qetzal
Posts: 311
Joined: Feb. 2006
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| Quote (Southstar @ Dec. 07 2011,09:57) | The objection made to this article is that there is no proof of novel genetic material in the study. Actually in all fairness it does state "Tail clips taken for DNA analysis confirmed that the Pod Mrcaru lizards were genetically identical to the source population on Pod Kopiste."
So one could assume that the mutations are only induced by the enviroment and are not genetic based? |
Mutations are genetically based, by definition. And the DNA analysis did not confirm the the lizards were genetically identical. It only confirmed that the PM lizards were genetically indistinguishable from the PK lizards by the method employed. The test was only designed to show that the lizards collected on PM were, in fact, descendents of the original 5 pairs of PK lizards that were introduced to PM. That test was not designed to identify possible mutations in the PM lizards that might account for the observed physical differences.
| Quote | another thing I have replied to this saying that the development of the Cecal valve which is only been developed on the lizards of one island can only be produced with an increase of the amount of genetic material. Would this be correct?
Or would it be possible that these genes were somehow latent and were only expressed when the animal turned to a heavier herbivourous diet?
Thanks
Marty |
No, I don't think you can't say the the development of cecal valves could only occur with an increase in the amount of genetic material. Remember that these lizards are descended from a total of 10 original lizards. So, any particular gene locus could have been present in multiple different versions (alleles) in the founding population. As the population expanded, those alleles would have reassorted into many combinations that weren't present in any single founding lizard. In addition, most traits are influenced by combinations of lots of genes and loci. So the appearance of cecal valves might not involve any new mutations. It might just involve new combinations of alleles that already existed individually in the founding population.
The fact that these traits appeared in only ~ 30 generations suggests to me that reassortment and selection of existing alleles is probably a significant factor here, though it's possible there were novel mutations as well.
Note that this is not really the same as saying that the genes were somehow latent, though your anti-evolutionist acquaintences may try to claim as much.
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