Monday, February 28, 2011
Sunday, February 27, 2011
This was nicely illustrated in a Science paper this week where they looked at the role of the Agouti gene in pattern development: The Developmental Role of Agouti in Color Pattern Evolution.
Agouti, ... governs color patterns in deer mice, the most widespread mammal in North America. This gene, found in all vertebrates, may establish color pattern in a wide variety of species, a process that has been poorly understood at both the molecular and the evolutionary level.
Agouti had previously been known to affect the type of pigment found in vertebrate fur, feathers, and scales: Little expression of the gene in adults results in the production of dark pigments, while robust Agouti activity generally yields light pigment production. But Manceau and Hoekstra found that subtle changes in the gene's embryonic activity can also make a profound difference in the distribution of pigments across the entire body.
"During embryogenesis, Agouti is expressed in the belly, where it delays maturation of the cells that will eventually produce pigments," says Hoekstra, John L. Loeb Associate Professor of the Natural Sciences at Harvard. "This leads to a lighter colored belly in adults, which is the most common color pattern across a wide variety of vertebrates, from fish to antelope."
Even small changes in Agouti gene expression can establish a completely new color pattern. In deer mice, natural selection drives changes in the amount and place of Agouti expression, which in turn results in new color patterns that can camouflage animals from visual predators in habitats including dark forests and light sandy beaches.
"It is hard not to speculate that Agouti plays a role in generating more complex patterns -- from stripes to spots -- in a diversity of vertebrates," Hoekstra says.
Saturday, February 26, 2011
I must confess that, beyond the novelty value, I don't quite get the amazing tomato-potato.
It seems more sensible from a plant physiology point of view to just plant a tomato next to a potato and have two sets of leaves each providing for one sink rather than have two large sinks competing for the same resources. I initially wondered if maybe the potatoes ripened first and then maybe the tomatoes but the inset photograph seems to show them both ripe together.
Given that tobacco is also in the Solanaceae family I wonder how long it will be before we see tomacco for real? Oh wait someone already did that.
Friday, February 25, 2011
I think it all started with a show called 'Walking with dinosaurs' that was , at the time, the most expensive documentary ever made. Using computer simulation and animatronics to create a 'realistic' wildlife show - but one with dinosaurs. You should check these out if you haven't seen them. I think they are available on Netflix and Veoh online.
Then there's Prehistoric Park, made by the same company, which now includes a 'time portal' and a narrator. Wikipedia calls it 'docu-fiction'. I almost posted a clip from this earlier in the quarter because they have a nice segment with one of those giant Carboniferous arthropods - Arthropleura.
Finally, keep the time portal and the dinosaurs but add in ludicrous characters, creatures from the future and the stupidest plotlines you can imagine and you have Primeval. Check out episode two of the first series for Arthropleura in the London Underground.
Choose your own level of prehistoric incredulity.
I was thinking it would be cool to have a CCS bio sweatshirt so I decided to create a design, but I want your input on a few things. One, do you like it? Two, do you prefer the blue or yellow? If you would prefer like a cat or something please don't message me but if you have something constructive to add to the design definitely let me know. The yellow looks brighter and more legible as a computer image but they'll both look good when printed. Also, its only going to cost $20 hooray! My email is firstname.lastname@example.org or you can find me on facebook if you have a question or suggestion. I'll bring all this to class on Tuesday and we can talk more about it. Have a good weekend ; )
Thursday, February 24, 2011
On an unrelated note next Monday's EEMB seminar is by Professor Mary Power of UC Berkeley. Her title is still listed as TBA but Mary works on food webs in rivers and their watersheds. She has been the president of the Ecological Society of America and usually gives a pretty enthusiastic talk.
Wednesday, February 23, 2011
Because these can cause hallucinogenic effects they are often ingested by those seeking just such an effect. When combined with alcohol the effects can be rapid. Although the plant can be eaten or smoked the most popular method of ingestion is to prepare a tea from the flowers and seeds.
Unfortunately because the levels of the alkaloids vary widely from season to season it is very easy to overdose and it is estimated that 'teas prepared from as few as 10 flowers could be extremely toxic if not fatal'. Angel's trumpet ingestion produces the classic symptoms of anticholinergic poisoning, so classic that they have their own mnemonic: 'hot as a hare, dry as a bone, blind as a bat, red as a beet and mad as a hatter.'
This paper, Ingestion of Angel's Trumpet: An increasingly Common Source of Toxicity, reports a ten fold increase in Brugmanisa poisoning in Florida in 1994. They failed to locate a particular reason for this (ie reference to Brugmania use in a movie) and suggest the idea was simply spread by word of mouth. And then the internet came along...
Tuesday, February 22, 2011
If anyone wants their garden to be as much of a night owl as they are, here are some amazing plants.
Night Blooming Cereus, made kind of famous in the book The Bean Trees by Barbara Kingsolver, the lovely Moon Flower, and according to this website you can watch a video of it blooming, our lovely deadly and possibly hallucinogenic flower from class, the Angel's Trumpet and for those of you who really want to plant stuff right now, The Evening Garden is a great book.
On another note, Wicked Plants is a great book on all kinds of nasty plants you don't want to run into. It's got amazing illustrations and stories for most of the plants.
Haplodiploidy has important consequences that seem to affect social behavior. Here's a nice description form an online Animal Behavior textbook:
- If a queen mates only once, her daughters are highly related to each other (called supersisters), because the father's sperm are all identical.
- A female is more related to her sisters (on average, 75% similar) than she is to her own daughters (on average 50% similar).
- A female is more related to her son (50 % similar) than she is to a brother (on average, 25% similar).
- That all workers will be female (males have no special pattern of relatedness in a haplodiploid system that would make working advantageous to them
- That workers will help their mother to lay and rear females, but
- That workers would prefer to lay their own male offspring, rather than rear brothers
CCBER Conservation and Restoration Seminar (RE 188/288) - Deciphering Local Diversity
Monday evenings, 6-7pm, Rm 1013 Harder South
- March 28th – Introduction – Lisa Stratton
- April 4th – Dan Fontaine – Interpreting animals signs
- April 11th – Mark Holmgren – Raptor ID and Behavior
- April 18th – John Bleck – Differentiating Succulents
- April 25th – Mary Carroll – Differentiating Sedges
- May 2nd – Marc Kummel – The story behind local Oak Galls
- May 9th – Mary Carroll – Learning the key to Grass Identification
- May 16th – Lisa Stratton – Local vernal pool hydrology and flora
- May 23rd – Scott Cooper – Below the surface of Vernal Pools: Invertebrate lifecycles
Monday, February 21, 2011
One of the reasons for this debate is that the Gnetophytes (one of the gymnosperm taxa we discussed) show several features that are typically associated with the angiosperms, including double fertilisation and vessel elements in their vascular tissue. Do these indicate a close relationship and that the gnetophytes are a sister taxa to the angiosperms or are they the results of parallel evolution?
Wikipedia actually has a nice clear discussion of the alternative hypotheses or for a meatier discussion there's this paper from 2009 in the American Journal of Botany:
Phylogenetic relationships among seed plants: Persistent questions and the limits of molecular data
Sunday, February 20, 2011
The Birds and the Bees and the Flowers and the Trees: Lessons from Genetic Mapping of Sex Determination in Plants and Animals
Sex determination is an important area of study in developmental and evolutionary biology, as well as ecology. Its importance for organisms might suggest that sex determination is highly conserved. However, genetic studies have shown that sex determination mechanisms, and the genes involved, are surprisingly labile.
Saturday, February 19, 2011
Friday, February 18, 2011
Sex chromosomes are an oddity in flowering plants. They are limited to dioecious species and only a few examples are known. The genus Silene, which includes the White Campion, includes both dioecious and hermaphrodite species and three of the dioecious species, Silene dioica, S. latifolia, and S. diclinis, have an X-Y sex-determination system where Y specifies maleness.
Although the X-Y system evolved quite recently in Silene (less than 10 million years ago) compared to mammals (about 320 million years ago), our results suggest that similar processes have been at work in the evolution of sex chromosomes in plants and mammals, and shed some light on the molecular mechanisms suppressing recombination between X and Y chromosomes.
Ref: Nicolas M, Marais G, Hykelova V, Janousek B, Laporte V, et al. (2005) A Gradual Process of Recombination Restriction in the Evolutionary History of the Sex Chromosomes in Dioecious Plants. PLoS Biol 3(1).
There's a synopsis of the article in the same issue: Evolution of Sex Chromosomes: The Case of the White Campion.
Thursday, February 17, 2011
It is becoming gradually clear that although plant and animal kingdoms diverged more than 1 billion years ago, similar mechanisms govern sexual reproduction in both kingdoms. The review by Márton and Dresselhaus (2008) outlines some of these parallels. The current idiosyncratic nomenclature used to designate plant reproduction has obscured the parallels that now become apparent between plants and animals. It is likely to be the time to rethink the designation of each actor of the reproductive process such that the literature in the field becomes relevant to a broader readership working in the field of reproductive biology.
A comparison of early molecular fertilization mechanisms in animals and flowering plants.
Wednesday, February 16, 2011
Fractal fern page if you are interested in math.
Can you tell which of these ferns is real and which is computer generated?
Tuesday, February 15, 2011
Every year the College of Letters and Science celebrates undergraduate research at UCSB by sponsoring a colloquium where students from all over campus may come together to showcase their research activities. I am
writing to invite you to attend this event to be held on Thursday, May 19, 2011, in the Corwin Pavilion. All presentations will be in poster form (poster size 2 ft by 3 ft portrait style). The event will run from 11:30
to 2:00 p.m.
Students interested in sharing their research efforts should submit the two-part entry application (entry and abstract submission forms) found on the URCA web site, www.ltsc.ucsb.edu/urca/colloquium.php, by Wednesday, April 6. Questions should be referred to the URCA Coordinator, urca@Ltsc.ucsb.edu.
Texas A&M is offering a summer Research Experiences for Undergraduates program, which will be held from June 1 to August 5 in College Station. The theme is Interdisciplinary Research on Imaging and Biomarkers. The application can be found at: http://etidweb.tamu.edu/hsieh/REU and the flyer is attached.
Activities will include joining a research group led by a faculty mentor, completion of a 10-week research project, and participation in weekly faculty seminars, field trips, and career development workshops. Students will write a report and present their research to their REU cohort and at an REU poster session on campus. They will also be strongly encouraged to polish their reports after completing the program, with a view toward presenting at a national conference and/or publishing in an academic journal.
Each participant will receive a stipend of $450/week for ten weeks. Other benefits include allowances for housing, meals and round trip travel to College Station; 1.0 credit hour of undergraduate course credit; and full access to university recreational facilities.
Criteria for selection include:
- Desire to participate in research as evidenced by application responses and faculty recommendation;
- Completion of at least the sophomore year of the curriculum for an academic major in engineering, computer science, or the life sciences;
- GPA of 3.00 or above (exceptions may be made based on review of an applicant's last 60 hours of coursework);
- Citizen or permanent resident of the U.S. or its possessions;
- Plan to graduate no earlier than December 2011.
Monday, February 14, 2011
Who is the culprit? Lactobacillus plantarum, a Gram-positive bacterium found in dairy products and other fermented foods. It is thought - researchers are not entirely certain - that the bacteria alter the flies' pheromone levels, making them more attractive and attracted to similar members of the opposite sex. The question arises...how much of this actually applies to humans?
An important concept put forth by the researchers is the holobiont. Rather than considering just the parts directly connected to an organism, we should take into account all its "normal flora" - the diverse hordes of microbes that inhabit the body, from our skin to our gut. Although it's initially mildly disturbing to think that 90 percent of the cells in our body are not our own, we should take into account the host of tasks they perform for us. When our normal flora are destroyed - for instance, by a long-term antibiotic - we too are destroyed, unable to digest food and plagued by infections that our normal flora would have otherwise caught.
So the holobiont theory certainly applies to humans. What about the influence on mating preferences? Hard to say. But if our resident bacteria can chew our food for us and protect us from hostile (albeit microscopic) strangers, I think I'll trust their judgment in choosing a suitable mate.
Here's another very simple tip for the ladies: frighten him. No, seriously. In 1974, University of British Columbia psychologists were studying human attraction using two bridges that crossed a local river. One bridge was solid, allowed firm footing, and was made of heavy cedar. It was only ten feet above the river, and had steady handrails. The other bridge was a five-foot-wide, 450-foot-long suspension bridge made of wire cables threaded through the ends of wooden boards. It would tilt, sway, and wobble as people tried to cross, 230 feet above the river.
Men who had just crossed one of the bridges were approached by an attractive female experimenter who asked them to complete several questionnaires. The men who had crossed the anxiety-inducing suspension bridge were more likely to attempt further contact with the experimenter than were the men who had crossed the stable bridge. The researchers suggest that it's as if the men misunderstood their anxiety-induced physiological arousal – elevated heart rate, sweaty palms, and so on – interpreting it as sexual attraction and desire.
Moral of the story: scare the crap out of him and he might just make a move.
Oh and don't forget - CCBER tomorrow.
Sunday, February 13, 2011
UC Santa Barbara Department of Philosophy Announcesa Steven Humphrey Fund for Excellence in Philosophy ConferenceDebating Darwin: Philosophical Issues in Evolution and Natural Selection
February 18-20, 2011
7:00 - 9:00 PM Reception/Buffet, UCSB Faculty Club
11:30 - 1:00 PM Lunch, Graduate Student Association Lounge
1:00 - 3:00 PM Paul Griffiths (Sydney), "How Evolution Tracks Truth"
3:00 - 3:15 PM Break
3:15 - 5:15 PM Jerry Fodor (Rutgers), "From the Darwin Wars"
11:30 - 1:00 PM Lunch, UCSB Faculty Club
1:00 - 3:00 PM Richard Boyd (Cornell), "Evolutionary Theory as Methodological Anesthesia: Methodological and Philosophical Lessons from Evolutionary Psychology"
3:00 - 3:15 PM Break
3:15 - 5:15 PM Alex Rosenberg (Duke), "How Jerry Fodor Slid Down the Slippery Slope to Anti-Darwinism, and How We Can Avoid the Same Fate"
Location: All talks will be in Theater & Dance 1701
Saturday, February 12, 2011
Friday, February 11, 2011
The Worster family has again graciously given EEMB a gift of $30,000. As in previous years, this award is to support the development of graduate and undergraduate research in ecology, evolution and/or marine biology through a mentoring program that pairs an undergraduate with a graduate student mentor during the summer. All graduate students that have their thesis committee chaired by an EEMB faculty member are eligible to apply for this award. We anticipate that stipends this year will be $6000 for each team ($3000 for the graduate and $3000 for the undergraduate, to be paid during the summer). We will be able to fund 5 teams this coming summer.
Applications for this award (electronic, Word or PDF files AND a printed copy delivered to my office or placed in my EEMB mailbox) are due to me by Friday, April 1st, 2011. Please be sure to send and to deliver both electronic and hard copies.
1. Brief (2 pages, prepared by the graduate student) description of the research project and how the undergraduate student will participate in it.
2. CV of the graduate student, including progress toward his/her degree and any prior mentoring experience.
3. A brief statement from the undergraduate regarding his or her professional goals and how the research experience will prepare him/her to meet them. Undergraduates are expected to complete a senior honors thesis during the 2011-2012 or 2012-2013 academic year and express their intent to do so. In addition, undergraduate promise, experience, and GPA in their major will factor into the decision for funding.
4. Letter of support from the grad student's major professor.
Please note that recipients will be obligated to write a summary of their team's progress and accomplishments at the end of the summer. These summaries will be sent to the Worster’s in the fall as part of a package thanking them for this important gift.
Undergraduates who will graduate in June 2011 are NOT eligible for this award.
If you have any questions, please don't hesitate to contact me.
Thursday, February 10, 2011
Each little pinpoint speck of light in Spitzer's image is a young star at some particular point in its development., and haven't even become true stars yet—that only occurs when thermonuclear fusion kicks off in their cores. Others have begun their stardom, but are still sheathed in spherical cocoons of gas and dust, shells of material that will gradually grow puffy and vaporous from the inner star's light and heat, until they whisper away on stellar winds. Many of these points of light are ringed by thick accretion disks of material that formed from the angular momentum of their initial gravitational collapse. Sometimes parts of the disk get sucked too close to the star, and are shocked into plasma and spun away and out from the star's poles in powerful collimated jets that can sculpt and shape the surrounding gas and dust into abstract whorls and tendrils. And, in the background, almost unnoticed against all the stellar fireworks, in all probability planets are slowly and surely forming. Perhaps, on a few them, the seeds of life are already being sown by comets and meteorites, the infalling detritus of star formation delivering water and complex chemical compounds brewed in the stellar clouds. Some are still undergoing their initial gravitational collapse.
I tried to find a website that could explain where the North America Nebula was in easy to understand terms and found just what I was looking for here. Unfortunately I then kept zooming out until my head exploded.
Here's a map showing the bike route from CCS (click for a larger version). As someone pointed out you don't have to cycle this way...
We will meet at the entrance.
Wednesday, February 9, 2011
Tuesday, February 8, 2011
In the Fantastic Four comics Dr Doom was expelled from Empire State University for carrying out 'Forbidden experiments'. The experiment in question involved contacting the dead so maybe that's not that surprising, but I was always amused by the notion that a University might have a big list of 'Forbidden experiments'. Ah yes, item number 147, 'Contacting the Dead', right after number 146 'Reanimating the Dead'.
Anyway, I was reminded of that when I took a quick look for some papers on insect gigantism and came across this recent review paper Atmospheric oxygen level and the evolution of insect body size, where they mention several experiments where people have selected for insect gigantism over many generations under high oxgyen conditions in the lab.
The effects of hyperoxia on growth and body size are less consistent and often nonlinear (Harrison et al. 2009). Body size increases in the giant mealworm, Z. morio (27% O2; Harrison et al. 2009) and in the scarabaeid beetle C. texana (40% O2; Harrison et al. 2009).
I'm pretty sure 'Creating Giant Insects' would also have been on empire State's list. Did Mothra not teach us anything?
But the answer to our question of what other giant insect (and other arthropod) fossils have been found is:
Among insects, gigantism in the Permo-Carboniferous has also been reported for Ephemeroptera, Diplura, Thysanura and the extinct order Paleodictyoptera (Briggs 1985; Kukalova-Peck 1985). Arthropleura, a group related to modern day millipedes, reached upwards of 2 m in length, almost six times the size of any extant millipede.
So no, no Lepidoptera, you'll just have to make do with Mothra.
I thought this article from the New York Times is very relevant to what were talking about in class! The plant Arabidopsis is really intersting, it has developed the ability to express genes at specific times to make it resistant to an infectious pathogen.
Specifically, twenty-two genes were discovered in Arabidopsis that are all connected to the plant’s ability to resist infection. These genes are unique in that they are expressed only from the evening onward, peaking at dawn.
This timing corresponds with the formation of spores in a funguslike pathogen that attacks the plant and results in a condition known as downy mildew disease. The disease weakens the plant and forms an unsavory coating of fuzzy mildew.
A surprising discovery published in the Nature journal, found that these new defense genes are under circadian control by the regulator CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1), allowing plants to ‘anticipate’ infection at dawn when the pathogen normally disperses the spores. Arabidopsis can then time its immune response according to the perception of different pathogenic signals upon infection. This plant then uses programmed cell death as its main contributor to resistance.
I think that the control of defensive genes by a circadian clock regulator is an amazing adaptation this plant has made to avoid being susceptible to dawn spore attacks, just like the grass in class on the copper mines flowering early to gain an advantage to remain resistant to the toxins in the soil. Hope you think this is interesting too!
Monday, February 7, 2011
A novel X-ray imaging technology is helping scientists better understand how in the course of evolution snakes have lost their legs. The researchers hope the new data will help resolve a heated debate about the origin of snakes: whether they evolved from a terrestrial lizard or from one that lived in the oceans. New, detailed 3-D images reveal that the internal architecture of an ancient snake's leg bones strongly resembles that of modern terrestrial lizard legs.
Sunday, February 6, 2011
To read more, and see a photograph of brown fluffiness, visit: http://www.sciencedaily.com/releases/2011/02/110203081451.htm
I hope you all remember how Daphnias' head shape changes with temperature leading to them having dating issues, if Dr. Latto is to be believed. Well, they get even cooler. They have been found to have the largest number of genes of any animal known, 31,000 to our 23,000. So you ask, why does something the size of half a grain of rice need all these genes? Well, the answer is we don’t know yet. 35% of their genes are new to science. Some of them allow the Daphnia to make basically armor and a spear right on the spot. Others allow it to produce hemoglobin when stressed, making the creature look red, thus giving it the name “bloodsucker”. The best part is that we know a huge amount about the Daphnia’s environment and reactions to different things. This allows us to link their genes to events nature which can tell us a huge amount about gene expression and the need for certain genes. Thank you tiny crustacean, even if some of you are pointy headed.
If you want to listen to the story click here, or read a shorter version of it on the NPR website, which is a good place to look for interesting science stories anyway.
As I mentioned in class if you remove the constraints of requiring lots of water and needing a large light capturing apparatus from photoautotrophs then we do see some mobile photoautotrophs - Euglena for example. Here they are having a party.
One way to lift this constraint for larger plants would be to be carnivorous - then they wouldn't need all that water or that light gathering apparatus. Although we colloquially call many plants 'carnivorous' they are not in fact heterotrophs because they still photosynthesize and use the animal bodies they capture for nitrogen, which is why we see the evolution of plant carnivory in nitrogen limited environments. They are still green, still need to be open to the atmosphere to take up carbon dioxide and still lose lots of water.
If a multicellular land plant did evolve towards true heterotrophy what would it look like? Thanks to the fertile imagination of British author John Wyndham we have the answer in the Triffids - and yes they would be mobile!
Although published in 1951 Wyndham's science fiction classic The Day of the Triffids is still a fantastic read. According to the director of the movie 28 days later, Danny Boyle, it was the opening sequence of The Day of the Triffids, in which a man wakes up in hospital to discover that a meteor shower has blinded his fellow countrymen, which first inspired Alex Garland to write the screenplay. As a bit of a triffid connoisseur I would rate the book and radio adaptation excellent, the BBC adaptations pretty good and the 1962 film version appallingly bad.
In England the book, and adaptations are so well known it is quite common for someone to refer to a large, somewhat creepy looking plant as 'triffid like'.
Saturday, February 5, 2011
A few biofilms you may come into contact with often: the plaque on your teeth, the slime on river stones, the spots on contact lenses, etc.
More than 99% of bacteria live in biofilms, some of which are beneficial to humans, while others create some major problems. Humans have almost no method of getting rid of or destroying these biofilms.
This is as intriguing as it is disturbing - scientists in the US and the Netherlands are independently researching methods to grow meat in labs.
Though the idea may conjure stomach-turning images of truly mad-science, there are actually some interesting prospects to this research. The scientists involved – such as Bernard Roelen of Utrecht University, Mark Post of Maastricht University, and Vladimir Mironov of the Medical University of South Carolina - argue that growing meat in a lab would require substantially less resources and land than growing meat the conventional way. As a result, lab-grown meat would be cheaper, and may help meet the ever increasing demand for food. There are also ethical ramifications since such meat would not involve the death of a real animal. PETA has even provided grants and created contests to encourage researchers to create non-meat “meats”.
However, there are also disturbing implications as the type of meat grown would not be limited to the animals normally grown for livestock. My favorite disturbing quote, courtesy of Mark Post of Maastricht University:
"In principle, we could harvest the meat progenitor cells from fresh human cadavers and grow meat from them… Once taken out of its disease and animalistic, cannibalistic context — you are not killing fellow citizens for it, they are already dead — there is no reason why not."
Post goes on to suggest that “marketing could overcome such hurdles” as the cannibalistic context.
Luckily, the progress on growing meat is slow – few institutions are willing to fund the research, especially in the US. What progress has been made is limited to thumbnail chunks akin to sausage. As a consumer – and a vegetarian at that – I am not sure what to make of this meatless “meat”. I find it in many ways disturbing, and yet there seem to be some practical benefits, including a researcher’s suggestion that “if we have interplanetary exploration, people will need to produce food in space and you can't take a cow with you.”
Yum! Space meat! Without the meat!
Here are the articles I read. Hope you enjoy!
Apart from the cool galloping mosses below one of the few examples of a mobile adult plant is the tumbleweed. A number of plants in dry and windy environments have evolved a similar strategy of disengaging from their roots when mature and then, although the mature plant is dead, using the large tumbling plant body as a mechanism of seed dispersal. Seeds may be dispersed as the plant tumbles along or in other species it actually requires the presence of moisture to cause the seed pods to open and release the seeds.
NASA have even used the tumbleweed as inspiration for a low cost (well, relatively low cost, it IS NASA) Mars Rover.
Friday, February 4, 2011
Hmm, just when I told you that plants don't move as adults - an assertion you think I'd be reasonably safe making - along comes the Botany Photo of the Day to proved me wrong.
"For my field work I am up in the (sub)Arctic quite a bit, and here I attach some pictures of an interesting plant phenomenon: mobile moss or what we jokingly call "galloping moss". These mosses are slowly creeping downhill, probably by daily frost-thaw cycles in spring and fall, and they seem perfectly happy with the movement. I have seen it in different moss species, including Sphagnum (not shown). Sometimes they stall out at a little crack or ridge, like in the photo, only to start moving again after a while. If the hill side steepens, their leading edges may be overrun by the rest and things get a little messy, but otherwise all is fine. "
Thursday, February 3, 2011
DDT is a chlorine-containing synthesized chemical that was first recognized as a pesticide in 1939. In 1955, the World Health Organization began a program to eradicate malaria worldwide, relying heavily on DDT. It was also used throughout the 1940s and 1950s to help control typhus, a disease caused by the bacteria Rickettsia. Both of these diseases were nearly wiped out in certain countries, but it was less effective in tropical regions and the application was not always permanent. Spraying programs were abandoned due to many concerns; one of the most widely studied was the eggshell-thinning effect it had on many birds of prey, including the bald eagle and the peregrine falcon. DDT also became a major concern when certain insects, including mosquitoes, began showing resistance to the chemical. More shockingly, recent studies have shown that insects that developed resistance to DDT gained additional genetic advantages over their rivals. For example, a study by the University of Bath showed that resistant fruit flies produce offspring that are more likely to thrive even once spraying has been abandoned. This is thought to be caused by females passing on an advantage associated with the metabolic enzyme cytochrome P450, which becomes over-expressed once exposure to DDT occurs. This is similar to how antibiotic resistance may potentially confer the same kind of genetic advantage to ‘superbug’ bacteria. Based on this knowledge, I think it is pertinent that scientists consider the effect that insecticides, herbicides, and antibiotics may have on a population before they are used. Resistant organisms may one day completely replace non-resistant organisms if large scale dispersion of chemical agents are used. In conclusion, although the World Health Organization estimates that approximately 25 million human lives have been saved by DDT use, a question of whether the ends justify the means comes into play, and must be carefully weighed in these situations.