Saturday, July 30, 2005

548: New animal species evolves via hybridization

New Scientist Breaking News - New animal species evolved in an instant:

A new species of insect may have arisen in an evolutionary eye-blink as a result of cross-species mating. The discovery suggests that hybridisation - well known to be an important force in producing new plant species - may also be widespread in animals. Until now, it had been assumed that new animal species almost always arise by gradually splitting off from an existing lineage.

The probable new species belongs to a group of flies known as fruit maggots – highly specialised fruit parasites in which each species infests its own particular plant species.

In 1997, Bruce McPheron and his colleagues at Pennsylvania State University in University Park, US, noticed a fruit maggot infestation on introduced Asian honeysuckle bushes in north-eastern Pennsylvania. Since the host plant had only been in North America for about 250 years, the researchers decided to investigate how it ended up with such specialised pests.

They found that, genetically, the honeysuckle maggots looked like the result of hybridisation between two fruit maggot pests of native species, the blueberry maggot and the snowberry maggot. For example, earlier studies had shown that each of the latter two species bore certain unique gene variants found in no other fruit maggot species - yet the honeysuckle maggots carried variants from both blueberry and snowberry maggots.

547: Banning Baytril from poultry farms

Citing Human Threat, U.S. Bans a Poultry Drug - New York Times:

The Food and Drug Administration said Thursday that it was banning the use of the antibiotic Baytril in poultry because of concerns that it could lead to antibiotic-resistant infections in people.

The agency's commissioner, Lester M. Crawford, ordered that approval for use of the drug, known generically as enrofloxacin, be withdrawn effective Sept. 12.

Baytril, manufactured by Bayer of Leverkusen, Germany, is in the same family as the popular drug Cipro, which is used in humans.

Dr. Crawford cited particular concerns about campylobacter bacteria, a growing source of serious illness in humans. Antibiotics used to treat the bacteria can be less effective if the germ has already developed resistance to Baytril, the agency said.

Campylobacter is commonly found in the intestinal tracts of turkeys and chickens, where it does not generally cause illness, Dr. Crawford said in his order.

Use of enrofloxacin in poultry does not eliminate campylobacter from the birds, but instead results in the development of bacteria resistant to this type of drug, he said.

Resistant bacteria may be present in poultry sold at retail outlets. Dr. Crawford noted that since the drug was introduced for poultry in the 1990's, the proportion of resistant campylobacter infections in humans has risen significantly.

That can prolong the length of infections in people and increase the risk of complications, he said. Complications can include reactive arthritis and blood stream infections. A Bayer spokesman, Bob Walker, said company officials were reviewing the ruling from a scientific and legal position before deciding whether to appeal it.
Antibiotic resistance is evolution at work, and overuse of antibiotics in farming exposes humans to greater risks. Baytril resistant bacteria are also resistant to Cipro, which you'll remember from the anthrax scare.

546: Water on Mars

Water ice spotted in crater at Martian north pole | Science Blog:

These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, show a patch of water ice sitting on the floor of an unnamed crater near the Martian north pole.

The HRSC obtained these images during orbit 1343 with a ground resolution of approximately 15 metres per pixel. The unnamed impact crater is located on Vastitas Borealis, a broad plain that covers much of Mars's far northern latitudes, at approximately 70.5° North and 103° East.

The crater is 35 kilometres wide and has a maximum depth of approximately 2 kilometres beneath the crater rim. The circular patch of bright material located at the centre of the crater is residual water ice.

This white patch is present all year round, as the temperature and pressure are not high enough to allow sublimation of water ice.

It cannot be frozen carbon dioxide since carbon dioxide ice had already disappeared from the north polar cap at the time the image was taken (late summer in the Martian northern hemisphere).
Water on Mars gives better odds of life on Mars.

Sunday, July 24, 2005

545: Reinforcement in butterflies

BBC NEWS | Science/Nature | Butterfly unlocks evolution secret:

researchers studying a family of butterflies think they have witnessed a subtle process, which could be forcing a wedge between newly formed species.

The team, from Harvard University, US, discovered that closely related species living in the same geographical space displayed unusually distinct wing markings.

These wing colours apparently evolved as a sort of "team strip", allowing butterflies to easily identify the species of a potential mate.

This process, called "reinforcement", prevents closely related species from interbreeding thus driving them further apart genetically and promoting speciation.
Speciation at work. Evolutionary theory predicts this process, and experimental evidence bears it out.

Wednesday, July 13, 2005

Don't trip

At TfK.

Sunday, July 10, 2005

544: Researchers unearth 11,000-year-old bones

Researchers unearth 11,000-year-old bones |

Remnants of early humans in the Great Plains were successfully located at a dig in northwestern Kansas by a group of researchers from the Kansas Geological Survey, at the University of Kansas, and the Denver Museum of Nature and Science.

The survey team… found bones from a bison killed by humans, and that shows evidence of some of the earliest human life in the Great Plains.

The bison bones date back to the Clovis period that began 12,200 years ago. The director of the dig, Kansas Geological Survey archaeological geologist Rolfe Mandel, said, “This find marks the first recorded Clovis period human campsite.”
More evidence of human evolution from right here in Kansas.

543: Jumping genes

From The Loom, Tangling the Tree:

Scientists at the European Bioinformatics Institute created [a phlyogeny of bacteria] by comparing 184 microbes. The scientists first identified genes that the microbes all inherited from a common ancestor that they then passed down in conventional parent-to-offspring fashion. By comparing their different sequences, the scientists were able to draw a conventional tree of the sort Darwin had in mind. Next, they scanned the genomes of these microbes for jumping genes. They drew the jumpers as vines from one branch to the next. They then produced this three-dimensional picture.

As you can see, the branches rise from a common ancestor, but they are enmeshed in vines. What's particularly fascinating about it is the way in which the vines connect the branches. It is not a random mesh. Instead, a few species are like hubs, with spokes radiating out to the other species. This is the same pattern that turns up in many networks in life, from the genes that interact in a cell to the nodes of the Internet.
Evolutionary hypotheses tested, and new information on the process of life's evolution.

Wednesday, July 06, 2005

539-542: Evolution of Language

Carl Zimmer summarizes recent work on Mice, Monkeys, and Muttering. The evolution of a gene tied to language ability maps out across the tree of life, showing how linguistic ability in humans evolved.

Tuesday, July 05, 2005

538: Lotuses evolve smaller on human picking

AP Wire | 07/04/2005 | Lotuses evolve smaller on human picking:

Take the case of the snow lotus, a rare plant that grows only at high levels in the Himalayas.

Researchers have discovered that one species of the plant has been shrinking over time - the one people like to pick.

A snow lotus species called Saussurea laniceps is used in traditional Tibetan and Chinese medicine and is increasingly sought after by tourists. The largest plants are picked, and that occurs during their only flowering period.

The result is that only smaller, unpicked plants go to seed.