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The human genome is about 770 MB, the C. elegans genome is about 100 MB, the yeast S. cerevisiae is about 12 MB. Different other genomes have been sequenced: how many GB of genomic DNA we have now?

Let say we would like to make a Noah hard-disk ark: how much space would it take to represent the genomes of all known species on earth? There is a way to provide an estimate?

I'm also interested in the total biodiversity: for instance, if two species each have 1 GB genomes and have half of their DNA in common this would count as 1.5 GB.

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I think this is an unanswerable question - there are a handful of species whose genomes have been sequenced, and many millions on the earth that remain completely uncharacterised! – Luke May 30 '12 at 8:42
The human genome has highly repetitive (“low complexity”) regions though, which means that it can be compressed much further. This is the real measure of biodiversity “size” since it measures the actual information content. And adding genome sizes is much more complex than you make it out, your 1.5 GB approximation isn’t very precise. – Konrad Rudolph May 30 '12 at 10:43
@KonradRudolph You have to choose between the most reductive representation of the genome and the fullest one. I'm sure we'll have records of hundreds of millions of variants in the human genome alone by the end of the next decade. There are proposals to move away from a single reference build for the human genome. Not only storing the sequence itself, but annotation describing how the variants are used already blows the doors off of 770 MB. – shigeta May 30 '12 at 16:20
@shigeta I don’t think this is relevant here. What Craig wants to measure is the combined information content of all genomes, and the information content is by definition the entropy which, again by definition, corresponds to the size of the data in its tightest (theoretically) possible representation. – Konrad Rudolph May 30 '12 at 16:23
It really depends on what you are trying to understand. Total information measures are convenient for bookkeeping, but considering the recent work that shows how frequently horizontal gene transfer occurs in bacteria,, its probably true that you will never run out of bacterial genomes to add to the sequence database as @MarkSchltheiss is pointing out. I'm definitely more of a pessimist w.r.t. the tractability a complete genomic sequence catalog. – shigeta May 30 '12 at 19:33
up vote 12 down vote accepted

If you simply take one order of insects, Coleoptera, there are just under 400,000 described species with estimates from 850,000 to 4,000,000 species total in just this order. The number of primates is under 1,000. If your assumption of say 10MB for all other primates would be accurate, just adding in the low end estimate of 850,000 at 10MB per 1000 we are quickly at 8,500GB which seems to be a factorial out of the GB range.

So, we have a broad estimate of non-bacterial of plants, animals etc. at say 8,700,000.

Jason Gans found in a 1 gram of soil survey approximatly 1,000,000 bacterial species.

SO the total accounting for species number is totally impossible to estimate for anything at this time, let alone the genome.

Even for something as "common" as a giraffe, there are up to 9 sub-species with genome differences within each subspecies.

So, once we get them all decribed, we can then work on the genome sequence for each and get you some answers!

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