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Comment by tlb | Hacker News Reader

What is the difference between a megacolony and a species? If I replaced s/ant/mouse/ and s/megacolony/species/, would there be anything surprising about their results?

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The ants in a megacolony are all genetically related, which is quite different from the way in which all members of a species are genetically related.

Ants, along with bees and a few other species have a haplodiploid sex determination system, unlike the XY system in mammals. This has a variety of consequences that are hard to swallow at first sight -- males have no father, all workers in a colony are clones, and so on. This is what leads to their highly social behavior within a colony: the good of one is the good of all. I don't yet understand how supercolony behavior arises out of ant genetics, but I'm sure it somehow does.

It appears to me that this one of those evolutionary behaviors gone awry due to the rapidly changing environment. In the past, you could expect that ant colonies would migrate geographically at a fixed rate (on average); so with a constant mutation rate, you'd expect territoriality to arise from this behavior -- ants colonies in regions within (say) a 100- mile radius would be co-operative. Quite clever, actually. However, since humans are capable of transmitting the ants anywhere instantaneously (in evolutionary time), it has produced results that evolution didn't "intend."

BTW here's the original paper http://www.springerlink.com/content/u081508512u7k421/

More info. about the species in question: http://en.wikipedia.org/wiki/Linepithema_humile

Also, http://en.wikipedia.org/wiki/Haplodiploid_sex-determination_...

I remember reading Mendel's Demon on the subject of sex differentiation as a means to prevent competition between mitochondrial DNA, and I wonder if there might be some interesting extensions beyond this that could be investigated using such "mega-colonies". I also wonder about the insights that could be gained into immune responses.... just makes me think there could be furious emergence at work here!

The workers are actually 3/4 related (assuming a monogomous queen), not clones of each other. This is because they all have the same genes from their father (since the father has just enough genes for one set of chromosomes), but only overlap on half of the genes they inherit from their mother (like mammals).

Oops, you're right, sorry, forgot that workers are female.

But then how do we define species in non-XY sex systems? I know that in such a system, the simplest test is do members of the group procreate with one another.

For example, there are two species of crickets that live amongst each other, are capable of producing viable offspring with each other, and behave identically except for the frequency of their mating calls. When we tweak the mating calls in a lab, we can get crickets from the different groups to mate. But since they don't mix in the wild, we call them two different species.

Generally speaking there is no altruism among members of a species unless they are very close genetic kin or at least part of a social group. You need to "expect" that the beneficiary of your altruism either has some of your genes, or will return the favor later.

By "expect", we don't mean conscious calculation, of course. Rather, we mean that the genes which favor this sort of behavior tend to be successful than genes that do not.

have you read the theory of the "baby face" phenotype being a ploy on this (and/or very similar) mechanism? I'll try and find the story I read. I always found this type of analysis to be where genetics/sociology becomes most interesting

EDIT: although it's well off topic, sorry EDIT': all I can find are the "babyface helps black CEOs" story... wasn't that one I read but it deals with similar findings

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