Data and annotations in CyanoBase (September 2009)
Nucleotides 266 584 858 1 That is the size of the Cyanobacteria genome, their genome hosts 260 million base pairs
Within the cyanobacterium life cycle, cyanobacteria undergo cell division approximately once per day under the influence of moderate constant light and through intensifying the light, the cells start dividing more frequently as more energy is available. It takes about 19 hours for the cyanobacteria to rest before it can process cell division once more. 2
Bacterial DNA Mutations 3
Spontaneous mutations occur at a rate of 1 in 10^5 to 10^8 and contribute to random population variation.
that is, if we suppose the lowest mutation ration, one mutation in every 100mio base pairs 100.000.000, in other words, 2,5 mutations per cell cycle.
If the first fully developed cyanobacteria emerged 3 billion years ago, and they replicate once per day, that means, there were 3.000.000.000 years x 360 days = 1080000000000 or 10,8 ^11 replication cycles. Now lets multiplicate this 2,5, since there were 2,5 mutations per cycle, that means, there would have had to be 2,700.000.000.000 or 2.7^12 mutations during this time period.
Since the genome size is 260 mio base pairs:
That means, they would have changed their genome 100%, 10150 times
We should expect to see a completely different organism. But here they are....
The history suggested by Proterozoic fossils is that cyanobacteria evolved early and quickly, and then just sat there, changing little over the eons. Many features of cyanobacterial biology are conserved across the entire phylum and so must already have been present when blue-greens began to diversify. Why should fossils from a 1.5-billionyear-old tidal flat look just like the cells observed in coastal mats today? The paleontological observation of long-term cyanobacterial stasis is particularly puzzling because we know that bacteria can evolve rapidly.
A tree showing evolutionary relationships among living cy anobacteria. Note that cy anobacteria with specialized cells fall on a fairly late branch of the tree. This means that fossils showing cell differentiation can place an upper bound on when the tree’s major branches formed.