Freethought & Rationalism Archive

MrDarwin · 11-22-2002, 07:51 AM

This was originally posted in the "Is the universe perfect?" thread, but I think it merits its own discussion:

The venom of the <a href="http://ww2.lafayette.edu/~hollidac/cicadakillerhome.html" target="_blank">cicada killer wasp</a> is a toxin that immobilizes cicadas, and it works effectively (if chillingly) to this end. This paralysis is a function of both the chemical composition of the venom, and the dose in which it is delivered. If delivered in a larger quantity it would kill the cicada, which would then decompose, leaving nothing for the cicada killer larva to feed on; if delivered in a lesser quantity, it would allow the cicada to move around or even escape, dislodging the larva of the cicada killer wasp, which would again starve and die. The dosage delivered is just right to keep the cicada (which does make feeble, if futile, attempts to escape) both alive but paralyzed (and remarkably, alive for longer than the adult cicada would live otherwise), providing fresh food to the cicada killer larva, which slowly eats the cicada alive.

In an interesting epilogue, cicada killer wasps provide their male larvae with a single cicada to eat, but their female larvae (which grow bigger) with two cicadas.

Is the cicada killer life cycle an example of irreducible complexity? Is this an example of design?

MortalWombat · 11-22-2002, 10:22 AM

Quote:

Originally posted by MrDarwin:
Is this an example of design?

If it is, the designer has a pretty twisted sense of humor.

pz · 11-22-2002, 11:31 AM

Since, if you modify the characteristics of the venom in any way, the organism presumably fails to reproduce, I'd have to say that it is IC. Of course, that doesn't mean anything about whether it is designed or evolved, and I also have some problems with the description of the system that could mean it is not really IC.

I'd have to ask how true it is that the dosage and potency of the venom must be that specific. There has to be variation of size and health in cicadas, and therefore in their sensitivity to venom. Are the wasp embryos/larvae really that fragile, that no significant movement can be tolerated? Do the wasps compensate behaviorally, for instance by stinging resistant cicadas multiple times, adjusting the volume injected to compensate for levels of activity, etc.?

Grumpy · 11-22-2002, 12:45 PM

Let me try to clarify the IC claim, to see if I understand:

If the ancestor wasp started out with venom that was too strong, the host cicadas would have died before the offspring could eat them. If the ancestral venom was too weak, the wasp eggs would be dilodged. Therefore, the correct dosage must have been arrived at in one big leap, since trial & error would have eliminated the wasps in one generation. Somebody (God?) must have made them that way.

Unless, of course, ancestral wasps had a variety of venom potencies, and those with the incorrect dosages did die out quickly, leaving only those with the correct dosage. Without knowing any better, I would also assume that the ancestral wasps parasitized other organisms in addition to, or instead of, cicadas, or led some other wasp-y lifestyle.

[ November 22, 2002: Message edited by: Grumpy ]

Peez · 11-22-2002, 02:18 PM

O.K., I'll bite.

What if the ancestral larva was better at hanging on? A smaller dose of venom slowed the cicada down enough for the larva to survive.

What if the ancestral larva developed more quickly? A larger dose of venom killed the cicada, and the larva ate and developed before the cicada rotted.

What if the ancestral venom did not need to have such a precise dosage? It has since been fine-tuned through natural selection.

What if the ancestral cicada was less fragile? Natural selection has favoured cicadas that die outright when injected with this venom.

Just a few ideas off the top of my head.

Peez

Mageth · 11-22-2002, 02:27 PM

if delivered in a lesser quantity, it would allow the cicada to move around or even escape, dislodging the larva of the cicada killer wasp, which would again starve and die

Cicada Killer wasps enclose the cicadas in underground cells. Would this allow for a little leeway towards the occasional lesser dose of venom?

(I used to see Cicada Killer wasps quite often growing up outside Houston; they are frighteningly huge, but very docile and almost never sting humans. Their numbers diminished considerably in the area over the last 30 years or so, possibly due to mosquito fogging and/or the encroachment of fire ants, which seriously impacted populations of many ground-dwelling small species).

Mageth · 11-22-2002, 02:28 PM

Note also that other species of wasps use similar techniques on other species. Dirt Dauber wasps fill their mud nests with paralyzed spiders for their larvae to feed on.

[ November 22, 2002: Message edited by: Mageth ]

Duvenoy · 11-23-2002, 02:11 AM

The IDers picked the wrong wasp for their argument.

A great many species deposit their eggs on paralyzed arthropods, but only the Ichneumons do it the hard way.

<a href="http://www.kwic.com/~pagodavista/schoolhouse/species/insects/ichneum.htm" target="_blank">http://www.kwic.com/~pagodavista/schoolhouse/species/insects/ichneum.htm</a>

They don't only drill through bark, but I've seen them going into pretty solid wood. It's amazing to see one work.

doov

[ November 23, 2002: Message edited by: Duvenoy ]

Duvenoy · 11-23-2002, 03:41 AM

Controlled envenomation is not all that uncommon, especally in serpents. Venom is precious to the snake and no more will be used than necesssary. In some defensive bites no venom at all might be injected (there is some discussion as to the percentage of dry bites, ranging from as low as 2 to as high as 50%, depending upon who you ask).

And, as noted earlier, venom evolves just like anything else. Some years ago, I read about a species of ground squirrel in the west that is the primary prey of one of the Crotalus viridis subspecies of Rattlesnake. It has developed a partial resistance to the snake's venom, making it harder to kill. As a result, the snake's venom is gradually becoming 'hotter'. I seem to remember that I read it in National Geographic, but don't recall the issue. Venom variations have also been noted in pocket populations of Canebrake Rattlesnakes (C. h. atricaudatus), that have a diet depending upon herps such as frogs.

Another excellent example that could be dribbled around by the IDers, that they seem to have overlooked, possibly due to intellectual myopia, are the sensory organs and injection mechanism of Pit Vipers. Complex? Yeah, buddy!

doov

lpetrich · 11-23-2002, 08:06 AM

Another thing that may help the evolution of this seemingly IC system is prey switching.

If cicada-killer wasps' ancestors had started out on less mobile prey, like caterpillars, it would have been easier for them to start without venom. And there are indeed some parasitic wasps that live off of caterpillars.

So caterpillars would have been the now-gone "scaffolding" for cicada wasps.

My favorite insect example of IC, however, is the honeybee hive. Queen honeybees are totally dependent on their workers, and when a queen tries to found a new hive, she takes with her a swarm of workers.

However, in bumblebees and many other social insects, the founders do so in isolation; a bumblebee queen has to do all the tasks that the workers would eventually do, collecting food and building a comb.

But it is not too difficult to imagine a queen producing some pheromone that gets some workers to follower her as she goes off to found a new hive. If that becomes a typical-enough occurrence, then there will be no selection pressure on queens to be able to do workers' jobs, and the queen eventually does nothing but lay eggs all day.

11-22-2002, 07:51 AM	#1
MrDarwin Veteran Member Join Date: May 2001 Location: Washington, DC Posts: 4,140	Cicada killer life cycle: irreducibly complex? This was originally posted in the "Is the universe perfect?" thread, but I think it merits its own discussion: The venom of the <a href="http://ww2.lafayette.edu/~hollidac/cicadakillerhome.html" target="_blank">cicada killer wasp</a> is a toxin that immobilizes cicadas, and it works effectively (if chillingly) to this end. This paralysis is a function of both the chemical composition of the venom, and the dose in which it is delivered. If delivered in a larger quantity it would kill the cicada, which would then decompose, leaving nothing for the cicada killer larva to feed on; if delivered in a lesser quantity, it would allow the cicada to move around or even escape, dislodging the larva of the cicada killer wasp, which would again starve and die. The dosage delivered is just right to keep the cicada (which does make feeble, if futile, attempts to escape) both alive but paralyzed (and remarkably, alive for longer than the adult cicada would live otherwise), providing fresh food to the cicada killer larva, which slowly eats the cicada alive. In an interesting epilogue, cicada killer wasps provide their male larvae with a single cicada to eat, but their female larvae (which grow bigger) with two cicadas. Is the cicada killer life cycle an example of irreducible complexity? Is this an example of design?

11-22-2002, 12:45 PM	#4
Grumpy Veteran Member Join Date: Jul 2000 Location: Alaska, USA Posts: 1,535	Let me try to clarify the IC claim, to see if I understand: If the ancestor wasp started out with venom that was too strong, the host cicadas would have died before the offspring could eat them. If the ancestral venom was too weak, the wasp eggs would be dilodged. Therefore, the correct dosage must have been arrived at in one big leap, since trial & error would have eliminated the wasps in one generation. Somebody (God?) must have made them that way. Unless, of course, ancestral wasps had a variety of venom potencies, and those with the incorrect dosages did die out quickly, leaving only those with the correct dosage. Without knowing any better, I would also assume that the ancestral wasps parasitized other organisms in addition to, or instead of, cicadas, or led some other wasp-y lifestyle. [ November 22, 2002: Message edited by: Grumpy ]</p>

11-22-2002, 02:28 PM	#7
Mageth Contributor Join Date: Jul 2001 Location: Deep in the heart of mother-lovin' Texas Posts: 29,689	Note also that other species of wasps use similar techniques on other species. Dirt Dauber wasps fill their mud nests with paralyzed spiders for their larvae to feed on. [ November 22, 2002: Message edited by: Mageth ]</p>

11-23-2002, 02:11 AM	#8
Duvenoy Veteran Member Join Date: May 2002 Location: Just another hick from the sticks. Posts: 1,108	The IDers picked the wrong wasp for their argument. A great many species deposit their eggs on paralyzed arthropods, but only the Ichneumons do it the hard way. <a href="http://www.kwic.com/~pagodavista/schoolhouse/species/insects/ichneum.htm" target="_blank">http://www.kwic.com/~pagodavista/schoolhouse/species/insects/ichneum.htm</a> They don't only drill through bark, but I've seen them going into pretty solid wood. It's amazing to see one work. doov [ November 23, 2002: Message edited by: Duvenoy ]</p>

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11-22-2002, 11:31 AM	#3
pz Veteran Member Join Date: Aug 2001 Location: Morris, MN Posts: 3,341	Since, if you modify the characteristics of the venom in any way, the organism presumably fails to reproduce, I'd have to say that it is IC. Of course, that doesn't mean anything about whether it is designed or evolved, and I also have some problems with the description of the system that could mean it is not really IC. I'd have to ask how true it is that the dosage and potency of the venom must be that specific. There has to be variation of size and health in cicadas, and therefore in their sensitivity to venom. Are the wasp embryos/larvae really that fragile, that no significant movement can be tolerated? Do the wasps compensate behaviorally, for instance by stinging resistant cicadas multiple times, adjusting the volume injected to compensate for levels of activity, etc.?

11-22-2002, 02:18 PM	#5
Peez Veteran Member Join Date: Apr 2001 Location: Canada Posts: 5,504	O.K., I'll bite. What if the ancestral larva was better at hanging on? A smaller dose of venom slowed the cicada down enough for the larva to survive. What if the ancestral larva developed more quickly? A larger dose of venom killed the cicada, and the larva ate and developed before the cicada rotted. What if the ancestral venom did not need to have such a precise dosage? It has since been fine-tuned through natural selection. What if the ancestral cicada was less fragile? Natural selection has favoured cicadas that die outright when injected with this venom. Just a few ideas off the top of my head. Peez

11-22-2002, 02:27 PM	#6
Mageth Contributor Join Date: Jul 2001 Location: Deep in the heart of mother-lovin' Texas Posts: 29,689	if delivered in a lesser quantity, it would allow the cicada to move around or even escape, dislodging the larva of the cicada killer wasp, which would again starve and die Cicada Killer wasps enclose the cicadas in underground cells. Would this allow for a little leeway towards the occasional lesser dose of venom? (I used to see Cicada Killer wasps quite often growing up outside Houston; they are frighteningly huge, but very docile and almost never sting humans. Their numbers diminished considerably in the area over the last 30 years or so, possibly due to mosquito fogging and/or the encroachment of fire ants, which seriously impacted populations of many ground-dwelling small species).

11-23-2002, 03:41 AM	#9
Duvenoy Veteran Member Join Date: May 2002 Location: Just another hick from the sticks. Posts: 1,108	Controlled envenomation is not all that uncommon, especally in serpents. Venom is precious to the snake and no more will be used than necesssary. In some defensive bites no venom at all might be injected (there is some discussion as to the percentage of dry bites, ranging from as low as 2 to as high as 50%, depending upon who you ask). And, as noted earlier, venom evolves just like anything else. Some years ago, I read about a species of ground squirrel in the west that is the primary prey of one of the Crotalus viridis subspecies of Rattlesnake. It has developed a partial resistance to the snake's venom, making it harder to kill. As a result, the snake's venom is gradually becoming 'hotter'. I seem to remember that I read it in National Geographic, but don't recall the issue. Venom variations have also been noted in pocket populations of Canebrake Rattlesnakes (C. h. atricaudatus), that have a diet depending upon herps such as frogs. Another excellent example that could be dribbled around by the IDers, that they seem to have overlooked, possibly due to intellectual myopia, are the sensory organs and injection mechanism of Pit Vipers. Complex? Yeah, buddy! doov

11-23-2002, 08:06 AM	#10
lpetrich Contributor Join Date: Jul 2000 Location: Lebanon, OR, USA Posts: 16,829	Another thing that may help the evolution of this seemingly IC system is prey switching. If cicada-killer wasps' ancestors had started out on less mobile prey, like caterpillars, it would have been easier for them to start without venom. And there are indeed some parasitic wasps that live off of caterpillars. So caterpillars would have been the now-gone "scaffolding" for cicada wasps. My favorite insect example of IC, however, is the honeybee hive. Queen honeybees are totally dependent on their workers, and when a queen tries to found a new hive, she takes with her a swarm of workers. However, in bumblebees and many other social insects, the founders do so in isolation; a bumblebee queen has to do all the tasks that the workers would eventually do, collecting food and building a comb. But it is not too difficult to imagine a queen producing some pheromone that gets some workers to follower her as she goes off to found a new hive. If that becomes a typical-enough occurrence, then there will be no selection pressure on queens to be able to do workers' jobs, and the queen eventually does nothing but lay eggs all day.

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