A casual conversation about science

Hey, friends! How about if I try another shot at this YouTube thing? I’m going to try to go live tomorrow, Saturday 7 December, at 2pm Central for what I’m calling A Casual Conversation About Science. I figure I’ll just start talking about what I’ve been reading about lately, or at least what I’ve been reading that maybe you’d find interesting.

There is no homework — this is casual, informal, all that stuff — but here’s a reading list. I figure I’ll just start at the top and work my way down, without an expectation that I’ll get to everything within an hour or so. I’ll take questions, and if there’s a lot of clamor for something, I can change up the order or talk about something completely different. I’m going in with an intent for some structure, but I can ramble if necessary. The reading list is mostly about genes and evolution.

Can new species evolve from cancers?

How Many Genes Do Cells Need? Maybe Almost All of Them

Light-regulated collective contractility in a multicellular choanoflagellate

The Early Ediacaran Caveasphaera Foreshadows the Evolutionary Origin of Animal-like Embryology

Developing an integrated understanding of the evolution of arthropod segmentation using fossils and evo-devo

I put the stuff I’m sure everyone can read first, but then the paywalls start going up in the last three. If you haven’t read it, don’t feel frustrated, we can still talk about it and I’ll try to explain it.

Note also: no spiders. OK, maybe a tiny bit about arachnid evolution in the last paper, but otherwise, this is mostly a spider-free session. Maybe we can have a spider conversation some other time.


Imagine this hurtling across the sand at you:

Unfortunately, there’s a limit.

The move doubles the spider’s speed, to 6.6 feet per second from 3.3. But since it uses so much energy, the maneuver is a last resort, called on only to escape predators.

“I can’t see any other reason,” Dr. Jäger said, adding: “It is a costly move. If it performs this five to 10 times within one day, then it dies.”

Don’t die, speedy spider! Slow down and take it easy! That’s what I tell myself every day.

Shy and nesting

A while back, I told you I had a slight problem: I probably had two nearly indistinguishable Parasteatoda species in my colony, P. tepidariorum and P. tabulata. The way to tell them apart is by close examination of their genitals, or by dissection, and a) I don’t have the skill to do that, and b) I’m trying to maintain a live, breeding colony, so taking individuals apart to figure out their sex is off the table.

I did hatch a cunning plan, however, to get a provisional identification. P. tabulata is known to build nests from scraps of debris and wind-blown litter, so I thought maybe I could get a tentative guess at their taxonomy by cluttering their cages with scraps and seeing who built homes for themselves. It’s not at all definitive, especially since they’re all living in a sheltered environment right now and even P. tabulata might find nesting superfluous, but I raided the department’s paper shredder and hole punch for little bits, and scattered them in all the tanks.

Most of the spiders ignored them. They couldn’t eat them, after all. But a few have slowly dragged bits and pieces of paper towards their roost and built little hidey-holes. Here’s Melisandre:

So maybe I can put together a rough behavioral test to estimate who is who? I don’t think a real taxonomist would be satisfied with it at all, but it’ll be useful for me, making it less likely that I send a P. tepidariorum male off to mate with a P. tabulata female, which probably wouldn’t go well.

By the way, P. tepidariorum is thought to be native to the Americas, that is, it hitch-hiked here with the first humans to move here; it colonized Europe when the human colonizers boats sailed back home. P. tabulata is probably native to Asia, and emigrated to the Americas and Europe much more recently. Both are thriving almost everywhere humans live now, but the timing would suggest that the two species diverged at least 15,000 years ago…or about 15,000 generations ago. It’s kind of neat how their morphology hasn’t drifted apart much, but their distinct genitalia make an uncrossable reproductive barrier.

Lilith and her shadow

I know you’re in shock that I posted a picture of a bird (what is this blog coming to?), so let’s quickly compensate. I went into the lab this morning to see how the new lab-bred generation is doing, and they were looking great — they had nice webbing everywhere, they had slung some hammocks, and were hanging about looking comfortable, always a good sign. I ambled back to my office, took care of some student stuff, and took my time about getting back to snap a few vacation photos of happy spiders lazing in their new digs. In the time it took me to wander back, Lilith (S. triangulosa, obviously) had up and molted!

This is also a very good sign. The new spiders are getting comfy and growing.

We had a visitor!

While I’ve been getting obsessed with spiders and driving visitors shrieking into the night with photographic closeups of my friends, Mary has taken up bird watching, and has set up feeders and water outside our window, so she can watch the flurry of birds who visit every day. Yesterday, a pileated woodpecker stopped by.

I know. So many people would be much happier if I posted only my wife’s photos of birds, but I’ve got to be me.

Cobweb construction under way #SpiderSunday

I had set up a bunch of new cages for my new generation of lab-born spiders (I keep wanting to call them azi) yesterday, and I popped in this morning to see how they were doing. They’re looking great! They still seem so small to me, but they’ll grow, I’m sure.

One of the signs that they’re doing well is that they started filling up all the open spaces in their cardboard frames with cobweb. This little Parasteatoda has been zipping back and forth all night to make lots of strands of webbing.

They also seem to have eaten all the flies I gave them yesterday. I may have to give them a few more tomorrow.

Spiders: The Next Generation

This is how I spent my morning:

I was cleaning up cages to set up more space for the next generation of spiders. The previous generation were all wild-caught; these are all lab-born, raised in isolation, so they’ve never seen another spider, which is why they are all flagged with a big “V” for virgin. The plan is to let them get cozy in their roomy new boxes, put up some cobwebs to decorate the place, and then next week I’ll introduce males to them, one by one. I’m going to watch them and then, as soon as the male has accomplished his duty, I’ll scoop him right up and put him in a vial, nice and safe.

I’ve got more juvenile females to set up with cages, but the remaining spiders are still on the small side. These spiders are small, too, especially compared to the behemoths I caught at the end of the summer, but they’ve got to start sexing it up sometime.

Triangles are fine, but Rorschach is lovely

My concern about my declining Parasteatoda population led me to check on the juvenile stock. They’re fine. They’re looking good. They look to be about 50:50 male:female, too, and the males are flaunting huge pedipalps, so maybe I should think about breeding them soon, even though they look so small compared to the big adults currently in the breeding cages. Here’s a quick look at the teenagers.

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