Fun with Liquid Nitrogen

[Ed: Today I'm excited to be able to put up this super-awesome guest post from Ainsley S. Ainsley studies bugs for a living and draws fantastic cartoons about it that would put any college newspaper hack cartoonist to shame. Wait a minute... I was a college newspaper hack cartoonist. Dammit.]

I work on the morphological and molecular systematics of a Gondwanan group of staphylinoid beetles. That is to say, a critical element of my research involves tromping around the temperate forests of the southern hemisphere, searching for cute little round beetles, and chucking them into 95% ethanol, which keeps their precious DNA stable and sequenceable. Although much of my time is spent on molecular phylogenetics, I’d like to start with a brief introduction to the forgotten, nigh-on-unfundable science of taxonomy (a topic most dear to the heart of any coleopterist).

The application of names to animals has been around for, arguably, quite some time, for as long as humans have needed to tell the difference between the tasty berries and the ones that give you the galloping scoots. That said, the naming of animals and other life forms didn’t acquire a truly robust or even remotely coherent system until the advent of the obsessive Swedish botanist Carolus “Carl” Linneaus, who described upwards of 10,000 plant and animal species with the Genus species-style binomials now commonly in use.

The truly miraculous thing about Linnean classification, however, is its hierarchical system of “ranks.” By organizing groups of animals and plants into nested sets, Linnaeus managed to converge perfectly (if wholly unsuspectingly) on the hierarchical pattern created by evolution itself. Systema Naturae really did contain a natural system of classification, albeit only for animals (the gentle reader can determine for himself why Linnean classification is suboptimal for, say, rocks).

Because of its hierarchical structure, Linnean classification gives biologists a tremendously valuable means of communicating taxonomic information: if you’re discussing some species that’s totally obscure to your audience, you need only ratchet up the hierarchy until you reach a rank everyone’s familiar with (try this navigation out for youself on the excellent web-based directories Wikispecies and tolweb.org). I guarantee that every entomologist out there has a conversation along these lines on a fairly regular basis:

In 1966 (right around the time Bob Dylan went electric), Willi Hennig electrified the world of systematics by explicitly plugging evolution into classification. He proposed naming only monophyletic groups– that is, only those organismal lineages that share an ancestor exclusive of all others. The shorter name for “monophyletic group” is a clade, and each clade can be distinguished by the unique characteristics– morphological and molecular– that its members share. Ever since Hennig, taxonomy and phylogenetics have become inextricably linked: in order to describe new taxa, you have to understand where they belong in the tree of life. Thus, taxonomists (i.e., people who refer to the “Tree of Life” with a straight face) have to understand not just the Linnean system of classification and its shawdowy, Opus Dei-esque enforcers at the ICZN, but also how to apply objective methods (see also: molecular phylogenetics) of delimiting clades.

Not unlike the naming of cats, the naming of taxa is something of a difficult matter: in order to name a new species, you must not only describe the organism in question, but must also adhere to a strict set of nomenclature rules. In order to apply a lasting, stable name above the species level, you also need some idea of phylogeny. Thus, while the discovery of, say, a new species of monkey or whale might make the newspaper, the discovery of a new species of insect is less of a novelty and perhaps something of a burden for the discoverer (especially given the pathetically miniscule extent of our knowledge of insect evolution– there’s rarely a ready-made tree to plug the new taxon into). This goes double for beetles, who clock in with upwards of 350,000 described species and untold thousands still awaiting description.

In the post-Hennig world, every taxonomist is at least a rudimentary phylogeneticist; each new genus or tribe erected has (or had better have) a tree behind it. Happily, a stupendous wealth of scholarship (and a not inconsiderable amount of debate) is dedicated each year to building better phylogenies on which to hang our names. With the same tree that we need for taxonomy, we old-fashioned descriptive biologists can also ask all sorts of incredibly neat (i.e., fundable) questions about adaptation, coevolution, biogeography, and the like. And I would contend that there’s no group of organisms with more juicy questions in store than the glorious order Coleoptera.

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A few additional notes in light of Naming Nature, Carol Kaesuk Yoon’s recently-released book on the origins and practice of taxonomy as a discipline. I should discloses that I have yet to read the full book; comments here are based on her 2009 NYT article, reviews, and excerpts from the book.

Yoon discusses the esoteric and often (sigh) quirky nature of taxonomists and taxonomy, and notes that old taxonomists seem to be dying off faster than new ones are being produced. Part of her solution for dwindling interest in taxonomy is the suggestion that nature aficionados come up with their own names– why not call a whale a fish, or an amphiuma a snake, if it helps you enjoy the staggering diversity of life around us?

Well, there’s at least one extremely good reason not to do this: it ignores the fundamental utility of nomenclature. The reason we name things isn’t just to be able to slap a label on that cool bird we just saw in the tree out front; it’s also — and most importantly– a system for referring to a specific point in conceptual space. That’s a little vague, but bear with me.
Consider the problem of mail. The federal government, your aunt Sheila, and Amazon.com Incorporated want to be able to convey tax refunds, voter registration cards, letters, and various goods specifically to you, one of the 300 million people inhabiting the country. Obviously, this is a complicated problem; how do you refer to one out of those 300,000,000+ census points? The solution used by the USPS is arguably analogous to that used by taxonomists: where we use a nested-set system to represent hierarchical relationships through time (that is, evolutionary relatedness), the Postal Service uses addresses that represent hierarchical relationships in space.

You are contained within a building, within a street, within a zip code, within a city, within a state, and so on. No matter what nicknames your family, friends, or boss have for you, you still need that unique, unambiguous identifier.



Consider Bob Dylan: you can call him Terry, you can call him Timmy, you can call him Bobby, you can call him Zimmy, but if you’re the IRS you probably call him Robert Allen Zimmerman, located at a fixed address in Malibu, CA.

Taxonomists face a similar challenge: for simplicity’s sake, let’s stick with arthropods. The arthropod taxonomist wants to be able to refer to a single species out of 1.6 million (and that’s just the described ones). In order to do this, we use a strictly organized nesting system (which, thanks to Darwin and Hennig, parallels the natural hierachy arising from the process of evolution).

So why does this hierarchy matter? Suppose Carol Kaesuk Yoon visits Sydney, Australia, to have tea with the taxonomists working at the Australian Museum. Whilst walking through the nearby botanical gardens, she is bitten on the ankle by a large hairy spider. Australia being what it is, there’s a good chance this spider is either relatively harmless or packed to the book lungs with a presynaptic neurotoxin.

Fig. 2. Atrax robustus.

Well, which is it? Whether she has collected the specimen or allowed it to escape, she can already identify it to order (Araneae, the spiders) and perhaps to infraorder (Mygalomorphae, tarantulas & co.). However, beyond this, she still has to describe it to a biologist or well-informed medical professional using enough diagnostic characteristics to pinpoint the family. It’s not hard to do, if you stick to useful characters (web shape, behavior, vestiture) and avoid biologically meaningless ones (number of legs, presence of fangs). Once you’ve figured out a family- or species-level identity, you know whether to go running for the hospital or to continue nursing your Coopers at the museum cafe. Applying your own made-up naming system may make biological “identifications” a little easier , but I imagine that by the point your interest has really been piqued (via spider bite, wasp sting, termite infestation, sharpshooters in your wine crop), you will also be highly interested in finding out the organism’s Actual Scientific Name.

I realize Yoon isn’t arguing for the abolition of traditional taxonomy nor that scientists embrace folk taxonomy, but a more helpful solution might be to encourage the legions of science nerds among her readership to consider becoming –or supporting– working taxonomists. It’s not at all a bad job, just an all-too-rare one.

This post is adapted from an entry in the 2007 “Just Science” challenge, organized by members of ScienceBlogs.com.

('’) delicious