Recent peer reviewed paper overturns Neo Darwinian mathematical model

  • Thread starter Thread starter crai7
  • Start date Start date
Status
Not open for further replies.
Wow! Mathematical Biology… could you give us the cliff notes version? Sounds interesting.
 
You fail to mention that they replaced it with a therom which includes the mutation rate, which works. I.hope you are not posting this in some attempt to show evolution is wrong. If so, it certainly fails to do so.
 
No, they replaced it with a theorem which shows it doesn’t work. Once they incorporated mutations into the model and used modern estimates as (name removed by moderator)ut into the model, it predicts declining fitness. Please read the paper again.
 
Last edited:
No. You are not understanding fitness in a biological sense. It changes which organisms adaptation is fitter not the overall population.

This theorum basically builds into what we know of natural selection the heightened likelihood of mutations. This was not as understood in Darwins era so this was not taken into consideration mathematifally until recently in it’s conclusions. The maths used (and I am a scientist not a mathematian - so don’t fully understand the application) simply changes the atatistical algorithm to include these likely mutant changes.

This paper very much acts as additional support to our current understanding of micro evolution. It is definitely not anti.
 
1.) Fitness is defined by Fisher as the Malthusian parameter; it works mathematically at the overall population level as a growth rate parameter and at the individual organism level as a potential to procreate. Basener and Sanford give a formula for the expected fitness of a specific individual organism - essentially mean population fitness, plus any increments due to the alleles a specific individual has. 2.) Basener and Sanford extend Fisher’s Fundamental Theorem to incorporate mutations. They used a distribution function to model the frequency of deleterious vs beneficial mutations. When they set the ratio as 1:1 (deletrious to beneficial), the result is the same as Fisher’s corollary. When they set it to 1,000:1 (which they point out is generous given an estimate of 1,000,000:1 in the literature), the numerical simulation shows declining fitness; because natural selection is unable to overcome the impact of deleterious mutations in the long run on overall population fitness. 3.) Most importantly, Observations accord with this. Fitness is declining across species in the range of 0.2% to 2% (see the original paper for the reference).
 
Last edited:
crai7 said:
because natural selection is unable to overcome the impact of deleterious mutations in the long run on overall population fitness
Click to expand...
Missing quite a few mutation types aren’t we!

You’ve only focused on deleterious. What of the more common mutations - in particular missense and nonsense. Keep reading. You have proven nothing.

I won’t go further because some people are so bent on “disproving” natural selection they will cherry pick studies that suit their argument. If you read the study in its entirety it is simply not what it is concluding.
 
Which article are you relying on ?

If you consider this theorem to be overturned, please explain in your own words why , and importantly, why you are deviating (pun intended) from the authors conclusions on their work.
 
Last edited:
1.) What other mutation ‘types’ are you referring to, and why does it matter?
2.) What do you mean “I’m only focused on deleterious.”? I mentioned beneficial and deleterious in my previous post. Of course these are collapsed into simplified verbal categories, and of course each mutation can differ in terms of the degree of impact on fitness.
3.) You say I’m “bent on disproving natural selection”. Where have I said I’m trying to disprove natural selection? It is part of the model we are discussing after all.
4.) I’ll quote two key passages from Basener and Sanford:

A.)
Apart from theoretical and mathematical reasons for doubting the biological validity
of Fisher’s central thesis (that fitness always increases), there is now also abundant
empirical evidence against his thesis. For example, ecological observations consistently
show that Fisher’s thesis is not true, and that as a general rule a natural
population’s fitness is static. Essentially all natural populations have substantial genetic
variance, yet most such populations do not show continuously increasing fitness. This
is due to very low fitness heritability, associated with high levels of environmental noise
(See Merila and Sheldon 2000; Kruuk et al. 2000, 2002). Furthermore, extinctions and
near extinctions happen all the time, which are clearly antithetical to Fisher’s thesis.
In addition, the genetic degeneration of certain organisms has been recorded within
historical time frames (Carter and Sanford 2012). Lastly, many population geneticists
have expressed grave concerns regarding possible conditions where human mutational
degeneration overwhelms the stabilizing effect of natural selection (See Lynch 2016).

B.) Studies across different species estimate that apart from selection, the decrease
_in fitness from mutations is 0.2–2% per generation, with human fitness decline estimated_
at 1% (See Lynch 2016; Lynch et al. 1999).

So what can we conclude? Within the confines of the authors numerical simulation we have declining fitness. Observations in nature show stasis as a general rule, but with some populations experiencing declining fitness and extinction in some cases. Neither the model nor observations support the notion of increasing fitness over the time periods studied.
 
Last edited:
crai7 said:
No, they replaced it with a theorem which shows it doesn’t work. Once they incorporated mutations into the model and used modern estimates as (name removed by moderator)ut into the model, it predicts declining fitness.
Click to expand...
To quote the paper:
Fisher did not include mutations in his model, but believed that mutations would provide a continual supply of variance resulting in perpetual increase in mean fitness, thus providing a foundation for neo-Darwinian theory. In this paper we re-examine Fisher’s Theorem, showing that because it disregards mutations, and because it is invalid beyond one instant in time, it has limited biological relevance. We build a differential equations model from Fisher’s first principles with mutations added, and prove a revised theorem showing the rate of change in mean fitness is equal to genetic variance plus a mutational effects term. We refer to our revised theorem as the fundamental theorem of natural selection with mutations.
Click to expand...
Or, in more brief terms: The model has a flaw, and they fixed that flaw, but they are not proposing a completely new one. It’s less about disproving a theory altogether and more about improving the math related to it. They even name their new model after his and just add “with mutations” to describe how they improved it.

You don’t even need to read most of the paper to get this point. It’s in the abstract!
 
crai7 said:
1.) What other mutation ‘types’ are you referring to, and why does it matter?
2.) What do you mean “I’m only focused on deleterious.”? I mentioned beneficial and deleterious in my previous post. Of course these are collapsed into simplified verbal categories, and of course each mutation can differ in terms of the degree of impact on fitness.
3.) You say I’m “bent on disproving natural selection”. Where have I said I’m trying to disprove natural selection? It is part of the model we are discussing after all.
Click to expand...
  1. There are numerous mutation types. Each are unique in their outcome of what amino acid chain they attract and subsequently the proteins they ultimately make. Your quote only focused on deleterious. You mention beneficial mutations in your text yes, but beneficial is not an actual category of mutations. Deleterious can still be beneficial. You are mixing up the terminology. If you continue reading the mathematical algorithm only focused on deleterious mutations. The nonsense and missense mutations are incredibly important when we look at the overall process (and the authors mention this). Asking ‘why does it matter?’ simply shows you don’t really understand protein synthesis (which ultimately drives about genetic change)
  2. See above.
  3. True you have not stated the words. But what exactly are you trying to debate? The mathematical application? Because yes it has been revised many times and probably will be many times over. Species change in their reproduction rates and mutagens can slow or increase in their frequency (ie. UV exposure has shown to increase frequency in human populations with high exposure). So these processes do get updated often. I get the impression you don’t have a keen interest in mathematical theories so am unsure what you feel this is disproving.
I’ve studied this paper before. It is simply revising the % of rise or decline in fitness on SOME species that fit the mutagen numbers. We have always known fitness can decline - this is changing the statistic slightly considering the math was originally worked out in the 1930’s.
 
Thank you very much for the article. I read it but to tell you the truth I felt a little like Penny from ‘The Big Bang Theory’ reading it and browsing through all the comments. I will leave the super smart stuff to the super smart people. Blessings.
 
What kind of environmental pressure would cause evolution/natural selection to morph a plant into a asparagus plant?
 
Thread drift coming:. That does seem to be the case if you need looks around at our society.
 
niceatheist said:
There’s no such thing
Click to expand...
de·volve

[dəˈvälv]

VERB

devolving (present participle)
  1. transfer or delegate (power) to a lower level, especially from central government to local or regional administration.
“measures to devolve power to the provinces”
  • (devolve on/upon/to)
(of duties or responsibility) pass to (a body or person at a lower level).

“his duties devolved on a comrade”
  • formal
(devolve into)

degenerate or be split into.

“the Empire devolved into separate warring states”
 
Last edited:
Status
Not open for further replies.
Back
Top