evolution
pharyngula | July 13, 2007
If you've been reading that fascinating graphic novel, Y: The Last Man(amzn/b&n/abe/pwll), you know the premise: a mysterious disease has swept over the planet and bloodily killed every male mammal except two, a human named Yorick and a monkey named Ampersand. Substantial parts of it are biologically nearly impossible: the wide cross-species susceptibility, the near instantaneous lethality, and the simultaneity of its effect everywhere (there are also all kinds of weird correlations with other sort of magical putative causes, which may be red herrings). On the other hand, the…
voltagegate | July 13, 2007So far we have established that spiders are distinct from insects for two reasons: physiology (mouth parts, body plan, respiratory structures) and more importantly, evolutionary history (or phylogeny, as scientists call it).
But where did spider's come from? How did they come to speciate ?
The answer, like many in invertebrate paleontology, is cloudy. Organisms without hard, thick shells rarely become fossilized. In fact, for any organism's parts to become fossilized, even vertebrates, is a profound rarity, as Bill Bryson illustrates in A Short History of Nearly Everything:
Only about one…
purepedantry | July 13, 2007Scientists have just documented (another) inheritable change in a species that occurred in response to a change in the environment -- in this case a parasite. Hence they have observed the process of natural selection.
In the latest issue of Science, Charlat et al. observed that the sex ratio in a species of Polynesian butterfly -- Hypolimnas bolina -- changed from 99:1 favoring females to parity in less than 10 generations. The sex ratio favored females because there is a parasite -- a bacteria called Wolbachia -- that selectively kills the male embryos.
However, in the space of ten…
pharyngula | July 12, 2007Manuscript note by Francis Crick: "I think the most significant aspect of DNA is the support it gives to evolution by natural selection." Note written on the back of a letter from D J E Stamp.
13 June 1989.
(hat tip to Branch of the NCSE)
sporte | July 12, 2007By now, many of you have probably seen the the new BLAST web interface at the NCBI. There are many good things that I can say about it, but there are a few others that caught me by surprise during my last couple of classes.
tags: blast, BLAST tutorial, science education
Because of these changes, and because I'm giving a workshop for teachers on BLAST at the Fralin Biotechnology Conference in Blacksburg, VA, next week, it seemed like a good time to update our animated BLAST tutorial at Geospiza Education and save myself some trouble.
I originally created the BLAST for beginners tutorial to…
hrynyshyn | July 12, 2007The fine folk at DefCon (shorthand for the imprecisely named Campaign to Defend the Constitution) have released a poll showing that intelligent design hasn't made much headway into the evangelic right wing. The polls also suggests that the new Creation Museum does not exhibit a vision of the past shared by most anyone. If true, that's good news. But as you might expect, there's bad news in the poll (a pdf), too.
According to the poll, 95% of Evangelicals reject the Creation Musuem's strange, dino-friendly version of Creationism. In addition, only 10% of self-identified Evangelicals support…
voltagegate | July 12, 2007So how is it that spiders are more closely related to horseshoe crabs - marine arthropods that haven't changed much in the past 250 million years - than to a more obvious choice, the insects?
The answer to that question is more complex than you might think.
Up until the middle of the 20th century, before evolutionary theory was completely accepted by mainstream biology and supported by genetic analysis, taxonomists (scientists who place organisms in groups) classified organisms according to their modern anatomy. If organisms shared common physical structures (like chelicerae or mandibles)…
pharyngula | July 12, 2007
Sometimes, I confess, this whole common descent thing gets in the way and is really annoying. What we've learned over the years is that the evolution of life on earth is constrained by historical factors at every turn; every animal bears this wonderfully powerful toolbox of common developmental genes, inherited from pre-Cambrian ancestors, and it's getting rather predictable that every time you open up some fundamental aspect of developmental pattern formation in a zebrafish, for instance, it is a modified echo of something we also see in a fruit fly. Sometimes you just want to see what…
pharyngula | July 12, 2007This is a nice, short summary of some of the explanations for the evolution of homosexuality. It could be shorter; there are really just two classes of explanation, the adaptationist strategy of trying to find a necessary enhancement to fitness, and the correct strategy of recognizing that not all attributes of an individual organism are going to be optimal for that individual's reproduction, so don't even try. Love isn't hardwired by biology, and it can go in all kinds of different directions.
So I'm saying the best answer in the list is #5. I wouldn't be biased by the fact that the author…
neurotopia | July 11, 2007It looks like somebody either never heard of Dover, or refused to learn from their lesson. It seems the local ID supporters of Chesterfield County aren't happy:
So far, the official actions of the CCSB have been limited to issuing a rather vague and confusing statement. ID proponents had hoped to influence the selection of science textbooks, but they started their campaign too late, and the CCSB approved the selection of standard biology texts. But there is still much concern about the situation in Chesterfield. ID supporters, backed by a local conservative group called the Family…
voltagegate | July 11, 2007I started this series of posts almost a year ago, incorporating some basics about taxonomy, evolution, and a little genetics while exploring my fascination with the Chelicerates. I'll be reposting the series, which is included in the Basic Concepts list, this week and next.
Perhaps nothing will spark a lengthy dissertation from an entomologist more quickly than calling a spider a "bug." And lengthy can be well, hours.
Truly, spiders do seem rather buggish; they're creepy, have loads of legs and the thick outer structure (an exoskeleton) that other bugs possess. In short, if it looks like it,…
voltagegate | July 11, 2007Found this on Google Vids this morning. It features all the regulars in the discussion - Miller, Dawkins - but to me, this doc is valuable and distinct because it features David Attenborough opining on ID and the neocon's dismissal of science, a man who has, for the most part, kept his opinions about this sort of thing to himself over his long career.
As an aside, damn American broadcasting. This is the third doc that has been produced for the BBC that I've wanted to watch for a while and couldn't until it was released online (the other's were A Short History of Disbelief, which I never…
mikethemadbiologist | July 11, 2007...and the Mad Biologist answers. Over at the World's Fair, David asks scientists:
1. What's your current scientific specialty?
Microbial population biology.
2. Were you originally pursuing a different academic course? If so, what was it?
Yep. I was originally a marine evolutionary ecologist. I studied botrylloid ascidians (specifically, the evolution of histocompatibility). Sadly, I had far more cache than a microbiologist.
3. Do you happen to wish you were involved in another scientific field? If so, what one?
Nope. Given the crappy wages, long hours, and work to get to the point where…
pharyngula | July 10, 2007We now have a draft of the sea anemone genome, and it is revealing tantalizing details of metazoan evolution. The subject is the starlet anemone, Nematostella vectensis, a beautiful little animal that is also an up-and-coming star of developmental biology research.
(click for larger image)Nematostella development. a. unfertilized egg (~200 micron diameter) with sperm head; b. early cleavage stage; c. blastula; d. gastrula; e. planula; f. juvenile polyp; g. adult stained with DAPI to show nematocysts with a zoom in on the tentacle in the inset; h, i. confocal images of a tentacle bud stage and…
oracknows | July 10, 2007I'm devastated.
Truly and totally devastated emotionally and intellectually. Indeed, I don't know how I'll ever be able to recover, how I'll ever be able to live down the shame and go on with my career.
What could bring me to this point, you ask? I'll tell you. Everybody's favorite creationist neurosurgeon and dualist Dr.Michael Egnor thinks I'm "unprofessional."
Worse, he does it while agreeing with Pat Sullivan's article in which Pat asserts that "Darwinism" has what he calls a "marketing problem," in essence seemingly saying that, because he can't understand "Darwinism" but can understand…
evolvingthoughts | July 9, 2007
I probably agree with Christopher Hitchens on many substantive points. But I won't be reading his book. Instead, we can thank this reviewer for their critical, ascerbic, and I suspect in the end accurate review of God is Not Great: How Religion Poisons Everything.
evolgen | July 9, 2007I thought I had come to grips with evo-devo. Then along come Hopi Hoekstra and Jerry Coyne to call shenanigans on Sean Carroll's model of evo-devo. This is nothing new for Coyne, but I can't recall Hoekstra ever getting involved in the debate before now.
Before we get to Hoekstra and Coyne, let's allow Carroll to describe evo-devo in his own words. His most recent summary of the evolution of transcriptional regulatory regions can be found in this paper from a recent National Academies Sackler Colloquium. Here's how he and his colleagues explain the importance of cis regulatory regions (CREs)…
clock | July 8, 2007
This is a post from June 28, 2005, reviewing one of my favourite new evolution books (reposted here):
Ever since I read Gould's Ontogeny and Phylogeny in about 1992 or 1993., I knew I wanted to do research that has something to do with evolution, development and timing. Well, when I applied to grad school, I could choose between evolution OR development OR timing, but not any combination of two or more - the true evo-devo folks were just not available for me at that precise moment in history. I chose timing and than worked dilligently to infuse my work with as much evolution and development…
clock | July 7, 2007Not really a review of Greg Bear's "Darwin's Radio" and "Darwin's Children" but musing (practically SF itself) on the topic of these books (from April 20, 2005, also reposted here so you can see the comments):
Did A Virus Make You Smart?
I've been reading science-fiction pretty much all my life. I usually go through "phases" when I hit on a particular author and read several books by the same person. Last year I was in my Greg Bear phase and I have read eight of his books. He is one of those writers who gets better with age: more recent his book, more I liked it.
His is also some of the…
evolgen | July 5, 2007Last month's issue of Evolution (aka Evolution Int J Org Evolution, aka Evolution (Lawrence Kansas), aka some other confusing way of referring to the journal published by the Society for the Study of Evolution) contains two articles on teaching evolution. The first is on creating museum exhibitions to showcase evolutionary biology. The article focuses on Explore Evolution, a project in which multiple museums in the midwestern United States put up permanent exhibits about evolution. The exhibits encourage problem solving to understand how evolution works and have multiple examples from diverse…