Another stupid question from Raz!

[Maximus]

There's always a chance for some random mutation during reproduction even if it is asexual.  There isn't nearly as much genetic variety possible, but it is there.

Sure, but how does selection work then if it's just random?

BTW, I was referring to these quotes:

Among those species that reproduce sexually, the queen may choose to fertilize eggs at will

Among ants who do not reproduce sexually, all of the members of the colony are female.

http://en.wikipedia.org/wiki/Queen_ant

[garbon]

They're both invasive species. American Grey Squirrels kill prettier Red Squirrels.

Even our squirrels are racists

Nah, we got black squirrels. Apparently some introduced them to the Stanford area.

[alfred russel]

Sure, but how does selection work then if it's just random?

You have mutation x that makes you strong and fast, I have mutation y that makes me slow and weak, you thrive while I die out.

[Maximus]

Sure, but how does selection work then if it's just random?

You have mutation x that makes you strong and fast, I have mutation y that makes me slow and weak, you thrive while I die out.

The only mutations that matter from an evolutionary standpoint are the ones that make it into a queen, which is what, one in a million ants? What does it mean for her to be competitive? She's fed and protected. All she has to do is lay eggs.

So I guess the selective pressure isn't for stronger, faster ants; it's for more ants. Which is likely why the individual ants don't change. Their evolution is mostly at a social level.

[Razgovory]

Well generally speaking, for most female ants mutation is not desirable as they are workers who will not reproduce.  Their only job is to care for the queens and drones who will pass on genes.

[Razgovory]

Sure, but how does selection work then if it's just random?

You have mutation x that makes you strong and fast, I have mutation y that makes me slow and weak, you thrive while I die out.

The only mutations that matter from an evolutionary standpoint are the ones that make it into a queen, which is what, one in a million ants? What does it mean for her to be competitive? She's fed and protected. All she has to do is lay eggs.

So I guess the selective pressure isn't for stronger, faster ants; it's for more ants. Which is likely why the individual ants don't change. Their evolution is mostly at a social level.

The worker ants share the genetic makeup with queen, so when she reproduces their genes (or copies of them) get passed on as well.  It is a bit counter intuitive, but works quite well.  Some interesting work has been done on hive species evolutionary biology.

[Maximus]

The worker ants share the genetic makeup with queen, so when she reproduces their genes (or copies of them) get passed on as well.  It is a bit counter intuitive, but works quite well.  Some interesting work has been done on hive species evolutionary biology.

There is as far as I know no mechanism where observing random mutation X in one offspring leads to increased likelihood of observing the same mutation in another offspring. So even if a worker gets a beneficial mutation, that mutation is a) not getting passed on and b) completely independent of any natural selection that is going on. The only case where a mutation is going to be selected is when it occurs in a queen AND is beneficial to the queen's reproduction. Being stronger, faster etc, does not seem likely to be a factor. What does seem likely to be a factor is the ability to produce more eggs more quickly. Therefor this seems to be what will be selected for.

Other hive species may be different. Honey bees, which I am more familiar with, reproduce sexually (as well as asexually), and the queens engage in deathmatches with each other so physical traits are more likely to be selected for.

[HVC]

A mutation doesn't have to benefit the queen solely, or at all. A mutation that aids workers (say larger antennae or something) makes the colony more successful and thus she can produce more queens who build their own successful colonies and so on.

[Razgovory]

Keep in mind, that the genetics for both the workers and the queens are in the queens. A worker who spontaneously has a mutation won't help the hive much, but a mutation in the genetics in the queen may only manifest in the workers.  Some people refer to hives of insects as "super-organisms", and that each individual can be compared to a cell.  That may go a little to far, but the analogy is good way to understand how they pass on genes.

[Maximus]

A mutation doesn't have to benefit the queen solely, or at all. A mutation that aids works (say larger antennae or something) makes the colony more successful and thus she can produce more queens how build their own successful colonies and so on.

But that's not going to pass the beneficial mutation on any more than if it doesn't exist. And it's only going to affect a single worker among thousands, so it's going to have minimal impact even in the short term.

Bear in mind that many, probably even most, mutations are harmful. More queens doesn't lead to the expectation of more beneficial mutations.

[Maximus]

a mutation in the genetics in the queen may only manifest in the workers.

This is a good point though.

Still, the low number of mutations getting passed on would go a long way to explain the slow rate of adaptation.

[alfred russel]

Max, I did my senior paper in college in evolution in eusocial species (though focusing on a rare species of spider that is one of the only eusocial species with "normal" sexual reproduction).

I don't remember all the mechanisms for bees and ants, but what is universal in eusocial species is very close kin relationships (generally through changes in the chromosome number for some members). It is also very common to have many members unable to reproduce.

The result is that the queen's DNA (in species with a single reproductive female) must support the creation of a new community. If the queen's DNA only supports a strong queen and weak workers, her offspring will fail, as the descendant communities will not establish themselves. At the same time, workers who are unable to reproduce are prone to work for the queen's success, because without a chance to reproduce otherwise their only way to spread their genes is through the success of their own kin, such as the queen.

A mutation in the queen that leads to strong workers is beneficial to the queen--her offspring will be better workers, and her fellow queen descendants will also produce better workers.

Sometimes ant communities (similar to some other eusocial species) are referred to as "superorganisms" because despite having many members they are genetically tied to a single cause (and from an evolutionary pov are similar to a single organism).

[HVC]

A mutation doesn't have to benefit the queen solely, or at all. A mutation that aids works (say larger antennae or something) makes the colony more successful and thus she can produce more queens how build their own successful colonies and so on.

But that's not going to pass the beneficial mutation on any more than if it doesn't exist. And it's only going to affect a single worker among thousands, so it's going to have minimal impact even in the short term.

Bear in mind that many, probably even most, mutations are harmful. More queens doesn't lead to the expectation of more beneficial mutations.

the mutation isnt at the worker level, it's at the queen level. Since one queen produces all the workers all the workers would have that trait. Long antennae or mandibles wouldn't benefit the queen, but they would benefit the colony, and thus would be passed down the generations

[Malthus]

They're both invasive species. American Grey Squirrels kill prettier Red Squirrels.

Even our squirrels are racists

Or at least, better armed. 

[alfred russel]

But that's not going to pass the beneficial mutation on any more than if it doesn't exist. And it's only going to affect a single worker among thousands, so it's going to have minimal impact even in the short term.

Bear in mind that many, probably even most, mutations are harmful. More queens doesn't lead to the expectation of more beneficial mutations.

A mutation that goes to a single worker is a dead end.

A mutation that goes to a future reproductive member, such as a future queen, is not.

I don't know that this would slow mutution rates. What could slow mutation rates is that in species with haplodiploidy (common in eusocial species) the haploid members will be unable to mask the effects of a negative mututation.