Friday Coffee Break

Every Friday at Nothing in Biology Makes Sense! our contributors pass around links to new scientific results, or science-y news, or videos of adorable wildlife, that they’re most likely to bring up while waiting in line for a latte.

It’s like the saddest picture book you’ve ever read. True stories about how some species went extinct. (from Jeremy)

The hoatzin becomes an even cooler bird. (from Noah)

Looking for a phylogenetics discussion board? Try phylobabble. Looking for free silhouette pictures of plants and animals? Try phylopic. (from Sarah)

When art and science meet – oh baby – that’s some good stuff. Awesome glass sculptures of viruses. (from CJ)

Are you an aspiring statistician? How to read histograms and use them in R.  (from Amy)

They look like ants, but they’re ain’ts! (from Jeremy)

Need help with the whole peer-review thing? Look no further than this guide from the British Ecological Society. (from Sarah)

The gold-star creationist?

2010.02.15 - Life Sciences South

The Life Sciences building at the University of Idaho. Photo by jby.

Academic freedom is a bedrock principle of higher education—part of the point of having classes taught by working scholars is that, at the university level, students should be exposed to the interplay of ideas at the cutting edge of each field of study, and so professors should have latitude to explore controversial topics and defend their own perspectives.

But there are limits to that principle. Common sense, and the need to organize prerequisites across a multi-year curriculum, dictates that even a tenured professor would get into trouble if she devoted her entire introductory chemistry course to a critical reading of The Lord of the Rings. In a (maybe) less extreme example, a professor who spent an astronomy class arguing that there is a scientific basis to the Zodiac would, at the very least, get a talking-to from his department chair. In order to meaningfully teach a given class, there are topics that need to be covered—and there is material that has no legitimate place in the syllabus.

This is why I was so surprised to learn, a few weeks ago, that the University of Idaho—the institution where I earned my Ph.D., where Noah earned his Master’s degree and Sarah earned both her B.S. and Master’s—has hired someone who believes that the Earth was created over the course of six days about six thousand years ago, to teach an introductory microbiology course.

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Friday Coffee Break

Every Friday at Nothing in Biology Makes Sense! our contributors pass around links to new scientific results, or science-y news, or videos of adorable wildlife, that they’re most likely to bring up while waiting in line for a latte.

Should we consider poop a drug or a tissue when it’s used to cure the ill? Or – now hear me out – a DIY project?

“Fairness” may have evolved out of spite, not goodness. (That sounds about right, wouldn’t you say, humans?)

Your brain and Fido’s are more similar than you might think.

Ever notice how the “impossible” actually happens sometimes? Why is that?

Friday Coffee Break

Every Friday at Nothing in Biology Makes Sense! our contributors pass around links to new scientific results, or science-y news, or videos of adorable wildlife, that they’re most likely to bring up while waiting in line for a latte.

Ant larvae only poop ONCE?!?! (From Jeremy)

Sir David Attenborough is losing patience with you people. (From Sarah)

Long-read (and Yong-read) on the endosymbiotic origin of eukaryotes. (From Jeremy)

5 misconceptions about evolution, with very nice graphics. (From CJ)

A nice synopsis on the joy of scientific discovery. (From Bill Nye, from Amy)

Why do stinky animals live alone? Hint: It’s not the reason stinky humans live alone. (From Jeremy)

Some harsh advice on your cover letter. (From Sarah)

Happy Darwin Day!

Panagaeus cruxmajor. Image via Wikimedia Commons.

This being the 12th of February, the birthday of Charles Darwin, here’s an excerpt from his autobiography (pages 62-63), about the inordinate fondness for beetles he had, as a student at Cambridge:

But no pursuit at Cambridge was followed with nearly so much eagerness or gave me so much pleasure as collecting beetles. It was the mere passion for collecting, for I did not dissect them and rarely compared their external characters with published descriptions, but got them named anyhow. I will give a proof of my zeal: one day, on tearing off some old bark, I saw two rare beetles and seized one in each hand; then I saw a third and new kind, which I could not bear to lose, so that I popped the one which I held in my right hand into my mouth. Alas it ejected some intensely acrid fluid, which burnt my tongue so that I was forced to spit the beetle out, which was lost, as well as the third one.

I was very successful in collecting and invented two new methods; I employed a labourer to scrape during the winter, moss off old trees and place [it] in a large bag, and likewise to collect the rubbish at the bottom of the barges in which reeds are brought from the fens, and thus I got some very rare species. No poet ever felt more delight at seeing his first poem published than I did at seeing in Stephen’s Illustrations of British Insects the magic words, “captured by C. Darwin, Esq.”

The Darwin Correspondence Project, which is digitizing Darwin’s entire collection of letters—basically turning the Victorian version of e-mail into the more current format—notes that the specific species of beetle that young Darwin “could not bear to lose” was probably the Crucifix Ground Beetle, Panagaeus cruxmajor. A good 30 per cent. of the Wikipedia page for P. cruxmajor consists of this very anecdote.

The cost of attracting pollinators is … attracting everyone else

Flowers of Dalechampia scan dens, with key measurements indicated. Figure 1 of Perez-Barrales et al. (2013).

Flowers of Dalechampia scandens, with key measurements indicated. Figure 1 of Perez-Barrales et al. (2013).

Flowers that rely on animal pollinators to remix their genetic material have evolved a tremendous diversity of strategies for attracting those pollinators—from beguiling scents to elaborate visual displays to pretending to be a lady pollinator.

But there’s a downside to making a big, showy display to attract pollinators—you might also attract visitors who have less helpful intentions than gathering up some pollen and moving on to the next flower. Showy flowers might attract animals that steal the rewards offered to pollinators—or they might attract animals that eat the flowers themselves, or the developing seeds created by pollination. So the evolution of attractive floral displays might very well be a compromise between attracting the right visitors, and attracting the wrong ones.

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Friday Coffee Break

Every Friday at Nothing in Biology Makes Sense! our contributors pass around links to new scientific results, or science-y news, or videos of adorable wildlife, that they’re most likely to bring up while waiting in line for a latte Turkish coffee.

Will the puma catch the monkey? Let the pictures tell the story. (From Noah)

What’s the connection between cycling success, birth control and attractiveness? Science. (From Amy)

Can’t get enough of the Bill Nye/Ken Ham debate? We’ve got “the most powerful evidence for evolution that you can imagine” (from Jeremy). Also, and dependent on your blood pressure, the somewhat baffling list of 22 messages from Creationists after the debate.

Boobies are amazing. (I know you want to click this one because you have no idea what’s going to come up. Am I right? From Sarah)

Bee sting, bad. Bee portrait, oh so good. (From Noah)

Better than citations, enter the hypercitation. (From Sarah)

Pssst. Your holobiont is showing.

Here’s a sad story: Species A mates with Species B. They succeed in making a Hybrid Baby but their Hybrid Baby dies before it can fully develop. (I warned you it was sad.) Why did that happen? Sure, sometimes two genomes are just too different to successfully coexist – both the stars and the chromosomes must align to make a baby. Other times, as recently reported by Brucker and Bordenstein, the Hybrid Baby’s microbiota is the problem.

I think (or rather Google thinks) this is a Nasonia wasp.

In Nasonia wasps, there are three closely related species that all diverged less than one million years ago: Nasonia vitripennis (who I’m going to refer to as the V wasp), N. giraulti (the G wasp) and N. longicornis (the L wasp). When L and G mate and their LG offspring are mated to other LG offspring, 8% of the males die. When V and G mate and their VG offspring are mated to other VG offspring, 90% of the males die.

The phylogeny of the three Nasonia wasps (left) and the crosses that result in hybrid male lethality.

The phylogeny of the three Nasonia wasps (left) and the crosses that result in hybrid male lethality.

Brucker and Bordenstein hypothesized that microbes were responsible for the hybrid lethality of the the VG hybrids. Through DNA sequencing, they found that the gut microbes of the VGxVG wasps were unlike either parental type (in abundance or diversity), whereas the LGxLG wasps were. So, when a hybrid’s gut microbiota is like one of the parental species, the hybrid males live. When the gut microbiota is unlike a parent, the hybrid males die. They further found this could be boiled down to a change in the single dominant species: whereas a Providencia bacterium was most abundant in both V and G parents, a Proteus bacterium was most abundant in VGxVG wasps.

But that doesn’t conclusively show that microbes are responsible for the hybrid lethality. Brucker and Bordenstein then compare germ-free hyrbids to conventional hybrids – in other words, if we remove the germs (the microbiota, that is), do the hybrids still die? The short answer is no. Under normal conditions, about 80% of the pure Vs and pure Gs survive, whereas only 10% of the VGxVGs survive. Under the germ-free conditions, about 70% of the pure Vs and pure Gs survive and 60% of the VGxVGs survive. That’s a pretty significant increase in living hybrids! And to strengthen the case even more – when the germ-free wasps were fed a mixture of Providencia and Proteus bacteria, the hybrid survival rates went down to about 30%.

The authors perform other experiments for this study that include analysis of wasp genomic loci that were previously linked to hybrid lethality and a transcriptomic analysis, where they find immune genes to be a significant player. However, I’m going to switch gears a little bit and talk about the context the authors frame their discoveries in: the HOLOGENOME concept.

Most evolutionary biologists probably consider the individual as the fundamental unit of natural selection. We think about the genes of one mother or one father being passed on to one descendant. But is this view too constrained? The “hologenome” is all the genomes that belong to the “holobiont” – an organism and all its microbes. The Hologenome Theory of Evolution posits that the holobiont is the fundamental unit of natural selection, not just “the big organism”. Generally speaking, this makes a lot of intuitive sense, I think: we macros are pretty dependent on micros to get our genes to the next generation. But is the reverse true? To be THE fundamental unit of selection, the holobiont must pass its hologenome to its offspring – and I’m not sure this assumption universally holds. Certainly some macro-organisms always pass specific micro-organisms to their offspring (coprophagy in mammals might be a good example). But in most cases, where our microorganisms come from is a mix of vertical transmission (from our parents) and horizontal transmission (from the environment). I just can’t make this distinction make sense with what I think I know about heredity and selection. Natural selection depends on traits that make an organism more fit being passed on to its offspring and if some – or most? – of our microbiota is randomly acquired from the environment, natural selection can’t act on it. On the other hand, it’s very possible reality doesn’t abide by our definitions: perhaps only a few microbial taxa need to be passed directly from parent to offspring and these “founders” get microbial communities off on the right track and the rest of the communities fall into place from the environment.

Regardless – Brucker and Bordenstein pretty conclusively turned that sad story into a science story by showing that in Nasonia wasps, gut microbes play an integral role in hybrid survival. And if the Hologenome Theory of Evolution applies anywhere, I’d say it does here!

A healthy viable Nasonia holobiont (top) and an unhealthy, inviable Nasonia holobiont (bottom). From Brucker and Bordenstein (2013), figure 1B.

The sad story told in pictures: A healthy, viable Nasonia holobiont (top) and an unhealthy, inviable Nasonia holobiont (bottom). From Brucker and Bordenstein (2013), figure 1B.

Brucker, R. M. & Bordenstein, S. R. 2013. The hologenomic basis of speciation: gut bacteria cause hybrid lethality in the genus Nasonia. Science 341: 667-669.