Complete Mitochondrial Genomes of Ancient Canids Suggest a European Origin of Domestic Dogs
by Elizabeth Pennisi
The story of dogs began thousands of years ago, when gray wolves began sidling out of the shadows and into the company of humans. There’s little argument about that scenario—but plenty about when and where it took place, with the leading theories suggesting dogs were domesticated either in the Middle East or in East Asia. A study on page 871 draws on a new source of evidence, DNA from the fossils of ancient dogs and wolves, and comes to a third conclusion: Dogs originated in Europe, from a now-extinct branch of gray wolves.
The dogfight goes on. Based on the new study, “you will be hard-pressed to come up with a narrative about how dogs were not domesticated in Europe,” says Greger Larson, an evolutionary biologist at the University of Durham in the United Kingdom.
But some fans of the East Asia theory argue that the DNA examined, from cell organelles called mitochondria, cannot tell the whole story and that the analysis may be skewed because the ancient samples are primarily from Europe. “Critical observers will need more than mitochondrial DNA to be convinced,” says Stephen O’Brien, a geneticist at St. Petersburg State University in Russia, who says he is in neither dog origin camp…
ome of us are born with wanderlust, but what exactly spurs a bird to journey thousands of miles each year? The answer is in part genetic, and a recent study of yellow-rumped warblers in the journal Evolution reveals how changes over generations could improve a bird’s abilities to become a master, long-distance flyer.
The research, conducted by zoologists and physiologists at the University of British Columbia, began with a genetic puzzle. There are four different groups of yellow-rumped warblers, each distinct in behavior and appearance: the Goldman’s, myrtle, Audubon’s, and black-fronted. Their genes, however, tell a different story.
Examining DNA obtained from the nucleus of these birds’ blood cells revealed that the Audubon’s and black-fronted warblers were indistinguishable. In other words, these birds are so closely related that, despite different appearances and the fact that Audubon’s migrate whereas black-fronteds don’t, these birds can’t be recognized as different species…
The disease that sours oranges and leaves them half green, already ravaging citrus crops across the world, had reached the state’s storied groves. Mr. Kress, the president of Southern Gardens Citrus, in charge of two and a half million orange trees and a factory that squeezes juice for Tropicana and Florida’s Natural, sat in silence for several long moments.
“O.K.,” he said finally on that fall day in 2005, “let’s make a plan.”
In the years that followed, he and the 8,000 other Florida growers who supply most of the nation’s orange juice poured everything they had into fighting the disease they call citrus greening.
To slow the spread of the bacterium that causes the scourge, they chopped down hundreds of thousands of infected trees and sprayed an expanding array of pesticides on the winged insect that carries it. But the contagion could not be contained.
They scoured Central Florida’s half-million acres of emerald groves and sent search parties around the world to find a naturally immune tree that could serve as a new progenitor for a crop that has thrived in the state since its arrival, it is said, with Ponce de León. But such a tree did not exist…
If you want to protect rare species, first you have to find them. In the past few years, biologists have developed a powerful new tool to do that. They’ve discovered that they can often find traces of animal DNA in streams, ponds — even oceans.
The idea took root just five years ago, when biologists in France found they could detect invasive American bullfrogs simply by sampling pond water and looking for an exact genetic match to the frogs’ DNA.
Now, all sorts of biologists are eagerly putting this test to use. The technology has been a hot topic at the Society for Conservation Biology’s global meeting in Baltimore this week.
Conservation scientist Stephen Spear, for example, has been sampling water to study one of the oddest (and most awesome) creatures in American streams: the elusive hellbender salamander (aka The ‘Snot Otter’)…
No animal has gone completely without sex for as long as bdelloid rotifers, who have been celibate for millions of years. The always female, translucent, and half-a-millimeter long creatures perplex evolutionary biologists, who believe that combining the DNA of two parents is necessary to create the genetic diversity that animal populations need to adapt to a changing environment. (Bacteria manage to diversify without sex because genes can easily jump from one bacterium to another.)
Yet with more than 460 species, bdelloid rotifers have managed to survive and diversify over evolutionary time too. So how do they do it? They may do it by “stealing” genes from other organisms.
Reporting online today in Nature, researchers have found that the genome of the bdelloid rotifer Adineta vaga (electron microscope image, above) contains an unusual amount of DNA from other organisms that appears to have “jumped” in through a process called horizontal gene transfer that occurs often in asexual bacteria, but very rarely in animals.
About 8% of Adineta's genes derive from bacteria and other nonanimal kingdoms of life. The authors suggest that fraction helps keep their populations genetically diverse and adaptable—no whoopee required.
700,000 Year Old Horse Becomes Oldest Animal To Have its Genome Sequenced
A genome sequence derived from a 700,000-year-old horse fossil (inset) sheds new light on equine evolution and confirms that Przewalski’s horse (pictured) is indeed genetically distinct from domesticated breeds.
by Gisela Telis
Scientists have sequenced the oldest genome to date—and shaken up the horse family tree in the process. Ancient DNA derived from a horse fossil that’s between 560,000 and 780,000 years old suggests that all living equids—members of the family that includes horses, donkeys, and zebras—shared a common ancestor that lived at least 4 million years ago, approximately 2 million years earlier than most previous estimates. The discovery offers new insights into equine evolution and raises the prospect of recovering and exploring older DNA than previously thought possible…
Scientists have long suspected that the killer whale, Orcinus orca, may actually be four different species or subspecies based of subtle differences in appearance and variations in behavior. The rarest of them all is known as type D. These fat-headed orcas, marked by tiny white patches around their eyes, were only recently observed in the wild, some 50 years after they were first identified in photographs from a mass stranding in New Zealand.
The skeleton of one of the type D whales that washed ashore in 1955 ended up at a museum in Wellington. In a new study, scientists analyzed DNA from the bones, showing, yes, type D is likely a distinct subspecies or species. The research, detailed in the journal Polar Biology, also suggests type D diverged from other killer whales about 390,000 years ago, making it the second oldest orca type…
We have many brightly-colored bird species, but few can compete with the North American tanagers. Molecular studies and other new research suggests the genus Piranga, including this Western Tanager (P. ludoviciana), are actually part of the cardinal Family (Cardinalidae), and not the tanager Family (Thraupidae) where they were originally placed.
The relationship is supported by their plumage: Piranga species are extensively red, orange or yellow - colors defined by carotinoid pigments - which is rarely seen in true tanagers but very common in the cardinal family. Despite the bright colors, they can often be hard to see as they spend much of their time high in the woodland canopy foraging on insects. Western Tanagers are a major consumer of the forestry crop pest Western Spruce Budworm (Choristoneura occidentalis).
This alien-looking creature is known as Nematostella vectensis, or the starlet sea anemone. Like other anemones, starlets start life as free-swimming larvae. They then settle into an appropriately mucky spot on the seafloor and metamorphose into their adult polyp form, seen here.
Anemones lack brains, but the section of the larvae containing the sensory organs actually becomes the bulbous root end of the adult, while the other side sprouts delicate tentacles and transforms into a filter-feeding mouth.
Researchers have now found that the “head genes” of N. vectensis, though held in what eventually becomes the animal’s “foot,” correspond to the head genes found in the actual heads of higher animals. Humans and other brainy beasts share a common, brainless, ancestor with sea anemones that lived 600 million to 700 million years ago. The findings were released Feb. 20, 2013 in the journal PLOS Biology.
The bladderwort, named for its water-filled bladders (shown left) that suck in unsuspecting prey, is a relative of the tomato. Since their evolutionary split 87 million years ago, both plants have experienced episodes of genetic duplication where the plants’ DNA doubled in size…
Ant Family Tree Constructed: Confirms Date of Evolutionary Origin, Underscores Importance of Neotropics
by Science Daily staff
Apr. 22, 2013 — Anyone who has spent time in the tropics knows that the diversity of species found there is astounding and the abundance and diversity of ants, in particular, is unparalleled. Scientists have grappled for centuries to understand why the tropics are home to more species of all kinds than the cooler temperate latitudes on both sides of the equator. Several hypotheses have been proposed to explain the higher species numbers in the tropics, but these hypotheses have never been tested for the ants, which are one of the most ecologically and numerically dominant groups of animals on the planet.
New research by evolutionary biologists Dr. Corrie Moreau of Chicago’s Field Museum and Dr. Charles Bell of the University of New Orleans is helping answer these questions. Their findings are presented this week in the journal Evolution.The scientists used DNA sequence data to build the largest ant tree-of-life to date. This tree-of-life, or family tree of ants, not only allowed them to better understand which ant species are related, but also made it possible to infer the age for modern ants because information from the fossil record in the form of geologic time was included in the research…
The coelacanth isn’t called a “living fossil” for nothing. The 2-meter-long, 90 kg fish was thought to have gone extinct 70 million years ago—until a fisherman caught one in 1938—and the animal looks a lot like its fossil ancestors dating back 300 million years. Now, the first analysis of the coelacanth’s genome reveals why the fish may have changed so little over the ages. It also may help explain how fish like it moved onto land long ago.
"I’m very excited about this paper because coelacanths are animals that we really want to know more about," says Per Ahlberg, a paleontologist at Uppsala University in Sweden who was not involved with the study.
In order to sequence a coelacanth’s (Latimeria chalumnae) genome, scientists required fresh tissue and blood. That’s no easy task: These fish dwell in deep-sea caves and are exceedingly rare. Only 309 have been spotted in the past 75 years, off the east coast of sub-Saharan Africa and Indonesia. Moreover, caught coelacanths die immediately because of the change in pressure and temperature, and under the hot tropical sun, their DNA quickly degrades…
First Migration from Africa Less Than 95,000 Years Ago: Ancient Hunter-Gatherer DNA Challenges Theory of Early Out-Of-Africa Migrations
by Science Daily staff
Mar. 22, 2013 — Recent measurements of the rate at which children show DNA changes not seen in their parents — the “mutation rate” — have challenged views about major dates in human evolution.
In particular these measurements have made geneticists think again about key dates in human evolution, like when modern non-Africans split from modern Africans. The recent measurements push back the best estimates of these dates by up to a factor of two. Now, however an international team led by researchers at the University of Tübingen and the Max Planck Institute for Evolutionary Anthropology in Leipzig, present results that point again to the more recent dates. The new study is published in Current Biology…
Scientists at the University of Alaska Museum of the North are using ancient DNA from museum specimens housed at several U.S. museums to find out whether one particular species of treeshrew (Tupaia glis) is actually several different species.
Thanks to a grant from the National Science Foundation, Mammals Curator Link Olson and his colleagues are using both DNA and skeletal evidence. Their work is featured on the cover of the current issue of the Journal of Mammalogy.
“We tested our own previous hypothesis based solely on DNA extracted from historic museum specimens up to 120 years old in the museum’s Ancient DNA Laboratory,” Olson said.
The scientists obtained skeletal data by X-raying the specimens to accurately measure the foot bones. “We found congruence between the two types of data and were consequently able to resurrect three species from synonymy, including the one gracing the cover. This served as a test case, and we anticipate many more treeshrew species will be rescued from taxonomic oblivion in the near future.”
The scientists hope their work will aid conservation and management decisions in Southeast Asia, one of the world’s hottest biodiversity hotspots that is undergoing rapid and accelerating rates of habitat destruction.
Each Tetrahymena has a gene for its own sex—or mating type—in its regular nucleus, but it also carries a second nucleus used only for reproduction. This “germline nucleus” contains incomplete versions of all seven mating type genes, which are cut and pasted together until one complete gene remains and the other six have been deleted…