Originally Posted By: Orac
So the most evolutionary advanced animal using that criteria is the marbled lungfish at a whopping 130Gb and the most evolved plant is the Japanese-native, pale-petal at 150Gb.

I would need ImagingGeek to explain what the hell that DNA much is needed for, I guess alot of it is junk.

Yes & no. In animals there is a tenancy to accumulate both extra genes and towards the accumulation of junk DNA (junk meaning the DNA is not required to maintain the fitness of the organism). This is a product of the cross-over process which occurs during the formation of eggs/sperm. The process is error-prone, with unequal cross-overs leading to duplication or deletion of DNA. Deletions are less likely to be passed on (simply because you may delete something important) so the net trend is towards genome growth.

When discussing agricultural plants things get complex. Plants have a tendency to duplicate their entire genomes (called polyploidy). Normally, polyploids don't survive well, but they do tend to have characteristics humans like - bigger fruits/seeds/flowers, etc. Paris japonica is octaploid - its whole-scale duplicated its genome 3 times, and is also allopolyploid, meaning its crossed with an unrelated species and retains some of that species genome. Whether polyploidy can be considered more information (as its simply a duplicate of what was already there) is unclear.

What sets the upper limit to genome growth is the energy required to maintain the genome relative to the organisms other needs. In the case of agricultural plants, human intervention provides a selective pressure that counters the natural selection that would normally suppress polyploidy.

Originally Posted By: Orac
If you think that is a fair criteria there is an obvious flaw in it and it comes up in the entry that things with this length DNA replicate very slowly because it takes a very very long time to replicate that ammount of DNA.

Actually, it doesn't take long to replicate the DNA. Again, you need to learn some biology before you start pontificating on it. DNA replication in eukaryotes does not start at a single site and progress from there. Rather, it starts at multiple sites within each chromosome. Since chromosomes typically grow via duplications, these sites are duplicated at the same rate as the chromosome in general, and thus you maintain a proportionate number of start sites relative to genome size.