Evolutionary Biology
gregladen | July 23, 2008The phrase "genomic imprinting" has come to refer the turning off of a gene (a particular instance of a gene on a particular chromosome duplicated across the cells in a body) so that the gene is not expressed at all, with the turning off of the gene not caused in the body in question, but rather, during the previous generation by a process happening in the soma of one of the parents. A maternally imprinted gene is passed on to junior, but will not be expressed in junior. a paternally imprinted gene is passed on to junior, but will not be expressed in junior. Typically (as far as we know) a…
gregladen | July 22, 2008Plants and their herbivores have an interesting and complex relationship. It has been true for quite some time (many tens of millions of years) that terrestrial plants do not move around while animal herbivores do (though I've got friends from Texas who claim that there is a Texan tree that will move from one side of your yard to the other if it is pleased to do so). Generally speaking, a plant can not avoid being consumed by the herbivores by running away. So, it must have a defensive strategy or two that work in situ, and most likely these strategies evolved in relation to the also-…
neurophilosophy | July 8, 2008The humble nematode Caenorhabditis elegans is a millimeter-long roundworm which eeks out its existence in the soil and feeds on bacteria.
Because it lives in a dark environment, and lacks specialized light-sensing organs, the nematode has always been assumed to be completely blind.
However, a new study published online in Nature Neuroscience shows that C. elegans they possess neurons which are sensitive to light. As well as showing for the first time that C. elegans has a rudimentary sense of vision, the findings also shed some light on the evolution of the eye.
Despite lacking eyes,…
gregladen | June 30, 2008A study just out in PLoS Medicine suggests that an increasing trend of delaying childbirth is associated wiht a rising rate of the use of cesarean delivery. The explanation appears to be impared uterine function.
From the editor's summary:
Though it was not studied here, the researchers hypothesize that impaired uterine contractility may be a consequence of prolonged stimulation of the uterus by estrogen and progesterone, resulting from a prolonged interval between menarche and first birth. Further research is needed to understand the determinants and management of dysfunctional labor in…
gregladen | June 28, 2008There is new information from an older idea (from about 2000) by Paul Sherman and colleagues. The idea underlying this research is simple: Symptoms of illnesses may be adaptive. Indeed, this may be true to the extent that we should not call certain things illnesses. Like "morning sickness."
Broadly speaking, there are two different kinds of reasons that a woman may experience nausea in association with pregnancy. 1) This pregnancy thing is a complicated mess with all kinds of hormonal (and other) things going on, so you puke; or 2) a woman who is pregnant feels nauseous for good…
gregladen | June 26, 2008... is certainly still in the future. But we have seen a step in that direction in a new paper, coming out this week in Science. This research applies intensive and extensive genomic analysis to the avian phylogenetic tree. The results are interesting.
This paper is summarized in a number of locations, most notably here on Living the Scientific Life. Here, I will summarize it only very briefly. However, there are two observations I would like to make about this paper and its apparent meaning. One has to do with the nature of science, and the other has to do with the nature of…
gregladen | June 24, 2008Continuing with our discussion of the Evolution 2008 conference ...
Yet another item from the first day of the conference, the pre-conference teachers day sponsored by Evolution 2008 and the Minnesota Citizens for Science Education (MnCSE) ...
The Minnesota Citizens for Science Education presented Ken Hubert with an award. I am blanking on the name of the award right now, but eventually, the MnCSE web site will probably have a page on this, or an announcement about it. (We need time for some dust to settle.)
Who is Ken Hubert?
Well, when it comes to the Evolution - Creationism 'debate…
gregladen | June 23, 2008Continuing with our discussion of the Evolution 2008 conference ...
Karen Oberhauser talked about the "single species" approach to pedagogy. This involves focusing on a single species and using it throughout an entire course. Karen has taught classes on this approach for teachers' professional development programs.
The species she uses is the Monarch Butterfly.
Karen is a world class expert on this insect, and runs a major research project with them.
The idea of a single-species approach is that a student learns a great deal about one particular species, to the extent that this…
gregladen | June 21, 2008Continuing with our discussion of the Evolution 2008 conference, I'd like to relate at least the essence, as I saw it, of an excellent talk by Mark Borrello.
I've seen Mark speak at least three times including yesterday, and soon after his talk we continued on the topic in a conversation over lunch and beers, so my comments here are less a summary of Mark's talk at the Evolution 2008 conference than a more general reaction to what I believe to be his main points.
Everyone knows that history repeats itself. Or, at least, as per Samuel Clemens, if history does not repeat itself, at least it…
gregladen | June 20, 2008The Evolution 2008 conference started out today with a special program for K-12 teachers (mainly life science teachers) organized by the Minnesota Citizens for Science Education (MNCSE). The opening speaker was Scott Lanyon, director of the Bell Museum of Natural History. (The Bell hosted this event.)
Scott's objective was to outline several areas of evolutionary biology where fundamental changes had occurred over recent years. This was to provide perspective and food for thought for the Life Sciences teachers attending the event, and Scott was very successful in this effort.
In each case…
neurophilosophy | June 17, 2008The winners of the first Kavli Prize were announced a couple of weeks ago. One of the three recipients of the prize for neuroscience was Pasko Rakic, a professor of neurobiology and neurology at the Yale School of Medicine.
Rakic has spent most of his career investigating the development of the cerebral cortex of man and other mammals, and it is for his outstanding contribution to this area of research that he has been awarded the Kavli Prize for Neuroscience.
Cortical development (or corticogenesis) is a highly dynamic and complex process, involving the tightly orchestrated movements of…
gregladen | June 13, 2008 A very Darwin-like god ponders what the nature of life will be like. From Monty Python's The Meaning of Life. The origin of life presents a number of fundamental difficulties to science. One of these is the seemingly irreducible complexity of life itself. For instance, DNA codes for the molecules that are essential to life. Some of these molecules, however, are the very enzymes that help DNA code for molecules. It is difficult to imagine DNA works without these enzymes, but the enzymes exist in a cell because, in part, of the activities of DNA. Even the basic process of moving…
neurophilosophy | June 11, 2008When it comes to human brain evolution, it is often said that size matters. The human cerebral cortex is much larger than that of other primates, and therefore its expansion must have been a vital feature of human evolution. Researchers have therefore emphasized the importance of encephalization, the process by which brain mass increased dramatically in relation to total body mass that occurred in the human lineage.
However, a new study which used bioinformatics to compare the synapses of distantly related species suggests that size may not be the most important factor in human brain…
gregladen | June 11, 2008This just in:
Perhaps he was inspired by the turnout for Young People Fucking, or maybe he misses all that media attention he got after taking credit for getting C-10 through the House with nary a peep over the controversial changes to the film tax rebate. Whatever the reason, Reverend Charles McVety is headed back to the capital to co-host a private screening of a very different kind of film: Expelled: The Movie, the controversial anti-Darwin documentary that purports to expose a sinister anti-creationism bias within the mainstream scientific community.
The details are HERE.
gregladen | May 28, 2008... But don't panic. Apparently, this is normal.
It turns out that bacteria living at the bottom of the sea are far more abundant and diverse than scientists had previously thought. These bacteria appear to be consuming the planet's oceanic crust. This raises several interesting questions regarding the interaction and co evolution of life on Earth and the Earth itself.
[UPDATED]
This is all according to a paper being published May 29 in Nature. According to one of the study's authors, Katrian Edwards of USC:
A 60,000 kilometer seam of basalt is exposed along the mid-ocean ridge…
gregladen | May 20, 2008 Could even this bird be reanimated, gene by gene? When you are extinct you're extinct. Everything about you is dead and gone. There are no more of you, every individual in your species is kaput, non existent, used up, as the Pima Indians would say, you are hokum (like a car with a flat tire). In fact, you are hohokum (like a car with no tires). Your existence is erased. You are as blotto as a budgie in Burbank.
Indeed, every bit of your being, every gene in your genome, every base pair in your DNA, is no longer extant.
...
Or is it?
Well, scientists have recently taken a bit of…
gregladen | May 17, 2008Mycologist Paul Stamets studies the mycelium -- and lists 6 ways that this astonishing fungus can help save the world.
...Paul Stamets believes that mushrooms can save our lives, restore our ecosystems and transform other worlds
gregladen | May 17, 2008MIT researchers found that phalaropes depend on a surface interaction known as contact angle hysteresis to propel drops of water containing prey upward to their throats. Photo by Robert Lewis The Phalarope starts out as an interesting bird because of its "reversed" sex-role mating behavior. For at least some species of Phalarope, females dominate males, forcing them to build nests and to care for the eggs that the females place there after mating. If a female suspects that a male is caring for eggs of another female, she may destroy the eggs and force the male to copulate with her a few…
gregladen | May 12, 2008Evolutionary biologist Paul Ewald drags us into the sewer to discuss germs. Why are some more harmful than others? How could we make the harmful ones benign? Searching for answers, he examines a disgusting, fascinating case: diarrhea.
gregladen | May 6, 2008A recent study of dog genetics, published in PLoS, seeks to improve the quality of genetic research by better understanding the underlying patterns of genetic variation at the level of specific dog breeds.
Sometimes we are interested in the evolutionary relationship between two "species" or populations, and genetics can be helpful. The more different the genetic sequence between two populations, the more distantly related they are (on average) and thus we can construct phylogenies ("family trees" of species or groups).
Sometimes we are interested in finding genes that are linked to…