Wednesday, May 28, 2014
Optimal foraging strategies of Scolasticus graduate* at Genomes to Biomes 2014
all graduate students, am primarily driven in life by the search for, and
attainment of, free food. Performing
experiments, writing your thesis, maintaining interpersonal relationships,
etc., are all important goals, but they pale in comparison to finding a
workshop that offers free pizza. This
primal drive is exhibited maybe most clearly at academic conferences, where
free food (and here I mean free as in “Buy this $2000 computer and get a free
mousepad”) is a predictable but limited resource.
The Genomes to Biomes conference currently being held in Montreal is no exception. In fact, the different resource densities and distribution patterns exhibited depending on the time of day (i.e. Welcome Reception, morning coffee break, or poster session) provides the perfect opportunity in which to study this behaviour. There also happens to be some scientific talks going on at this conference, which offer the chance to compare the behaviour of the graduate student to the organisms they study, which range from daphnia to blue whales.
Starting with the Welcome Reception at UQAM on Sunday night, small prey items, such as scallop sliders, shrimp-kabobs, and tiny-steaks-in-a-spoon were moving freely throughout the population. In some areas of the habitat, like the far corners of the room, these prey items were found at a fairly low density, which sometimes elicited a chase behaviour (very costly in terms of social value) in order to secure a bite. However, I soon discovered that the space right next to the catering door contained a very high density of prey, allowing the students to simply stand in place, even continue their conversations (high gains in social value), and the prey would actually APPROACH the students. This difference in behaviour depending on the density of prey is mirrored in the blue whales that Jeremy Goldbogen studies (“Krill density and depth distribution drive the optimal foraging strategies and maneuverability of lunge feeding in blue whales”). He found (by tagging the whales with accelerometers!) that when eating deep, dense patches of krill, whales tended to swim in a fairly even plane, but when they encountered shallow, diffuse patches of krill they became much more acrobatic, even performing 360° turns. The reason for this difference is likely due to the energetic costs and pay-offs of the two strategies. However, please note that these results don’t mean that you should perform somersaults at the Closing Reception in order to get more dessert—it (probably) won’t work.
Moving to the coffee breaks, where the food offered a high energetic value (you probably don’t want to know how many calories are in one of those one-bite brownies) but acquirement incurred an energetic cost in the form of queuing. However, the sharp (or desperate) ones among you may have discovered that the queues on the top floor (Mont-Royal) were considerably shorter than those on the Cartier/International floor. What compelled some people to disperse downwards, while others dispersed upwards? Sure, not wanting to walk up the stairs (thereby wasting valuable brownie-calories) might be part of the reason, but perhaps those who went to the top floor are genetically driven to explore strange new worlds, to seek out new life and new civilizations, and to boldly go where no graduate student has gone before. This was certainly what Allan Edelsparre (“On the move: How food, genes, and environmental heterogeneity affect dispersal”) found with his drosophila larvae—those with the “rover” genotype had higher expression of a foraging gene that drove them to travel longer and farther in their Petrie dishes in search of food than those with the “sitter” genotype. These same results were found in adult flies both in the lab and in the wild, where fluorescently-tagged flies (sourced from a nearby drosophila all-night rave party) were released then recaught at various distances from the release point. I propose someone (not me) take cheek swabs from all attendees for genotyping at the foraging locus along with data on which floor they foraged on.
Finally, the last official food source of the day before the after-hours
drinking opportunities begin; the poster sessions. Any foraging behaviour at this event is more
difficult to ascertain due to confounding effects of alcohol availability, but I
will do my best. At this point in the
day, energy reserves are low and fatigue is high. Food is a highly sought-after resource, and
yet this is when prey distribution is at its most patchy—yesterday there were a
total of 4 bowls of pretzels per floor (trust me, I counted). This highly patchy distribution causes
students to aggregate around said bowls, making weak efforts to move towards
the closest poster, but often giving up halfway through their migration and
returning to the bowl. The parallels
between this behaviour and that of daphnia are uncanny. Audrey Reid (“Influence of prey patches on Daphnia pulex foraging behaviour”) found
that daphnia placed in tanks with patchy algae resources moved more slowly and
turned in more circles than those in tanks with evenly-distributed algae. She also found that growth was higher in the
patchy tanks, which is an effect I hope is not replicated in the student-pretzel
system (bathing suit season is just around the corner).
Unfortunately, this blog post is going to press before the Closing Reception at the Sucrerie de la Montagne on Thursday, so my observations on the behaviour of the student in a highly novel environment (i.e. the napkin is not made of paper nor is the cutlery made of plastic) will probably remain unpublished. I just hope I don’t end up lying on my back in a pile of mud, in a futile effort to eat a piece of kelp (if you have no idea what I’m talking about, find Katie MacGregor (“Crazy for kelp? Movement behaviour of the green sea urchin (Strongylocentrotus droebachiensis) in the presence of a preferred food”) and ask her).
*apologies to the taxonomists in the crowd if this is not the correct binomial
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