Archive for the ‘Evolution’ Category

Scientists investigating the silence of the crickets in Hawaii have uncovered a bizarre evolutionary story that is part horror movie, part Cyrano de Bergerac.

In the most recent edition of the journal Current Biology, researchers from Scotland’s University of St. Andrews report on the separate but nearly simultaneous quieting of chirping crickets on Kauai and Oahu.

As lead researcher Nathan Bailey explained, Hawaii crickets appear to have abandoned their chirplike mating songs to avoid parasitoid flies. The flies, which are attracted to male cricket song, would lay larvae that would then burrow into the host crickets, killing them within a week.

Adaptive crickets survived and reproduced by silencing their own songs but positioning themselves — like Christian to Cyrano — next to crickets who continued to use their chirps to woo female crickets.

The silent flatwing crickets are present on both Oahu and Kauai. At first, Bailey and his team believed that a single population of silent crickets evolved on one island and spread to the other. However, further investigation made it clear that the crickets came from separate populations but adopted the same trait around the same time.

“This is an exciting opportunity to detect genomic evolution in real time in a wild system, which has usually been quite an challenge owing to the long timescales over which evolution acts,” Bailey said in a release. “With the crickets, we can act as relatively unobtrusive observers while the drama unfolds in the wild.”

http://www.staradvertiser.com/news/breaking/20140531_Evolution_silences_some_isle_cricket_populations.html?mobile=true

Thanks to Da Brayn for bringing this to the attention of the It’s Interesting community.

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Tastes are a privilege. The oral sensations not only satisfy foodies, but also on a primal level, protect animals from toxic substances. Yet cetaceans—whales and dolphins—may lack this crucial ability, according to a new study. Mutations in a cetacean ancestor obliterated their basic machinery for four of the five primary tastes, making them the first group of mammals to have lost the majority of this sensory system.

The five primary tastes are sweet, bitter, umami (savory), sour, and salty. These flavors are recognized by taste receptors—proteins that coat neurons embedded in the tongue. For the most part, taste receptor genes present across all vertebrates.

Except, it seems, cetaceans. Researchers uncovered a massive loss of taste receptors in these animals by screening the genomes of 15 species. The investigation spanned the two major lineages of cetaceans: Krill-loving baleen whales—such as bowheads and minkes—were surveyed along with those with teeth, like bottlenose dolphins and sperm whales.

The taste genes weren’t gone per se, but were irreparably damaged by mutations, the team reports online this month in Genome Biology and Evolution. Genes encode proteins, which in turn execute certain functions in cells. Certain errors in the code can derail protein production—at which point the gene becomes a “pseudogene” or a lingering shell of a trait forgotten. Identical pseudogene corpses were discovered across the different cetacean species for sweet, bitter, umami, and sour taste receptors. Salty tastes were the only exception.

“The loss of bitter taste is a complete surprise, because natural toxins typically taste bitter,” says zoologist Huabin Zhao of Wuhan University in China who led the study. All whales likely descend from raccoon-esque raoellids, a group of herbivorous land mammals that transitioned to the sea where they became fish eaters. Plants range in flavors—from sugary apples to tart, poisonous rhubarb leaves—and to survive, primitive animals learned the taste cues that signal whether food is delicious or dangerous. Based on the findings, taste dissipated after this common ancestor became fully aquatic—53 million years ago—but before the group split 36 million years ago into toothed and baleen whales.

“Pseudogenes arise when a trait is no longer needed,” says evolutionary biologist Jianzhi Zhang of the University of Michigan, Ann Arbor, who was not involved in the study. “So it still raises the question as to why whales could afford to lose four of the five primary tastes.” The retention of salty taste receptors suggests that they have other vital roles, such as maintaining sodium levels and blood pressure.

But dulled taste perception might be dangerous if noxious substances spill into the water. Orcas have unwittingly migrated into oil spills, while algal toxins created by fertilizer runoff consistently seep into the fish prey of dolphins living off the Florida coast.

“When you have a sense of taste, it dictates whether you swallow or not,” says Danielle Reed, a geneticist at the Monell Chemical Senses Center in Philadelphia, Pennsylvania. She was not involved with the current work, but co-authored a 2012 paper that found the first genetic inklings that umami and sweet taste receptors were missing in cetaceans, albeit in only one species—bottlenose dolphins.

Flavors are typically released by chewing, but cetaceans tend to swallow their food whole. “The message seems clear. If you don’t chew your food and prefer swallowing food whole, then taste really becomes irrelevant,” Reed says.

http://news.sciencemag.org/biology/2014/05/whales-cant-taste-anything-salt

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.

<img src="https://itsinterestingdotcom.files.wordpress.com/2014/04

The Columbian Mammoth is about to become an official state symbol of South Carolina, but its path to the limelight was long and fraught with controversy.

Here's the text of the bill that made it official:

Section 1-1-712A. The Columbian Mammoth, which was created on the Sixth Day with the other beasts of the field, is designated as the official State Fossil of South Carolina and must be officially referred to as the ‘Columbian Mammoth’, which was created on the Sixth Day with the other beasts of the field.

This is actually the watered-down version of the bill; one version, proposed earlier, made even more explicit references to the role of a divine creator in the mammoth’s history.

This all started when an 8-year-old suggested that the Columbian mammoth become South Carolina’s state fossil. Olivia McConnell had some good reasoning behind her suggestion: Mammoth teeth found in a South Carolina swamp in 1725 were the first vertebrate fossils identified in North America.

Her submission became a bill. The original draft was simple enough: “Section 1-1-691. The Wooly Mammoth is designated as the official State Fossil of South Carolina.” But almost immediately the proposal ran into trouble. On a practical level: Senate Majority Leader Harvey Peeler objected strenuously to having any new state symbols enacted in a state that already has a state spider, state beverage and a state hospitality beverage among many others. On a philosophical level: proclaiming a state fossil in a state where there is still intense debate over teaching evolution as fact creates some problems.

From USA Today:

State Sen. Mike Fair, a Greenville Republican who serves on the panel that will decide the science standards, said that natural selection should be taught as theory rather than as scientific fact. He argues that natural selection can make biological changes within species but it can’t explain the whole progression from microbes to humans.

“This whole subject should be taught as a pro and con,” he said.

Last week, Fair had raised his own objection that temporarily killed Olivia’s bill but withdrew it after another senator told him the story of the Lake City girl’s campaign to get an official state fossil.

Fair wasn’t the only one who had objections. Another State Senator, Kevin Bryant started a pushing a change that would add some biblical flair to the otherwise direct language. The New York Times:

But then Senator Kevin Bryant proposed an amendment rooted in the Book of Genesis, imputing God as the creator of the woolly mammoth: “And God made the beast of the earth after his kind, the cattle after their kind, and everything that creepeth upon the earth after his kind: and God saw that it was good.”
Bryant’s version was struck down, but the final version of the bill did include that language about the Mammoth being created on the sixth day.

There was one other addition, too. Frustrated by the amount of time spent discussing state symbols instead of governing, legislators also added an amendment to the bill prohibiting the General Assembly from enacting any new state symbols “until such time as the General Assembly directly by legislative enactment removes this moratorium.”

Read more: http://www.smithsonianmag.com/smart-news/south-carolinas-state-fossil-creation-controversy-180950474/#4mOTlJmLsprzxrmM.99

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.

Faces-of-the-Future-4

Designer Lamm’s depiction of how the human face might look in 100,000 years

We’ve come along way looks-wise from our homo sapien ancestors. Between 800,000 and 200,000 years ago, for instance, rapid changes in Earth climate coincided with a tripling in the size of the human brain and skull, leading to a flattening of the face. But how might the physiological features of human beings change in the future, especially as new, wearable technology like Google Glass change the way we use our bodies and faces? Artist and researcher Nickolay Lamm has partnered with a computational geneticist to research and illustrate what we might look like 20,000 years in the future, as well as 60,000 years and 100,000 years out. His full, eye-popping illustrations are at the bottom of this post.

Lamm says this is “one possible timeline,” where, thanks to zygotic genome engineering technology, our future selves would have the ability to control human biology and human evolution in much the same way we control electrons today.

Lamm speaks of “wresting control” of the human form from natural evolution and bending human biology to suit our needs. The illustrations were inspired by conversations with Dr. Alan Kwan, who holds a PhD in computational genomics from Washington University.

Kwan based his predictions on what living environments might look like in the future, climate and technological advancements. One of the big changes will be a larger forehead, Kwan predicts – a feature that has already expanding since the 14th and 16th centuries. Scientists writing in the British Dental Journal have suggested that skull-measurement comparisons from that time show modern-day people have less prominent facial features but higher foreheads, and Kwan expects the human head to trend larger to accommodate a larger brain.

Kwan says that 60,000 years from now, our ability to control the human genome will also make the effect of evolution on our facial features moot. As genetic engineering becomes the norm, “the fate of the human face will be increasingly determined by human tastes,” he says in a research document. Eyes will meanwhile get larger, as attempts to colonize Earth’s solar system and beyond see people living in the dimmer environments of colonies further away from the Sun than Earth. Similarly, skin will become more pigmented to lesson the damage from harmful UV radiation outside of the Earth’s protective ozone. Kwan expects people to have thicker eyelids and a more pronounced superciliary arch (the smooth, frontal bone of the skull under the brow), to deal with the effects of low gravity.

The remaining 40,000 years, or 100,000 years from now, Kwan believes the human face will reflect “total mastery over human morphological genetics. This human face will be heavily biased towards features that humans find fundamentally appealing: strong, regal lines, straight nose, intense eyes, and placement of facial features that adhere to the golden ratio and left/right perfect symmetry,” he says.

Eyes will seem “unnervingly large” — as least from our viewpoint today — and will feature eye-shine and even a sideways blink from the re-introduced plica semilunaris to further protect from cosmic ray effects.

There will be other functional necessities: larger nostrils for easier breathing in off-planet environments, denser hair to contain heat loss from a larger head — features which people may have to weigh up against their tastes for what’s genetically trendy at the time. Instead of just debating what to name a child as new parents do today, they might also have to decide if they want their children to carry the most natural expression of a couple’s DNA, such as their eye-color, teeth and other features they can genetically alter.

Excessive Borg-like technological implants would start to become untrendy, though, as people start to increasingly value that which makes us look naturally human. That “will be ever more important to us in an age where we have the ability to determine any feature,” Kwan says.

Wearable technology will still be around, but in far more subtle forms. Instead of Google Glass and iWatch, people will seek discrete implants that preserve the natural human look – think communication lenses (a technologically souped up version of today’s contacts) and miniature bone-conduction devices implanted above the ear. These might have imbedded nano-chips that communicate to another separate device to chat with others or for entertainment.

The bird’s eye view of human beings in 100,000 years will be people who want to be wirelessly plugged in, Kwan says, but with minimal disruption to what may then be perceived as the “perfect” human face.

His Predictions:

In 20,000 years: Humans have a larger head with a forehead that is subtly too large. A future “communications lens” will be manifested as a the yellow ring around their eyes. These lenses will be the ‘Google Glass’ of the future.

In 60,000 years: Human beings have even larger heads, larger eyes and pigmented skin. A pronounced superciliary arch makes for a darker area below eyebrows. Miniature bone-conduction devices may be implanted above the ear now to work with communications lenses.

In 100,000 years: The human face is proportioned to the ‘golden ratio,’ though it features unnervingly large eyes. There is green “eye shine” from the tapetum lucidum, and a more pronounced superciliary arch. A sideways blink of the reintroduced plica semilunaris seen in the light gray areas of the eyes, while miniature bone-conduction devices implanted above the ear work with the communications lenses on the eyes.

Thanks to Ray Gaudette for bringing this to the attention of the It’s Interesting community.

http://news.yahoo.com/human-face-might-look-100-171207969.html

fossil

Christopher Cameron of the University of Montreal’s Department of Biological Sciences and his colleagues have unearthed a major scientific discovery — a strange phallus-shaped creature they found in Canada’s Burgess Shale fossil beds, located in Yoho National Park. The fossils were found in an area of shale beds that are 505 million years old.

Their study, published online in the journal Nature on March 13, 2013, confirms Spartobranchus tenuis is a member of the acorn worms group which are seldom-seen animals that thrive today in the fine sands and mud of shallow and deeper waters. Acorn worms are themselves part of the hemichordates, a group of marine animals closely related to today’s sea stars and sea urchins. “Unlike animals with hard parts including teeth, scales and bones, these worms were soft-bodied, so their fossil record is extremely rare,” said author Dr. Chris Cameron of the University of Montreal. “Our description of Spartobranchus tenuis, a creature previously unknown to science, pushes the fossil record of the enteropneusts back 200 million years to the Cambrian period, fundamentally changing our understanding of biodiversity from this period.”

Since their discovery in the 19th-century, some of the biggest questions in hemichordate evolution have focused on the group’s origins and the relationship between its two main branches: the enteropneusts and the pterobranchs, including graptolites. “One of the big punchlines from my graduate work, was molecular evidence that enteropneusts and pterobranchs are closely related” said Cameron, a specialist on the taxonomy, evolution and biogeography of hemichordates.

“It’s astonishing how similar Spartobranchus tenuis fossils are to modern day acorn worms, except that they also formed fibrous tubes.” The tubes provide a key missing link that connects the two main hemichordate groups. “The explosive radiation of graptolites in the Paleozoic planktonic ecosystems is known only from the diversity of their tubes. Our findings suggest that the tubes were lost in the lineage leading to modern day enteropneusts, but elaborated on in graptolites and retained to the present day in pterobranchs” added Cameron.

Hemichordates also share many of the same characteristics as chordates — a group of animals that includes humans — with the name hemichordate roughly translating to ‘half a chordate.’

“Work from my lab has shown that enteropneusts filter feed using a pharynx perforated with gill slits, just like the invertebrate chordates” added Cameron. Spartobranchus tenuisprobably fed on small particles of matter filtered from the seawater. “There are thousands of specimens at the Walcott Quarry in Yoho National Park, so it’s possible Spartobranchus tenuis may have played an important role in moving carbon from the water column to the sediment in the early Burgess Shale environment” said Cameron.

Detailed analysis suggests Spartobranchus tenuis had a flexible body consisting of a short proboscis, collar and narrow elongate trunk terminating in a bulbous structure, which may have served as an anchor. The largest complete specimens examined were 10 centimetres long with the proboscis accounting for about half a centimetre. A large proportion of these worms was preserved in tubes, of which some were branched, suggesting the tubes were used as a dwelling structure.

Other members of the Spartobranchus tenuis research team are lead author Jean-Bernard Caron of the Royal Ontario Museum and Simon Conway Morris of the University of Cambridge.

http://www.sciencedaily.com/releases/2013/03/130313141450.htm

The caverns of Lechuguilla Cave are some of the strangest on the planet. Its acid-carved passages extend for over 120 miles. Parts of Lechuguilla have been cut off from the surface for four to seven million years, and the life-forms there – mainly bacteria and other microbes – have charted their own evolutionary courses. But Gerry Wright from McMaster University in Canada has found that many of these cave bacteria can resist our antibiotics. They have been living underground for as long as modern humans have existed, but they can fend off our most potent weapons.

read more here:  http://blogs.discovermagazine.com/notrocketscience/2012/04/13/isolated-for-millions-of-years-cave-bacteria-resist-modern-antibiotics/