sensei writes:
Do you have similar data on shared ERVs with other mammals or with reptiles or fish?
Over time ERV's will accumulate mutations to the point that they can no longer be compared to one another. This is true for the vast majority of sequence in vertebrate genomes. Over those evolutionary distances (humans to distantly related mammals, reptiles, fish) it is better to compare conserved sequences which tend to be functional sequences. Since the vast majority of ERV's are not functional and accumulate mutations at a rate consistent with neutral drift they fade into the background much faster than functional DNA. There is also the problem of recombination and indels which can make synteny and orthology hard to determine.
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