Never write off a rank outsider. A female mammal that carries a “male” chromosome should struggle to reproduce, but not if that animal is an African pygmy mouse. For females of this species, a male chromosome spells reproductive supremacy.
The mouse’s most remarkable feature is hidden within its cells. In the 1960s, geneticists found three sex chromosomes floating in its gene pool, rather than the two most mammals carry. As well as the normal X and Y sex chromosomes, there is a modified X called X* (Experientia, doi.org/bvsx8x)…
Mystery of bottle gourd migration to Americas solved:
(Phys.org) —A team with members from several institutions in the U.S. has finally set to rest the mystery of how the bottle gourd found its way to the Americas. In their paper published in Proceedings of the National Academy of Sciences, the team explains that new DNA analysis has revealed that the bottle gourd made its way to South America by floating over from Africa.
For several decades, scientists have been wrangling with the mystery of how the bottle gourd, which is believed to be native to Africa and Asia, made its way to the Americas where it grew wild approximately 10,000 years prior to being domesticated. Some believed the mystery had been solved when a research team using DNA techniques reported back in 2005 that the bottle gourd in the Americas had Asian DNA, suggesting the gourd made its way to North America by early people carrying it across the land bridge that existed between what is now Alaska and Russia.
In this new effort, the research team contradicts that earlier finding claiming that newer DNA analysis tools show that gourds in the Americas actually have African DNA, which suggests they made it to the New World by floating across the ocean…
Before farming began to spread across Europe some 8500 years ago, the continent’s occupants were hunter-gatherers. They were unable to digest starch and milk, according to a new ancient DNA study of a nearly 8000-year-old human skeleton from Spain.
But these original occupants did already possess immune defenses against some of the diseases that would later become the scourge of civilization, and they apparently had dark skin. The findings are helping researchers understand what genetic and biological changes humans went through as they made the transition from hunting and gathering to farming.
The rise of farming about 10,000 years ago was one of the most dramatic events in human history. Europe’s farmers came originally from the Middle East and migrated west via Greece and Bulgaria. For decades, the only way scientists could study these events was by extrapolating back from the genetics of modern-day Europeans, a rough guide at best to what had happened in the past.
But over the past several years, ever more sophisticated techniques for extracting and sequencing DNA from ancient skeletons have opened the window on to the genetics of ancient hunter-gatherers and farmers alike, allowing researchers to not only trace their movements and interactions but also how the rise of farming changed their biology…
… is perhaps North America’s most variable squirrel species. The color morph the species is named for is the traditional gray one (bottom center), which is found throughout their range. The black morph is also common, although it is absent from the very south of the squirrel’s range. In parts of the north however, black often outnumbers gray.
Some studies suggest the black coat presents a survival advantage in these cooler latitudes. Sprinkled in with these two are several other much rarer color morphs, often quite regional. At middle latitudes, the non-gray colors are often associated with urban centers, where lower predation threat means all morphs have a roughly equal chance of survival. Coat color is a genetically inherited trait, and a pairing of two morphs will sometimes result in mixed-coat litters.
The Gray Squirrel is native to eastern North America, but has been introduced to the west coast as well as a number of places overseas, such as the UK, where it has become an invasive pest…
[Photos - top, left to right: scarlatti2004, Hewlett, NY; Adventures of KM&G-Morris, Vancouver, BC; Manda (postmoderngirl), Austin, TX bottom, left to right:D.Derbyshire, eastern ON; Craig Elliot (Tjflex2), Richmond, BC; Robert Taylor (Bobolink), Stirling, ON; All but D.Derbyshire on Flickr]
Scorpion’s sting evolved from insects’ defensive proteins
by Ashley Yeager
The proteins that prevent viral, bacterial or fungal infections in insects are similar in structure to stinging proteins in scorpions. Removing a tiny loop on one defensive insect protein changed the molecule’s function from fighting against microbes to having the ability to paralyze prey, researchers report January 14 in Molecular Biology and Evolution.
The experiment is the first to show how insect proteins could have evolved into the more damaging toxins seen in scorpions.
Weird and wonderful, plant DNA is challenging preconceptions about the evolution of life, including our own species.
by Megan Scudellari
Today, with the advent of high-throughput sequencing, that legacy of firsts in the plant field is extending to genomics research. In the tens of millions of nucleic acids of familiar and not-so-familiar plant species—from fluffy, domesticated cotton to aquatic, carnivorous bladderwort—plant biologists are uncovering surprising principles about how genomes are organized and how they evolved.
In the last two years, researchers have stumbled upon some “mind-blowing” phenomena in plant genomics, including genomes so strange that “we didn’t think [they] could be like that,” says R. Keith Slotkin, a geneticist at Ohio State University. Examples include the peaceful coexistence of two different genomes in a single nucleus and the willy-nilly way plants swap genes among species. And just as with Hooke’s, Brown’s, and Mendel’s fundamental discoveries in plant biology, the bizarre behavior of plant genomes often applies to animals as well…
Mysterious peoples from the north and Middle Easterners joined prehistoric locals.
by Ewen Callaway
Newly released genome sequences from almost a dozen early human inhabitants of Europe suggest that the continent was once a melting pot in which brown-eyed farmers encountered blue-eyed hunter-gatherers.
Present-day Europeans, the latest work shows, trace their ancestry to three groups in various combinations: hunter-gatherers, some of them blue-eyed, who arrived from Africa more than 40,000 years ago; Middle Eastern farmers who migrated west much more recently; and a novel, more mysterious population whose range probably spanned northern Europe and Siberia.
That conclusion comes from the genomes of 8,000-year-old hunter-gatherers — one man from Luxembourg and seven individuals from Sweden — as well as the genome of a 7,500-year-old woman from Germany. The analysis, led by Johannes Krause of the University of Tübingen, Germany, and David Reich of Harvard Medical School in Boston, Massachusetts, was posted on the biology preprint website bioRxiv.org on 23 December 20131. The results have not yet been published in a peer-reviewed journal…
… is a cartilaginous fish (not actually a shark but a ratfish or chimera) native to the Southwest Pacific off southern Australia and New Zealand. Because of its relatively small genome, this species has been targeted as a model organism for vertebrate molecular evolution.
In a whole-genome analysis published in Nature today, Byrappa Venkatesh & colleagues report that the elephant shark has the slowest rate of evolution of any known vertebrate. Its genome has not changed substantially in hundreds of millions of years. Comparison of the elephant shark genome with those of other vertebrates also provides intriguing insights into the evolution of vertebrate skeletons and immune systems.
'Elephant Shark' Takes Record for Slowest Evolution
by Bob Homes
It’s a living fossil to beat all others. The elephant shark, Callorhinchus milii, has the slowest-evolving genome of any vertebrate.
C. milii is not actually a true shark but belongs to a group known as ratfish, which diverged from sharks about 400 million years ago. When a team led by Byrappa Venkatesh of the Institute of Molecular and Cell Biology in Singapore compared its genome with those of other vertebrates, they found it had changed less from its presumed ancestral form than any other.
C. milii outstrips the coelacanth, the fish that previously held the slow-evolution record.
Such limited change means the elephant shark’s genome is the closest yet to that of the first jawed vertebrate, which lived more than 450 million years ago and gave rise to many modern animals including humans. It makes the elephant shark an important reference point for unlocking how this long-lost ancestor evolved. As well as jaws, the earliest fish pioneered bony skeletons and a sophisticated immune system, but it is not known when or how these features appeared…
New Study Brings Scientists Closer to the Origin of RNA
(Phys.org) — One of the biggest questions in science is how life arose from the chemical soup that existed on early Earth. One theory is that RNA, a close relative of DNA, was the first genetic molecule to arise around 4 billion years ago, but in a primitive form that later evolved into the RNA and DNA molecules that we have in life today. New research shows one way this chain of events might have started.
Chemists at the Georgia Institute of Technology have shown how molecules that may have been present on early Earth can self-assemble into structures that could represent a starting point of RNA. The spontaneous formation of RNA building blocks is seen as a crucial step in the origin of life, but one that scientists have struggled with for decades…
Non-insect invertebrates are focus of new global genome-sequencing alliance
For scientists who study non-insect invertebrates, the sheer diversity of these odd and fascinating creatures is both intoxicating and daunting. Occupying niches in habitats the world over are a stunning array of mollusks, worms, jellyfish, sponges, crustaceans, corals and other spineless animals representing more than 500 million years of evolution. But where does science begin to organize the vast biodiversity revealed in the morphology of these animals and unlock their genetic secrets, information that could help us understand our own genetic evolution?
An important step toward this goal was made recently with the founding of the Global Invertebrate Genomics Alliance, an organization created to bring together the world’s top researchers to sequence the genomes of non-insect invertebrates. GIGA originated at the Nova Southeastern University Oceanographic Center in Florida, spearheaded by Professor Jose Lopez. To find out more about this new alliance, Smithsonian Science turned to Karen Osborn and Allen Collins, zoologists in the Department of Invertebrate Zoology at the Natural History Museum, who are founding members of GIGA…
Research groups around the world are attempting to resurrect extinct species.
by Abby Olena
The only ever successful de-extinction was the birth of a baby bucardo (Capra pyrenaica pyrenaica)—a type of ibex specifically adapted to the Pyrenees Mountains in Europe—in 2003, though the young animal died soon after birth because its lungs did not function properly, according to BBC News. The clone was generated using frozen cells harvested in 1999 from the last bucardo, an old female that died in 2000. Now, the BBC reports that the Centre for Research and Food Technology of Aragon (CITA) in Zaragoza, Spain, will begin a new project to examine the burcado frozen cells to determine whether de-extinction efforts ought to be resurrected.
“At this moment, we are not initiating a bucardo recovery plan,” Alberto Fernandez-Arias, the head of the Service of Hunting, Fishing and Wetlands in the Aragon government, told the BBC. “We only want to know if Celia’s cells are still alive after having been maintained frozen during 14 years in liquid nitrogen.” Fernandez-Arias told the story of the 2003 bucardo de-extinction experiment in one of 25 talks at the TEDxDeExtinction meeting held this spring (March 15) in Washington, D.C…
A new species of wild cat has been identified in South America by using molecular markers, researchers claim. By comparing DNA sequences, the team revealed that two populations of tigrina in Brazil do not interbreed and are evolutionarily distinct.
Results also show the two populations have contrasting interactions with the closely related pampas cat and Geoffroy’s cat. The findings are published in the journal Current Biology.
There are at least seven species of small wild cat in the genus Leopardus in Central and South America, which are thought to have first colonised the region during the late Pliocene (2.5 - 3.5 million years ago).
A team of researchers led by Dr Eduardo Eizirik from the Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil collected samples of DNA from pampas cats (Leopardus colocolo) in the north of the country, Geoffroy’s cats (L. geoffroyi) from the south and two separate populations - north eastern and southern - of tigrina (L. tigrinus)…
About 54 million years ago, a semiaquatic deer-like creature headed into the water for good, giving rise to whales and their relatives. The newly sequenced genome of the minke whale, a baleen whale found worldwide, tells the story of how stressful this move to live underwater was.
An international team has decoded the genomes of four minke whales, a fin whale, a bottlenose dolphin, and a finless porpoise, comparing these cetaceans’ genes to the equivalent genes in other mammals. It found whale-specific mutations in genes important for the regulation of salt and of blood pressure and for antioxidants that get rid of charged oxygen molecules that can harm cells.