Let your neurons relax, the predators are gone!

Predators eat prey. Prey, over time, evolve features to evade predators. But what happens when predators go away?

This paper by Fullard and colleagues is almost a perfect storm of topics that I’ve talked about several times before on this blog. We got crickets (previous appearances here, here, and here), we got bats (previous appearances here and here), we got reverse evolution (discussed here).

Teleogryllus oceanicus is found on landmasses across the Pacific Ocean, ranging from mainland Australia to remote islands. The distances between populations are so large that you would expect these populations to be slowly separating by genetic drift alone. Using highly variable regions of DNA, Fullard and colleagues showed that there were genetic differences in the crickets based on the geographic distance between them. The most distinct populations were from the Australia city of Darwin, and Moorea in French Polynesia. While a few people might know Darwin is located in Australia’s top end, I expect very few could pinpoint Moorea on a map, so I’ve done it for you. Moorea’s the one on the right.


Not only is it a bit tricky for humans to locate, being far in the middle of the Pacific Ocean, bats haven’t located it either. There are no bats living on Moorea, in contrast to the Australia mainland, which boasts a rich assemblage of the flying mammals. Bats are cricket predators, So this creates an interesting situation where there are expected to be clear differences in selection pressure on the crickets. Many aspects of crickets’ sensory systems, particularly hearing, seem to be specifically tuned to detecting and avoiding bats. Several big auditory neurons respond strongly to the ultrasound that bats make when echolocating, and crickets will fly away from ultrasound pulses (negative phonotaxis).

One critical neuron that crickets use, in some contexts, as a bat detector: ascending neuron 2 (mentioned before here; red in the picture). Ascending neuron 2 (AN2) isn’t the only auditory interneuron that can respond to high frequency bat sounds that bats make when echolocating, however. Another neuron is omega neuron 1 (ON1), which responds both to high frequency, bat-like sounds, but it also critical to the processing of low-frequency, cricket like sounds (green in the picture).

Thus, the prediction from evolutionary theory is that in a situation with no bats, you would expect there to be reduced selection pressure to maintain the neurons’ sensitivity to high-frequency, bat-like sounds. The decrease in selection pressure should be stronger for AN2 than ON1, because AN2 seems to be more strongly dedicated to a single task than ON1.

There are many different parameters of a neuron’s response to a stimulus, but the authors present for sensitivity: What is the lowest level of sound needed to get the neuron to fire? The Moorea population’s threshold for AN2 is significantly higher across the board, whereas the sensitivity for ON1 is not significantly different at almost every frequency. There is a significant difference at one frequency, 15 kHz, but this seems to be a chance finding due to the large number of comparisons being made.

This difference is also reflected in the behaviour. There was no significant difference between the populations in turning towards a cricket-like low-frequency sound, but there is a significant difference in populations when turning away from bat-like high-frequency sound.

What this paper doesn’t have is a good description of the suspected history of cricket colonization or bat colonization across the range. This is probably because it is unknown, but it would be interesting to have some idea of how long the crickets in French Polynesia may have been in a bat-free environment.

A great follow-up study would be to look at what level this evolutionary change has occurred at. There are many ways that an interneuron could lose sensitivity to a stimulus. The ear could change; the sensory neurons in the ear could change; the connections of the sensory neurons to the interneurons; the physiology of the interneuron could change... and so on.

Full disclosure: One of the authors here was my boss about a decade ago. I wish he’d been working on this project then!

Reference

Fullard, J., Hofstede, H., Ratcliffe, J., Pollack, G., Brigidi, G., Tinghitella, R., & Zuk, M. (2009). Release from bats: genetic distance and sensoribehavioural regression in the Pacific field cricket, Teleogryllus oceanicus Naturwissenschaften DOI: 10.1007/s00114-009-0610-1

Neuron picture from Scholarpedia.

Crawling back up

My review article has climbed back up a notch to #2 in Brain, Behavior and Evolution. That’s five months in top three, for those playing along at home.


If you think this article is interesting, tell your friends. I’d be interested to see if the article can reclaim top spot.

Comments for second half of October 2009

Laelaps covered a paper I'd also done (clubbed tails in glyptodonts), so I left a little link for those wanting more.

Slides that Stick made a comment about the shape that brains are best at absorbing information from. I wanted more...

The Online Laboratory of Kevin Zelnio takes issue with an ad. I am nonplussed.

Finite Attention Span talks about making lecture time into practice time. I point out that this takes more than an instructor’s willingness to do so.

Storytelling in science, part 2

Earlier this week, I commented about the importance of stories, and how denialists of science have a lock on the “little guy fighting the establishment” story. I mused about what the counter story is to that.

As much as I hate to suggest this, I think I have one.

Zombie apocalypse.

You face an world of dangers that are slow and stupid but many and unrelenting. You have limited resources. If you let your guard down, that’s it. If you don’t have the weapons and some knowledge and a little technology, you’re done.

The zombies are the natural world, always throwing up little surprises like a new strain of H1N1 virus. We are finding out to our peril that some of our resources really are limited, or pose their own threat, like fossil fuels.

Scientists?

We’re the ones with shotguns and a stash of shells, baby.


We have decided to fight and we might just be able to help a lot of other people. When the shit hits the fan, the chips are down, you want scientists on your side, because they just might be the only thing standing between you and a a messy end.

(And for the record, I repeat: I hate zombie fiction! But happy Hallowe’en weekend, anyway!)

Picture from here. And yes, I put this up in full knowledge that I will never be one tiny fraction of that bad-ass.

Earning it versus enforcing it

I wonder if students realize how deflating it is for their instructor when, in a class with 20 registered students, only three students show up on time for the start of the class after a couple of months.

Some would say that I haven’t earned the student’s attention, and that I haven’t put in enough effort to make the class so completely engaging that my students couldn’t imagine being any place else three days a week at 8:45 am besides my classroom.

But you know, I can only juggle chainsaws for so long.

Laura Bergalls, over at More Than PowerPoint, talked about the need to earn attention:

A modern audience uses modern tools. As a presenter, I need to learn to adapt my style to fit their needs. Why should the audience have to pacify my selfish needs for their attention? Why should I force my audience to stop using tools that let them learn and share information?

Indeed, Olivia Mitchell encourages presenters to embrace things like Twitter.

As a presenter, I agree. As an educator, I am torn over this.

On the one hand, I do try to make a talk something that is enjoyable rather than painful, and I do want to earn that attention.

On the other hand... What if I have evidence that laptop use in class hurts student performance? (There is.) That multitasking hurts learning? Should I just let them have their laptops running (and let everyone fight over the two or three seats in the room near a power outlet)?

I think doing nothing in that case is irresponsible of me as an educator. It makes me feel that I have given in to the wasteful “sink or swim” teaching technique, where absolutely everyone is on their own for everything at all times. As an educator, I don’t think it’s selfish of me to make a student aware of behaviours that are not productive to their learning. “I notice you haven’t been in class much” or reminding students to turn off their phones or even banning laptops are ways to try enforcing attention. I wonder if they are occasionally necessary to use in an educational setting, even as I try my damnedest to earn their attention.

Storytelling in science

When I saw the silent film version of The Lost World, I was amazed at how it set the template for monster movies for decades. Watch The Lost World, and you can see the mold being set for King Kong, The Beast from 20,000 Fathoms, Godzilla, Varan the Unbelievable, Valley of the Gwangi, Gorgo, Cloverfield, and on the list goes.

It’s something that Randy Olson talks about in Don’t be Such A Scientist (which I reviewed here): there are a few really strong story narratives that we love to hear over and over again. If you want to have an audience for your science, it helps to know what those are, and tell people a story they want to hear.

I’ve had questions have been bugging me about this. First, why do we seem to have such a limited range of narratives that resonate and stick with us? Why do we love hearing the same basic story over and over again? Can we create new stories that are as powerful as the “hero’s journey”?

Second, do stories have opposites?

I think I need some examples to explain that question.

I read once a claim that any effective messages in advertising or branding has an opposite. If one business advertises low prices, its competitor sells quality. If one corporation pitches itself as family friendly, the other says, “Grow up.”

A recent post on the Respectful Insolence blog talked about a dubious magazine article, and blogger Orac noted:

Journalists do so love that cliché, don't they? It's an irresistable (sic) hook, cliché or not. People love reading about issues that we thought to be true but – surprise! surprise! – turn out not to be true. ... Framing an issue as arguing that conventional wisdom is wrong and highlighting a couple of “lone voices in the wilderness” warning, Cassandra-like, of impending disaster represent a time-honored journalistic trope, not to mention a story structure that goes back thousands of years to, well, Cassandra at least.

Same analysis over at Effect Measure:

Our main point was that it was a straw man argument built around the narrative device of the brave, mavericky truth teller who is shunned by colleagues and has to eat alone at conferences.

The “I’m an oppressed little guy fighting against a hide-bound establishment” is a story that you see when you look at denialists of all stripes.

What’s the counter-story? If the denialists are able to get such mileage out of claiming that they are oppressed by an evil conspiracy (even when they’re not), surely there’s some story that can be used to illustrate the slow, hard-won accumulation of evidence that is the way most science progresses.

Tuesday Crustie: Peek-a-boo!

Hermit crab (Pagurus bernhardus).

Photo by David Spreekmeester on Flickr, used under a Creative Commons license.

The princess and the perfume, a hermit crab fairy tale

Once upon a time, there lived a princess in a far away land. The princess was young and fair, and this drew the attention of a knight. Though the knight was strong, the princess loved him not.

Enraged, the knight captured the princess and held her in his castle, and told her cruelly that they would soon be wed.

The princess was not strong enough to escape the knight, though she tried many times. Still the knight kept her, guarded in his castle.

But though the princess was not powerful or strong, she was clever. She realized that while she may never be strong enough to defeat the cruel knight, surely there was someone else in the kingdom who was powerful enough to defeat the knight. But how could she find a champion?

Feigning interest, the princess told the knight she wanted to create a perfume, whose wonderful scent would mark her wedding day. The knight eagerly supplied her with all she requested, and with that, the princess created a magic perfume.

From the highest tower of the knight’s castle, the princess let her magic perfume be carried by the winds throughout the kingdom, knowing that strong men who caught the scent would be compelled to follow it back to the castle and challenge the knight...

---

Male hermit crabs often get what they want by being bullies. Males of the species Pagurus filholi (pictured) attempt to monopolize mating access to females by guarding the females, often for several days. Females are not physically able to challenge the males, so what can they do to ensure that they have the opportunity to mate with the fittest males? Okamura and Goshima suggest that the females incite a riot among rival males by releasing pheromones into the water.

This paper contains six short experiments. Several revolve around using “pheromone water,” which is just water that an female unmated female had been kept in; the actual chemicals that might be involved in the signal are unknown.

The authors also made simulacra of guarding pairs by using a live male, gluing a typical shell that a female might have, onto the male’s claw, which is apparently a pretty good visual imitation. To get the smell right, they stuffed the “female” shell with cotton batting containing seawater or some variation of the “pheromone water.”

In the first two experiments, they show that more fights break out when a guarding pair of crabs, or a reasonable simulacrum thereof, is introduced into a collection of males than if a lone male is introduced. Males will normally fight, but if there are chemicals indicating there is a guarded female around, they will fight longer, which is the main evidence for a female pheromone that encourages male competition.

The third experiment tries to ascertain which sensory cues the males are using to detect guarding pairs. If able to see, the males are more likely to be aggressive if there is also a pheromone cue in the water. They found no difference between sewater scent and putative pheromone, however, if the non-guarding males were blinded before the imitation guarding pair was introduced. The blinding of the males makes this experiment difficult to interpret, because they literally cut the eyes off. It would be a cleaner experiment if the effect was reversible (say, by temporarily painting the eyes with something opaque), so it could be tested if the same animals that did not respond when blinded would then respond if they could see. Also, there is an error in the text for this experiment: the words say an effect is not significant, but the statistics listed says it is.

The crucial experiment is the fourth. When there is water from an unmated female is introduced into a tank, males fight longer than if sea water, or water from a mated female (one with eggs) is introduced into the tank.

The last couple of experiments are “dotting the Is and crossing the Ts” experiments. Experiment five tests responses of lone males to just the pheromone-containing water, and finds guarding of uninhabited shells increases when males are exposed to pheromone water compared to sea water. It seems that there is a greater response to pheromone water collected from a guarding pair than a female that had been guarded, but was not guarded at the time the water was collected. Again, it is a little difficult to interpret, because there are three treatments, the text is a bit ambiguous as two which treatments differ from the others.

The final experiment shows that when fighting breaks out between males, the biggest males tend to win, and take over the “guarding” position of the female. No surprise there, as body size is almost always the major factor determining fight outcomes in crustaceans.

That there are so many short experiments makes me a little annoyed that the standard journal practice of separating methods and results means that there is much flipping back and forth between the two. It would be much more readable if each experiment was discussed in total, in on part of the text.

This is a very interesting social system where it seems that the females are both powerless and powerful. They are powerless in the literal sense that they cannot resist being guarded by males. But they are powerful in the sense that they encourage and exploit male aggression, presumably in an attempt to ensure they are guarded by the highest quality males.

Reference

Okamura, S., & Goshima, S. (2009). Indirect female choice mediated by sex pheromones in the hermit crab Pagurus filholi Journal of Ethology DOI: 10.1007/s10164-009-0188-2

Photo from here.

Reading Week panel on Darwin

Last night, I had the fun of participating in a panel discussion at a local community college for their reading week. The organizer had picked evolution as the theme, because we are nearing the 150^th anniversary of the publication of On the Origin of Species.

To my surprise and delight, the auditorium was packed.

This did cause us to start quite a bit late, as the organizer was fretting about the possibility of us violating a fire code, and set off to find more chairs. But spirits were so good! In his introduction, organizer Jerry Freeman mentioned some video on the net* where people were singing “Happy Birthday” on Darwin Day, and somebody started singing it, and the audience joined in for an impromptu birthday song to Charles Darwin.

I was the first speaker, and I talked a bit about all the fantastic transitional fossils that have been found in the last 150 years, how we’ve got a much better handle on genetics and heredity and DNA, and how we’ve developed methods to assemble and test phylogenetic trees, which have allowed us to make trees like this.

Because this was Reading Week, I was asked to read a little evolutionary writing, and I though reading something from Origin was too obvious. Instead, I picked a favourite paragraph from the last page of Stephen Jay Gould’s magnum opus, The Structure of Evolutionary Theory, about what evolutionary biology would be like if Darwin had not existed:

(W)e would have experienced the same biological revolution without the stunning clarity, illustrated by wonderfully apposite metaphors, of a complex central logic so brilliantly formulated, and so bristling with implications extending nearly forever outward, at least well past our current reckoning. In this alternate world, we would probably be honoring a different and far less compelling founder by occasional visits to a statue in a musty pantheon, and not by constant dialogue with a man whose ideas live, breath, challenge, taunt, and inspire us every day of our lives, more than a century after his bones came to rest on a cathedral floor at the foot of whatever persists in the material being of Isaac Newton.

I was followed by a talk on evolutionary thinking as related to human sex and aggression, and a philosophical one on how Darwin’s ideas had changed our sense of telos, or purpose.

The audience made it awesome on a stick. Awesome on a stick dipped in chocolate.

Thanks to all who attended.

* I think he might have been thinking of this one.

Tuesday Crustie: Take me to your leader

A porcelain crab, Petrolisthes elongatus. The photographer titled it, "The face of the alien," and more than a few aliens in old movies did look very crustacean inspired.

Picture by user Nuytsia@Tas on Flickr. Used under a Creative Commons license.

Looking at the genitals of naked mole rats

Since Heterocephalus glaber are naked mole rats, they shouldn’t mind anyone looking at their sex organs, right? I mean, they’re naked, so it’s not like they’re ashamed or anything.

Seney and colleagues noticed that male and female naked mole rats had very similar looking sex organs. Naked mole rats happen to be famous for having a social system that is very much like social insects, with normally a single reproductive adult female and non-reproductive workers. They wondered if this unsual similarity might be related to the social structure of the mole rats.

Rufus notwithstanding (below), naked mole rats are obliged to live in social colonies, and will die if alone, so they couldn’t really do an experiment. Instead, they went looking for another species that showed some similar social features, and found the Damaraland mole-rat (Fukomys damarensis). It also lives in colonies, but the colonies are smaller, meaning more individuals, on average, reproduce. Seney and colleague predicted that the Damaraland mole-rat should have genitals that were more similar in males and females that other, non-social mole rats.

In short, that’s pretty much what they found. Out of six features they authors examined, the Damaraland mole-rat resembled the non-social mole rats on three measures, the naked mole rats on one, and sat in the middle on two.

Interpreting these results hinges upon the relatedness of these species. The authors note that sociality has either evolved more than once, or been lost more than once within the family. The authors argue that the naked and Damaraland mole rats “seem” to have evolved sociality separately, but the information presented in this paper don’t do a great job of convincing here.

The authors also note that the naked mole rat situation seems to be the reverse situation to hyenas. Hyenas also have very similar genitals, but this seems to be because the females’ genitals have been masculinized to resemble the males’. Here, the males’ genitals seem to be feminized to resemble the females’. It’s not at all clear, however, what the relevant selection pressure, or lack thereof, is that is creating similar genitals. It’s slightly surprising that even the “king” males in a naked mole rat colony, that actually do breed, stills has genitals that resemble the females.


Reference

Seney, M., Kelly, D., Goldman, B., Šumbera, R., & Forger, N. (2009). Social Structure Predicts Genital Morphology in African Mole-Rats PLoS ONE, 4 (10) DOI: 10.1371/journal.pone.0007477

A doubting collection of blog posts

A new blogging anthology is planned for early next year: the Skeptical Blog Anthology. You can find more details, and a link to a submission form, here.

Warrior caste

Does the difficulty of reverse evolution mean evolution is impossible?

My recent post on reverse evolution included some recent work by Joe Thornton. I was not aware that his work had been discussed in the context of creationism. Thornton’s response and description of his work has gone up at Carl Zimmer’s blog, The Loom.

Should we give up anonymous reviewing?

Has anonymity ever elevated the level of discourse?

A recent blog post describes the toxic effect of anonymous online chatter on a conference:

I felt sorry for the conference organizers, who were obviously reading the BackNoise chatter. They started out the day with enthusiasm, energy and confidence. They visibly sagged as the day wore on, making almost apologetic comments to the audience in between speakers.

It reminded me of famed British anatomist Richard Owen.

Owen was, by all accounts, a real piece of work. He was undeniably brilliant, tutor to royalty, critical in establishing institutions like the British Museum, but he was also just plain nasty.

Owen wrote a review of On the Origin of Species by Charles Darwin that proves that snarkiness was invented long before the 20^th century. Most famously, Owen talked about his own work but feigned objectivity by writing about himself in the third person:

In his last published work Professor Owen does not hesitate to state ‘that perhaps the most important and significant result of palæontological research has been the establishment of the axiom of the continuous operation of the ordained becoming of living things.’

Indeed, Owen’s review has a lot of the sort of backchannel nastiness that prompted Stacy Williams to write the post that started us off. Owen was able to do this because at the time, book reviews were published anonymously, for reasons that sound fine in theory: “The reviewer has to feel absolutely free to say anything.” Eventually, the practice of anonymous scientific book reviews faded for reasons that I haven’t been able to trace.

To this day, however, review of technical papers are almost always anonymous to the authors of the article being reviewed. Even journals that argue that they are trying to do science publishing in a new way, like the PLoS family of journals, keep peer review anonymous. The argument is the same as used to be used for book reviews: “The reviewer has to feel absolutely free to say anything.” Stories like Owen’s review and the effect of anonymous and pseudonymous writing on the internet suggests anonymity is more likely to breed invective than constructive criticism.

Arguments for keeping reviews anonymous include that a slighted author may take some sort of revenge against a negative reviewer. Is there anyone in a research field who is so powerful that they can completely prevent a researcher from publishing in all journals and prevent someone from getting any funding?

The scientific community is no longer a clique of wealthy Victorian gentlemen publishing in a scarce number of journals, where angering the wrong people could block you from publication. If privacy is dead, maybe anonymity should join it.

Geek space

From Finite Attention Span.

Retracting a paper when the science is sound

The most recent issue of PNAS has an editorial explaining why they required a paper that appeared online to be retracted. It’s a situation that is, as far as I can tell, without a clear precedent.

The paper, which has four authors, was published online at the end of August. Apparently unbeknownst to some of the other authors, one author signed an agreement with the National Institutes of Health (NIH) not to publish data arising from the project until near the end of September.

Nobody is denying that there’s a problem here. But was retraction the best or only option?

Retraction is a serious business. It is a formal expunging of a paper from the scientific record. In theory, that paper should never be cited. It’s all very mannered and Victorian: “We shall never speak of this again.”

Previously, when I’ve seen papers retracted, it’s usually been due to a problem with the science, where questions have been raised about the truth of the data (due to error or scientific naughtiness). Occasionally, there has been some other sort of weirdness that has resulted in retraction, but in all cases, only two parties have been involved: the authors and the editors.

This situation adds a strange new wrinkle: the ethical violation involves a third party. And as Newtonian physicists learned, three body problems can be insanely difficult. There are many questions arising from this action.

Nobody is questioning the science presented in the paper. Because retraction was usually reserved for papers that were wrong, it ensured the scientific record remained free of known error. That purpose is not served by retraction here.

Can this paper be published in another journal at a later time? Retracting a paper for an ethical violation other than those related to the integrity of the data or text is so rare that I have no idea if there will be any issues with trying to publish the results elsewhere later.

Only one author signed off on the embargo, but three more people are suffering the consequences of the retraction. This seems to be an offshoot of the standards for authorship established by journal editors: Every author is responsible for every claim in the paper equally. Authorship conveys equal responsibility for everything in the paper.

Except that again, the problem is not with the text. The problem is with an agreement entered into with a third party. If NIH’s policy is being violated, shouldn’t NIH be the one responsible for enforcing any consequences of breaking embargo rather than the journal? Maybe this journal’s action was requested by NIH, but if so, the editorial doesn’t say.

The whole situation seems analogous to someone not paying his power bills and having his car, and the cars of his business partners, repossessed.

The editorial course of action seems unsatisfying. The Adventures in Ethics and Science blog raised a similar point. It seems that when dealing with scientific misconduct, there are only two options: a slap on the wrist or the firing squad. That, I think, is the heart of the problem. Editors have an limited range of tools to deal with ethical violations. The editors can either “wag their finger” at the authors, which could be seen as complicity with an ethical violation, or retract the paper, which could be seen as swatting a fly with a hammer.

I’m all for dead flies, but I hate the holes in the wall. There’s got to be room for sanctions that are less destructive.

Update, March 2010: The Embargo Watch blog follows up on this story.

Reference

Schekman, R. (2009). PNAS takes action regarding breach of NIH embargo policy on a PNAS paper Proceedings of the National Academy of Sciences, 106 (40), 16893-16893 DOI: 10.1073/pnas.0910317106

Comments for first half of October, 2009

Over at Neurotopia, I talk a bit about whether PLoS One is really as accepting of negative results as they claim to be.

People don’t recognize Chewbacca? Reminds me of when Anita made the mistake of mentioning tribbles in class.

I get all pedantic on poor Olivia Mitchell for a neuromyth about reptile brains.

Problems of reality or perception?

Randy Olson often says scientists are handicapped by their blind obsession with the truth.

Rory Sutherland puts it this way:

And this shows that engineers, medical people, scientific people, have an obsession with solving the problems of reality. When actually most problems, once you reach a basic level of wealth in society, most problems are actually problems of perception.

I love that quote, but you should do yourself a favour and watch his whole TED talk. It is brilliant.

And I’m not just saying that because it features Shreddies. (Homesickness trigger.)

Everybody click the tortoise!

In mid-July, a preprint about stickleback size appeared in the journal Evolution.

In August, I wrote a post about it.

Now, a new column in SEED magazine has some material from that post. It also refers (and links to) my more recent post on Komodo dragons. And it’s featured even on the home page! Check out “Evolved for extinction.”