Rising temperatures in Australia have caused birds on that continent to shrink–some by nearly 4 percent. The findings of a study published in the journal Proceedings of the Royal Society B are the first to show that birds’ sizes are affected by global warming, although this phenomenon previously has been shown in fish and Soay sheep. Scientists postulate that the relationship between a warmer climate and smaller animals may be true for the animal kingdom as a whole.
Temperature has a clear impact on body size; it’s old news among scientists that birds closer to the equator evolved to be smaller than their peers near the poles. One possible explanation for this, called Bergmann’s Rule, is that larger animals conserve heat more efficiently, and this trait is naturally selected for in colder climates, but not in warmer climates. On this basis, scientists have predicted that climate change will affect the way animals vary in size at different latitudes [ABC Science]. The recent research on sheep and fish has corroborated this hypothesis by showing that these animals have become smaller as temperatures have risen.
(more…)
Mosquitoes that have made their way to the Galapagos Islands via tourist planes and boats are threatening the rare native species endemic to the region, according to a study published in the journal Proceedings of the Royal Society B.
Culex quinquefasciatus, known as the southern house mosquito, can carry diseases dangerous to wildlife, such as avian pox and West Nile virus. Not only have the insects hopped a ride onto the islands, but they’ve also bred with native species once they reach the shore, the study found. That means they pose an ongoing threat to the Galapagos’ rare species and delicate ecosystem, which inspired Darwin’s theory of evolution after he observed the island’s unique array of wildlife. “You only need a single infectious mosquito to initiate a disease cycle,” [co-author Simon] Goodman…[T]he Galapagos “have globally important biodiversity — endemic species found nowhere else in the world,” said Goodman [Telegraph].
(more…)
Using the first known animal instruments, orangutans use leaves to make their voices sound deeper, perhaps thereby tricking predators into thinking the apes are bigger than they really are, according to a study published in the journal Proceedings of the Royal Society B.
Orangutans produce a noise known as “kiss squeaks” to let predators like snakes and leopards know that they’ve been spotted, and can use their lips and fingers or folded leaves to make the sound. To find out more about why the animals produce the noise, researchers recorded kiss squeaks between 2003 and 2005 near a research station … on the island of Borneo. The team noted whether the sounds had been made with hands, leaves, or lips alone [National Geographic News]. They found that squeaks made using only the lips had a higher pitch than those produced using hands, and that leaf-produced pitches had the lowest frequency and therefore the deepest sound.
(more…)
Scientists trying to determine where dogs were first domesticated have been sent back to the drawing board by a new study. Back in 2002, researchers sampled DNA from dogs around the world, and determined that dogs in East Asia had the most genetic diversity, suggesting that the species originated there and that dogs in that region have had the longest time to evolve. But the new study suggests that those earlier results were skewed, because DNA sampling of African street dogs has revealed equal genetic diversity.
The earlier findings may have been thrown off because the large-scale study included both purebred dogs, whose evolution has been closely guided by human hands, and street dogs, who have bred more autonomously and randomly, and who therefore show more genetic diversity. But the 2002 researchers drew DNA from different types of dogs in different regions. Says Adam Boyko, lead researcher of the new study: “I think it means that the conclusion that was drawn before might have been premature. It’s a consequence of having a lot of street dogs from East Asia that were sampled, compared to elsewhere” [BBC News].
(more…)
The oldest known tree-dwelling vertebrate lived 30 million years before the dinosaurs, scientists have found. The animal, known as Suminia getmanovi, had opposable thumbs and long hands, which would have allowed it to live in trees, according to a study published in the journal Proceedings of the Royal Society B.
A team of researchers found that Suminia, which lived about 260 million years ago, had disproportionately long arms and slender, curved fingers that were well-adapted to grabbing tree branches. But perhaps most importantly, one finger on each hand and foot was “opposed” to the rest, much like a thumb. “It’s the first time in the fossil record that we’ve seen evidence of an opposable thumb,” [said lead researcher Jorg Frobisch], adding that the creature was an early ancestor of mammals [BBC News]. The 12 well-preserved Suminia skeletons the scientists analyzed, which were found in Russia the 1990s, predate by 100 million years what was previously thought to be the earliest tree-dwelling animal.
(more…)
Changes in an organism’s genome that once took years to make in a lab can now be done in a fraction of the time, thanks to a new method of genome engineering. “This technique allows us to do some amount of rapid evolution” [New Scientist], says lead researcher Harris Wang.
In the experiment, the scientists used a technique called Multiplex Automated Genome Engineering, or MAGE, to program E. coli bacteria to produce five times as much of an antioxidant called lycopene than normal. In addition, using the process, which grafts pieces of synthetic DNA into the genomes of dividing cells, researchers generated 15 billion different genomic patterns in just three days. The process would normally take years, and could eventually be used to produce industrial chemicals, drugs, fuel and anything else that comes out of bacteria [Wired.com]. The process is significantly faster than previous techniques, in which scientists had to modify genes by changing bases one by one, for example, or by cutting genes from one genome and gluing them into another, modifying and inserting them one at a time.
(more…)
Scientists have long known that chimpanzees and other nonhuman primates can become infected with simian immunodeficiency virus, or SIV, a variant of HIV. It was thought, however, that only Asian macaque monkeys could die from the infection. But a new study published in Nature contradicts this assumption by finding that the virus can also be deadly to chimpanzees, humans’ closest relatives.
Some wild primates appear to have developed a way to keep SIV from becoming deadly, and scientists had hoped that studying chimpanzees could reveal how this mechanism works, possibly opening to the door to a human remedy. The new results suggest that it will not be possible to find the key to HIV immunity in the chimpanzee genome, as scientists had hoped. However, the study… sets the stage for researchers to gain insight into how HIV and SIV cause disease in their hosts by studying the responses of different primates to the viruses [Nature News].
(more…)
Why does a wiener dog look like a wiener, with its body poised on such short, stubby legs? Researchers say they’ve discovered the answer in a single genetic mutation that’s found in dachshunds, corgis, basset hounds, and other short-legged dog breeds. Study coauthor Heidi Parker says this gene may turn on growth mechanisms at the wrong time during foetal development, stunting the growth of long bones in the leg and making them curvy. The trait affects only the legs, unlike the small-all-over effect seen in miniature or toy breeds, such as poodles [Reuters].
The mutation popped up sometime after modern dogs diverged from wolves, researchers say, and it’s a dominant gene–meaning that a dog with only one copy of the gene will show obvious signs of it. Having joined the genetic repertoire of dogs, the gene was available for selection by dog breeders whenever they wanted to develop a downsized breed. The basset hound, for example, was bred for its short legs so people on horseback could keep up with it during hunting, Dr. Parker said [The New York Times].
(more…)
Lightning may have produced an important source of food for the planet’s first microbes: a rare form of phosphorus, according to a study published in Nature Geoscience.Researchers examined 10 chunks of sand melted together by lightning, formations called fulgurites, and found a high concentration of the minerals phosphite and hypophosphite in five of them. The soil surrounding the fulgurites contained only phosphate, not phosphites, suggesting that the lightning itself gave rise to phosphites.
“When lightning strikes, it acts like a mini smelter, and the organic molecules strip off oxygen from the phosphorus” [Scientific American], says study coauthor Matthew Pasek.The fact that microbes still have the machinery to digest these phosphites has long puzzled scientists, since phosphites are much rarer than other forms of phosphorus. Lightning forges about two to three tons of the [phosphite] compounds each year, barely enough for life to take notice. But modern bacteria still retain the ability to eat phosphite, which may be a holdover from antiquity [Discovery News].
(more…)
Of all vertebrate animals, turtles have one of the stranger body plans. Unlike all other four-limbed critters, which have their shoulder blades riding on the outside of their ribs, the turtle’s ribs are outside of its shoulder blades. This allows turtles to make their shell out of fused bones–the only animal to do so [ScienceNOW Daily News]. Now, scientists have determined that embryonic turtles develop this set-up through a neat bit of origami.
Researchers compared the developing embryos of turtles, chickens, and mice to watch for the point at which turtle development diverged. At first a turtle embryo grows much like a chicken or mouse. But then the developing body wall makes a critical fold, and the usual body plan starts to become an unusual turtle…. The developing muscle tissue that would lie along adult ribs in a standard amniote began to fold underneath itself in the turtle. This tissue tucked inward, bending up to lie below the developing ribs. On this kinked-under section, the shoulder blades, or scapulas, formed [Science News].
(more…)
Cotton-top tamarin monkeys can distinguish between “right” and “wrong” grammatical patterns, according to a study published in the journal Biology Letters. The findings suggest that humans share the ability with other species to identify certain patterns that are crucial to spoken communication.
Researchers wanted to find out if the monkeys, which do not communicate using spoken language, could recognize grammatical sequences. To do this, the scientists familiarized the monkeys with a series of sounds and patterns. They did this by first playing recordings of humans saying two-syllable nonsense words, and familiarized the monkeys with either a prefix or a suffix. “In the prefixation condition, they heard ’shoy-bi’, ’shoy-la’, ’shoy-ro’ and so on,” explained Ansgar Endress, lead author of the study. “The idea is that they get used to the pattern if you play it long enough” [BBC News].
The next day the scientists played new words for the prefix monkeys, but this time included some words in which the prefix had been changed to a suffix, like “na-shoy.” (They did the reverse for the suffix monkeys.) The scientists hypothesized that when the monkeys heard this “incorrect” sequence of sounds, they would be more likely to look at the loudspeakers from which the sounds were coming, the same way a human would. For example, if a person said he or she “walked to the store,” and then [used] the word “edwalk” instead of “walked,” the listener, used to hearing “walked” might stare at the speaker as if to say, “Huh?” [Discovery News].
(more…)
Japanese giant hornets can wreak havoc on a hive of Japanese honeybees, slicing off the heads of worker bees, feeding on the hive’s honey, and carrying back the larvae to feed to their own young. But the native bees do have one effective defense against the giant marauders, and it’s a battle plan that uses the bees’ one clear advantage: numbers. When a hornet scout appears, hundreds of bees instantly swarm around the invader in what’s known as a “bee ball.” In a new experiment, researchers say they’ve determined exactly how the bee ball kills.
Previously, scientists thought that the heat generated by the mass of vibrating bees killed the hornet. But in the study, published in the journal Naturwissenschaften, researchers found that temperature alone can’t do the trick. The hornets “can survive for 10 minutes at a temperature up to 47C (or 116 degrees Fahrenheit), and the temperature inside the bee balls does not rise higher than 46C” [BBC News], says lead author Fumio Sakamoto. The researchers determined that increased carbon dioxide levels inside the bee ball also plays a role.
(more…)
Don’t be alarmed, but on a remote island in Scotland the sheep are shrinking.
Instead of gradually increasing in size as expected due to evolution, the average weight of the wild sheep has decreased as average temperatures heat up. The discovery shows that a species’ response to global warming can be unpredictable, and can be based on multiple factors. According to a study published in Science, warmer and wetter winters have made it easier for smaller sheep to survive the hard months and go on to bear offspring, thus passing these “small” genes onto the next generation of sheep.
Since 1985, the average weight of the wild Soay sheep living on the island of Hirta has decreased by about 5 percent. Due to global warming, the winters on the Scottish isles are becoming becoming shorter and milder. That makes food more abundant and allows some of the smaller, more vulnerable and younger sheep to survive. Then they go on to have offspring that tend to be small themselves — and have a better chance of survival because of the increasingly mild winters. “The environmental and evolutionary processes are intertwined. There’s still natural selection, but it’s not leaving as big a signature as it used to. There’s still a disadvantage to being small, but not as much” [Time], says lead researcher Tim Coulson.
(more…)
In the heat and humidity of the tropics you might expect that mammals take it slow and easy–but on the genetic level, they’re accelerating past their mammalian relations that live in more temperate zones. A new study has discovered that tropical mammals are accumulating mutations more quickly and are therefore evolving faster, in a finding that could help account for the phenomenal biodiversity of the rainforests. But the study’s unexpected results have posed a puzzle for biologists. “[It's] an empirical pattern that is begging for an explanation” [The Scientist], says evolutionary ecologist James Brown, who was not involved in the current study.
Previous research had shown that plants and marine microorganisms evolve more quickly in the tropical zone near the equator, but scientists believed that pattern would hold true only for cold-blooded creatures, whose body temperatures and metabolisms are determined by the temperature of the surrounding environment. Scientists believe that this link between temperature and metabolic rate means that, in warmer climates, the germ cells that eventually develop into sperm and eggs divide more frequently. “An increase in cell division provides more opportunities for mutations in the population over a given time,” explained [lead researcher Len] Gillman. “This increases the probability of advantageous mutations that are selected for within the species” [BBC News]. But this mechanism wouldn’t work in warm-blooded mammals, whose body temperatures remain roughly constant regardless of environmental factors.
(more…)
A husband and wife team that for 35 years has researched finches’ evolutionary responses to environmental changes have won the prestigious Kyoto Prize in the basic sciences category. Peter and Rosemary Grant, both emeritus professors at Princeton University, have studied finches that lives on the Galapagos Islands for decades and will share the $515,000 prize. The Kyoto Prize is a Japanese award similar to the Nobel Prize.
The two evolutionary biologists devoted their careers to furthering Charles Darwin’s theory of evolution. Both 72, the Grants have been traveling regularly since 1973 to the Galápagos, the remote islands west of Ecuador. There, they have painstakingly recorded the characteristics of numerous varieties of finches [Philadelphia Inquirer]. Darwin stumbled upon these finches during his famous tour of the Galapagos Islands in 1835, later chronicled in his book The Voyage of the Beagle.
(more…)
