Attack of the flesh-eating parasitoid maggots!! Mutant mute crickets run rampant in tropical paradise!! The headlines may sound like a trailer for a cheap horror flick — but in fact, these sensationalist sound bites accurately describe the situation on the Hawaiian island of Kauai. The “flesh-eating parasitoid maggots” are the offspring of the fly, Ormia ochracea, which invaded Hawaii from North America, and the mutant crickets are the flies’ would-be victims. The flies follow the chirps of a calling cricket and then deposit a smattering of wriggling maggots onto the cricket’s back. The maggots burrow into the cricket, and emerge, much fatter, a week later — killing the cricket in the process. But this fall, biologists Marlene Zuk, John Rotenberry, and Robin Tinghitella announced a breakdown in business-as-usual in this gruesome interaction: in just a few years, the crickets of Kauai have evolved a strategy to avoid becoming a maggot’s lunch — but the strategy comes at a cost…Read more »
Cries of “Save the rainforest! Save the coral reefs!” may rally the conservation movement — but what about the arctic tundra, or the semiarid desert? Are those ecosystems unthreatened? Far from it; ecosystems all around the world and at every latitude are endangered in some way by human activity. So why do rainforests and reefs get so much attention? Well, one reason is the simple fact that largely tropical ecosystems (like rainforests and coral reefs) house more biodiversity — and so have more to lose than ecosystems further from the equator. Two or three times as many species live in the tropics as live in temperate regions — and perhaps ten times as many species live in the tropics as live in the arctic! Now, scientists think they understand why…Read more »
Lions and great white sharks may boast the most famous jaws in the animal kingdom — but theirs are nowhere near the fastest. In August 2006, biologists Sheila Patek, Andy Suarez, and colleagues awarded that honor to Odontomachus bauri, a tiny trap-jaw ant native to Central and South America, whose mandibles (or jaws) can snap shut at a remarkable 145 miles per hour! That rapid-fire bite is quick enough to decapitate a soldier termite before it launches its own defense — a jet of sticky fluid that entangles and incapacitates predators. The ant’s quick bite also does double-duty as an escape mechanism: when faced with a larger nest intruder, an ant may use its jaws to strike the invader, simultaneously flinging itself 8 or 9 inches away (known as the “bouncer defense”) — or it may snap its jaws against the ground, propelling itself into the air and out of the way of such dangers as an anteater’s tongue (known as an “escape jump”).Read more »
Evolution is a slow process through which species gradually adapt to their environments, right? Well perhaps sometimes, but not for the blue mussel. In August of 2006, Aaren Freeman and James Byers of the University of New Hampshire announced that the blue mussel has evolved defenses against a new invasive predator in just 15 years! Compared to the million-year time scale of the fossil record, that’s the blink of an eye.
The Asian shore crab invaded the eastern coast of the U.S. about 15 years ago and began foraging on the native blue mussel, which, at the time, had no defenses against the exotic, aggressive crab. But these days, the blue mussel responds to the crab’s presence by building up a thicker shell over the course of a few months. That extra buttressing helps thwart the crab’s attacks — and makes the mussel a harder nut to crack!Read more »
A six-ton carnivore with teeth the size of bananas is bound to make the news — even if that animal has been extinct for 65 million years. The recent spate of T. rex discoveries that have made headlines confirms this species’ star status. In June 2006, T. rex was reported to have had much better vision than previously thought — perhaps 13 times sharper than human vision! In July, a team of researchers estimated that T. rex had an average body temperature just 7 or 8°F lower than our own mammalian temperature. And most recently, biologists published work suggesting that, though relatively secure as youngsters, tyrannosaurs faced new dangers as they reached sexual maturity — causing their teen death rate to soar!Read more »
Global warming is, quite literally, a hot topic. Though the mechanism of global warming — temperature rise due to humans’ production of heat-trapping greenhouse gases — may not be big news, the projected impact of global warming often makes headlines. Al Gore’s recent documentary on the topic has focused even more attention on the potentially disastrous effects of even a few degree temperature rise. Whole island countries could disappear into the ocean as polar ice melts and sea level rises. Hurricanes and tropical storms may intensify. And ecological interactions could change in unpredictable ways. For example, a recent news story reports that melting sea ice may be forcing some polar bears into cannibalism now that fewer seal hunting opportunities are available. Increasingly, it seems, global warming shows up on the front page of the newspaper — but the evolutionary implications of global warming often remain hidden.Read more »
Ever wonder why the Amazon is loaded with different species while the Antarctic boasts just a few? Well, so did New Zealand biologists Shane Wright, Jeanette Keeling, and Len Gillman — and the answer they discovered would be no surprise to any sun-worshipping tourist: duh, it’s the weather! The team compared DNA from tropical plant species with the DNA from species in cooler climates and found that the tropical species’ DNA had evolved about twice as fast as that of their cold-weather cousins! The researchers chalked this difference up to the warmer weather of the tropics — which encourages lush growth, higher metabolic rates, and hence, higher rates of mutation. Those high mutation rates could boost the pace of speciation — resulting in a myriad of tropical species.Read more »
Tiktaalik, of course. Pronounced tik-TAA-lik, this 375 million year old fossil splashed across headlines as soon as its discovery was announced in April of 2006. Unearthed in Arctic Canada by a team of researchers led by Neil Shubin, Edward Daeschler, and Farish Jenkins, Tiktaalik is technically a fish, complete with scales and gills — but it has the flattened head of a crocodile and unusual fins. Its fins have thin ray bones for paddling like most fishes’, but they also have sturdy interior bones that would have allowed Tiktaalik to prop itself up in shallow water and use its limbs for support as most four-legged animals do. Those fins and a suite of other characteristics set Tiktaalik apart as something special; it has a combination of features that show the evolutionary transition between swimming fish and their descendants, the four-legged vertebrates — a clade which includes amphibians, dinosaurs, birds, mammals, and of course, humans.Read more »
When the kakapo, a critically endangered parrot, makes the papers, it’s generally not good news. In 1995, just 51 of these large flightless birds waddled around the forests of island sanctuaries in their native New Zealand. The kakapo used to be more widespread, but having evolved with few natural predators on the islands, the birds were poorly adapted for the modern world — and the rat and stoat invasions that came along with it. Already slow-moving and largely defenseless, the kakapo made even easier prey for those mammals by virtue of their conspicuous smell. Biologists became so concerned about the species’ extinction that, beginning in 1982, they gathered up all the remaining wild kakapo and moved them to remote islands that had been cleared of all mammals. Nevertheless, even there under the fastidious care and regular feeding provided by biologists, the kakapo did not flourish — there are now just 86 of them alive. Now we may understand why. In January 2006, biologists revealed how the kakapo’s problems might largely come down to sex — and how a simple diet could help save them from extinction.Read more »
The tests confirm, beyond a shadow of doubt, that Roger Keith Coleman did it, but Alan Crotzer did not. In 1992, Coleman was executed for the rape and murder of his sister-in-law. In 1981, Crotzer was sentenced to 130 years in prison for a robbery and pair of rapes. Though the crimes themselves are old, judgments long since rendered, and punishments already meted out, for many observers, the actual guilt or innocence of these two defendants for two different crimes was only just settled by an increasingly important test: the DNA fingerprint. Recent DNA tests revealed that it was, indeed, Coleman’s semen in the body of his victim, and that he had actually committed the crime for which he was executed more than 10 years ago. And recent DNA tests revealed that Crotzer is not a rapist and has spent 24 years in prison for crimes he did not commit.Read more »
The zebrafish, a small but flashy aquarium pet, may seem like an unlikely informant on questions of human genetics — yet its genome could hold the keys to understanding many diseases and, surprisingly, the genes underlying human skin color. In December 2005, a cancer research team headed by Keith Cheng at Penn State University announced that their studies of the mutant “golden” zebrafish had taken an unexpected turn: they had discovered a single human gene that accounts for about 30% of the difference in skin color between African and European descendants. This color difference can be traced back to a tiny difference in two versions (or alleles) of the gene. The “G” allele is common among African descendants and causes more of the dark pigment melanin to be present in skin cells, while the “A” allele is common among European descendants and causes less melanin in skin cells.Read more »
The previously unknown SARS virus generated widespread panic in 2002 and 2003 when the airborne germ caused 774 deaths and more than 8000 cases of illness. But where did this mystery virus come from? Scientists immediately suspected that it had jumped to humans from some other organism. In May of 2003, attention focused in on cat-like mammals called civets. Infected civets were discovered at a live animal market in southern China (where they are occasionally eaten). However, since further searches failed to turn up more tainted civets, scientists concluded that they were not the original source of SARS and continued their quest. Then in the fall of 2005, two teams of researchers independently discovered large reservoirs of a SARS-like virus in Chinese horseshoe bats. The bats now appear to be both culprit and victim in this mystery: they are the carriers of the SARS virus, but the virus is probably only passed to humans through intermediate hosts when bats are captured and brought to market.