The Mismeasure of the Y-Chromosome

March 14, 2014 at 9:52 pm (Uncategorized)

E&NV has a new post up by Ann Gauger, in which she claims:

Our Y-chromosomes are strikingly different from those of chimps, for example. This was a surprise to researchers, given the relatively short time our species supposedly diverged from one another. – See more at: http://www.evolutionnews.org/2014/03/the_mismeasure083011.html#sthash.fSEVGuDP.dpuf

 

However, these findings do not contradict the fact that Chimps are our close cousins, these findings just confirm that the Y evolves much faster than the rest of the genome. Wiki puts it this way:

 

The human Y chromosome is particularly exposed to high mutation rates due to the environment in which it is housed. The Y chromosome is passed exclusively through sperm, which undergo multiple cell divisions during gametogenesis. Each cellular division provides further opportunity to accumulate base pair mutations. Additionally, sperm are stored in the highly oxidative environment of the testis, which encourages further mutation. These two conditions combined put the Y chromosome at a greater risk of mutation than the rest of the genome.[12] The increased mutation risk for the Y chromosome is reported by Graves as a factor 4.8.[12] However, her original reference obtains this number for the relative mutation rates in male and female germ lines for the lineage leading to humans.[20]

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Minor Correction

February 17, 2013 at 6:25 pm (Uncategorized)

In a post about fish evolution, PZ Myers writes :

This fits a model in which tetrapod ancestors carried a genetic variation that expanded the core of mesodermal tissue in their fins, which was then organized by the standard rules of limb mesoderm into bone and muscle. Again, this is opportunity, a new field of potential that in these early stages of evolution hadn’t yet been refined into a specific, and now familiar, pattern, although elements of that pattern are foreshadowed here.

Instead of “genetic variation” I would say “gene regulatory network” since the whole wiring of genes required for extra limb growth is what was already present in the common ancestor of tetrapodes and fishes. Maybe all the crazy feminism is starting to unglue him.

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