A really nice example of how to communicate some fascinating evolutionary biology. Illinois Natural History Survey ornithologist Kevin Johnson describes his research on the history of feather lice. Anyone who works with birds knows they are lousy–as in, usually covered in lice.
But how did all those lice evolve? Did they share a common louse ancestor, and then diverge as their bird hosts diverged? Bird winglice from a parrot look a lot like bird wing lice on a duck–but those are very different and unrelated hosts. What does that tell us about the history of lice?
You can read the paper this work is based on here:
Johnson, K.P., Shreve, S.M. & Smith, V.S. (2012). Repeated adaptive divergence of microhabitat specialization in avian feather lice, BMC Biology, 10 (1) DOI: 10.1186/1741-7007-10-52
(Looking for a text transcript of the video; you can get most of the content text here)
Quite a few people, including PZ, have posted this video of a student completely loosing it in a classroom. From the school paper:
“Associate Professor Stephen M. Kajiura was reviewing with his evolution class in GS 120 for a midterm when FAU student Jonatha Carr interrupted him: “How does evolution kill black people?” she asked. Kajiura attempted to explain that evolution doesn’t kill anyone.…..The classmate reported that Kajiura was discussing attraction between peacocks when Carr raised her hand to ask her question about evolution. She asked it four times, and became increasingly upset each time Kajiura’s answer failed to satisfy her.
A video taken by Bustamante shows Carr ranting and threatening to kill the professor and several students.”
I’ve discussed violence before that is motivated by anti-evolution, both directed against me and others.
Honestly, I don’t think this outburst had that much to do with evolution, although it’s certainly scary that evolution seems to be the topic that triggered the student’s outburst. What I was struck by, watching that video as someone who’s been teaching for over 25 years, is the behavior of the instructor and the other students:
- They tried to engage in dialog with a person that is clearly in severe mental distress
- They did not clear the classroom
- It took way too long before anyone called 911
- The students were more interested in filming the student’s meltdown than getting to safety
That? Honestly? Bothers me far more than what the woman was yelling.
If there is anything that needs to be discussed and post-processed about this, it’s that the area was not secured, not that she was angry about evolution.
Do you teach?
Do you have a plan for what you would do in your class if something like this happened?
Have you thought about how you might get all your students to safety in case of an emergency?
Have you recieved training–or at least instructions–about what to do with a distressed student?
If someone is this out of control, your best bet is to GTFO. Get the distressed person in a quiet room, or make the room quiet by getting everyone else out. But don’t expect rational discourse to work.
If you are going to watch this video, do it with an eye to how you would have handled this situation as an instructor.
And learn from it.
When I first heard the title of this television show, my first thought was that it would involve a dancing E. O. Wilson in tights. Sadly, no.
Or, maybe that’s a good thing–you tell me. I think Dancing with the Stars could really use an evolutionary biologist to liven things up.
Either way, this is a neat profile of someone who’s been incredibly influential in biology for the last 50 years. I don’t agree with everything he’s written, since I tend to think more along the lines of Lewontin in terms of my issues with sociobiology. The idea of a “unified theory” of animal behavior is a snipe hunt. (There is also a nice biography of Wilson in the Atlantic this week, BTW, where he has some surprisingly harsh words for Stephen J. Gould over this topic.)
Wilson’s work on biodiversity, biogeography, ecology, and conservation is solid and important. He used his unexpected fame (infamy?) to really push forward conservation. He took his bully pulpit and did something with it.
Enjoy this long interview with Dr. Wilson. He IS the Lord of the Ants.
(I can also report that he’s charming in person, and I’m fairly sure he will find my photoshopping liberties amusing.)
That’s not a quote from a Batman Episode; it’s a new species found in only one area in South Africa. They were discovered by accident when two entomologists were sweep-netting a meadow.
BOHN, H., M. PICKER, K.-D. KLASS & J. COLVILLE 2010.A jumping cockroach from South Africa, Saltoblattella montistabularis, gen. nov., spec. nov. (Blattodea: Blattellidae). - Arthropod Systematics & Phylogeny, 68 (1): 53-69.
As you can see from these photos, the cockroaches have unusual hind legs that are modified for jumping, just like a grasshopper. (The authors christened this animal the “leaproach”, although I would have lobbied for “cockhopper” myself.)
Now, I know that a lot of people don’t count roaches in their list of favorite insects. So, a roach that can bound around like a kangaroo, which -I- think is really cool, is probably a nightmare for some. Humans are most familiar with pest roaches, but those species only make up an estimated 1% of total roach diversity. The rest of the 4000 species of roaches are benign, and often essential to ecosystem health.
Roaches have an amazing amount of modifications to the basic roachy body plan that let them survive in all sorts of environments. There are diving roaches, sand-burrowing cockroaches, wood-eating roaches, and bioluminescent roaches. Frustratingly, there is little information in the paper about why these leaproaches might have left scuttling behind for leaping. The biggest hint is that they are found hopping around in grasslands during the day, pretty much side-by-side with grasshoppers. Being able to jump long distances to avoid predators and find new food sources is handy for both grasshoppers and roaches.
Regular roaches can jump pretty well; the common German cockroach Blattella germanica can jump distances of 4 cm without any special leg modifications. It’s not hard to imagine that day-active roaches that could jump a bit farther might be selected for over many generations.
Leaproaches are a really neat example of convergent evolution. Convergent evolution describes what happens when species that are distantly related–a grasshopper and a roach, for example–become more similar in appearance or structure because of natural selection.
Convergent evolution is the reason why a salmon, a shark, and a dolphin have similar body shapes, while they are not closely related taxonomically. The physical environment they live in shaped their evolution in similar ways to solve similar problems–moving through an aquatic environment, in this example.
The leaproach in this photo clearly has several body changes that are analogous with what you see on a grasshopper–primarily enlarged hind legs and big eyes.
Why not enlarged front legs? Well, if you want to go forward, the direction your eyes and other sensory organs are pointed, large jumpy front legs are not that helpful. Hind legs help to propel you in the right direction, plus you have 4 legs you can reach out in front as you jump to grab onto passing stems of grass and hold on.
Similar environment, similar environmental constraints, and TA DA! Leaproaches. Neato!
An incredibly exciting paper came out in Nature last week about my favorite group of insects–the treehoppers, Membracidae. This group is instantly recognizable by their enlarged pronotum, or thoracic shield. It’s usually big and strangely shaped, letting these tiny insects mimic thorns, leaves, and even ants.
This paper is one that even non-pointy-headed academics should be excited about, because it provides a neat explanation to one of the central questions of evolution: how do really complex structures evolve?
Jerry Coyne and Ed Yong already wrote about this paper, but because I have huge brass ones, I’m going to take a stab at explaining this paper too, hopefully in a lay-reader-friendly way. I’m doing this in part because news coverage of the paper makes it clear that a lot of people don’t understand what homology is. It’s a confusing concept, because homology can be described at many levels, from basic anatomy to molecular biology.
In its simplest definition, homology means that organisms share a common ancestor. Most of us are introduced to this concept with a diagram showing how the bones in human arms, horse legs, and bird wings all share the same pattern. These are homologous structures.
Let’s begin at the beginning of insects (and most animals) with segmentation. Segmentation is a wonderful way to make an animal–it allows the same pattern to be used over and over. Segmentation allows parts of an animal to have separate and specialized functions–business in front, party in the rear, if you will.
If you look at an ancestral arthropod like a trilobite, what you see is that they have a segmented body with appendages on each segment. Over the history of arthropod evolution, those appendages have specialized in different ways–or been lost all together.
So, the first three segments’ appendages became mouthparts or antennae and were lumped together into the head; and different numbers of appendages were lost or joined into the basic body plans for centipedes, spiders, and insects.
Here’s a nice detailed chart showing homologous segments between trilobites (ancestral arthropod) and modern arthropods like spiders and insects. We know that these animals all share a common ancestry and homologous structures.
Somehow, in the evolution of these arthropods, different sets of genes were modified and turned on and off, changing structures and where they appear. Organisms have the same DNA in each cell, but only some of it is “turned on” to make organs or different tissue types. This is the domain of “evo-devo” or evolutionary developmental biology.
How does your body “know” that genitals only go in one specific spot during development? Why doesn’t it build a scrotum on your head like a jaunty beret? Or, in the case of an insect, why do legs and wings develop only on the thorax, in specific spots? Regulatory genes give the instructions. By looking at the way in which regulatory genes control the change from an egg to an adult, biologists can also infer how changes from ancestral organisms have evolved.
The key that unlocked a whole lot of evo-devo knowledge was the discovery of Hox genes. Hox genes are genes that specify identity—whether a segment of the embryo will form part of the head, thorax, or abdomen of an insect, for instance. (If you want a detailed explanation of Hox genes, check out this post by PZ; I’m trying to keep this post light on molecular bio.)
A classic mutation in a hox gene is called Antennapedia. It shows clearly what goes wrong when the command for “put a leg here” is garbled. This fly has a nice looking thoracic leg in place of its antenna.
It would be correct to say that this leg is homologous to an antenna; it wouldn’t be correct to say that it IS an antenna. And that is where the news coverage of this research paper on treehoppers (we’ll get there eventually, I promise!) doesn’t get it quite right.
The way this paper has been reported has been, for the most part:
That’s not technically correct. However, it’s a lot more marketable to a general audience than saying:
“Treehoppers have a fused prothoracic pair of appendages serially homologous to the wings on the meso and metathorax!”
Both statements are pretty exciting (if you are a bug dork, anyway.) The treehopper paper used a clever combination of molecular biology, anatomical studies, and developmental biology to illustrate the evolutionary history of a really complex structure. Here’s the actual paper citation:
Prud’homme, B., Minervino, C., Hocine, M., Cande, J., Aouane, A., Dufour, H., Kassner, V., & Gompel, N. (2011). Body plan innovation in treehoppers through the evolution of an extra wing-like appendage Nature, 473 (7345), 83-86 DOI: 10.1038/nature09977
Treehoppers and their pointy helmets start showing up around 40 million years ago. And the variety is amazing. (Apparently they use the same hatters as the one that created the fallopian monstrosity on Princess Beatrice for the Royal Wedding.)
Just HOW membracids evolved all their strange pointy hats, and what the structure was derived from, has been a source of argument amongst entomologists for many years. Prud’homme and his co-authors have shown fairly conclusively that hopper hats are related to activation of a long dormant genetic control sequence.
In modern insects, wings occur only on the second and third thoracic segments. This is controlled by regulatory hox genes like the antennapedia one I mentioned above. Somehow, the sequence that suppresses wing formation on the first thoracic segment was lost in hoppers. And that provided the raw material for evolution to create endless forms most wonderful.
Prud’homme et al.’s evidence is based upon:
- Anatomical studies showing that the helmet structure has a hinge–like wings do.
- Morphological studies on wing-venation-like structures on helmets, and demonstrating that helmets inflate during a moult like wings do.
- Developmental studies found that the helmet structure is formed from tissue that is similar to wing precursors.
- Molecular studies identified a wing gene (nubbin) that is activated in the tissue of the helmet. This is unusual, because in all other insects, a hox gene called Scr blocks wings from developing on the first thoracic segment.
In fact, the researchers actually manipulated their suspect regulatory genes in another insect to see if they could get wing tissue to develop on the first thoracic segment (T1) of an insect.
The photo at the right shows a mealworm, which is a beetle larva. The top photo shows a normal mealworm, with tissue that will eventually become wings on the 2nd and 3rd thoracic segments (T2 & T3) highlighted using a molecular marker.
The second photo shows what happens when they disable the hox gene that they suspect suppresses wing formation–wing tissue occurs in T1.
It’s a compelling way to wrap up a great evolutionary story. Regulatory genes that control how organisms develop over their lifetime also provide the raw material for many different structures. The crazy hats of hoppers didn’t evolve from new genetic material, but from modification of what already existed.
So that’s my attempt to explain this wonderful discovery to folks who may not have a molecular biology or entomology background. This paper will certainly become a classic in evolutionary biology, as it nicely provides an explanation for the evolution of an elaborate trait using multiple lines of evidence.
And if you’ve read all this way, here is your reward! A video from the author’s supplemental material that shows a hopper in its final molt, first inflating its wings and then expanding it’s pronotum. The similarity to wings is pretty remarkable! (Alas, I was unable to embed it.)
Sadly, Michigan is home to an awful lot of racist bastards with guns. The Hutaree group arrested in May 2010 for stockpiling guns and explosives is a pretty good example. Once again, Americans were shooting and plotting terrorism–and they were doing it in the name of Christianity.
To those of us who have been targeted by Christian Identity folks, this isn’t all that surprising. Christian Identity is a particularly virulent (and violent) form of creationism and apocalyptic thinking. It disguises racism, antisemitism, and brutality under happy, Christian sounding churches and groups. Can you spot the hate group in this line up?
- America’s Promise Ministries
- By Yahweh’s Design
- Church of Jesus Christ Christian
- Church of True Israel
- Ecclesiastical Council for the Restoration of Covenant Israel (ECRCI)
- Fellowship of God’s Covenant People
- Gospel Ministries
- House of Yahweh
- Kingdom Identity Ministries
- Present Truth Ministries
- Scriptures for America Ministries
- Tabernacle of the Phineas Priesthood
- United Identity Church of Christ
- United Church of YHWH
- Yahweh’s Truth
Since, in THEORY, I will have a new job sometime this year (still looking), I thought this might be a good time to start trying to clean up my office. I re-discovered a whole bunch of old folders that I stashed in a box many years ago.
I found an entire NSF grant proposal that I have absolutely no memory of. It got a positive review, it had all sorts of collaborators, but wasn’t funded. And I remembered None. Of. It. Scary!
I found 2 half-written manuscripts that I never finished, and will probably just give up on.
One was an examination of how advertising has historically used gendered entomophobia in order to sell pesticides and cleaning projects. If you want to pick that one up, let me know; I’ll mail you everything I’ve got.
The other was a project I started working on in the late 90s. I was placed on several prayer lists courtesy of some students in my evolution classes. I got interested in writing about how millennial fears factored into different styles of Creationism. Millenialism isn’t much of a hot topic now that it’s almost 2011, so I guess that one is dead in the water.
I also found lots of strange things stashed away in folders. In 1996, there was not a web as we know it now: “In 1996, Americans with Internet access spent fewer than 30 minutes a month surfing the Web.“ So, when I got kinda crazy stuff about Beware the Blue Beam, I couldn’t just blog about it, or post it to Flickr. I could maybe post something to alt.science.biology’s listserver on Usenet.
But now, with Web 2.0, you are welcome to riffle through my files!
I got stuck on The Institute for Creation Research mailing list from 1994 to 1997. Before the novelty wore off, I used to actually open and read all the stuff they sent me. ICR even produced little daily devotional booklets, I guess so you could read something condemning evilutionists every morning with your coffee.
Most of them featured the standard bible verses that showed up on nearly all of my class evaluations: False prophets, Fools that think they are wise, yadda yadda.
But some of them were really weird. Like Henry Morris, Mr. Creationism, suggesting that teachers of evolution should be hanged and drowned.
In fact, he said it twice–here’s a link to the second time.
WWJD? My reading of texts about Jesus give me the distinct sense he would not be down with this. While I might like for JC to put a smiting on ICR, that isn’t his style. Dude’s a pacifist. (Except for bankers, maybe. But who hasn’t felt that way recently?)
Check out all the strangeness in my Flickr Stream; I’ll be adding things over time.
I discovered that bed bug evolution–specifically resistance to pesticides–was also the subject of the National Evolutionary Synthesis Center‘s podcast this month. A FASCINATING interview with one of the grand old men of evolutionary genetics, James Crow. He worked on DDT resistance back in the late 40s and 50s.
“Like pyrethrums, DDT kills insects by acting on the sodium pores in their nerve cells — and it just so happens that many of the same mutations that protect an insect against DDT also happen to protect it from pyrethrums. When DDT was first introduced, such mutations were probably extremely rare. However, with the widespread use of DDT in the 1950s and 60s, such mutations became much more common among bed bugs through the process of natural selection. Though DDT is rarely used today because of its environmental effects, these mutations have stuck around and are still present in modern bed bug populations. Because of the action of natural selection in the past (favoring resistance to DDT), many bed bug populations today are primed with the right sort of genetic variation to evolve resistance to pyrethrums rapidly.”
I had forgotten I was a “CHILD OF SATIN!”
This, I’m sure, explains a great deal for some of you.
I am trying to remember how I got this–I think it was under my windshield when my car was vandalized (silly me–I had a Darwin Fish on it.)
Anyway, I have all these amazing bluebook essays and comments from my teaching evaluations where students discuss creationism and evolution. I would love to share them, to give people a flavor of the sorts of things I run into when teaching evolution. These are old enough that they probably can’t be identified to any individual (and the evaluations are anonymous anyway.)
Should I scan and post them?