Science online, pick a little, talk a little edition

There’s a reason you have to make small talk with your barber. Photo by Dave Fayram.

If you’re gay, lesbian, bi, trans, or straight and supportive, and you have an even slightly science-related blog, why haven’t you submitted a post for the Diversity in Science Carnival? Go, do it now—you can read these great science articles afterward.

* I do not, in fact, wear a lab coat.

Freeloading caterpillars get in the way of plant-ant mutualism

Cecropia obtusifolia provides food for ants that come and protect it—unless caterpillars get there first. Photo by wallygroom.

ResearchBlogging.orgImagine you need a team of security guards. To find them, you decide not to place an ad in the local paper or on Craigslist. Instead, you build an apartment complex next to your home, complete with a full-service cafeteria providing free hot meals 24 hours a day. You leave the front doors unlocked, then hope that anyone who shows up to live in the apartments will also keep an eye on your home.

If you took that strategy to protect your assets, you’d have to be crazy. But that’s pretty much what ant-protected plants do all the time. They grow hollow structures called domatia, secrete nectar from special structures, and even produce tasty and nutritious “food bodies.” Then they wait for ants to move into the domatia, eat the nectar and the food bodies, and hopefully chase away anything that might want to do the plant harm. The crazy thing is, it works.

Well, it mostly works.

One gap in the ant-protection mutualism is the period when an ant-protected plant hasn’t grown big enough to support a whole colony of ants. In this early stage, ants won’t colonize the plant, but other insects might be quite happy to take the rewards that are already being offered. That’s exactly what larvae of the butterfly Pseudocabima guianalis do—they make themselves at home on unprotected ant-plants.

The ant-plant Pseudocabima caterpillars target is Cecropia obtusifolia, a shrubby Central American tree that relies on ants in the genus Azteca for protection. Azteca ants make vicious and well-coordinated bodyguards. Here’s video Ed Yong posted last year, showing a bunch of the ants flushing a hapless moth into an ambush.

However, Cecropia saplings can’t produce enough food to support a colony of ants until the plants grow to more than a meter tall. What’s too little for thousands of ants is a feast for a Pseudocabima caterpillar, however. Each caterpillar builds a silk shelter around a region of the plant that grows food bodies, and settles in to eat. As it grow larger, the caterpillar moves into a domatium near its original shelter, covering the entrance hole with silk. Finally the caterpillar pupates inside the domatium, emerging as an adult to lay eggs on another unprotected Cecropia plant.

Eventually the Cecropia saplings grow large enough to attract ants, who run off the caterpillars. However, as the paper I linked to above describes, the caterpillars seem to be able to resist an ant colony’s establishment on the plant—the silk shelters prevent ants from getting to the best sources of food. Cecropia saplings occupied by caterpillars didn’t seem to suffer more herbivore damage than ant-protected plants, but they did grow more slowly over the course of several years’ observations. Caterpillar-infested Cecropia plants were also more vulnerable to infection by a fungus, which the ants removed quite effectively.

Interestingly, though, caterpillar-infested plants also produced less food than those guarded by ants. This is a point of circumstantial evidence for a new model of mutualism I wrote about earlier this year, in which cheating is reduced or prevented when a host like Cecropia better mutualists help create better rewards. An ant-protected plant can divert more resources to feeding its tenants, so their work rewards itself. However, Pseudocabima caterpillars are glad to take the lower level of rewards that Cecropia plants offer up to all comers.

In other words, if you’re going to give out free lunches, you can’t really expect everyone who eats to pay you back.


Roux, O., Céréghino, R., Solano, P.J., & Dejean, A. (2011). Caterpillars and fungal pathogens: Two co-occurring parasites of an ant-plant mutualism. PLoS ONE, 6 : 10.1371/journal.pone.0020538

Denim and Tweed blocked on Facebook?

Blocked?! Photo by jby.

Just found the following in my inbox:

This morning I noticed the Lego-Blimp post and decided some of my Facebook family would be amused. I found the post ‘blocked’ by FB, presumably because of the ‘gay’ content. Bleh. I filled out the ‘why this content should not be blocked’ form but lard knows what will happen. In anycase I’ll keep trying to link to your site.

(Hyperlink added for context, otherwise sic.) I’ve just tried to post a few links from D&T myself to the D&T Facebook page (in a separate issue, the widget I use to automatically send new posts to that page had broken) and it seems as though today’s linkfest (but only that) has indeed been blocked as “abusive.” What the deuce?

I’ve filed an appeal, as did the reader who initially found the problem, but I’m not sure what else to do. Has anyone else run across this? What more can I do?

And for the record, if whoever flagged that post and/or this blog as “abusive” is reading, no one is forcing you to read Denim and Tweed, much less follow it on Facebook.

Science online, helium dreams edition

Picturesque, but maybe not practical. Photo by jimw.

Like Denim and Tweed? Spread the word on Facebook!

Blogging the field season at White Sands

Light and dark examples of Holbrookia maculata. Photo courtesy Simone Des Roches.

So, remember my posts back in February about three lizards that evolved lighter coloration after colonizing the white gypsum sand of White Sands, New Mexico, and about Erica Bree Rosenblum, the University of Idaho biologist who has studied them for most of her career? Sure you do. Well, Rosenblum’s grad student (and my former office-mate and continuing friend) Simone Des Roches has started a blog about her work at White Sands this spring and summer. Go check it out for the latest on Holbrookia maculata, and for Simone’s fantastic photography of the beautiful desert landscape and its inhabitants.

Show off your pride and your science! Diversity in Science Carnival submissions due 27 June

Photo by littleREDelf.

Happy Pride Month! There’s just 26 days left to send in your posts for a special Pride edition of the Diversity in Science Blog Carnival to be hosted right here at Denim and Tweed at the end of the month.

Diversity in Science CarnivalAlberto Roca of Minority Postdoc and I are looking for blog posts and other online writing about the science of human sexual diversity, the experiences of sexual minorities in the sciences, and everything in between. Write something brand new, or submit a classic post. Tell us how science, engineering, or technology helped it get better for you—or tell us how they didn’t help at all.

You can submit posts directly to me by e-mailing a link, or use the handy online form Alberto has set up. Please send submissions by Monday, 27 June so I have time to put everything together for the 30th.

Thanks to all the folks who have contributed so far—it’s shaping up to be a great carnival.

Carnival of Evolution, June 2011

A hyena. Photo by Sabi Sabi Private Game Reserve.

Greg Laden hosts this month’s Carnival of Evolution, the monthly compendium of online writing about descent with modification and all its consequences, complications, and controversies. This month, there’s everything from altruistic robots to blind cave fish to bacteria used by hyenas for scent signalling. Check it out!