Now my brain is stuck on spider evolution, which is an awesomely cool subject, and how annoyed I am that creationists can spit on it with such ignorant contempt. So I have to mention another good article on the subject, Reconstructing web evolution and spider diversification in the molecular era. There are so many papers on this topic, and there’s a guy affiliated with the Discovery Institute writing a whole book on the subject while unforgivably ignorant of it all. So here, cogitate on this:
Optimization of web architecture on the preferred topology. Black stars indicate strong support for a node from both MP (jackknife > 75%) and Bayesian (posterior probabilities > 90%) analyses, and gray stars indicate nodes strongly supported only by one methodology or with jackknife 50–74%. Branch colors represent MP reconstruction of webs, and pie charts represent the relative probabilities from ML reconstructions. Colors of boxes to the left of taxon names represent their webs, and open boxes indicate that taxa do not spin prey capture webs.
There’s also information on the topic of orb web monophyly that I mentioned in the previous post.
The monophyletic origin of orb webs is strongly supported, despite conspicuous differences in the silk used to spin different types of orbs. This has important implications for understanding both web evolution and spider diversification. Instead of cribellate and ecribellate orb webs evolving in parallel, orb monophyly explicitly implies that dry cribellate capture spirals were replaced by ecribellate gluey spirals. This involves 2 major changes. First, a shift in the silk used to produce the core fibers of capture threads, resulting in novel tensile properties. The core fibers of modern (ecribellate) orb weavers are composed of flagelliform silk, which is much more elastic than the pseudoflagelliform silk core fibers of cribellate spiders. Mechanically, flagelliform silk functions like rubber, relying on entropy to resist motion of silk molecules and absorb kinetic energy during prey capture, allowing the capture spiral to expand and contract repeatedly. In contrast, cribellate silk relies on permanent rupturing of molecular bonds to absorb kinetic energy and deforms irreversibly during prey capture. The second major shift involves the mechanism of adhesion, from dry cribellate fibrils that adhere through van der Waals forces and hygroscopic interactions to chemically adhesive viscid glue in ecribellate spiders. This results in webs with greater adhesion per surface area and may have facilitated the transition from horizontal to vertical web orientation in modern orb spiders, which is associated with increased prey interception rates.
That paper also discusses something I didn’t mention. Did you know that about half of all spider species don’t make prey capture webs at all? They’re active hunters, like wolf spiders and jumping spiders, and they belong to an extremely successful monophyletic group called the RTA clade, short for retrolateral tibial apophysis, the best band name ever.
I think I need to go spend some time in the lab with my spiders to cool my brain down, before participating in the podcast this afternoon, which will not be about spiders.
When my mind is free of class prep stuff, you can tell where it drifts, I guess.
Moar good news as you relax: South African sources see preliminary signs the omricon variant may cause milder disease.
My mind drifts to a possible solution of “how do we kill the fascists without killing non-fascists”: encourage the anti-vaxxer Qanon eejits.
A front line bulletin from the War on Christmas:
The claim is true: the Republicans for National Renewal did in fact misspell “Merry Christmas” on its party invitation posters, the group’s Executive Director revealed.
I’m afraid that the best band name ever would be Higgs Boson and the Large Hadron Colliders. I picture them as alt-country metal.
But but but where are the transitional webs…?
OT
How the hell has the winter weather enough energy to generate a fucking tornado?
Don’t you need immense heat and thunderstorms for that?
It is as if the Matrix just glitched.
@6 Almost as if global warming were real….
I get it. The MAGA Republicans are descended from the RTA clade, and the corporate Democrats are just sitting in their dusty webs while the world gets eaten around them.
Question. Do the creationists believe spiders are descended from the Ungoliant?
Ok, I’m not a spider fan but this stuff is very interesting especially at the detail you are showing.
Thank you, Dr. M.
OT
Now that you have time to relax, here is more good news. Sildenafil seems correlated to a 69% reduction of the risk of getting Alzheimers.
birgerjohansson:
It seems, does it? To two figures of accuracy, even!
—
Re “hip hop” bands, that’s something for the pure finders. Just less useful.
birgerjohansson @6
Tornado newsiness from NBC
Well, OT, but I’ve learned of a new Gen Z thing. Birds aren’t real, a tongue in cheek poke in the eye against all of the other conspiracy theory drivel out there.
BTW, they omitted webless spiders, I guess that they just don’t count?
@2 Well over here in GB ,some people are saying it will cause 75,000 deaths over the winter.
John Morales @ 12
Yes, since the correlation was found by data mining more strict experiments obviously needs to be done. That is why I wrote “seems”.
But since Alzheimers is such a bloody awful disease that has withstood so many experimental drugs, I thought this news was worth passing on.
.
The idiot governor of Florida has set aside 1 billion $ for flood control infrastructure, but still denies climate change is a problem .
Thanks for the science PZ.
I have a dreadful phobia of spiders. Over the years I made a promise not to kill them out of hand but, where I can, capture them and relocate. In Australia that is a bit daunting.
Your articles give me good reason to look at actual spiders and see their anatomy. This helps reduce and contain my phobic reaction. That’s very pleasing.
I tend to freak when I see spiders but there’s a large daddy long legs spider in my bathroom that I refrained from killing and will watch . (Yes I can tell the difference between a daddy long legs and a daddy long legs spider )
Is there a distinction made between webs used to catch prey and a web mass used as shelter?
I couldn’t find the brown recluse (Sicariidae) on any of the diagrams. I got bit by one when I rolled onto it in bed. It died, I had a huge burning hive like reaction down my back. I told the Dr. that I had vacuumed up its web from behind the nightstand by my bed earlier that day. He stated flatly that the brown recluse doesn’t make a web. In hindsight I think we may have both been wrong or at least made incomplete statements.
I took its corpse in with me to the doctor for positive id (3 sets of duplex eyes). And made peace with the numerous other brown recluse in the turn of the previous century house because I really enjoyed not having other bugs (especially silverfish) in there.