Saturday, July 15, 2006
There's more life in India than we have counted so far. Yet, for a change this population increase in our country is not at all crisis-inducing.
It's being counted as a blessing and is being celebrated as our contribution to global biodiversity. This good news story begins with ecologically significant events from the recent past.
Like the first scientific sighting of a primate, Macaca munzala, in the Arunachal Pradesh's forests. It's the first new macaque species to be identified in a hundred years. About the same time came the discovery of a Jurassic frog in the Western Ghats. Ancestors of this primitive and purple-bodied pignose frog originally hopped around the Gondwana landmass before the Indian subcontinent was created.
And in the Northeast, wildlife experts are trying to capture on camera the spectacular green, crimson and grey-feathered Liochichla, a possible new bird species that may soon expand our avian horizons.
Of course, none of these beings are new to the earth. Unclassified and unstudied so far, the significance of these species comes from being "new to science" and formal studies such as DNA analysis, community ecology and biogeography.
Could a predatory relationship between two ancient species reveal an early driving force of evolution? Absolutely, according to Mark Wilson, professor of geology at The College of Wooster, and Paul Taylor of The Natural History Museum in London.
In an article from the July issue of Geology, titled "Predatory Drill Holes and Partial Mortality in Devonian Colonial Metazoans," Wilson and Taylor explain how a 380-million-year-old animal, known as a hederellid, reacted to repeated attacks by an unknown assailant.
Hederellids are extinct colonial animals that made skeletons of branching tubes. According to the two scientists, new evidence shows that hederellids responded to these predators, who drilled through their tubes (most likely with a radula-like device), by plugging the holes with skeletal patches secreted by internal tissues. They also closed off damaged sections with skeletal plugs.
Friday, July 14, 2006
As the August 1, 2006, Kansas primary election approaches, evolution is a burning issue. The state board of education is at the center of the furor, of course; in November 2005, the board voted 6-4 to adopt a set of state science standards that were rewritten, under the tutelage of local 'intelligent design' activists, to impugn the scientific status of evolution.
The standards were denounced by a host of critics, including a group of 38 Nobel laureates (PDF), the National Science Teachers Association, the National Academy of Sciences, the American Association for the Advancement of Science, the American Institute for Biological Sciences, the committee that wrote the original standards, the authors of the Fordham Foundation's report (PDF) on state science standards, and the Kansas Association of Teachers of Science.
In addition, the standards have been rejected by at least one local school district. Because the terms of five of the seats on the board expire in 2006, the primary election (as well as the general election in November) afford a chance for supporters of evolution education to change the balance of power on the board, just as they did in 2000.
Queensland, Australia: What is said to be the world's oldest known crocodile fossil will be revealed to the public today in the area where it was discovered 10 years ago.
Isisfordia Duncani, thought to be 95 to 98 million years old, made headlines around the world when it was revealed last month because crocodiles were previously thought to have originated in North America or Europe.
It will be housed in a $1.5 million outer Barcoo interpretation centre in western Queensland being opened today.
Competition between two species of finch in the Galapagos has caused the beak size of one species to shrink, and scientists have watched it happen. Detailed observations of the birds, which Darwin famously studied while formulating his theory of evolution, have provided one of the best descriptions of a characteristic trait evolving in the wild.
In a paper appearing in this week's issue of Science, Peter and Rosemary Grant, both biologists at Princeton University, New Jersey, describe the struggle between the medium ground finch (Geospiza fortis) and the large ground finch (Geospiza magnirostris).
In the harsh environment of the tiny Galapagos island Daphne Major, the medium ground finch subsists mainly on small seeds. Members of the population with sufficiently large beaks, however, have been able to tackle the bigger seeds of a low herbaceous plant called Tribulus cistoides.
These larger-beaked birds met with competition upon the arrival of the bigger G. magnirostris, a few members of which flew to the island in 1982 and set up a colony. Their universally large beaks made cracking into big seeds an easy job.
A Tribulus seed is like 'an orange wedge with two great big long spines sticking out the back of it,' says Dolph Schluter, a zoologist at the University of British Columbia in Vancouver, Canada, who worked with the Grants when he was a graduate student. 'The medium ground finches twist off the ends, but it takes a lot of force to do it. G. magnirostris has no problem with it.'
The two species lived fairly happily together for many years, until two factors forced the birds into harsh competition.
The above news report is also available here
Abstract of the Science report (Evolution of Character Displacement in Darwin's Finches) available here
Thursday, July 13, 2006
Biologists at Washington University in St. Louis have made an important breakthrough in understanding a pathway plant cells take to silence unwanted or extra genes using short bits of RNA. Basically, they have made it possible to see where, and how, the events in the pathway unfold within the cell, and seeing is believing, as the old saying goes.
Craig Pikaard, Ph.D., Washington University professor of biology in Arts & Sciences and his collaborators have described the roles that eight proteins in Arabidopsis plants play in a pathway that brings about DNA methylation, an epigenetic function that involves a chemical modification of cytosine, one of the four chemical subunits of DNA. Without proper DNA methylation, higher organisms from plants to humans have a host of developmental problems, from dwarfing in plants to certain tumors in humans, and death in mice.
One role of DNA methylation is to turn off repetitive genes, such as transposable elements that can move or spread throughout a genome and disrupt other gene functions if left unchecked.
There is also interest in DNA methylation because understanding how some genes are selectively silenced and how silenced alleles can be turned on again may someday have practical benefits.
A new DNA mapping technique may solve an ancient mystery: Do modern humans carry Neanderthal genes?
On a forest-choked expanse of land that will one day be called Germany, a herd of bison huddles together to ward off the cold. Hidden in the foliage nearby squats a man. Like the animals he's hunting, he has evolved over hundreds of thousands of years to cope with freezing temperatures. His massive jaw juts out, and his forehead slopes forward to form a heavy brow - providing a thick layer of bone that protects his sinuses and large brain from the icy air. His barrel-shaped body and short limbs help him retain heat. So do the furs he wears and the fires his family builds in the cave where they live.
Forty thousand years after the bison hunter went down, a tall, lanky man with disheveled white hair and scuffed hiking shoes is using one of his species' own state-of-the art tools to pulverize the Neanderthal even further. On a warm spring day in Walnut Creek, California, geneticist Eddy Rubin stands surrounded by huge glass tanks. Inside, robotic arms move with frenetic precision over plates holding genetic material, reducing the Neanderthal's remains to tiny strings of nucleotides and producing the world's first extended sequence of Neanderthal DNA.
Wednesday, July 12, 2006
'Killer kangaroos' evidence found: Palaeontologists digging in northern Australia have found fossil evidence of several new species - including a 'killer kangaroo'.
The flesh-eating marsupial would have lived between 10 and 20 million years ago, scientists say.
The research team has also unearthed evidence of a large carnivorous bird dubbed the 'demon duck of doom'.
The dig site in Queensland has yielded remains of at least 20 previously unknown creatures.
The team from the University of New South Wales made the discoveries in the Riversleigh fossil fields in the north-west of the state.
Fossil News: Luca and Daniel Haas got an opportunity to do something Monday that few kids their ages will ever get to do. They held the giant tooth of an extinct mammal in their hands.
They were standing at the site of the owner's final resting place. It was uncovered Friday, some 11,000 years after the mastodon died in a swampy area that borders what is now Rochester Hills and Auburn Hills.
'I couldn't believe it,' said 12-year-old Daniel, who has an interest in geology. 'Right here in Auburn Hills ... it's amazing.'
His sister, Luca, 10, was equally impressed.
'It's awesome,' echoed Luca, who had rushed over with her mother and siblings after a friend told them a mastodon had been uncovered. 'I didn't know they were in Michigan.'
Scientists from the Cranbrook Institute of Science sifted through the site Monday morning in search of more remains to add to the ones recovered by road construction crews on Friday.
Tuesday, July 11, 2006
The bigger a dinosaur was, the warmer its blood, a study of the big beasts' fossil remains shows.
Dinosaurs were long considered to be cold-blooded reptiles.
More recently, some researchers have proposed that the extinct creatures actively regulated their body temperature like mammals.
A study in the journal Plos Biology now suggests this is not the case, but that bigger dinosaurs may have lost heat so slowly that they stayed warm anyway.
Reptiles tend to be cold-blooded ectotherms, whose internal body temperature is dependent on the outside environment. For example, lizards and snakes will sun themselves on rocks in order to heat themselves up.
Birds and mammals, on the other hand, tend to be warm-blooded endotherms.
Biologists generally accept that evolutionary change can take from decades to millennia, while ecological change can occur over mere days or seasons. However, a new Cornell study shows that evolution and ecology can operate on the same time scale.
When evolution occurs so quickly, the researchers conclude, it can change how populations of various species interact. Ecologists need to consider such evolutionary dynamics in their studies because evolution could affect populations being studied. This insight is critical to predicting the recovery time needed for threatened populations or for predicting disease dynamics, says Justin Meyer '04, who conducted the study as an undergraduate student with Cornell ecologists Stephen Ellner, Nelson Hairston and colleagues.
The study is published in the July 11 issue of Proceedings of the National Academy of Sciences:
Prey evolution on the time scale of predator- prey dynamics revealed by allele- specific quantitative PCR (Abstract available here)
Monday, July 10, 2006
The Scopes "monkey" trial, which began 81 years ago today, is one of the most frequently revisited events in American history.
As creationism keeps popping up in new guises, such as Creation Science and Intelligent Design, the Scopes trial gets dusted off for each new generation.
The trial has been an evergreen subject for dramatizations and documentaries on stage, film, and television, most recently on the History Channel series 10 Days That Unexpectedly Changed America.
But how true to life have these accounts of the Scopes trial been? Here are some questions and answers to help our readers keep things straight.
Sunday, July 09, 2006
Revisiting intelligent design: Less than five months after evolution won a round in the State Board of Education, some board members want to reopen the debate.
Colleen Grady, a board member from the Cleveland suburb of Strongsville, wants to add guidelines to the state science standards for teaching on such topics as evolution, global warming, stem-cell research and cloning.
Grady said she views her proposal as a compromise to ensure that differing views are considered when teaching such hot-button issues.
'We would provide a template so schools would be comfortable discussing controversial issues,' she said last week.
Grady sits on the board's Achievement Committee, which is expected to discuss the proposal when it meets Monday in Columbus.
Scientists may have revealed the origin of the battle of the sexes - in our genes.
UCLA researchers report in a new study that thousands of genes behave differently in the same organs of males and females - something never detected to this degree. The study, published in the August issue of the journal Genome Research, sheds light on why the same disease often strikes males and females differently, and why the genders may respond differently to the same drug.
'We previously had no good understanding of why the sexes vary in their relationship to different diseases,' said Xia Yang, Ph.D., first author of the study and postdoctoral fellow in cardiology at the David Geffen School of Medicine at UCLA. 'Our study discovered a genetic disparity that may explain why males and females diverge in terms of disease risk, rate and severity.'
'This research holds important implications for understanding disorders such as diabetes, heart disease and obesity, and identifies targets for the development of gender-specific therapies,' said Jake Lusis, Ph.D., co-investigator and UCLA professor of human genetics.
The UCLA team examined brain, liver, fat and muscle tissue from mice, with the goal of finding genetic clues related to mental illnesses, diabetes, obesity and atherosclerosis. Humans and mice share 99 percent of their genes.
The scientists focused on gene expression - the process by which a gene's DNA sequence is converted into cellular proteins. With the help of genomic-research company Rosetta Inpharmatics, the team scrutinized more than 23,000 genes to measure their expression level in male and female tissue.