# In this poisson distribution in olfactory receptor (OR) pseudogenes neutral mutation rate, how is the mean used?

The 2005 paper A comparison of the human and chimpanzee olfactory receptor gene repertoires describes a poisson distribution, with a mean of 0.701

From that mean, how is the gene disruption rate of 1kb per year calculated? And, how is the age 3.86 Ma for relaxation of selective constraint calculated from (0.451/0.701)·6 Mya = 3.86 Mya?

The parts of the paper,

TL;DR How is mean = 0.701 used to calculate stuff in that paper?

• Do they have a typo/miscalculation? λ=0.701 is the mean number of disruptions per shared pseudogene since the last common ancestor (6 Mya). Therefore, the neutral gene disruption rate is 0.701 / 6 Ma = 1.17·10$^{-7}$ disruptions/gene/year. This value differs from the paper by a factor of 10. – canadianer Aug 4 '17 at 19:11
• They also report the mean number of CDS disruptions per human specific pseudogenes was 0.480, but then used 0.451 in the subsequent calculation. As far as I can tell (which is not very far), this is also a typo. However, this is not my field and so it is more likely that I am wrong. – canadianer Aug 4 '17 at 19:15
• Does 1.17*10^−7 disruptions/gene/year mean roughly 1 disruption per gene over 8.547 million years? – Genetica44 Aug 5 '17 at 10:23
• I am having a bit of trouble understanding what 1 disruption/gene/8.547Ma would mean. Is a disruption defined as anything from a single base-pair mutation, to a whole codon or similar being replaced/lost in transcription? If so, then with around 400 shared pseudogenes, and 1 base pair mutation per gene, that sounds like a lot less then 0.1kb per year since every base pair is 2 bits. Sounds more like 800 bits per 8.5 million years, which is 0.1 kb – Genetica44 Aug 5 '17 at 11:10