Saturday, 10 November 2007


While just browsing the internet I came across a couple of facts that I found rather interesting:

The first is about the infamous fugu pufferfish (Takifugu spp.) It's a well known fact that a great majority of the human genome is comprised of so called "junk DNA" (regions of DNA that has no aparent function, for those of you who dont know). What's interesting about Fugu is that it has pretty much no junk DNA whatsoever.

According to Daniel Rokhsar, "within each taxonomic grouping, there can be wide variations in genome size that are not necessarily related to the complexity of the organism. These variations appear to be due to differing amounts of 'junk' or 'selfish' DNA, often dominated by the remains of ancient viral-like genomic infections that left hundreds of thousands of repetitive elements littered throughout the genome. The Fugu genome seems to have avoided these events and sequencing it will therefore allow us to obtain a complete vertebrate genome extremely rapidly."

It may be that Fugu represents a pristiene "primitive" verterbrate genome, since it's been untained with retrotransposons or pseudogenes. It would be interesting to find out how the species has been able to avoid this. Maybe it's genome will shed some light on the divergance of verterbrates from inverterbrates some 530 million years ago.

The second interesting thing I came across was a paper on an experiment done in 1989 by Diane Dodd (Reproductive Isolation as a consequence of adaptive divergence in Drosophila pseudoobscura 1989 Evolution 43(6) pp. 1308-1311). This experiment is awesome because it shows speciation in action. What she did was raise one strain of D. pseudoobscura which, obviously, could breed with each other. She then seperated the population in two groups. One group was raised using a starch-based food, and the other was raised on a maltose-based food. These groups were reared for several generations (I think it was 8), and after were combined into one larger group again. What resulted was the maltose group only mated with the other maltose group flies; the starch flies only mated with other starch flies. There was reproductive isolation - in other words, speciation - between the two groups that started off as one interbreeding population.

This is evolution in action, folks! If anyone ever doubts that evolution is true because "no one has ever observed it", kick 'em in the shins and point them to this paper. Not only can we see the beginnings of evolution, but we can see it in as few as 8 generations.

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