All Videos Tagged zoology (Atheist Nexus) - Atheist Nexus 2014-08-23T02:27:33Z http://www.atheistnexus.org/video/video/listTagged?tag=zoology&rss=yes&xn_auth=no Researchers Reconstruct the Common Ancestor of Placental Mammals tag:www.atheistnexus.org,2013-02-09:2182797:Video:2160012 2013-02-09T02:49:58.889Z Donegal http://www.atheistnexus.org/profile/Donegal <a href="http://www.atheistnexus.org/video/researchers-reconstruct-the-common-ancestor-of-placental-mammals"><br /> <img alt="Thumbnail" height="180" src="http://api.ning.com:80/files/rRlLHC*Dey06CdPm-iO3fNSDb7viIkmB7YCFXV1Rj254BeO-v*xQPxU7Q4ltzKd-JIdpp0ubljegd7KTtn*vszAO5Flo0c5I/1008498120.jpeg?width=240&amp;height=180" width="240"></img><br /> </a> <br></br>A tiny, furry-tailed creature was the earliest ancestor of placental mammals -- a widely diverse group of animals ranging from bats to humans -- according to a new study by a team of international scientists, including a core group of Museum researchers. In findings published in the February 8 issue of the journal Science, the researchers… <a href="http://www.atheistnexus.org/video/researchers-reconstruct-the-common-ancestor-of-placental-mammals"><br /> <img src="http://api.ning.com:80/files/rRlLHC*Dey06CdPm-iO3fNSDb7viIkmB7YCFXV1Rj254BeO-v*xQPxU7Q4ltzKd-JIdpp0ubljegd7KTtn*vszAO5Flo0c5I/1008498120.jpeg?width=240&amp;height=180" width="240" height="180" alt="Thumbnail" /><br /> </a><br />A tiny, furry-tailed creature was the earliest ancestor of placental mammals -- a widely diverse group of animals ranging from bats to humans -- according to a new study by a team of international scientists, including a core group of Museum researchers. In findings published in the February 8 issue of the journal Science, the researchers analyzed the world's largest dataset of genetic and physical traits to find that placental mammals diversified into present-day lineages much later than is commonly thought: after the extinction event 65 million years ago that eliminated non-avian dinosaurs. This finding, and the visualization of the placental ancestor -- an insect-eating animal that weighed less than a pound -- was made with the help of a cloud-based and publicly accessible database called MorphoBank.<br /> <br /> MorphoBank is an initiative funded primarily by NSF with additional support from Stony Brook University, the American Museum of Natural History, the National Oceanic and Atmospheric Administration, and the National Evolutionary Synthesis Center.<br /> <br /> Visit MorphoBank: <a href="http://mammaltree.informatics.sunysb.edu/">http://mammaltree.informatics.sunysb.edu/</a> Richard Dawkins - Global Atheist Convention 2010 tag:www.atheistnexus.org,2011-08-28:2182797:Video:1585620 2011-08-28T20:05:16.561Z Donegal http://www.atheistnexus.org/profile/Donegal <a href="http://www.atheistnexus.org/video/richard-dawkins-global-atheist-convention-2010"><br /> <img alt="Thumbnail" height="180" src="http://api.ning.com:80/files/mgrl1oZs-vDd6FDoEe6H0rAUQz7vafQHC8yMOX8I8n7rGgBYnrvE1kazqb6kA*kcLallfIlW-Ki8kMMNGfEaAuaYD8m57pmS/949414514.jpeg?width=240&amp;height=180" width="240"></img><br /> </a> <br></br>Richard Dawkins at the Global Atheist Convention Melbourne March 2010.…<br></br> <br></br> <a href="http://www.atheistnexus.org/video/richard-dawkins-global-atheist-convention-2010"><br /> <img src="http://api.ning.com:80/files/mgrl1oZs-vDd6FDoEe6H0rAUQz7vafQHC8yMOX8I8n7rGgBYnrvE1kazqb6kA*kcLallfIlW-Ki8kMMNGfEaAuaYD8m57pmS/949414514.jpeg?width=240&amp;height=180" width="240" height="180" alt="Thumbnail" /><br /> </a><br />Richard Dawkins at the Global Atheist Convention Melbourne March 2010.<br /> <br /> <a href="http://www.atheistconvention.org.au">http://www.atheistconvention.org.au</a> Gender Role Reversal In Jacanas tag:www.atheistnexus.org,2011-08-24:2182797:Video:1571283 2011-08-24T13:26:58.915Z Donegal http://www.atheistnexus.org/profile/Donegal <a href="http://www.atheistnexus.org/video/gender-role-reversal-in-jacanas"><br /> <img alt="Thumbnail" height="180" src="http://api.ning.com:80/files/jtJ*qNn0PbWEG8PQd1TQrj9HC9X-KC1k3mwGQ1ZoYrMogwreA*0hP7OWmFjSKkOJDvyLmB7naPAqwIMeCGOERDv0NL*RLyd4/982932224.jpeg?width=240&amp;height=180" width="240"></img><br /> </a> <br></br>A switch in traditional gender-role behavior gives an advantage to male and female shorebirds called jacanas. Found in tropical regions, jacanas have evolved a social system that confused early ornithologists into mistaking males for females.<br></br> <br></br> In a sexually reproducing species, males and females are defined by the kind of gametes (reproductive cells) they produce.… <a href="http://www.atheistnexus.org/video/gender-role-reversal-in-jacanas"><br /> <img src="http://api.ning.com:80/files/jtJ*qNn0PbWEG8PQd1TQrj9HC9X-KC1k3mwGQ1ZoYrMogwreA*0hP7OWmFjSKkOJDvyLmB7naPAqwIMeCGOERDv0NL*RLyd4/982932224.jpeg?width=240&amp;height=180" width="240" height="180" alt="Thumbnail" /><br /> </a><br />A switch in traditional gender-role behavior gives an advantage to male and female shorebirds called jacanas. Found in tropical regions, jacanas have evolved a social system that confused early ornithologists into mistaking males for females.<br /> <br /> In a sexually reproducing species, males and females are defined by the kind of gametes (reproductive cells) they produce. The individuals who produce lots of small, mobile gametes are called males. Those who invest everything in a relatively few large gametes are called females. Because of all the resources a female will put into each egg, it makes sense, in most cases, for her to be choosy about whose genes she allows to combine with it, and to continue to invest in its growth and survival after fertilization. For the male, it usually pays best to compete with other males for access to as many eggs as possible. This tends to give rise to the more traditional male/female sex roles.<br /> <br /> But there is nothing inevitable about these familiar sex roles. Evolution favors whatever works, and for the jacana, what works is quite different.<br /> <br /> To begin with, female jacanas weigh 60 percent more than males and can lay many successive "clutches" of eggs in a single breeding season. Once their eggs are on the ground, the females are gone, leaving the males to incubate the eggs and take care of the newborn young. Males even have special wing adaptations that allow them to carry two chicks under each wing.<br /> <br /> The aggressive females, meanwhile, are busy gathering harems of as many as five males, mating promiscuously and defending territory against other females. Not only that, female jacanas will move in on another female's territory, go to the nest, and kill the chicks. Freed from his parenting duties, the male then becomes the object of the invading female's courting. If successful, the mating is followed a week later by a new clutch of eggs for the male to incubate.<br /> <br /> This entire system based on female dominance has evolved, some researchers believe, to compensate for an extraordinarily high rate of egg loss to predators. The world of the jacana has, in effect, turned the female into "an egg-making machine," says Cornell University biologist Stephen Emlen, who has spent years studying the remarkable adaptation. And it is the males who are primarily responsible for the care of the young.<br /> <br /> One lesson from the jacana is that the behaviors we automatically label "male" or "female" aren't something inherent in the physiology or looks of the individual. For the jacana, it's just an unusual way of giving their offspring -- and their genes -- a better chance at survival.<br /> <br /> Please Subscribe To The WhyEvolutionIsTrue Youtube Channel.<br /> <a href="http://www.youtube.com/WhyEvolutionIsTrue">http://www.youtube.com/WhyEvolutionIsTrue</a><br /> <br /> More Short Videos On Evolution:<br /> <a href="http://tinyurl.com/3sfgtrn">http://tinyurl.com/3sfgtrn</a> Sexual And Asexual Reproduction tag:www.atheistnexus.org,2011-08-24:2182797:Video:1571936 2011-08-24T13:21:42.490Z Donegal http://www.atheistnexus.org/profile/Donegal <a href="http://www.atheistnexus.org/video/sexual-and-asexual-reproduction"><br /> <img alt="Thumbnail" height="180" src="http://api.ning.com:80/files/NK5hirFQIz3tTQa5PVo3hv*LT7oaI1GelQiYXVLVtXsEv9WSronB6t-4Pa8yxYC2MifUIKUqbe-jOQVBlgfF2*iwyKRhBkJN/898953964.jpeg?width=240&amp;height=180" width="240"></img><br /> </a> <br></br>Biologist Robert Vrijenhoek has been studying the Mexican Poeciliid fish for more than 30 years. Some species of Poeciliopsis reproduce sexually while others reproduce asexually. Vrijenhoek found that the genetic diversity produced by sexual reproduction allowed the sexual fish to survive a parasite more successfully than the asexual fish. Invoking the Red Queen hypothesis,… <a href="http://www.atheistnexus.org/video/sexual-and-asexual-reproduction"><br /> <img src="http://api.ning.com:80/files/NK5hirFQIz3tTQa5PVo3hv*LT7oaI1GelQiYXVLVtXsEv9WSronB6t-4Pa8yxYC2MifUIKUqbe-jOQVBlgfF2*iwyKRhBkJN/898953964.jpeg?width=240&amp;height=180" width="240" height="180" alt="Thumbnail" /><br /> </a><br />Biologist Robert Vrijenhoek has been studying the Mexican Poeciliid fish for more than 30 years. Some species of Poeciliopsis reproduce sexually while others reproduce asexually. Vrijenhoek found that the genetic diversity produced by sexual reproduction allowed the sexual fish to survive a parasite more successfully than the asexual fish. Invoking the Red Queen hypothesis, Vrijenhoek suggests the sexual populations are able to keep up or adapt to new selective challenges, while the asexual populations, essentially clonal, are not. From Evolution: "Why Sex?" Also featured: Meredith Small.<br /> <br /> Many say that our culture is obsessed with sex, and uses sexual references to sell everything from fragrances to cars. And wouldn't life be dull without it? Yet from the viewpoint of evolutionary theory, sex isn't the most efficient way of reproducing. In fact, scientists have been asking for decades, why does sexual reproduction even exist?<br /> <br /> If the goal of life is spreading one's genes far and wide, asexually reproducing organisms seem to have the edge. They do not have to invest time and energy finding a mate. Asexual individuals can pass on their genes twice as fast as those reproducing sexually, because they pass on all their genes -- and only their genes. When reproduction is sexual, half of the genes handed on to the next generation are those of the other parent. The offspring may lose some of the genetic traits that made each parent successful.<br /> <br /> There are many hypotheses but, until recently, little hard evidence on the advantages of sex. They stem from the notion that the genetic variation created in sexual reproduction is worth the cost. And at least in some environments, that variation must give a competitive edge over asexual organisms that can spread their genes efficiently, but vary little from one generation to the next.<br /> <br /> One explanation is the increasingly popular Red Queen hypothesis, referring to the huffy chess piece in Lewis Carroll's Through the Looking Glass. In Looking Glass Land, the Queen tells Alice, "It takes all the running you can do, to keep in the same place." According to the Red Queen hypothesis, sexual reproduction persists because it enables many species to rapidly evolve new genetic defenses against parasites that attempt to live off them.<br /> <br /> Scientists from Rutgers University in New Jersey have tested this idea by observing different groups of small fish called topminnow in Mexico. Some populations of the topminnow reproduce sexually, while others reproduce asexually, so they provide the perfect opportunity to test these ideas. The topminnow is under constant attack by a parasite, a worm that causes something called black-spot disease.<br /> <br /> The researchers found that identical populations ("clones") of the asexually reproducing topminnows harbored many more black-spot worms than did those producing sexually, a finding that fit the Red Queen hypothesis: The sexual topminnows could devise new defenses faster by recombination than the asexually producing clones.<br /> <br /> Please Subscribe To The WhyEvolutionIsTrue Youtube Channel.<br /> <a href="http://www.youtube.com/WhyEvolutionIsTrue">http://www.youtube.com/WhyEvolutionIsTrue</a><br /> <br /> More Short Videos On Evolution:<br /> <a href="http://tinyurl.com/3sfgtrn">http://tinyurl.com/3sfgtrn</a> Bill Nye: 100 Greatest Discoveries tag:www.atheistnexus.org,2011-08-08:2182797:Video:1506248 2011-08-08T22:35:50.334Z Donegal http://www.atheistnexus.org/profile/Donegal <a href="http://www.atheistnexus.org/video/sexual-and-asexual-reproduction"><br /> <img alt="Thumbnail" height="180" src="http://api.ning.com:80/files/NK5hirFQIz3tTQa5PVo3hv*LT7oaI1GelQiYXVLVtXsEv9WSronB6t-4Pa8yxYC2MifUIKUqbe-jOQVBlgfF2*iwyKRhBkJN/898953964.jpeg?width=240&amp;height=180" width="240"></img><br /> </a> <br></br>Where would we be today if it weren't for the scientists of the past? From the miniature world of genetics to the vast expanse of space, review the greatest discoveries of all time across eight different scientific categories in this multi-part series. Join host Bill Nye as he recounts the 100 most important discoveries and explains how each one has had a hand in shaping the… <a href="http://www.atheistnexus.org/video/sexual-and-asexual-reproduction"><br /> <img src="http://api.ning.com:80/files/NK5hirFQIz3tTQa5PVo3hv*LT7oaI1GelQiYXVLVtXsEv9WSronB6t-4Pa8yxYC2MifUIKUqbe-jOQVBlgfF2*iwyKRhBkJN/898953964.jpeg?width=240&amp;height=180" width="240" height="180" alt="Thumbnail" /><br /> </a><br />Where would we be today if it weren't for the scientists of the past? From the miniature world of genetics to the vast expanse of space, review the greatest discoveries of all time across eight different scientific categories in this multi-part series. Join host Bill Nye as he recounts the 100 most important discoveries and explains how each one has had a hand in shaping the modern world. Watch his lively and dramatic accounts and learn how the great discoveries were made, how they impacted the development of scientific knowledge and how they touch our lives today.<br /> <br /> Episode list:<br /> <br /> 1) Evolution<br /> 2) Biology<br /> 3) Genetics<br /> 4) Earth Sciences<br /> <br /> NOTE: This playlist will be updated as more episodes are uploaded!