March 24, 2007
For the most part, deserts occur in a consistent band at 30 degrees north and south, with some exceptions on the coasts of North and South America. Dry, subtropical air robs these areas of moisture as it descends, circulating it to more temperate zones. Not all deserts are as parched as the Sahara in Africa or the Atacama-Sechura in Chile and Peru, which receive less than an inch of rain per year - essentially nil. The Sonoran Desert, for example, receives as much rain as the lower threshold of a temperate grassland, about 300 mm per year. The Sonoran remains a desert because of this cardinal rule of being: evaporation exceeds precipitation.
Temperatures are typically hot during the day and freezing at night because of the lack of cloud cover, though in areas of the Gobi Desert in Mongolia, the average temperature is only about 3.6 degrees C annually, with temperatures dropping well below zero C.
Soil has a low concentration of organic matter, so much so that it is often classified as lithosols, or strictly inorganic soils. This is especially evident in aged, undisturbed soils, where a special limestone horizon called a caliche is formed (because of its inherent low level of disturbance, ecologists can use this layer to accurately age a desert). Great salt flats are common in desert areas, where pools of accumulated water from heavy rains evaporate, leaving crusts of salt crystals spanning large areas, making it more difficult for organisms to extract water from their environment.
But extract they do, in various specialized ways. Desert perennials like the prickly pear have evolved a thick, waxy cuticle capable of retaining water more effectively year round. The stems have low surface area exposure, its "thin" parts facing into the sun. Roots extend horizontally below the surface, increasing their area of absorption. Their leaves, which would have been a liability in the extreme sun and moisture sapping aridity, have become reduced to non-photosynthesizing, defensive spines. Even their cycle of photosynthesis is different than most plants, closing their carbon dioxide absorbing stomata during the day, when the potential for water loss is greater (CAM).
Annuals are a different story. Given the extreme rarity of significant rainfall, these plants grow rapidly when water is available, producing seeds that can lie dormant for years, until the rains come again. Some of these plants keep a death grip on their seeds until the touch of water hydrates the cellulose of their seed pods, opening the pod releasing the seed.
Some plants, called halophytes, have even adapted to thrive in the salt flats. Atriplex is an extraordinary example. It can maintain higher levels of salt within its cells in order to extract water from the salt flats. Some of these cells burst, coating Atriplex with a defensive layer of salt, making the plant a dangerous meal for any water conserving herbivore.
One species, however, has found a way around this problem: The red vizcacha rat (in the same family as the chinchilla) has evolved a series of teeth that can remove the outer salty layer from Atriplex, making it just edible for the resourceful animal.
Other animals have similarly adapted to the heat and aridity; in fact, some, like the camel, have independently evolved the same measures as plants for keeping cool and hydrated. The camel faces into sun, keeping a slim profile, reducing its surface area exposure. It maintains a store of fat in its hump in order to produce metabolic water. A thick coat of hair, much like cactus spines, covers its body, reducing heat absorption. As the prickly pear keeps its stomata closed during the day, the camel does not sweat, reducing its own loss of water.
Most desert animals, however, are nowhere near the size of the camel, preferring to hide in burrows during the day, emerging to hunt and/or forage at dusk.
I could go on indefinitely about this biome. The extremity of the climate has produced fascinating characteristics in desert wildlife, and they are so different from region to region that they deserve descriptions of their own (especially areas like the Madagascar succulent woodlands, home of the bizarre Didiereans, pictured at the beginning of this post). Perhaps I will return to these areas of interest at a later date.
Next we'll look at the bread baskets of the world - the temperate grasslands.
March 19, 2007
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March 18, 2007
March 15, 2007
March 13, 2007
A population of 3,000 bonobos was recently found in the Congo bring the world population to about 10,000 individuals.
100 percent of Americans support the use of DNA evidence in the court room; only 50 percent support the use of DNA evidence in evolutionary theory.
Have you seen the 2007 Hooter's calendar (it's not what you think)?
20,000 big nerve cells get this model invertebrate through the day; it takes about 100 billion for us.
There were about 30 birds flying back and forth from the trees outside of the window, picking the dried berries and harassing each other.
It's funny; our winters are so long here that the very sound of birds chirping and fluttering is alien come March. It's a nice signal that spring is on its way, however.
More pictures and some interesting tidbits on waxwing behavior and ecology below the fold.
In the winter, waxwings typically follow the cold fronts south, as seen below, but since the bird is so nomadic, it will linger where ever it can find good food.
Waxwings are frugivorous (fruit eating), and usually stick to old growth forests (our little visitors are somewhat of an exception). They are sowers of seed in the forest, as all frugivorous animals are; they keep trees and shrubs well dispersed and varied.
The waxwing's song is not the most appealing, but it was definitely welcome in the desolate Appalachian March.
March 12, 2007
-Aldo Leopold, A Sand County Almanac
March 11, 2007
I'll be in Manhattan for five days starting this Wednesday for the College Media Adviser's Spring National Convention, and coincidentally, St. Patrick's Day. Last year's parade was a blast, and we never made it to the Guggenheim or the Met, so we have some make up to do.
The CMA conference is centered more around technology and new media, and I have already spied a couple of interesting sessions, not to mention the free tours of publications like the New York Times and the Village Voice. There may even be a sign up for a taping of the Daily Show. Maybe.
So, it will be more conference blogging from New York starting Thursday, hopefully including a hearty review of the American Natural History Museum's Hall of Human Origins, which opened just a month or so ago.
If any other bloggers planning on attending the conference (like the ones I tagged below), shoot me an e-mail or leave a comment on this thread.
Tagged: Big Mike, Paul Conley, Digidave, Kaira, Bryan
Spring Break begins after this week, and of course, Climate Crisis Action Day in DC. I'll have more on that later.
March 9, 2007
This idea is popularized by Charles Mann's book, 1491: New Revelations of the Americas Before Columbus; you can read a shortened, pie-in-the-sky version here.
Obviously, it's a touchy subject among ecologists and conservation biologists who have traditionally held the area as the quintessential wilderness, among the last on the planet. Researchers from the Florida Institute of Technology recently published evidence that supports the traditional view, adding new facets to the debate.
"We don't contradict that there were major settlements in key areas flanking the Amazon Channel -- there could have been millions of people living there," says Mark Bush, a British-born paleo-ecologist who travels to extremely remote rain forest locations to collect core samples from ancient lakes. He then analyzes those samples for pollen and charcoal and thus is able to conclude with a high degree of accuracy the extent of human settlement in that region.
"What we do say is that when you start to look away from known settlements, you may see very long-term local use," he says. "These people didn't stray very far from home, or from local bodies of water for several thousands of years. We looked at clusters of lakes and landscapes where people lived, and asked, did they leave their homesite to farm around other nearby lakes? No they didn't. These findings argue for a very localized use of Amazonian forest resources outside the main, known, archaeological areas."Bush says the evidence comes from a geographically diverse area: three districts, each with 3 (in two cases) or four lakes.
"In each we have one lake occupied and used, and the others little used or not used at all," he says. "So this is a total of 10 lakes that provide three separate instances -- one in Brazil, one in Ecuador and one in Peru, where there is evidence of long, continuous occupation of more than 5,000 years that did not spread to the adjacent, 8 to 10 kilometer distant lakes."
"These data are directly relevant to the resilience of Amazonian conservation, as they do not support the contention that all of Amazonia is a 'built landscape' and therefore a product of past human land use," Bush says. "Most archaeologists are buying into the argument that you had big populations that transformed the landscape en masse. Another group of archaeologists say that transformation was very much limited to river corridors, and if you went away from the river corridors there wasn't that much impact. That's what our findings tend to support."
Bush doesn't expect that his new findings will settle the debate, however.
"There's just too much passion on this issue. People who are inclined to believe what we're talking about will say this is very strong evidence, and say 'let's have more.' The archaeologists will say this study only examines two districts."
Those damn archaeologists. Look what else they say:
"While the majority of archaeologists argue the rivers were the major conduit for populations," he adds, "there is an increasing vocalization that there was much more widespread habitat transformation; that you still had a bulk of people along the river but their influence extended deep into the forest. It's still nebulous, and difficult to get people to map stuff, or put hard numbers on it, but there is a sentiment that the Amazonia has been disturbed and that the view of the Amazonian rainforest as a built landscape is gaining momentum. There are extremes at either ends, and the majority of people are in middle but there's a tendency of drifting toward the high end."
Bush is implying a split between scientific disciplines on the issue. I don't want to generalize, but it's probably safe to say that proponents at either end are wrong and clinging fast to dynamic ideas that they like.
The idea that native peoples were responsible for creating Amazonia in its entirety is just as ridiculous as rejecting the notion that those same peoples had a lasting localized effect on the ecosystem, and perhaps did stimulate growth and development on some level.
March 8, 2007
Also, we're still looking for hosts after August this year. E-mail me if you're interested.
March 7, 2007
A male orb-web spider leaves behind a post-coital gift that helps to ensure that any subsequent offspring are his. He leaves the tip of his genitals in the females' sexual orifice, effectively blocking future males' efforts to inseminate the female, new research shows.
The behavior damages the males' genitals while corking up the females' potential for lengthy and therefore successful subsequent mating, says Gabriele Uhl of the University of Bonn.
Believe it or not, this voluntary castration has no statistical effect on the survival of the male.
Pope Benedict XVI met on March 5 with Lutheran Archbishop Anders Wejryd, who was heading an ecumenical delegation from Sweden.
Archbishop Wejryd, the 69th leader of the Swedish Lutheran Church, told Vatican Radio that his conversation with the Holy Father had centered on ecumenical affairs, and particularly on the relations between Christian groups in Sweden.
The Lutheran archbishop said that during his private audience, he had also spoken with the Pontiff about ecological concerns, and the role of religious bodies in protecting “the future of this earth.”
Archbishop Wejryd observed that it is “pretty sure we will have to change our ways of life in a rather profound way” to avoid ecological disaster. Citing the Kyoto Protocol concerns about global warming, he said that religions should help people to examine their lives and make appropriate changes.
It should be a natural transition, actually; Christian tradition dictates that a modest person living a modest life has the potential to grow closer to God. It's too bad the fundies ignore that part of the doctrine.
The existence of supernatural events in a natural world represents a violation of the NOMA model and proves that science and religion do not address different realms. The resurrection of Lazarus from his tomb or the night journey of Mohammed on a flying horse to Mecca or the parting of the red sea—all of which have supposedly taken place in the natural universe—violate physical laws backed by centuries of empirical evidence. If science rules this natural world in which these people lived and interacted, then these events are impossible, and religion is extending beyond its territory.
I have no solution to this problem. If the religious choose to interpret the Bible and other texts literally (and statistics show that a majority of Christians do), then there will be, without a doubt, conflict between science and religion. If the religious choose to believe in the message of these stories as indicative of the human experience and our internal struggle with existence, there is very little conflict, but the dogma will deteriorate. If the story of Jesus sacrificing himself for the good of man is indeed just the extension of an agricultural metaphor, then why have faith?
By its very nature, science cannot change to support a religious view of the natural world while maintaining its integrity. That is not to say that science shouldn’t be more transparent and accessible, but if the relationship between science and religion is to improve, the burden of change lies upon the religious. Paradigms must shift, especially in the Big Three: Christianity, Judaism and Islam.
I'm hoping it will stimulate some conversation on campus and get people thinking about the realities of a cross section between science and religion. This is a problem that needs to be honestly addressed, without placating either camp. The two can be reconciled, but it needs to be made clear just how.
I have talked to several of the students that were involved in organizing and presenting the religious forum from last week, and each of them expressed disappointment with the event, mostly for its lack of diversity and organization. It would be nice to see a reorganized forum in the future where dialogue doesn't become diatribe (as Donovan put it).
March 6, 2007
An international team of scientists led by the Wildlife Conservation Society working in Iran has successfully fitted two Asiatic cheetahs with Global Positioning System (GPS) collars, marking the first time this highly endangered population of big cats can be tracked by conservationists. Once found throughout the continent, Asiatic cheetahs now live only in extremely arid habitat on the edges of Iran's Kavir Desert. WCS's government partner in Iran, the Department of Environment/CACP project estimates their remaining numbers between 60 and 100 animals, making the Asiatic cheetah one of the most imperiled cats on earth.
"This is an amazing milestone in securing the long-term future for the Asiatic cheetah," said Wildlife Conservation Society biologist Dr. Luke Hunter, who led the international team. "We know very little about the important ecological needs of the species in Iran except that they require vast areas for their survival. Understanding their movements as they travel between reserves is one of the first steps in establishing a plan to secure and connect the few remaining populations of this incredible animal."
What's the difference between the African and Asiatic cheetahs?
Well, the Asiatic cheetah is generally more boldly marked, its tail is a bit different and they often have white tips to their ears. The entire species went through a genetic bottleneck about 10,000 years ago, so the differences between individual cheetahs, not to mention populations, are slim, despite their substantial historical range.
There was talk of cloning the cheetah to reintroduce a population in India, where the cat has been nonexistent since 1953 . Researchers in India were working with the Iranian government and local conservation groups to procure live specimens, or at the very least, tissue samples from Iran.
"Biotechnological intervention for the long-term conservation of species is a sound and most modern way of saving species that are headed towards extinction," the team leader, Dr Lalji Singh, was quoted as saying by the Indian Express newspaper.The project never panned out, however.
Dr Singh and his team will take the genetic material from live cheetah cells and fuse it with empty leopard eggs. Any resulting embryos would then be carried to term in leopard surrogates.
Iran has refused to send two cheetahs — a male and a female — to India for research purposes. They have also refused to allow a team of scientists from Hyderabad-based Centre for Cellular and Molecular Biology (CCMB) to travel to Iran to collect sperm and tissue samples from a cheetah in a zoo there.
The final refusal was made just as Iranian President Mohammad Khatami was on his way out, and Ahmadinejad stepped up to replace him. There may be no connection here whatsoever, but this type of action seems consistent with the new president's xenophobic policies.
March 5, 2007
From left to right we have a muskox, a caribou, an arctic fox (fur starting to brown in the summer), a snowy owl and a pair of brown lemmings. The ground cover was inspired by Western Mountain Heather (go figure), Cassiope mertensiana.
March 4, 2007
There are a few mammoth projects in the LibriVox world that take extra effort and energy, and take a long long time to complete. Often these are important texts, dense and challenging to read, and complicated to manage, coordinate, and catalog. Many hands, voices and microphones usually touch these books before they finally see the light out here in public.
One such book is Darwin’s The Origin of Species. And we are proud to announce that this one is: COMPLETE.
Might make for a good companion on a long trip. Check out the entire site, already have a decent catalogue of audio books so far (they're also on iTunes).
-David Attenborough from Life in the Undergrowth
Also consider joining the Maryland Blogger Alliance:
You don't need to be a member of the Maryland Blogger Alliance (see sidebar) to contribute to our carnival, but we strongly urge you to join if you're a blogger in Maryland. There are no political litmus tests. We have liberal, moderate, conservative, and libertarian members, and members whose views are unknown. We have political blogs, a science blog, an art blog, a sports blog, and an idiot blog (mine). Some of our members have been published in dead-tree media; others have had premature (I hope) obituaries written for them in dead-tree media. We're an eclectic bunch. I was the founder of the Alliance and for some time its only member, but now we're 20 members strong. This is where all the cool kids in Maryland can be found.
Give Attila an e-mail either way; join up and/or submit!
March 3, 2007
Jonathan Eisen and other researchers at UC Davis sequenced the genome of a giant deep sea clam (Calyptogena magnifica), which entirely relies on "gardens" of chemosynthesizing bacteria for its food (more here and here).
“The energy from hydrogen sulfide is used to drive carbon fixation in much the same way that chloroplasts carry out carbon fixation,” said Eisen. The symbiotic bacteria also fix nitrogen and produce amino acids, vitamins and other nutrients required by the clam.
Studies of the deep sea have implications for studying the origins of life, Eisen said. Life on Earth may have got its start with microbes living on such chemical reactions, before the evolution of photosynthesis.
“And they’re just plain interesting,” Eisen added.
It's not the only clam that plays host to food synthesizing symbionts, however. Tridacna clams (including the five foot, 500 pound T. gigas or giant clam) play host to symbiotic zooanthellae, colorful dinoflagellate algae, which photosynthesize food for the giant mollusk while it sun bathes in the shallow waters of South Pacific coral reefs. (Zooanthellae are a classical example of host-symbiont relations in sessile organisms.)
“The difference here is that while plants get their energy and carbon via photosynthesis by chloroplast symbionts, this clam gets its energy via chemosynthesis,” said... Eisen.
Eisen, it turns out, is a fairly active blogger. On his blog, The Tree of Life, Eisen laments his colleagues' decision to publish the article in Science:
[...] my collaborators failed to keep me in the loop that the paper was accepted in Science. Thus I did not find out about the paper until I did a google search for some other reason and noticed this Deep-Sea News Blog which had a story, well, about the paper in Science. It would of course have been nice to know the paper was accepted and coming out. It would have been even better to have seen the page proofs, which might have given me the chance to catch some little and not so little mistakes (e.g., the paper claims that this species has the largest genome of any intracellular symbiont sequenced to date - which is unfortunately not true).
Eisen would have rather been published in an Open Access journal:
I tried and tried to get Irene Newton the first author to submit this to another journal. But in the end, she did the brunt of the work, and thus she and her advisor, Colleen, got to pick the place.
[...] by choosing to publish the paper there [in Science] but not elsewhere, the field of deep sea symbionts may have been hurt rather than helped.
How could a Science paper hurt the field? Well, for one, Science with its page length obsession forced Irene to turn her enormous body of work on this genome into a single page paper with most of the detail cut out. I do not think a one page paper does justice to the interesting biology or to her work. A four page paper could have both educated people about the ecosystems in the deep sea, about intracellular symbionts in general, and about this symbiosis in particular. The deep sea is wildly interesting, and also at some risk from human activities. This paper could have been used to do more than just promote someone's resume (which really is the only reason to publish a one page page in Science).
You can read his entire post about the paper here (Eisen also has a nice embedded video of Calyptogena).
In the past, problems like these would be publicly addressed in letters to the editor, most likely published in scientific publications. This is a painfully slow process, relatively speaking. As soon as he heard about his paper being published under the wire, as it were, Eisen was able to respond publicly, sharing a perspective that was once confined to a lab or a community or a trade-specific publication.
Over the next decade (maybe less?), it will be interesting to watch how perspectives like Eisen's affect publication policy and the proliferation of info within the scientific community, and between scientists, writers and the public.
March 2, 2007
The panel directing the dialogue was strange in itself: There were two Protestant pastors (the Catholic priest could not make it) and three students, none of whom were tied to a particular church but who still professed connections to Christian beliefs.
The crowd was relatively sparse. A few people in the front row were overdressed and clutching Bibles. Many of the students in the room were nervous and fidgety. It was calm, but a little edgy.
The students on the panel spoke first. I suppose they would fill the "searching" category, though I suspect one or two of them were thinly veiling outright contempt for religion. They talked about the benefits of religion - community and charity - and emphasized that the differences in interpretation were positive as long as you had an open mind.
Today, we look at groups of people in terms of absolutes, one student pointed out. "This is dangerous," he said. "The whole Christian or Muslim community is not to blame for the actions of one group. We need to be more objective."
The student said that he could talk easily to people of all philosophies and accept their beliefs: Christians, Muslims, Jews, even agnostics. But not atheists: "Atheists are hard to talk to. They're too set in their beliefs."
So much for rejecting absolutes.
One of the pastors talked about the ascetic desert excursions of the Israelites and Jesus, citing these periods of deprivation and transformation as illustrations of the power of faith.
"Faith should be about transforming ourselves and the world," said the pastor, so we can be "more in tune with the Kingdom of God."
I can't disagree with that. Faith has certainly transformed the world (if not terraformed).
Eventually, the discussion was passed into the crowd. A couple of challenging questions were asked in the beginning, about faith as an escape from reality, a socially valid excuse to kill or to abuse or to justify just about anything. Not surprisingly, the question went unanswered.
Instead the conversation moved efficiently into mass catharsis and professions of faith, condemning the media and the internet for dismantling the community and personal connections promoted by religion.
Like I pointed out at the forum, this apparent breakdown of religious communities is symptomatic of a larger breakdown among nations taking the step into the information age. Regional tribalism is deteriorating, being replaced with the far reaching unity of online communities (with some exceptions of course). Generally, I think people are realizing their part in a global community.
There was a lot of fear and confusion in that room the other night. Nothing was accomplished though everyone praised the effort. In one respect, the consensus was "it's all up for interpretation and we should respect that", but none of us would have been sitting in that room if that were truly the case.
March 1, 2007
Today marks the beginning of the International Polar Year (IPY), a two-year mission to explore Earth's poles. Some 50,000 scientists, artists and other participants from 63 nations will undertake 460 projects—ranging from lacing the Antarctic ice with neutrino-spotting sensors to a survey of historic Inuit knowledge of Arctic sea ice—in a massive effort to enhance scientific understanding of the poles before they change. "The scientific community feels that we need an urgent and comprehensive look at the polar regions," says David Carlson, director of the IPY's international program office.
The IPY homepage has some great resources, including this life cycle chart of emperor penguins (you might have to enlarge it),
as well as blogs, event listings and research reports; you can even watch some of the openings. It will be interesting to keep up with their progress over the next couple years.
(The series doesn't actually start until the March 25, but there's a really neat website set up for the series here.)
"This is the first study that has been able to study the calls by directly observing the animal while it is calling and gathering key information such as depth and body orientation—getting a sense of what the animal is doing underwater," said [Erin] Oleson [one of the lead researchers]. "Once you understand the context of specific types of sounds, then you can use those sounds to infer something about what they are doing when you are not there to actually see them doing it."
The researchers found that only males produced sounds known as "AB" calls while "D" calls were heard from both sexes, typically during foraging. The researchers note in the paper, published in the January 25 issue of the Marine Ecology Progress Series journal, that the sex bias evident in AB callers suggests that those calls probably play a role in reproduction.
Oleson hopes such call and behavior information will eventually be used for better understanding whale habitats and calculating species abundances.
While the study is certainly not exhaustive, it is a good first step; the blue whale is supposedly the "loudest" animal on Earth (vocalizing at 150+ dB), but the fundamental frequency of its song is on the lowest threshold of our sound perception, requiring extra steps in analysis. The Scripps-sponsored Voices of the Sea site has recordings and spectrograms from eight different cetaceans, including the blue whale. If you turn up your speakers, you can just barely hear its low grumble.
Direct observation of the animal is exceedingly difficult - it spends 90 percent of its life underwater - so by tying song to behaviors (such as mating), researchers can make indirect observations of how blue whales go about their daily, and perhaps, seasonal lives.
-George F. Kunz, president of the American Scenic and Historic Preservation Society, 1914
The survey [...] represents the first in-depth look at Indonesia's sharks and rays since Dutch scientist Pieter Bleeker described more than 1,100 fish species from 1842-60.
[It] was part of a broader project working toward improved management of sharks and rays in Indonesia and Australia, researchers said.
"Good taxonomic information is critical to managing shark and ray species, which reproduce relatively slowly and are extremely vulnerable to overfishing," White said in a statement. "It provides the foundation for estimating population sizes, assessing the effects of fishing and developing plans for fisheries management and conservation."