Ant Slave Rebellion

[felix_dakat]

I heard about this phenomenon on the radio and figured you might find it interesting.

Slave ants rebel

By Susan MiliusSeptember 13th, 2008; Science News Vol.174 #6

Kidnapped worker ants do a little quiet sabotage

Tiny ants enslaved inside acorns across the northeastern United States could be resisting their captors with a covert army of killer nannies.

About the size of newspaper commas, ants in the genus Temnothorax fall prey to a marginally larger ant species that doesn’t do its own housework.

Instead the do-little ants, Protomognathus americanus, raid smaller species’ nests and steal babies in the larval and pupal stages. The youngsters grow up inside the acorn home of the slave-makers’ queen, doing her housework and nursemaiding her young.

Biologists have seen that the species vulnerable to enslavement evolve ways to try to fight off raids. But ways for the kidnapped youngsters to resist captivity haven’t shown up. Theorists have even argued that post-enslavement resistance couldn’t evolve. But observers are giving up on the slaves too fast, says Susanne Foitzik of Ludwig-Maximilians University in Munich.

Kidnapped workers of two Temnothorax species kill off a good portion of their charges in the nurseries of slave-maker colonies, Foitzik said at the 12th International Behavioral Ecology Congress held August 9 through 15 at Cornell University.

Yet, in their birth colonies, Temnothorax ants readily nurture their baby sisters and half-sisters to adulthood.

Killing sprees by slave nannies could be an overlooked form of resistance, Foitzik suggests. The baby-killing offers any kin in nearby colonies some protection from slave-makers, since the kidnapper queen’s offspring make up the raiding parties. Paring back their number cuts back the raiding power. Foitzik proposes that this benefit to kin could drive the evolution of the trait.

“This is evolution to be a bad nanny,” says Peter Nonacs of the University of California, Los Angeles.

He compares the ant dynamics to other resistance puzzles that have intrigued evolutionary biologists. A wide variety of bird species, for example, seem able to evolve the urge to kill the eggs of parasitic cowbirds, but hardly any species kills cowbird hatchlings.

Foitzik began to wonder about baby-killing among ants, she says, because the slave-maker colonies contain surprisingly few workers of their own species. The kidnapper queens do lay plenty of eggs. If tended properly, they grow into workers that don’t do a lot of work, depending on slaves for food even as adults. These slave-makers attack other colonies to refresh the supply of household help.

At a West Virginia study site, slave-maker nests averaged only two worker adults of the queen’s species, and several dozen slaves. “That’s not a raiding party — that’s a raiding duet,” Foitzik says. New York colonies averaged only five slave-maker adult workers. The slave-maker ants have large, fierce jaws and use chemical weaponry during attacks, but these reduced numbers can still make raids iffy.

When Foitzik brought colonies into her lab, the slave-maker queen’s young failed to thrive. She discovered that slave nursemaids care for the eggs and young larvae but turn into horror nannies once slave-maker young reach the pupal stage. “They take pupae and dump them in some corner. Mold grows on them and they die,” Foitzik says. Or the slaves rip apart other pupae and eat the chunks.

Overall, slave nursemaids kill some 80 percent of their captors’ young queens and some 60 percent of the young workers, Foitzik reports. To see if lab life, rather than enslavement, was driving the ants to such extremes, Foitzik also kept in the lab colonies of the slave species that hadn’t been raided. There, more than 90 percent of the young survived to adulthood.

[nrhy]

nvm…that was stupid of me >.<

[Cyrene]

Ants engage in some very complex social behavior for such small organisms. I didn’t read enough about this subject specifically, but i remember reading how ants act is predictable by how genetically related they are to each other (it was in the selfish gene) so its gotta be a pretty well-known explanation by now. On top of that the slave-taking is cool, I remember reading about that as well.

Which ants is it that engage in agriculture, the growing of fungus to eat. Was it the leaf-cutter ants? Some of them engage in husbandry too, milking aphids.

They also engage in raiding (stealing eggs) wars against other ants. Stuff you see more typically among some of the higher organisms. I’m going to re-read some of the stuff about ants.

Oh, and if you weighed all the ground species on land, 20% of it would be the weight of the mass of ants. Thats how many ants we have.

[Tab]

Great article Felix. Eu-societies, gotta love 'em.

Kidnapped workers of two Temnothorax species kill off a good portion of their charges in the nurseries of slave-maker colonies, Foitzik said at the 12th International Behavioral Ecology Congress held August 9 through 15 at Cornell University.

Yet, in their birth colonies, Temnothorax ants readily nurture their baby sisters and half-sisters to adulthood.

My only thought was that maybe no special evolution is required. Perhaps the Temnothorax workers simply have a built in quality control mecahnism concerning the eggs/larvae, that reaches a head at the pupal stage. ie. workers automatically dispose of/kill off pupae that they detect as malformed. Pupae of their own species wouldn’t usually trigger a high response, but pupae of another species would.

Be interesting to see the percentages of pupae that get discarded in the home nests, and compare them to the percentages of the slavers.

Slaver fucking ants. Who’d of thought. Take that intelligent design freaks !!!

[Lollipop_King]

Maybe God enlightened them.

[felix_dakat]

@Tabula Rasa

Great article Felix. Eu-societies, gotta love 'em.

Kidnapped workers of two Temnothorax species kill off a good portion of their charges in the nurseries of slave-maker colonies, Foitzik said at the 12th International Behavioral Ecology Congress held August 9 through 15 at Cornell University.

Yet, in their birth colonies, Temnothorax ants readily nurture their baby sisters and half-sisters to adulthood.

My only thought was that maybe no special evolution is required. Perhaps the Temnothorax workers simply have a built in quality control mecahnism concerning the eggs/larvae, that reaches a head at the pupal stage. ie. workers automatically dispose of/kill off pupae that they detect as malformed. Pupae of their own species wouldn’t usually trigger a high response, but pupae of another species would.

Be interesting to see the percentages of pupae that get discarded in the home nests, and compare them to the percentages of the slavers.

Slaver fucking ants. Who’d of thought. Take that intelligent design freaks !!!

Killing the slaver ant larvae clearly has survival value for the slaves since it reduces the slaver ant raids on the parent colonies of the enslaved. I wonder: Will the slaver ants get wiped out or evolve?

[Tab]

Overall, slave nursemaids kill some 80 percent of their captors’ young queens and some 60 percent of the young workers, Foitzik reports. To see if lab life, rather than enslavement, was driving the ants to such extremes, Foitzik also kept in the lab colonies of the slave species that hadn’t been raided. There, more than 90 percent of the young survived to adulthood.

Actually, you gotta wonder whether these ‘slaves’ are really slaves at all. Just a thought, but it seems to me that the ‘slavery’ involved benfits the slave-donating colony much more than the slave-taking colony, if they compete for the same territory. I wonder if it is not the ‘slaves’ that have evolved a way to pheremonally influence/decieve the slaver ants into taking them into their nest, like double-agents, where they can do the most damage for the least expense.

I mean - as it stands, the slaver ants are rapidly breeding themselves out of the game. One would have thought such a behavioural trait - if soley undertaken and supported by the slaver side - would have disappeared long ago. I think co-evolution has pushed the balance of power over to the Temnothorax team, and now they control the behaviour of the Protomognathus americanus varient…?

[felix_dakat]

@Tabula Rasa

Overall, slave nursemaids kill some 80 percent of their captors’ young queens and some 60 percent of the young workers, Foitzik reports. To see if lab life, rather than enslavement, was driving the ants to such extremes, Foitzik also kept in the lab colonies of the slave species that hadn’t been raided. There, more than 90 percent of the young survived to adulthood.

Actually, you gotta wonder whether these ‘slaves’ are really slaves at all. Just a thought, but it seems to me that the ‘slavery’ involved benfits the slave-donating colony much more than the slave-taking colony, if they compete for the same territory. I wonder if it is not the ‘slaves’ that have evolved a way to pheremonally influence/decieve the slaver ants into taking them into their nest, like double-agents, where they can do the most damage for the least expense.

I mean - as it stands, the slaver ants are rapidly breeding themselves out of the game. One would have thought such a behavioural trait - if soley undertaken and supported by the slaver side - would have disappeared long ago. I think co-evolution has pushed the balance of power over to the Temnothorax team, and now they control the behaviour of the Protomognathus americanus varient…?

Right. The slaves are really genocidal terrorists. This could be the same behavior the slaves would display in their own colonies… disposing of foreigners. I wonder under what conditions the kidnapping strategy worked successfully for the Protomognathus americanus or, if it is a new behavior on the part of the Temnothorax ants, under what conditions it emerged.

[Tab]

I wonder under what conditions the kidnapping strategy worked successfully for the Protomognathus

Okay, let’s dream a little. Say that the Protomognathus are great at procreation, and kick out offspring by the truckload. But in attaining such speed of reproduction they’ve sacrificed on quality - and a lot of their young contain deletarious mutations. Thay also lack any instinctive mechanisms for quality control.

But luckily, the neighboring Temnothorax guys are whizzes at detecting abherrations at the pupal stage, and the two species are closely enough related for the same quality criteria to be equally, or near equally applicable. So, by some evolutionary jiggery-pokery, the Protomognathus evolve the slave-taking behaviour, and use the captive (and infanticidal) Temnothorax to quality control their young for them. So - though in the process they ‘lose’ 80 % of young queens, and 60 % of young workers - overall, the quality and fitness of the nest is improved.

Okay - sounds like a lot of effort for little result. But it would work if resources are plentiful, and reproduction rates high enough to make up the losses. Maths:

Let’s disregard queens. They are probably produced far less often than workers rendering them negligable to population counts.

No Temnothorax - 90% survival - 10 from a 100 die from natural causes, 90 (Q/non-Q mix) live.
With Temnothorax - 40% survival* - 60 from a 100 are killed, 40 (Q) live.
[size=90]*I’m including the natural 10% mortality as part of the 60% kill rate.
Q=quality worker[/size]

Say the cost of sustaining a full worker adult throughout its life is 400u. But to the Pupal stage is only 10u units. Say - worst case scenario - all non-Q workers are total spastics, and don’t produce any helpful work, in fact, they get in the way of others, and disrupt the nest costing an extra 100u per capita. And say that the Q workers are best case scenarios, and return 100% of the energy they consume as beneficial work. And finally say the nonQ phenotype occurs (based on the quality control mortality rate-natural causes) at a 50% rate.

So let’s do the math:

No Temnothorax - 90x400u = 36000u
(36000u spentX50%) - (45x100u disruption) = 13500 return beneficial work .

With Temnothorax - (40x400u live)+(60x10u pupal)=16600u
16600u spent - 600u wasted on defective pupa= 16000u return beneficial work.

So, as long as the differential in energy cost between pupa and full worker lifespan is great enough, and the fitness of a non-Q defective worker sufficiently poor to severely compromise the energy spent/beneficial work ratio…

…Then importing quality-control ‘experts’ from another species would be advantageous.

[felix_dakat]

@Tabula Rasa

I wonder under what conditions the kidnapping strategy worked successfully for the Protomognathus

Okay, let’s dream a little. Say that the Protomognathus are great at procreation, and kick out offspring by the truckload. But in attaining such speed of reproduction they’ve sacrificed on quality - and a lot of their young contain deletarious mutations. Thay also lack any instinctive mechanisms for quality control.

But luckily, the neighboring Temnothorax guys are whizzes at detecting abherrations at the pupal stage, and the two species are closely enough related for the same quality criteria to be equally, or near equally applicable. So, by some evolutionary jiggery-pokery, the Protomognathus evolve the slave-taking behaviour, and use the captive (and infanticidal) Temnothorax to quality control their young for them. So - though in the process they ‘lose’ 80 % of young queens, and 60 % of young workers - overall, the quality and fitness of the nest is improved.

Okay - sounds like a lot of effort for little result. But it would work if resources are plentiful, and reproduction rates high enough to make up the losses. Maths:

Let’s disregard queens. They are probably produced far less often than workers rendering them negligable to population counts.

No Temnothorax - 90% survival - 10 from a 100 die from natural causes, 90 (Q/non-Q mix) live.
With Temnothorax - 40% survival* - 60 from a 100 are killed, 40 (Q) live.
[size=90]*I’m including the natural 10% mortality as part of the 60% kill rate.
Q=quality worker[/size]

Say the cost of sustaining a full worker adult throughout its life is 400u. But to the Pupal stage is only 10u units. Say - worst case scenario - all non-Q workers are total spastics, and don’t produce any helpful work, in fact, they get in the way of others, and disrupt the nest costing an extra 100u per capita. And say that the Q workers are best case scenarios, and return 100% of the energy they consume as beneficial work. And finally say the nonQ phenotype occurs (based on the quality control mortality rate-natural causes) at a 50% rate.

So let’s do the math:

No Temnothorax - 90x400u = 36000u
(36000u spentX50%) - (45x100u disruption) = 13500 return beneficial work .

With Temnothorax - (40x400u live)+(60x10u pupal)=16600u
16600u spent - 600u wasted on defective pupa= 16000u return beneficial work.

So, as long as the differential in energy cost between pupa and full worker lifespan is great enough, and the fitness of a non-Q defective worker sufficiently poor to severely compromise the energy spent/beneficial work ratio…

…Then importing quality-control ‘experts’ from another species would be advantageous.

A kind of symbiotic relationship between the temnos and protos. Gotta keep producing those strong workers so they can keep stealing and enslaving our pupae. But really, if that’s the case, what are the Temnos getting out of it? I guess the protos let them eat so they can keep on doing the work. This is starting to feel a bit like the global economy.

[Tab]

Actually, re-reading the OP, it doesn’t look like the Slavers need many ants of their own species to form a functioning acorn nest - so perhaps they can thrive even with a 60% mortality rate. Still, fun to build ant-nests in the sky.

[Knox]

Woody Allen predicted this.