Monthly Archives: April 2011

Things I have learned in the past couple of weeks…

Guglielmo_Marconi

Image by roberthuffstutter via Flickr. This picture of Marconi was suggested by WordPress, and is in no way related to the subject of the post.

  1. Everybody and their dog goes on holiday starting right about … oh, the time you need to talk to them because your house is on fire.
  2. I’ve heard it again and again, but I never listened:  when you start a collaboration, be damn sure that you know who’s doing what, who’s getting what credit, and where the project is headed.  Otherwise, you’re begging for one huge train wreck at the end.
  3. When you narrowly avert said train wreck, thank your lucky stars.
  4. Universities suck at writing regulations about doctoral theses.  Just sayin’.
  5. I need a damn vacation.
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Evaluating the fitness consequences of signalling…

Robert Kurzban, over at the Evolutionary Psychology blog, has a post up which caught my attention because it deals with an area of behavioral ecology that I happen to know a little bit about:  signalling.  My master’s degree was done on animal aggressive communication models, under the supervision of Pete Hurd.  So I was intrigued to see what Robert had to say.

The post itself was fairly underwhelming for me, because Robert only seems interested in using a (somewhat overstated) terminological dustup over signals versus cues.  But about halfway through the post, he decides to throw a rather large stone in a surprisingly glass house:

Let’s turn to the substance of the matter. Maynard-Smith and Harper (2003) define a signal as “any act or structure that alters the behaviour of other organisms, which evolved owing to that effect, and which is effective because the receiver’s response has also evolved” (p. 3).

Their first example is distinguishing two ways a stag might make another stag retreat: push him or roar at him. Pushing, they argue, isn’t a signal – it does alter the behavior or the other organism, but the response, moving backwards, didn’t evolve as a response to pushing – it’s simply a physical consequence. In contrast, retreating in response to a roar, they argue, makes the roar a signal. Roaring evolved because retreating from roars is an evolved response, the argument goes.

Note how casually Maynard-Smith and Harper make this strong claim. Labeling the stag’s roar a signal is an adaptationist claim, that the behavior in question has a function, in this case, conveying information – signaling – to a rival which, in turn, is useful in the context of intra-sexual conflict. I find it worthwhile to reiterate, at the risk of undue repetition, that this illustrates how biologists routinely make adaptationist claims based on observed patterns of behavior, rather than measuring fitness consequences, heritability, and the like.  [Emphasis mine].

I was astounded by this claim for two reasons.  First, an evolutionary psychologist is telling biologists that they don’t measure fitness consequences?  When was the last time an evolutionary psychologist did an experiment in which they manipulated a trait and measured fitness consequences, i.e. survival and / or babies made as a result?  I would love to be on the ethics committee that processes that application, I really would.  Every EP study that I have ever read which deals with fitness in any way is either a correlational study (e.g. using historical birth record data or doing a cross-sectional analysis) or uses some proxy  for fitness, like asking women to rate the attractiveness of male body odours that they sniffed from used t-shirts to assess the “fitness consequences” of MHC (major histocampatibility complex) preferences.  Don’t get me wrong, I find a lot of this work interesting, but to criticize biologists for not assessing fitness consequences is quite the santicmonious move.

In behavioural ecology we often do as the MHC researchers do and use proxies for fitness, by which I mean that we measure a trait that we argue (or assume) is correlated with fitness.  For instance, in foraging research, we assume that food intake rates will correlate with fitness and so suggest that the adaptive value of a behavioural trait can be measured – at least indirectly – by manipulating the trait in some way and seeing how that impacts food intake.  Would we prefer to measure fitness directly?  Sure we would!  The reasons we use proxies usually boil down to the difficulty, or downright impossibility, of measuring fitness in that way.  Primatologists, for instance, are going to be about as likely to perform such direct fitness studies as evolutionary psychologists are, and even those of us who work with smaller and easier to handle animals are going to find such research challenging.

But that brings me to my second objection, which is that biologists do measure fitness consequences (and heritability, and the like, but I’ll focus on fitness here).  Some examples:

–  The obvious:  twisting Drosophila into various shapes and seeing the consequences (fitness or otherwise) of that is practically an industry by now.  It took me about four seconds and a single Google search to find a nice-looking study on sexual selection and fitness outcomes in Drosophila by Promislow et al. (1998), and the related links lead to a flood of more recent research.
–  The awesome:  many examples are found in sexual selection research, for obvious reasons.  Frogs have some good examples of this, like work on the Australian frog by Jeremy Robertson that showed that female choice of male calls was adaptive by showing the consequences to female clutch fertilization by a mismatch between call and male body size.  And I’m pretty sure that Mike Ryan, who has done a lot of incredible studies on the signalling system in túngara frogs, would be surprised to find out that biologists don’t assess fitness consequences.

–  The vaguely frightening:  ever seen hermit crabs fight?  It’s a bit scary.  Check out this video from the Royal Society in which one crab thoroughly kicks the snot out of another and then steals the other guy’s house:

Research on the fitness consequences of these fights goes back decades, both intra- and interspecifically.  The signalling system used by hermit crabs (like shell rapping) is also a fascinating area of study.

–  The avian:  birds are a common target for this, too.  A particular example I like comes from an area close to home, the zebra finch.  Remember the assumption I was talking about above, using foraging intake rates as a proxy for fitness? William Lemon decided to test this directly, and so he manipulated the feeding rates of four zebra finch populations to determine the adaptive value of energy maximization (and its suitability as a proxy for fitness) by directly measuring survival and reproduction in the populations.  Show me the EP study that does that.

This is just a short list cobbled together from what I can think of off the top of my head and some quick Googling, and I even confined myself to just studies looking at reproductive benefits;  many more have done work on the survival component of fitness, and to cover even a fraction of those would require an inconveniently long book.  Even the examples I’ve chosen are slanted towards behaviour, for obvious reasons, and people skewing towards the genetics side of things have done a lot more work on these types of questions than we have in behavioural ecology.

When I began my undergraduate career in psychology, I was attracted to evolutionary psychology.  I felt then, as I do now, that the core concept of taking evolution’s effects on homo sapiens into account is true and needs attention.  It’s what inspired me to shift to biology, so that I could study the tools of biology and bring them back to the sort of questions that EP studies.  And if Robert’s feelings are shared by other current practitioners of EP, I can’t help thinking that the field needs more people who will do the same.

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Standing for science..

Okay, the title makes the post sound dramatic, but it’s a bit of misdirection. Really, what I’m talking about is the standing desk phenomenon that’s been getting some attention lately. Given how much of my day is spent sitting hunched over staring at a computer screen, I decided to throw caution to the winds and give it a shot. Mind you, I didn’t feel like spending a bunch of money on the project – and my office space comes complete with a desk heavy enough to withstand your basic nuclear strike – so I decided to get on my feet on the cheap. A trip to IKEA last night and $30 later (and with the help of the guys in the shop downstairs who operate those awesome power tools), here’s what I’ve come up with:

1000000280.JPG by Winawer0
1000000280.JPG, a photo by Winawer0 on Flickr.
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An ode to statistics..

I was pretty sleepy after my Ph.D. seminar, and was browsing on Facebook when I saw that one of my friends was talking about a possibly significant interaction in her data.  The form was quirky, though, and started off:  “Hark…”.  For some reason, this inspired my sleep-deprived and addled brain to bastardize a bit of Shakespeare (which is apparently from Cymbeline, Act 2, Scene 3).  Since she got a kick out of it, I thought that it might be blog worthy:

Hark, hark, the lark at Fisher’s gate sings,
And Student ‘gins arise,
His p-values to water at those things
On data values that lies;
And significant ANOVA tests begin
To show their golden prize;
With everything that significant is,
My conclusions sweet, arise:
Arise, arise!

With apologies to The Bard. And anyone who read this exercise in sleep deprivation.

Valuable lessons were learned…

At UQAM, one of the required activities to achieve the Ph.D. is to complete a seminar for the department, which I bused into Montréal yesterday to give today.  As I have been reading and thinking about presentations in science lately (including Presentation Zen, the great book by Garr Reynolds), I spent a long time working on the visuals for my talk and doing my best to create a talk with a coherent narrative and a sound logical structure.  Having arrived in Montréal yesterday, it occurred to me to actually – well, you know – practice the talk I had spent so long on.  Now, I don’t usually have timing troubles with my talks, but when I practiced it last night I came in way over time.  And I mean well over time – to the tune of at least a half an hour if not more.  Much panicked re-arranging and paring-down ensued, ending with me cutting nearly a quarter of my slides.

I had to practice the talk several more times over the evening and then again in the morning, and then race into the lab to give the bloody.  Of course, due to a series of awesome coincidences – including my talk apparently being scheduled during a large training session which soaked up most of my audience – I ended up giving my talk to a mostly empty room.  Add to that a MacBook which has developed a new and exciting habit of randomly rebooting without warning and a projector that flickered on and off in a stochastic fashion, and it was a pretty stressful couple of days.

But I can’t complain too much:  the talk went off okay and was received well, I passed the “course”, and my advisor tells me that my thesis is ready to submit.  So despite the issues, it’s been a good couple of days.

One thing that makes me a bit sad, however, is that many of the slides I had to cut contained illustrations from my wife;  her work greatly enhanced the visual presentation of the work, and it’s a shame that no-one got to see some of them.  With that in mind (and following up on this post), I’ll wrap this up with a few slides from the cutting room floor and a couple that were actually in the talk.

The incompatibility slide.

A slide about the incompatibility assumption in producer-scrounger games.

A slide about the patch discovery rate in producer-scrounger games.

The scrounger convergence assumption in producer-scrounger games.

And one of my favorite slides of the whole talk:

A slide I used while I was arguing for the importance of spatial processes in social foraging.

Ooh, and one final one that I can’t forget:

And a slide introducing a model I worked on about foraging and animal personality...

(Note:  she gave me permission to post these, so please don’t rip them off.  If for some reason you think that they could be useful to you, drop me an e-mail).

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Wish me luck!

I get on a bus in a couple of hours to go to Montréal again, and I give my seminar on Friday.  I’ll update in this space how things go, but in the mean time, wish me luck!  (Or talk amongst yourselves, o ye sudden and inexplicable spike in traffic…)

From my upcoming PhD seminar..

I haven’t had a lot of time to post in the past few days as I prepare for my Ph.D. seminar at UQAM on the 15th, and I get on a bus Monday to go to Montréal (from Edmonton!), so it’s unlikely I’ll be doing anything inspiring from there either.  So, just to prove that I’m still alive, here’s a slide from my slide deck for the presentation I’ll be giving…

Note:  this is the required seminar that I have to give, not my thesis defense.  (That’s still to come, hopefully in a couple of months!)

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