Probability for a megafauna specimen to exhibit a gene not present in either parent

What is the rough probability for a megafauna specimen to exhibit a gene not present in either parent?

I'm looking, ideally, at the chance for one specific individual to be the first in a breeding population to have a given gene.

• So similar : biology.stackexchange.com/q/86138/38451 – Solar Mike Aug 14 '19 at 15:44
• Not similar at all. – iayork Aug 14 '19 at 15:46
• @Christos Similar to what iayork's answer has expressed, when do you think a mutation results in a new gene? If you had a protein with one function (e.g. kinase activity) that gradually evolved another function (e.g. trafficking), where is the cutoff between them? Which is the kinase gene and which is the trafficking gene? For this reason, your question is incomplete and cannot have a definite answer. – Jam Aug 14 '19 at 18:57
• well for scale every single human carries around ~100 mutation in is sequence. but this is going to depend a lot on the size of the genome. – John Aug 15 '19 at 18:40
• The rate of evolution (as a result of germline mutagenesis) depends on many environmental factors. Scally (2016) suggests that germline mutation rate is approximately $0.5 \times 10^{-9} \text{bp}^{−1} \text{year}^{−1}$ in humans. You may be able to calculate the probability from here. It may be different for other organisms. Moreover, evolution can also happen because of gene duplication (as David said) and horizontal gene transfer, transposition etc. So you may narrow your question down a bit. – WYSIWYG Aug 19 '19 at 8:42

1 Answer

You need to define “gene” for your question to make sense. In humans, each individual has roughly 100 novel mutations (that neither parent had) (Human mutation rate revealed). However, those are not necessarily “new genes”, since many occur in non-functional DNA, even those that occur in functional regions may not alter any function, and even those that alter function may not be part of a gene, depending on your personal definition.

• I wouldn't think the poster needs to define gene. It's evident that he's talking about new genes, not mutations that change existing ones. Most new genes appear to arise by duplication, and it's possible to compare species and identify differences e.g. in gene families like globins or blood group antigens. If someone has some figures for differences between rodents or primates and estimates of time of evolutionary divergence this would give a rate. To calculate a probability you would probably have to estimate the number of generations and the population of each. So this is not an answer. – David Aug 15 '19 at 22:37