2012 Stories
Grasshoppers change their tune. Is it evolution in action?
Whizzing down the interstate, the sounds that concern most of us include the radio’s tuning, conversation with our fellow passengers, and, of course, the ominous howl of a siren approaching from behind. But just outside the car door, the soundscape is quite different. On busy thoroughfares, traffic noise approximates a non-stop, low-pitched roar that necessitates shouting to communicate if one is unlucky enough to need to change a tire at the side of the road. Now, new research shows that it is not just humans who strain to be heard over the din of a highway …
Read more »A new look at dinosaur fossils pushes back the evolution of feathered wings
Last month, paleontologists from Canada, the U.S., and Japan announced an exciting discovery: feathered dinosaur fossils in North America. When Ornithomimus edmontonicus was first studied in the 1930s, its ostrich-like skeleton earned it a name that translates to “bird mimic.” Now new fossils and a re-evaluation of old ones have revealed that its body covering also fits the moniker. A newly unearthed, year-old juvenile specimen is covered in downy, hair-like feathers, and re-examination of an adult specimen turned up traces of standard feathers with a central shaft. While most popular reporting has focused on the idea that these shafted feathers may have been used to attract mates, the real news in this research lies elsewhere …
Read more »Acidic oceans prompt evolution
It’s no secret that greenhouse gases warm the planet and that this has dire consequences for the environment — whole islands swallowed up by rising seas, animal and plant species stressed by higher temperatures, and upsets in ecological interactions as populations move to cooler areas. However, carbon dioxide has another, less familiar environmental repercussion: making the Earth’s oceans more acidic. Higher levels of carbon dioxide in the atmosphere mean that more carbon dioxide dissolves in the ocean. This dissolved carbon dioxide forms carbonic acid — the same substance that helps give carbonated beverages their acidic kick. While this process isn’t going to make the ocean fizzy anytime soon, it is introducing its own set of challenges for marine organisms like plankton and coral. Recent research suggests that evolution may have the power to temper some of this shake-up …
Read more »What comes after mass extinctions?
Extinction is a fact of modern life. Humanity’s relentless encroachment on the wilderness has marred the diversity of life with conspicuous gaps where the Tasmanian tiger, the Passenger Pigeon, the Ivory-billed Woodpecker, and countless others used to be. As these extinctions accumulate, the Earth inches closer and closer to its sixth mass extinction. We are all too familiar with the concept of mass extinction — a disaster strikes and sets off a chain of events that result in a massive die-off. But you may not have considered what comes next: what happens to surviving species in the wake of a massive extinction event? Recent research suggests that mass extinctions shake up life on Earth in surprising ways …
Read more »Lessons for today in ancient mass extinctions
If you follow environmental news at all, you’ll be familiar with the most common cause of extinction in the world today: habitat loss. Habitat destruction threatens the survival of some the world’s most charismatic organisms — animals like the giant panda, the Sumatran tiger, and the Asian elephant. Humans have encroached on the wilderness in order to farm, mine, log, and build, and in the process, we’ve pushed the natural inhabitants of those areas into smaller and smaller refuges. Making matters worse, global climate change caused by our production of greenhouse gases is altering the environments within those refuges, forcing species to contend with new challenges. While these might seem like entirely modern problems, recent research indicates that’s not the case — and that current levels of habitat loss and climate change could have devastating consequences …
Read more »Climate change causes loss of genetic diversity
If you’d visited Tuolumne Meadows in Yosemite National Park 100 years ago, you probably would have encountered the alpine chipmunk, Tamias alpinus. Today, however, park visitors will have to hike up a nearby mountain to see one of these critters. That’s because this species is sensitive to temperature — and over the last hundred years of global climate change, Yosemite has warmed by about 5.5 degrees Fahrenheit. As the temperature increased, the chipmunks retreated to higher and higher elevations where it was cooler. Today, they occupy a fraction of their original range. If climate change continues, they could be squeezed right off the tops of their mountains and out of existence. Now, new research has revealed that the chipmunks (and probably other temperature-sensitive species) are losing not just territory and individuals, but genetic variation as well — a hidden threat that adds to the risk of extinction.
Read more »Evolutionary history in a tiny package
Scientists discover new species all the time, but usually these new species are microbes, plants, insects, and other forms of non-vertebrate life. Few vertebrate species have thus far evaded the curious gaze of biologists intent on understanding the diversity of life on Earth — that is, unless the vertebrate in question happens to be very, very tiny. Last month, scientists announced the discovery of not one, but four miniscule lizard species. The smallest of these new chameleons, which live in the far north of the African island of Madagascar and inhabit leaf litter, reaches an adult body size of just two centimeters. Most popular media stories have focused on the impressively small size of these critters — it’s hard not to coo over an animal that is dwarfed by a matchstick — but the evolutionary story behind the discovery is equally interesting …
Read more »Hybrid sharks aren’t “trying” to adapt
Last month, biologists announced the discovery of hybrid sharks in Australian waters. The new sharks may not warrant a marine park attraction — they look much like their closely-related parent species — but do represent an unexpected twist of biology and evolution. This is the first time that scientists have found evidence of shark hybridization — an event that was thought to be rare because, unlike the many fish that simply release eggs and sperm into the water, sharks mate. Clearly, though, the widely-distributed common blacktip shark and the Australian blacktip shark (which is restricted to northern and eastern Australia) have few qualms about each other: 57 apparently healthy hybrid individuals were discovered in the first investigation of these animals. What does this mean for the future evolution of blacktip sharks?
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