Ecology “What if?”

Popular science-y webcomic xkcd has an associated feature called “What if?”, in which the author (a former NASA engineer) answers hypothetical questions from readers using back-of-the-envelope physics calculations. For instance, if you’ve ever wondered how many model rocket engines it would take to launch a real rocket into space, or if it’s possible to stop a runaway train by shooting it with enough BB guns, “What if?” has you covered.

Which got me thinking about ecological “What if?” questions. In the broadest sense, of course, much of science is about asking, and answering, “What if?” questions. What if assumptions X, Y, and Z were true? What if the top predators were removed from this ecosystem? What if we raised the annual catch quota for this fish? Etc. But I’m thinking here of amusingly hypothetical “What if?” questions, in the spirit of those addressed at xkcd.

The first one that comes to mind is “What if the Loch Ness Monster existed?” This is a question ecologists actually have asked several times, a literature reviewed in a fun little essay by Lawton (1996). Various independent lines of argument suggest that, if a piscivorous poikilotherm large enough to be called a monster existed in Loch Ness, the population size would have to be very small, on the order of ten to maybe a few hundred individuals. And of course, it’s questionable whether a population that small would have persisted since the end of the last glaciation 12,000 years ago. All of which of course suggests that the Loch Ness monster doesn’t in fact exist.

Can anyone think of other good fun ecological “What if?” questions? The Lab and Field recently did a post on how many gulls it would take to lift the giant peach in James and the Giant Peach. And of course, recent discussions of the physiological ecology of horse-sized ducks fall squarely into this category. Anyone have any other suggestions?

Silly “What if?” questions, such as about the existence of the Loch Ness monster, could be good exam questions for undergraduates. The students would enjoy them–but they’d also have to think. Plus, silly hypotheticals like “What if the Loch Ness Monster existed?” often have serious, non-hypothetical analogues, like “What if Ivory-Billed Woodpeckers still existed?” So asking this sort of “What if?” question on an exam doesn’t necessarily mean sacrificing relevance.

p.s. While this is all in good fun, facility with back of the envelope calculations or “guesstimation” is a really useful skill. You have to be able to get to the heart of the problem and strip away irrelevancies. The classic book on back of the envelope calculations is Polya’s How To Solve It.

17 thoughts on “Ecology “What if?”

    • There’s a paper, cited in an old post, that uses putative sighting records of “bigfoot” to do habitat modeling. It finds that “bigfoot” is probably “misidentified black bears”, since the resulting habitat model is good at predicting the distribution of black bears.

  1. My undergrad ichthyology final had a question where we had to use all the knowledge we acquired during the course to invent a fish that would live in some bizarre habitat – everything from morphology, behaviour, mating, sensory organs, diet, etc. Probably one of the best exam questions I’ve had.

  2. What if the dungeons of random Asian temples could maintain populations so explosive of Australian Walking Sticks and Madagascar Hissing Cockroaches that the next intrepid explorer (say Indiana Jones) could be completely covered in them. Double for the snakes. What is the ecology of that?

  3. What if a present-day tropical island really was seeded with small populations of various species of dinosaurs? That were facultatively parthenogenic? What’s the population and community ecology of this? Would they be more or less doomed to extinction, and if so, why?

  4. something for Invasion Ecology: what if an extraterrestrial species would come to Earth? When and how could it establish viable, self-sustaining populations on Earth? What life history traits would it need? Would more diverse regions like the tropics be more resistant? More perturbed habitats like cities or agricultural land be more prone to invasions?

    • Hmm, interesting! Might need to flesh out a bit more what “no moon” means? I guess it would mean no tides, or at least not much. Also no moonlight at night. Anything else?

      • Yeah, that’s about what I was thinking.

        If there were no moon, there wouldn’t be any tides (except for swells driven by wind), which means no intertidal zone, no mudflats etc which suggests that there would be much less species richness and turnover at the shoreline.

        Perhaps there would be less mixing between fresh and saltwater at deltas and estuaries, so maybe not as much opportunity for anadromous things to evolve. There would be less shoreline erosion.

        Without a moon, there’d be no moonlight, so nocturnal creatures might be less reliant on light for navigation, or they’d be much better at gathering starlight.

        Also, Spielberg would have had to find a different, less iconic cover image for ET and who knows how different his career would be!

  5. To make sure we understood principles such as atmospheric circulation, we had an oceanography prof who used to pose questions about how the Earth’s climate would differ if the rotation was horizontal rather than 23deg to vertical. Or if no rotation at all. etc etc.

  6. Nice post! I’m a big fan of speculative biology (surely that’s a journal just waiting to emerge – J. Spec. Biol.) since reading a book as a kid that predicted what animals and plants might look like a few million years in the future. Wish I could recall its name.

    Improbable species interactions and their adaptations are great fun to consider, e.g. carnivorous elephants, plants with whale-dispersed seeds, plants which parasitise animals, etc. In a News and Views piece in Nature back in 1998 I managed to sneak in some speculation that there may even be a fish pollinated flowering plant waiting to be discovered. I haven’t given up hope on that one…….

  7. Cool. A real-life ‘what if’ :the atmosphere has double the concentration of O2? Most of the most interesting hypotheses can’t be tested using fossils and phylogenetic reconstruction.

    • That one sort of reminds me of a common “what if” in introductory biology, noting that if ice were denser than water, aquatic life as we know it would be impossible in any environment in which water freezes in the winter, since even deep water bodies would just freeze solid.

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