Mutations

There is indeed a heck of a lot of mutation. Every new human individual carries some in the order of magnitude of a hundred new mutations.You really need to begin with a few basics of evolutionary biology; and there are a number of web sites that can help with this. The talkorigins archive provides Introduction to Evolutionary Biology; it provides background for people who encounter the subject within the context of evolution/creationism disputes.Another really excellent set of pages is provided by University of California Museum of Paleontology. It is Understanding Evolution, an evolution website for teachers. Here you will find an introduction on the nature of science; an Evolution 101 course, then additional pages specifically on supporting evidence, relevance, misconceptions, history, and aids for teachers.With respect to your specific question, you should note that natural selection does not give rise to diversity; in fact it acts to reduce diversity by weeding out what is not viable. Diversity arises by the introduction of variety, and this occurs primarily by mutation.So in a sense, all evolution is based on mutation; since this is the underlying source of variety. The moderating effects of selection work upon that raw material to maintain viability in many diverging forms. Do check out the links I have suggested for more carefully presented information; they should help you with the data you need. The talkorigins site is less glossy; but it contains more technical details on the different kinds of mutation that exist, especially if you start exploring further within the archive.Cheers -- Sylas

All mutations in the germ line get passed to offspring; and no others. That is, mutations which occur in sperm, or eggs, or in cells from which sperm or eggs are produced, will be passed on. No others.In humans, roughly 1 to 6 new non-silent germ-line mutations in coding DNA per generation, based on numbers from Rates of Spontaneous Mutation by JW Drake et al, in Genetics 148:1667-1686, April 1998; as discussed at the talkorigins archive (along with a lot more info on mutations generally) in the FAQ Are Mutations Harmful?. This could be out of date, but it should be in the ballpark for a good crude estimate. That FAQ goes into rather more detail about the different kinds of mutation than either of the references I gave previously. Drake's paper is on-line, but highly technical. The numbers are estimates, and the figure of 1 to 6 non-silent mutations in coding DNA, used in the FAQ, is an inference from raw mutation rates and the proportion of coding DNA in the genome. I think.Pinning down mutation rates is an active area of on-going research. I'm impressed. I have never studied this formally, but I have picked up a fair bit over the years on my own behalf. I'll rapidly defer to any professionals present. I think that the level of the talkorigins archive varies widely, but the more technical material would be above the level you indicate; yet within the range of a keen student who is willing to go beyond what is covered in school classes. The Berkeley material seems fairly basic, but covers quite a broad range of ground.But of course you may be the better judge of how well it matches your needs.Cheers -- Sylas(Added in edit. To give you an idea of the level and the credibility of material, the Introduction to Evolutionary Biology which I cited above, and a number of other files in the talkorigins archive, are included by Professor Rob Gedron of the Biology Department at Indiana University of Pennsylvania as a useful supplement for his undergraduate students in BI 112 - Principles of Biology II. Prof. Gedron lists these with a range of other resources at his pages on Evolution on the Web for Biology Students. Looking more closely at the Berkeley site, there are additional links I have missed previously. It also can take you quite deep into the material.)[This message has been edited by Sylas aka cjhs, 02-13-2004]

The answer is in the numbers I gave previously, but I'll try to spell it out more clearly, with a few more numbers of interest.What is passed on to you from your parents is a mix of their genomes. You get something like 3 billion base pairs from each parent, and this makes up your own diploid genome of something like 6 billion base pairs.Something like 5% of the human genome is made up of genes coding for proteins. (Ref: Human genome project) A smaller fraction will still have sequence significance; but not directly coding proteins; they may bind to other proteins and have a regulatory function, for example. But most of the genome is apparently "junk".Something like 64 (Drake's figure; this may be a bit low) new mutations show up in the germ-line of each human generation. This means that your own genome is 50% from Mum, 50% from Dad, and 0.000001% due to new mutations arising between you and your parents. Of those new mutations, around about 3 will be in coding DNA (5% of 64). Since the genetic code is redundant, a change to a codon might not actually change the amino acid sequence in expressed proteins; although it will give scope for more change as mutations accumulate in your own descendents.Perhaps as few as one or two mutations between you and your parents will actually make a difference in the proteins produced in your body. However, your children will add a few more, and so on, and over time your descendents will represent a range of diverse changes. This is the raw material of evolution.All this is "random", which means it occurs without any particular correlation for your own needs. You might have more, or less than these numbers; and the effects of any changes to your proteins might be neutral, or less often detrimental, or less often still beneficial. Detriment or benefit is a measure of the overall consequence for your reproductive fitness in your present environment; and can result from whole cascades of subtle effects.A lot of evolution is simply due to genetic drift, which refers to the accumulation of change that is neutral for fitness.The whole issue is complicated by other kinds of mutation, in which whole subsequences of DNA are cut and pasted from one place to another, or chromosomal changes (as in mice on Madeira, discussed in another thread). These are rather less frequent. Most evolutionary change seems to be simple point substitutions, or small insertions or deletions; and so the number quoted previously of 1 to 6 non-silent changes in coding DNA gives you the ball park figure.This is the background showing up in every new individual. It does not mean deformities, nor does it imply sterility. It is the normal background rate of mutation. Sure, no worries. But as I tried to hint earlier, you won't simply be able to look up answers quickly. What you need to do is continue learning the basics, both at school and as you do extended study for your own interest from other sources. It is well worth the effort, and I'm impressed that you are proposing to tackle the subject in more detail. You will find it very rewarding. I often wish I had done more biology in my own studies.Cheers -- Sylas