Oribatid mites–plunging into the dizzying diversity of the brown food web

BrittanyB, a tuba-playing entomologist extraordinaire, has been tasked with developing methods to catalogue the diversity of our oribatid mites–little fungal grazers in the brown food web. Brown food webs convert the dead into minerals and carbon dioxide; they are nature’s cleanup crews, and a subject of endless fascination for us here in the AntLab. Our latest big project will explore how these food webs work at six sites, from the rainforests of Oregon to the alpine forests in Colorado,  from the diverse forests of the Smokey mountains to even “diversier” forests in Panama.

So, after years of splashing around in the kiddy-pool of ant diversity–our first love, but relatively well known–we in the AntLab are moving into the calm, dark waters of the soil’s meso- and micro-fauna, starting with collembola (springtails) and oribatids (box mites). This requires a dive into the baroque literature of each group’s taxonomists–the high priestesses of biodiversity–and to learn the the secret language of the guild, the road marks and way signs embedded in form. We also must o photograph the little darlings, using cameras attached to microscopes.  This involves fidgeting with lights, angles, magnification, and embedding media (some in the lab were relieved to know that the K-Y Jelly experiment was a flop, sparing them the embarrassment of a tube at every microscope station). Then these images must be stitched together and further manipulated with software. Lotsa variables, lotsa play, lotsa art.

For me, this is magical. For years, having simply counted petri dishes  of “collembola” and “oribatids”, pushing them around into little grey piles before plopping them into centrifuge tubes, it is unimaginably exciting to finally get a good look at what I’ve been squinting at.

So here are a few of Brittany’s first attempts. This is gonna be fun.

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The joy of field biology

You can’t fake this smile for the camera.

An ecologist in the field is one of the happiest persons on the planet.

Brown Food Web Friday–millipede ecstasy

I spend much of my scientific life crawling around in the forest litter, studying the microbes, the microbivores, and their predators that teem in this fantastic world beneath our feet. One of my favorite litter critters is the millipede. What’s not to like? They carry around in their guts a poorly explored plethora of microbial symbionts that help them digest old dead leaves. It’s hard to see a millipede and not think of a commuter train that runs on biofuels with the help of its passengers.

The other reason to love millipedes is that, because they are slow moving litter fermentation tanks, millipedes are sitting ducks (at the risk of mixing our taxonomic metaphors). If there were to be any new generations of millipedes, the ones that were somehow defended would have to leave more offspring. In fact, National Academy member Tom Eisner has done a bang-up job discovering the many ways (from spines, to crunchy exoskeletons, to cyanide and other poisons) that millipedes have evolved to make sure this train stays on the track.

And where nature produces toxins, there are always intelligent-ish animals waiting to get high…

Grace Note: Spring in New England

Back home in Oklahoma the summer is gearing up, and most of our yard birds are already starting on their second clutch. But here at Harvard Forest, the breeding season is just cranking up. You can almost smell the avian testosterone. But, far more emotionally uplifting (and less olfactorily disturbing) is the plethora of bird song that starts around 4:45 in the morning.

And of all the bird song, that of the hermit thrush echoing through the greening forest, is the best .

“Hermit on the rocks” by Debby Kaspari, pastel and graphite on paper.

The residue of design

As a scientist, you know you’ve made it when Boing Boing covers your stuff. I recently collaborated with a team of scientists (Steve Yanoviak, Robert Dudley, and George Poinar) on a manuscript coming out in The American Naturalist. It’s about a nematode whose life cycle has it spending time in the guts of birds and ants, and that has a pretty unique way of doing it. Here’s the, um, straight poop.

Worker ants of the species Cephalotes atratus, like many ants of the treetops, have a hankering for bird poop (lots of nitrogen and salts in a piece of bird poop). Some bird poop, however, is infected with the eggs of our nematode parasite. Now most adult worker ants can’t take solid food; they feed it, instead to their brood back in the nest. However, when infected poop is fed to the brood of Cephalotes atratus ants by their older sisters, the nematodes cause the brood to grow up with bright red (dare we say, berry-like?) gasters. In the paper we build a plausible hypothesis that birds mistake the red gasters (now full of nematode eggs) for fruit, harvest them, pass them as feces, the feces are harvested by Cephalotes workers who bring them back to the nest, and the cycle continues (one key bit of evidence–it’s easy to pluck off an infected gaster and much, much harder to remove the gaster of a healthy ant).

There is no evidence this is a voluntary arrangement–we see no advantage to the ants of harboring these nematodes. Rather, this seems to be another case of a parasite, once inside its host and with its hands on the wiring and machinery, tweaking the host to do its bidding (my endocrinologically inclined pal points out that the nematodes and ants share a host of neurochemicals, so replace “hands” above with “hormones”). The nematodes even make infected ants raise their gasters vertically, making the egg-filled butt-berries infinitely pluckable.

Long before there were neurobiologists, apparently, there were parasites paving the way.

Below the fold, the real story of how this sordid story of manipulation came about.

10 things I like about ants

Image from Alex Wild’s amazing Myrmecos.net

From the home office in Wahoo Nebraska, here are 10 amazing ant facts.

10. If you weighed all the ants in a tropical forest, then weighed all the mammals, birds, reptiles and amphibians, the ants would weigh four time as much.

9. Fire ants are attracted to electricity. No one knows why.

8. The tiniest mature ant colony has 5 workers; the largest has over 100 million.

7. Most ant species have broad diets, but many are incredibly specialized–one eats only spider eggs.

6. Ants invented agriculture–growing fungi on leaves they harvest and mulch–long before humans did.

5. Ants are so successful and common that many ant species specialize on eating other ants.

4. The queens of some ant colonies can live over 10 years, making them some of the longest lived insects.

3. All the worker ants you see are females; all the worker ants from a single colony are most likely sisters.

2. You can recognize the few ant males in a colony by their pinheads and large googley eyes.

1. No ant has been elected to higher office in the United States. Yet.

Visual explanations: what lies ahead

I first saw this video by Michael Welsch a couple of weeks ago and was impressed but didn’t think it particularly blogworthy. Then Seth Godin placed it in the proper context.

Publish or perish indeed. Now that the publishing part is free and without friction, and now that a professor can boil down complex topics to vivid videos, why aren’t tens of thousands of professors scrambling to do this?

Welsch’s video has gone totally viral…how many more folks now grok Web 2.0 because of it? Isn’t that one of your jobs as an academic?

You likely have the technology on your computer right now that would allow you to tell a compelling story about your research and at the same time expand and hone your personal brand. If you had to do such a video as a class assignment, what would be the topic?

Always the trendsetter among myrmecologists in the use of new media, here’s a short video by the artiste, Jack Longino (let it load in the background).

The latest Tangled Bank is up

Check out this week’s compendium of the best blogging in science and medicine, hosted by the always cheeky ouroboros.

The tangled bank, of course, is a reference to EEB’s own Chucky D, perfectly capturing his experiences in the tropical forest:

  “It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the conditions of life and from use and disuse: a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less-improved forms.”

How to be creative–variations on a theme

All scientists value creativity: the ability to generate a long list of ideas combined with the ability recognize the best of those ideas. The list grows in proportion to the amount you  read broadly and keep yourselves open to a diversity of experience (something it is hard to justify at times, when it seems its all you can do to master the discipline you are really passionate about). But what about the culling part?  How do you sort through all this experience to  find a new and profitable connection?

Variations on a theme is one creativity technique as old as the diversity of life. Its simple: find something that works and apply it in a different context.

My favorite example of VOT in EEB is optimal foraging theory–a set of models that predict which habitats, prey, and parts of a prey that a predator should eat. Robert MacArthur and Eric Pianka could have invented this theory from scratch, but instead they knew that similar work had been done by economists (ecology/economics … same root) and they borrowed it, changed the names of the variables, and voila a citation classic that raised helped invent Behavioral Ecology. Likewise, Eric Charnov saw something from Microeconomics 101 that asked how the value of an activity declined with the time you put into it– Marginal Value –and applied it to the question of how long a forager stays in a patch that is taught in every Intro Ecology course.

Variations on a theme–same tune, different lyrics–serving the arts and sciences since 954 B.C.

Illustration from BMClocks’s excellent Natural History Artworks

Brown Food Web Friday–in praise of litter ants

 

How’re y’all doing this fine Friday? I’m slogging through a cold once thought vanquished. Now seems intent on hanging over me like a stale chain mail party dress. Bleah.

    In today’s BFWF we contemplate one of the great biological systems on earth–the litter ant nest. Litter ants live on the forest floor in small hollow twigs, empty acorns, or even between leaves. The whole colony may consist of only 100 or so ants, just enough to cover the tip of your pinky. This small size allows litter ants to be incredibly abundant: in a tropical rainforest there may be 5-10 species living together in a meter square plot. Yes, I will admit it, litter ants changed my life.

Every scientist has the occasional “aha!” moment. Mine came sitting on my butt on the forest floor at La Selva, cracking twigs with Margaret Byrne, a graduate student at the University of Florida at the time. I was in the middle of a PhD project happily placing bits of seed and bird poop across the forest floor to see what ants arrived, who consumed what, and if they preferred some bits of habitat and climate more than others. I only saw the ants when they emerged from the leaf litter to crawl on my baits, but that was fine. I was getting my data, and every night at the microscope I would empty my vials and see the biodiversity.

Margaret was collecting litter ant colonies for her research and she offered to show me how. Turns out, it wasn’t hard.