[Musicforawhile (OP)]

So as I understand, in the beginning microbes got heavier and more complicated and multiplied (asexually) by dividing. My question is, did sexual reproduction begin by the exchange of information through the antennae of microbes? So that they were trying to find out about each other and about the environment, and by exchanging information through the antennae they inadvertently began the process of sexual reproduction.

[CliffordK]

I'm not sure about the antenna idea. 

However, bacteria will exchange DNA using plasmids, as well as sampling environmental DNA.  One of the fears of having multiple multi-drug resistant bacteria is that they'll share their drug resistance genes across species, and develop a super-bug.  Although while it is theoretically possible that VRE and MRSA would share genes, it doesn't seem to be naturally occurring, at least not to the point where it has become a problem..

Viruses can also be thought of little gene/DNA packages that move from one cell to another. 

Meiosis is a very complicated system to create haploid gametes, but the system may be developed as a more controlled version of previous gene sharing.  Higher organisms such as humans may require a rigorous method for both genetic stability, as well as gene sharing and may not be possible with simple bacteria gene reproduction (with errors) and sharing plasmids.

[Musicforawhile (OP)]

Why do they share DNA? Is it about communication or something else?

[Musicforawhile (OP)]

No-one knows, huh?

[RD]

Sexual reproduction produces more rapid evolution than asexual because of increased rates of genetic variation and accumulation of beneficial traits ... http://en.wikipedia.org/wiki/Evolution_of_sexual_reproduction

[CliffordK]

I'm not sure about bacteria communication.  There is some recent data that it may be relatively complex. 

As far as sharing DNA.  One could think of bacteria as being selfish or sharing. 

In a selfish world, an entity (or group) would want to pick up as many novel genes as possible with the hopes that some new genes would be beneficial, perhaps give them some environmental resistance characteristic.  However, how do those genes get out in the environment to be picked up?  Only picking up genes from dead organisms may be counterproductive. 

However, if bacteria in a diverse colony occasionally shares plasmids, then there would be a the potential for sharing and building up beneficial genes could help the colony as a whole. 

As RD mentioned, sexual reproduction both gives stability to the gene pool, but also a method to disseminate useful characteristics across the population.

[dlorde]

In a selfish world, an entity (or group) would want to pick up as many novel genes as possible with the hopes that some new genes would be beneficial...

Point of order m'lud - this athropomorphic description risks being taken literally by the less well-informed; there's not really any wanting or hoping going on in this respect.

Just sayin'.

[CliffordK]

Ok, so perhaps no "desires" in single cell organisms. 

One can consider bacteria having a purpose of surviving, replicating, and passing on their genes in perpetuity.  And, not necessarily just individuals, but the survival of the colony. 

[Musicforawhile (OP)]

Well I know they really don't hope for anything lol. And they don't desire or have a purpose either, just like we don't have a purpose.

[dlorde]

One can consider bacteria having a purpose of surviving, replicating, and passing on their genes in perpetuity.  And, not necessarily just individuals, but the survival of the colony.

In the same way one can consider the sun having a purpose of fusing hydrogen into helium.

[CliffordK]

You exist to replicate, and you replicate to exist.

Those families that don't replicate cease to exist. 

[dlorde]

You exist to replicate, and you replicate to exist.

I realise the intention is to emphasise that 'you' are no more than a replicator, but I'm being pedantic because 'you exist to replicate' can be shorthand for 'you exist in order to replicate', which implies goal-seeking, or purpose - which would be misleading. It's the fine line between 'in order to' or 'so that', and plain 'because' that is important in evolution talk. I've met young people who think there's purposefulness or a goal to evolution because they've heard a trait evolved in order to gain some advantage, or so that an advantage could be gained.

I'm honestly not trying to annoy you, it's just a pet peeve of mine - but I think it's important.

Those families that don't replicate cease to exist.

Yes []