That's an implication of the paper. If the mutation rate were so high that individual proteins were accumulating deleterious mutations faster than they could be purged by selection, then yes, that species will go extinct. I know of no such species, though. Measured mutation rates are quite tolerable.
What about the 99% of other species in the past that have gone extinct through the accumulation of mutations. How can we tell whether there are no current species going down the same path? Don’t we lose 1,000’s of species every year and some of these are because of harmful mutations? When you say the measured mutation rate is tolerable, isn’t this really saying that mutations have to be tolerated and therefore mutations are slightly harmful.
As Michael Lynch in his paper states that all complex life suffers from higher deleterious mutations and extinction rates because they experience reduced recombination rates which diminish the power of natural selection.
Multicellular species experience reduced population sizes, reduced recombination rates, and increased deleterious mutation rates, all of which diminish the efficiency of selection (13). It may be no coincidence that such species also have substantially higher extinction rates than do unicellular taxa (
47,
48).
The frailty of adaptive hypotheses for the origins of organismal complexity
Considering that most vertebrates have smaller populations, often separate into smaller populations to develop new species and had to have begun as smaller populations throughout the history of evolution it seems inevitable that many species have experienced the harmful effects of mutations and continue to do so. Perhaps it is that we just cannot see the harm at present just as natural selection cannot always see the slightly harmful mutations to eradicate them. As stated in the paper I posted earlier scientists are discovering harmful mutations that have been hidden in the genome.
Now that genetic sequencing and other technologies have made it easier to recognize mutations that occur in only a subset of cells, researchers are finding more and more harmful mutations hidden among unaffected cells.
Harmful mutations can fly under the radar
But that's something that isn't actually happening.
Then why do humans, for example, have so many diseases and disorders caused by mutations. As evolution is supposed to be a slow process we are not going to see the end results of deleterious mutations right away but rather the progression towards gradual fitness costs which seems to be what we are seeing with the increasing number of genetic disorders happening as time goes by. If this rate continues then the human genome is going to gradually become more and more dysfunctional.
Mutations aren't meant to be anything, as far as we can tell. They're inevitable errors. Most of them either do nothing or damage the organism, while some of them improve it. Those are simply facts.
Fair enough, but as you say most do nothing or damage the organism. Some say that even the mutations that do nothing are actually well tolerated slightly harmful mutations that appear to do nothing. It is these that can sit in the genome and gradually add up to a drag on fitness.
I know of only one class of mutations that are non-random (in the sense that evolutionary biology means), and I doubt those are mutations that you're thinking of.
As stated in the video I linked in the previous post some mutations are non-random and target specific sites in the DNA to make changes that allow creatures to adapt to their environments. This seems to relate to what I had posted earlier about developmental bias and facilitated variation where phenotypic change is facilitated through the environmental pressures on the cells and tissues of creatures. Complex biological systems can come about through regulatory genetic changes from the differential re-use of pre-existing developmental components.
Non-Random and Targeted Mutations
Species have an error correcting ability and are designed to be able to adapt to certain environmental stressors. It is not a random process, they are not accidentally stumbling into these serendipitous variations that are selected for. It’s the other way around, the stress of the environments is producing these variations in a non-random way.
Some work on developmental bias suggests that phenotypic variation can be channelled and directed towards functional types by the processes of development [27,28]. The rationale is that development relies on highly robust ‘core processes’, from microtubule formation and signal transduction pathways to organogenesis, which at the same time exhibit ‘exploratory behaviour’ [28], allowing them to stabilize and select certain states over others. Exploratory behaviour followed by somatic selection enables core processes to be responsive to changes in genetic and environmental input, while their robustness and conservation maintain their ability to generate functional (i.e. well integrated) outcomes in the face of perturbations. This phenomenon, known as facilitated variation [28,34], provides a mechanistic explanation for how small, genetic changes can sometimes elicit substantial, non-random, well-integrated and apparently adaptive innovations in the phenotype.
The extended evolutionary synthesis: its structure, assumptions and predictions
That's completely wrong. No recent research says that humans are accumulating slightly harmful mutations. Because our population size has soared in recent millennia, we are actually reducing the number of deleterious mutations that we carry.
Actually it is the fast-increasing population that is causing the increase in mutations and with this the increase in harmful mutations. The accumulation of mutations is more to do with the high rate of mutations in human and the speed in which they happen. This along with the lifestyle of modern humans and the improvements in technology to allow people to live longer is making it hard for natural selection to weed out these harmful mutations. Hence, we are seeing over 250 new genetic disorders happening every year and increasing.
The ironic thing is though if Darwinian evolution is the mechanism of Gods creation then the ability of humans to save other humans which by all measures would seem a Godly thing to do is what is causing the evolution of humans to fail and perhaps lead to humans becoming disease-ridden and eventually being threatened with extinction which would equate to causing Gods own creative process to fail. So the act of saving a person is the very act that is actually destroying Gods creation of humans.
That's wrong. As I suspected, it's from Sanford, who's a creationist who has some odd ideas about population genetics.
Sanford is also a plant geneticist and understands the topic well. All he is saying is that mutations are happening too often and too fast for natural selection to get rid of, so they are building up and humans are progressively becoming more laden with diseases. This is supported by a number of other papers which I have already posted. All he is saying is that our DNA must have more optimal in the past and is gradually degrading hense genetic entropy.
The deleterious mutations come and go, every generation. The beneficial mutations stick around (well, some of them anyway). This filtering process is highly effective.
I think the mutation level has been and still is a contentious issue and there is debate about what effects they are having and whether natural selection is sufficient enough to rid all mutations. It is not just a case of having this nice synchronized and finely balanced process where we get heaps of harmful mutations, but they are all overcome at the right time and place by natural selection and then a very few rare beneficial mutations step in to do their job.
The fact is harmful mutations are always entering the genome and cannot be weeded out before harm is done. They are not always spotted by selection regardless of population size. But even so many vertebrate populations are of small size and therefore can be affected. Regardless of what is said the proof is in the pudding in that we see more and more genetic harm as time goes by. Once again I will leave it up to Lynch who I quoted earlier in regards to complex life being more susceptible to the effects of harmful mutations. He describes the process of evolution as not just being natural selection but also 3 other non-adaptive forces which can overpower selection in smaller populations like vertebrates which includes all humans.
With regard to the above evolutionary forces, this means that mutations occur at random, independent of whether they help or harm, and recombination occurs at random, whether or not it produces helpful or harmful new combinations of genes.1 Similarly, genetic drift increases the likelihood that a potentially beneficial mutation will be lost before it becomes widespread in the population. This is particularly true for organisms with small effective population sizes, such as vertebrates. The net effect of genetic drift in such populations is “to encourage the fixation of mildly deleterious mutations and discourage the promotion of beneficial mutations,”, in the words of one evolutionary biologist.2 Only natural selection is adaptive, that is to say, working to ensure that beneficial changes are preserved in the population, and harmful changes are eliminated.
Thus, in organisms with small effective population size (e.g. all vertebrates, which includes us humans), the stochastic and non-adaptive forces of mutation, recombination, and drift will tend to drive evolution in non-adaptive directions.
The frailty of adaptive hypotheses for the origins of organismal complexity
