'Regressive Evolution' In Cavefish: Natural Selection Or Genetic Drift:
"Regressive evolution," or the reduction of traits over time, is the result of either natural selection or genetic drift, according to a study on cavefish by researchers at New York University's Department of Biology, the University of California at Berkeley's Department of Integrative Biology, and the Harvard Medical School. Previously, scientists could not determine which forces contributed to regressive evolution in cave-adapted species, and many doubt the role of natural selection in this process. Darwin himself, who famously questioned the role of natural selection in eye loss in cave fishes, said, "As it is difficult to imagine that eyes, although useless, could be in any way injurious to animals living in darkness, I attribute their loss wholly to disuse."
Antarctic Warming To Reduce Animals At Base Of Ecosystem, Shift Some Penguin Populations Southward:
The warming most global climate models predict will do more harm than simply raise the sea levels that most observers fear. It will make drastic changes in fragile ecosystems throughout the world, especially in the Antarctic. A warming trend during the last few decades in the Antarctic Peninsula has already forced penguin populations to migrate south and perhaps diminished the abundance of krill that are at the base of the massive food chain at the bottom of the world.
Fatal Attraction: Elephants And Marula Fruit:
Being female can be a risky business, especially if you are a Marula tree in Africa receiving the attention of elephants. The tasty, nutritious and vitamin C-rich Marula fruits are much sought after by both man and animals. It is a stable "wild food" and base for the popular Amarula liquor. But Marula has separate male and female trees so fruiting females attract browsing elephants, which cause damage to branches and bark.
Lots more cool stuff under the fold....
World's Largest Field Experiment Examines Long-term Effects Of Global Change On Forest Dynamics:
The Smithsonian Tropical Research Institute (STRI) has received an $8 million grant from HSBC to fund the world's largest field experiment on the long-term effects of global change on forest dynamics. A new Global Earth Observatory system will compare climate change and forest carbon data from 17 countries around the world.
The San Francisco area is well-known for its beautiful waters. In fact, it is one of the most biologically productive areas in the United States' waters. But with global warming, says Natural Sciences and Engineering Research Council (NSERC) grantee Vera Pospelova, those waters are going to change. Pospelova studies sedimentary records of dinoflagellates -- small plankton creatures, eaten by fish, that depend on the sun for their survival. There are dozens of species of these creatures, but the ones that produce toxic blooms concern her the most.
Bacterial Gene That May Affect Climate And Weather:
A University of Queensland microbiologist is part of an international team that has identified a bacterial gene that may affect climate and weather. Dr Phil Bond, from UQ's Advanced Wastewater Management Centre, and his former colleagues at the University of East Anglia in England, have found how a particular type of marine bacteria - Marinomonas - generates a compound that is a key component in global sulfur and carbon cycles.
Cold Climate Produced By Algae Contributed To Onset Of Multicellular Life:
The rise of multicellular animals about 540 million years ago was a turning point in the history of life. A group of Finnish scientists suggests a new climate-biosphere interaction mechanism for the underlying processes in a new study, which will be published on February 14, 2007 in PLoS ONE, the international, peer-reviewed, open-access, online publication from the Public Library of Science (PLoS). The theory invokes cold, ice-containing climates as a key precursor for multicellular life. If the model turns out to be correct, one can assume that complex life might exist also around stars which are more massive and short-lived than the Sun. Since remote sensing of highly reflecting glaciers should be possible, this may help designing future astronomical observation programmes for earthlike extrasolar planets.
World Shark Attacks Rise Slightly But Continue Long-term Dip:
Shark attacks edged up slightly in 2006 but continued an overall long-term decline as overfishing and more cautious swimmers helped take a bite out of the aggressive encounters, new University of Florida research finds. The total number of shark attacks worldwide increased from 61 in 2005 to 62 in 2006 and the number of fatalities remained stable at four, far below the 79 attacks and 11 fatalities recorded in 2000, said George Burgess, director of the International Shark Attack File housed at UF's Florida Museum of Natural History.
Rats' Senses A Whisker Away From Humans:
The sophisticated way in which rats use their whiskers in their surrounding environments show significant parallels with how humans use their fingertips, according to new research carried out at the University of Sheffield. Rats are tactile animals that use their facial whiskers as their primary sense. These whiskers are swept back and forth, or 'whisked´ many times each second. Research carried out by Dr Tony Prescott and colleagues from the University´s Department of Psychology found that these whisker movements are actively controlled like human fingertips.
What Recognizes What In Plant Disease Resistance?:
Plants have an immune system that resists infection, yet 10% of the world's agricultural production is lost annually to diseases caused by bacteria, fungi, and viruses. Understanding how disease resistance works may help combat this scourge. In a new study published online this week in the open-access journal PLoS Biology, Tessa Burch-Smith, Savithramma Dinesh-Kumar, and colleagues show how one aspect of the plant immune system is defined by the gene-for-gene hypothesis: a plant Resistance (R) gene encodes a protein that specifically recognizes and protects against one pathogen or strain of a pathogen carrying a corresponding Avirulence (Avr) gene.
Is There A Pilot In The Insect?:
When they fly, insects use their vision for piloting, just like human pilots. The electric signals from their facetted eyes travel through specialized neurons to stimulate the wing muscles, which let the insects correct their flight and avoid crashes. Could these same neurons be used in a sort of "automatic pilot"? This is what Nicolas Franceschini, Franck Ruffier and Julien Serres have just shown. These biorobotics specialists from the Movement and Perception Laboratory (CNRS/Université de la Méditerranée) in Marseille, France have revealed an automatic mechanism called the "optic flow regulator" that controls the lift force. The researchers obtained these results by modeling the overland flight navigation of insects using experiments carried out on OCTAVE, a captive flying robot microhelicopter that can reproduce much of the mysterious natural insect behavior. Their work is published online in Current Biology, February 8, 2007.
Grizzly Bears Feast On Diverse Diet:
There's no such thing as picky grizzly bears--they'll eat almost anything they can find. A new University of Alberta study that tracked food habits of the Alberta grizzly bear living in the foothills sheds some light on the animal's varied diet and their activity pattern. "Alberta bears have remarkably diverse diets," said Dr. Mark Boyce, biological sciences professor at the U of A and co-author on the study. "They'll eat just about anything."
Paper Challenges Controversial Theories About Mode Of Formation Of Spinal Precursors:
Tadahiro Iimura, Ph.D., Senior Research Associate in the Pourquié Lab, is the lead author on a paper challenging controversial theories about the mode of formation of the vertebral column precursor, known as the paraxial mesoderm. The paper, "Dual mode of paraxial mesoderm formation during chick gastrulation," which was posted to the Web site of the Proceedings of the National Academy of Sciences, demonstrated that the cellular mode of paraxial mesoderm formation is largely conserved across vertebrates. "Until now, we believed that spine precursors developed one way in lower vertebrates and another way in birds, reptiles, and mammals," said Olivier Pourquié, PhD., Stowers Institute and Howard Hughes Medical Institute Investigator. "These findings demonstrate that both of those development modes are present in both lower and higher vertebrates."
Americans Cultivated And Traded Chili Peppers 6,000 Years Ago:
Smithsonian researchers and colleagues report that across the Americas, chili peppers (Capsicum species) were cultivated and traded as early as 6,000 years ago--predating the invention of pottery in some areas of the Americas. The researchers analyzed starch grains to trace the history of chili peppers in the Americas. Their findings contribute significantly to the current understanding of ancient agricultural practices in the Americas. The report is published in the Feb. 16 issue of the journal Science.
Out Of Africa -- Bacteria, As Well: Homo Sapiens And H. Pylori Jointly Spread Across The Globe:
When man made his way out of Africa some 60,000 years ago to populate the world, he was not alone: He was accompanied by the bacterium Helicobacter pylori, which causes gastritis in many people today. Together, man and the bacterium spread throughout the entire world. This is the conclusion reached by an international team of scientists led by Mark Achtman from the Max Planck Institute for Infection Biology in Berlin, Germany. The researchers also discovered that differences developed in the genetic makeup of the bacteria populations, just as it did in that of the various peoples of the world. This has also given scientists new insight into the paths taken by man as he journeyed across the Earth (Nature online, February 7, 2007).
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I read what I thought was a more interesting treatment of the evolutionary aspects of eye loss in cavefish in Seed Magazine, one of the magazines given out at your Science Blogging Conference. I wrote a short review of the article on my blog.