The centrifugal theory of species diversity

Photo: Jaguar – a large-bodied tropical mammal. U.S. Fish and Wildlife Service Digital Library System, public domain.

It’s frequently claimed that a person can expect to have only a handful of truly good ideas in a lifetime. One should, therefore, use them well! I had one of my best ideas (with tongue in cheek, that is) as a grad student – but I buried it in an issue of the Ecological Society of America Bulletin. If blogs had existed back then, perhaps things would have been different; but they do now, so I thought I’d resurrect this piece it from its obscure tomb.

I’m pleased that the ESA Bulletin occasionally indulges itself in a bit of levity, and am grateful for permission to repost it here. I hope you’ll enjoy the piece. Here it is, as originally published (ESA Bulletin (72(1):13, 1991):

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The Centrifugal Theory of Species Diversity

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Sheep, lupines, pattern, and process

Photo: Lupines below Öræfajökull, and sheep grazing at Sandfell, Iceland (S. Heard)

Last summer, we were driving around southern Iceland, admiring the fields of lupines (beautiful, even though they’re invasive) and the gamboling sheep (also invasive, at least to the extent they’re allowed to graze free). Before long, we noticed an interesting pattern: we saw dense fields of lupines, without sheep; and we saw thousands upon thousands of sheep, in fields without lupines – but we drove for days without ever seeing sheep and lupines together.

Being a nerd scientist, I came up with a hypothesis to explain this pattern:

The “one thing I teach that nobody ever forgets” may be wrong!

Image credit:  “Semele consumed by Jupiter’s [=Zeus’s] thunder”, 1733, Bernard Picart. In Tafereel, of Beschryving van den prachtigen Tempel der Zang-Godinnen, H. Chatelain, Amsterdam.

Recently I blogged about the one thing I teach that nobody ever forgets: the meaning, and etymology, of the life-history term semelparity. If you haven’t read that post, and want this one to make sense, go ahead and read it now (I’ll wait). But it turns out that etymology I explained there might be wrong*.

A sharp-eyed reader (Jon Benstead) alerted me to an alternative etymology, laid out by James Rader in a brief letter to Natural History. According to Rader, “the notion that the semel in semelparity…has some connection with the Semele of Greek mythology looks like a bit of biologists’ folklore”.

Is everything “broken”?

Photo: Chair (cropped), Zen Sutherland via Flickr.com CC BY-NC-SA 2.0

No, it isn’t, of course, but you’d sure think it is if you chat around the water cooler, pay attention to Twitter, or read blogs or Nature News.  Publishing is broken. Tenure is broken. Peer review is broken. Academia is broken. Reassuringly (I guess), at FiveThirtyEight Christie Aschwanden recently posted a long essay arguing that science isn’t broken. It’s an excellent and persuasive read, but the fact that it exists at all is pretty good evidence that a lot of people think science is broken. It’s not just science, either: Google will return lots of hits for “politics is broken”, “health care is broken”, “the music industry is broken”, and many more. What a broken world, we tell each other, we’re living in!

Why is our discourse so rich in “X is broken”?

Why do we make statistics so hard for our students?

(Warning: long and slightly wonkish)

If you’re like me, you’re continually frustrated by the fact that undergraduate students struggle to understand statistics. Actually, that’s putting it mildly: a large fraction of undergraduates simply refuse to understand statistics; mention a requirement for statistical data analysis in your course and you’ll get eye-rolling, groans, or (if it’s early enough in the semester) a rash of course-dropping.

This bothers me, because we can’t do inference in science without statistics*. Why are students so unreceptive to something so important?

Why do not we use contractions in scientific writing?

Scientific writing has a reputation for being dense, even occasionally impenetrable. Partly that’s because we write about intellectually complex matters using (necessarily) a highly technical vocabulary. But our writing becomes denser still because we love condensed words: acronyms, initialisms, and abbreviations*. As an example, consider this sentence:

To evaluate the role of extracellular cAMP in sperm capacitation, 10–15 × 10⁶ spermatozoa/mL were incubated in 0.3% BSA sp-TALP at 38.5°C and 5% CO₂ atmosphere for 45 min in the presence of 0.1, 1 or 10 nM cAMP (Osycka-Salut et al. 2014 Molec Human Reprod 20:89-99).

I’m not picking on these authors – such sentences have become completely unremarkable in our literature. What’s interesting about this, though, is that there’s a peculiar exception to our passion for condensed words: a general refusal to use common contractions (don’t, it’s, we’re, etc.) in scientific writing.