form since the beginning of time.'' Creationism generally refers to a literal reading of the Bible's story of the creation of man.
Almost half, 48 percent, said they believed humans have evolved over time. Some of those people, 26 percent of all those polled, said they believe evolution occurred through natural selection, and another 18 percent of all those polled, said evolution was guided by a supreme being.
To summarize, 42% of those polled believed only in strict creationism. 48% of our country believes in evolution, but only 26% believe that it was caused by natural selection. 18% believe that evolution is guided by a "supreme being."
Also, 64% of people believe in teaching both creationism and evolution in schools. Americans are divided over whether humans and other living things evolved over time or... more
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If you can't watch all eight and a half minutes of it, make sure to check out
2:15
3:30 for about a minute
5:00
5:40 (don't miss this one)
6:20If you can't watch all eight and a half minutes of it, make sure to check out... more
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Fhay_A
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added this
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4 years ago
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