What is the definition of “Natural Selection”?
$begingroup$
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
Natural selection, process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype, or genetic constitution.
Natural selection, then, can be defined as the differential reproduction of alternative hereditary variants, determined by the fact that some variants increase the likelihood that the organisms having them will survive and reproduce more successfully than will organisms carrying alternative variants.
Darwin's definition of natural selection his book "On The Origin Of Species By Means Of Natural Selection or the Preservation Of Favoured Races In The Struggle For Life" is:
The preservation of favorable variations and the rejection of injurious variations
In Evolution 101, natural selection is not defined, but rather the concept "evolution by natural section" is characterized as the outcome of variation, differential reproduction and Heredity, and an clarifying example is provided.
Clearly the wordings in all of the above are different!
I searched biology StackExchange for any explicit statement of the definition of natural selection, I couldn't manage to find one. There are some discussions about whether it is a tautology or not, but even in those discussions the definition of natural selection was not quoted.
I tried to search tags "natural selection" and "definitions" of biology StackExchange, and yet I didn't see any particular wording mentioned as the official definition of natural selection.
Actually the tag [natural selection] mentions this definition in the tag information itself:
Natural Selection is a mechanism of evolution that leads to non-random spread of genes due to the effect that genes have on reproductive success
Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly?
evolution terminology natural-selection definitions
asked 9 hours ago
Zuhair Al-JoharZuhair Al-Johar
1197
$endgroup$
|
show 1 more comment
$begingroup$
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
Natural selection, process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype, or genetic constitution.
Natural selection, then, can be defined as the differential reproduction of alternative hereditary variants, determined by the fact that some variants increase the likelihood that the organisms having them will survive and reproduce more successfully than will organisms carrying alternative variants.
Darwin's definition of natural selection his book "On The Origin Of Species By Means Of Natural Selection or the Preservation Of Favoured Races In The Struggle For Life" is:
The preservation of favorable variations and the rejection of injurious variations
In Evolution 101, natural selection is not defined, but rather the concept "evolution by natural section" is characterized as the outcome of variation, differential reproduction and Heredity, and an clarifying example is provided.
Clearly the wordings in all of the above are different!
I searched biology StackExchange for any explicit statement of the definition of natural selection, I couldn't manage to find one. There are some discussions about whether it is a tautology or not, but even in those discussions the definition of natural selection was not quoted.
I tried to search tags "natural selection" and "definitions" of biology StackExchange, and yet I didn't see any particular wording mentioned as the official definition of natural selection.
Actually the tag [natural selection] mentions this definition in the tag information itself:
Natural Selection is a mechanism of evolution that leads to non-random spread of genes due to the effect that genes have on reproductive success
Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly?
evolution terminology natural-selection definitions
asked 9 hours ago
Zuhair Al-JoharZuhair Al-Johar
1197
$endgroup$
7
$begingroup$
I think it's unrealistic to expect to find word-for-word congruence b/w definitions from multiple sources. All your definitions still describe the same phenomenon conceptually. From a broader viewpoint, no 2 textbooks (or at least few) define "simpler" biological concepts the same (e.g., even the word cell). The same can be said of common non-scientific words (e.g., see dictionary.com, OED, Merriam-Webster, etc. for any given word). In conclusion, there is no "official" wording for this definition or most definitions. This is why bio instruction emphasizes learning concepts not words...
$endgroup$
– theforestecologist♦
8 hours ago
$begingroup$
Then there's the definition which pops up when you hover your cursor over the tag "natural-selection" at the bottom of this question.
$endgroup$
– mgkrebbs
7 hours ago
$begingroup$
@mgkrebbs, oh yes, thanks, i didn't notice that really. I'll add it.
$endgroup$
– Zuhair Al-Johar
7 hours ago
1
$begingroup$
Of all the definitions, I think the SE tag one is possibly the worst. Maybe @Remi.b would take a stab at editing it, if you agree?
$endgroup$
– Bryan Krause♦
7 hours ago
$begingroup$
As to whether it's a tautology: it's a tautology that the most fecund phenotypes will have more offspring, but it's not a tautology that there are more fecund phenotypes, or that heredity occurs, or that what qualifies as fit varies slowly (in fact, it might not). Nor is it a tautology that this is where adaptation comes from (or even primarily where it does), or that drift isn't also an important mechanism (which it is). These are all issues where evidence is key.
$endgroup$
– J.G.
5 hours ago
|
show 1 more comment
$begingroup$
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
Natural selection, process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype, or genetic constitution.
Natural selection, then, can be defined as the differential reproduction of alternative hereditary variants, determined by the fact that some variants increase the likelihood that the organisms having them will survive and reproduce more successfully than will organisms carrying alternative variants.
Darwin's definition of natural selection his book "On The Origin Of Species By Means Of Natural Selection or the Preservation Of Favoured Races In The Struggle For Life" is:
The preservation of favorable variations and the rejection of injurious variations
In Evolution 101, natural selection is not defined, but rather the concept "evolution by natural section" is characterized as the outcome of variation, differential reproduction and Heredity, and an clarifying example is provided.
Clearly the wordings in all of the above are different!
I searched biology StackExchange for any explicit statement of the definition of natural selection, I couldn't manage to find one. There are some discussions about whether it is a tautology or not, but even in those discussions the definition of natural selection was not quoted.
I tried to search tags "natural selection" and "definitions" of biology StackExchange, and yet I didn't see any particular wording mentioned as the official definition of natural selection.
Actually the tag [natural selection] mentions this definition in the tag information itself:
Natural Selection is a mechanism of evolution that leads to non-random spread of genes due to the effect that genes have on reproductive success
Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly?
evolution terminology natural-selection definitions
asked 9 hours ago
Zuhair Al-JoharZuhair Al-Johar
1197
$endgroup$
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
Natural selection, process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype, or genetic constitution.
Natural selection, then, can be defined as the differential reproduction of alternative hereditary variants, determined by the fact that some variants increase the likelihood that the organisms having them will survive and reproduce more successfully than will organisms carrying alternative variants.
Darwin's definition of natural selection his book "On The Origin Of Species By Means Of Natural Selection or the Preservation Of Favoured Races In The Struggle For Life" is:
The preservation of favorable variations and the rejection of injurious variations
In Evolution 101, natural selection is not defined, but rather the concept "evolution by natural section" is characterized as the outcome of variation, differential reproduction and Heredity, and an clarifying example is provided.
Clearly the wordings in all of the above are different!
I searched biology StackExchange for any explicit statement of the definition of natural selection, I couldn't manage to find one. There are some discussions about whether it is a tautology or not, but even in those discussions the definition of natural selection was not quoted.
I tried to search tags "natural selection" and "definitions" of biology StackExchange, and yet I didn't see any particular wording mentioned as the official definition of natural selection.
Actually the tag [natural selection] mentions this definition in the tag information itself:
Natural Selection is a mechanism of evolution that leads to non-random spread of genes due to the effect that genes have on reproductive success
Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly?
evolution terminology natural-selection definitions
evolution terminology natural-selection definitions
asked 9 hours ago
Zuhair Al-JoharZuhair Al-Johar
1197
asked 9 hours ago
Zuhair Al-JoharZuhair Al-Johar
1197
edited 7 hours ago
Zuhair Al-Johar
asked 9 hours ago
Zuhair Al-JoharZuhair Al-Johar
1197
asked 9 hours ago
Zuhair Al-JoharZuhair Al-Johar
1197
asked 9 hours ago
Zuhair Al-JoharZuhair Al-Johar
1197
1197
7
$begingroup$
I think it's unrealistic to expect to find word-for-word congruence b/w definitions from multiple sources. All your definitions still describe the same phenomenon conceptually. From a broader viewpoint, no 2 textbooks (or at least few) define "simpler" biological concepts the same (e.g., even the word cell). The same can be said of common non-scientific words (e.g., see dictionary.com, OED, Merriam-Webster, etc. for any given word). In conclusion, there is no "official" wording for this definition or most definitions. This is why bio instruction emphasizes learning concepts not words...
$endgroup$
– theforestecologist♦
8 hours ago
$begingroup$
Then there's the definition which pops up when you hover your cursor over the tag "natural-selection" at the bottom of this question.
$endgroup$
– mgkrebbs
7 hours ago
$begingroup$
@mgkrebbs, oh yes, thanks, i didn't notice that really. I'll add it.
$endgroup$
– Zuhair Al-Johar
7 hours ago
1
$begingroup$
Of all the definitions, I think the SE tag one is possibly the worst. Maybe @Remi.b would take a stab at editing it, if you agree?
$endgroup$
– Bryan Krause♦
7 hours ago
$begingroup$
As to whether it's a tautology: it's a tautology that the most fecund phenotypes will have more offspring, but it's not a tautology that there are more fecund phenotypes, or that heredity occurs, or that what qualifies as fit varies slowly (in fact, it might not). Nor is it a tautology that this is where adaptation comes from (or even primarily where it does), or that drift isn't also an important mechanism (which it is). These are all issues where evidence is key.
$endgroup$
– J.G.
5 hours ago
|
show 1 more comment
7
$begingroup$
I think it's unrealistic to expect to find word-for-word congruence b/w definitions from multiple sources. All your definitions still describe the same phenomenon conceptually. From a broader viewpoint, no 2 textbooks (or at least few) define "simpler" biological concepts the same (e.g., even the word cell). The same can be said of common non-scientific words (e.g., see dictionary.com, OED, Merriam-Webster, etc. for any given word). In conclusion, there is no "official" wording for this definition or most definitions. This is why bio instruction emphasizes learning concepts not words...
$endgroup$
– theforestecologist♦
8 hours ago
$begingroup$
Then there's the definition which pops up when you hover your cursor over the tag "natural-selection" at the bottom of this question.
$endgroup$
– mgkrebbs
7 hours ago
$begingroup$
@mgkrebbs, oh yes, thanks, i didn't notice that really. I'll add it.
$endgroup$
– Zuhair Al-Johar
7 hours ago
1
$begingroup$
Of all the definitions, I think the SE tag one is possibly the worst. Maybe @Remi.b would take a stab at editing it, if you agree?
$endgroup$
– Bryan Krause♦
7 hours ago
$begingroup$
As to whether it's a tautology: it's a tautology that the most fecund phenotypes will have more offspring, but it's not a tautology that there are more fecund phenotypes, or that heredity occurs, or that what qualifies as fit varies slowly (in fact, it might not). Nor is it a tautology that this is where adaptation comes from (or even primarily where it does), or that drift isn't also an important mechanism (which it is). These are all issues where evidence is key.
$endgroup$
– J.G.
5 hours ago
7
7
$begingroup$
I think it's unrealistic to expect to find word-for-word congruence b/w definitions from multiple sources. All your definitions still describe the same phenomenon conceptually. From a broader viewpoint, no 2 textbooks (or at least few) define "simpler" biological concepts the same (e.g., even the word cell). The same can be said of common non-scientific words (e.g., see dictionary.com, OED, Merriam-Webster, etc. for any given word). In conclusion, there is no "official" wording for this definition or most definitions. This is why bio instruction emphasizes learning concepts not words...
$endgroup$
– theforestecologist♦
8 hours ago
$begingroup$
I think it's unrealistic to expect to find word-for-word congruence b/w definitions from multiple sources. All your definitions still describe the same phenomenon conceptually. From a broader viewpoint, no 2 textbooks (or at least few) define "simpler" biological concepts the same (e.g., even the word cell). The same can be said of common non-scientific words (e.g., see dictionary.com, OED, Merriam-Webster, etc. for any given word). In conclusion, there is no "official" wording for this definition or most definitions. This is why bio instruction emphasizes learning concepts not words...
$endgroup$
– theforestecologist♦
8 hours ago
$begingroup$
Then there's the definition which pops up when you hover your cursor over the tag "natural-selection" at the bottom of this question.
$endgroup$
– mgkrebbs
7 hours ago
$begingroup$
Then there's the definition which pops up when you hover your cursor over the tag "natural-selection" at the bottom of this question.
$endgroup$
– mgkrebbs
7 hours ago
$begingroup$
@mgkrebbs, oh yes, thanks, i didn't notice that really. I'll add it.
$endgroup$
– Zuhair Al-Johar
7 hours ago
$begingroup$
@mgkrebbs, oh yes, thanks, i didn't notice that really. I'll add it.
$endgroup$
– Zuhair Al-Johar
7 hours ago
1
1
$begingroup$
Of all the definitions, I think the SE tag one is possibly the worst. Maybe @Remi.b would take a stab at editing it, if you agree?
$endgroup$
– Bryan Krause♦
7 hours ago
$begingroup$
Of all the definitions, I think the SE tag one is possibly the worst. Maybe @Remi.b would take a stab at editing it, if you agree?
$endgroup$
– Bryan Krause♦
7 hours ago
$begingroup$
As to whether it's a tautology: it's a tautology that the most fecund phenotypes will have more offspring, but it's not a tautology that there are more fecund phenotypes, or that heredity occurs, or that what qualifies as fit varies slowly (in fact, it might not). Nor is it a tautology that this is where adaptation comes from (or even primarily where it does), or that drift isn't also an important mechanism (which it is). These are all issues where evidence is key.
$endgroup$
– J.G.
5 hours ago
$begingroup$
As to whether it's a tautology: it's a tautology that the most fecund phenotypes will have more offspring, but it's not a tautology that there are more fecund phenotypes, or that heredity occurs, or that what qualifies as fit varies slowly (in fact, it might not). Nor is it a tautology that this is where adaptation comes from (or even primarily where it does), or that drift isn't also an important mechanism (which it is). These are all issues where evidence is key.
$endgroup$
– J.G.
5 hours ago
|
show 1 more comment
2 Answers
2
active
oldest
votes
$begingroup$
Official definition
Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly?
I don't think there is such concept as an "official definition" of any concept in science. There are common ones though.
The three definitions you cite
Let's go through your three definitions
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
This is probably the most common definition.
Natural selection, process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype, or genetic constitution.
Part of the phrasing is about the consequence of the process rather than the process itself. The part that describes the process itself is "selectively reproducing changes in its genotype, or genetic constitution." which is a rather unusual phrasing and I would argue is slightly vague. I personally prefer the first one.
Note that while most authors refer to natural selection as the fitness differential, it is not impossible to refer to natural selection as the resulting change in allele frequency. I have never seen cases where this semantic difference matters though.
Natural selection, then, can be defined as the differential reproduction of alternative hereditary variants, determined by the fact that some variants increase the likelihood that the organisms having them will survive and reproduce more successfully than will organisms carrying alternative variants.
I have never encounter the expression "alternative hereditary variants". I think the author made it up. It sounds like the author tried to avoid the term "allele" by replacing it with "alternative hereditary variants". The author also seem to have tried to avoid the term "fitness" by replacing it with "likelihood that the organisms having them will survive and reproduce more successfully".
But overall the definition sounds correct to me. There is an important difference between the first and the third definition is that in the first definition, it emphasizes the fact that the genetic elements that explain fitness variance is doing so via its effect on the phenotype. The third definition just ignores the phenotype. As such, I would consider the first definition more complete (and more compact).
Natural Selection is a mechanism of evolution that leads to non-random spread of genes due to the effect that genes have on reproductive success
Here, the definition is again very much based on the consequence of the process rather than the process itself. Only "due to the effect that genes have on reproductive success" refers to the actual process of natural selection.
I don't really like the term "random" here as the concept of randomness is somewhat unpleasant to define outside of a well define model. I don't really like the term "genes" either because selection doesn't only act on genes (but can act at any locus) and because sounds like the term "allele" would be more appropriate even if the phrasing would still remain unclear.
So in short, shame on us, the StackExchange definition is pretty bad!
Mathematical modelling
You might want also to consider as a definition the mathematical modelling of the process. In absence of genetic drift (assuming infinite population size), assuming a bi-allelic locus with alleles a and A, one can model (haploid) selection as
$$p_{t+1} = frac{P_t W_a}{P_t W_a + (1-P_t) W_A}$$
, where $P_t$ is the frequency of the allele a at time $t$. $W_a$ and $W_A$ are the fitness of the genotype with alleles a and A, respectively. Of course, you can extend this model to any kind of ploidy and any number of alleles. You can also extend this model to include genetic drift (typically done via the use of diffusion equations or via branching patterns).
For more information about these mathematical modelling, please have a look at an intro book in evolutionary genetics (see here for book recommendation).
answered 8 hours ago
Remi.bRemi.b
58.8k8108195
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add a comment |
$begingroup$
I've adapted your definitions to another process that I think will be less controversial to you.
Eating is the intake of food by taking into the mouth, chewing, and swallowing.
Eating, the process that results in digestion by taking in food and chewing and then swallowing.
Eating, then, can be defined as the intake and digestion of food items, determined by the fact that organisms take in foods to the mouth and then chew and swallow them leading to digestion of those foods into nutrients used by that organism.
If you look up dictionary definitions of the verb "to eat" you will also get a variety of answers, but there is no controversy about what "eating" is: it's a concept you learn and agree on. Some of the definitions reach further, mentioning digestion. Some focus on the "just eating" part. However, they all agree with each other, there is no conflict. In fact, a lot of the words are just rearrangements of the same words into different grammatical constructs.
All of the definitions you cite are reasonable descriptions of the term; all of the sources you cite also go further into those definitions to describe the whole process. You should focus on that whole process rather than trying to find fault in the definition. Natural selection is not a tautology, and arguments that it is are misguided.
answered 8 hours ago
Bryan Krause♦Bryan Krause
19.3k23254
$endgroup$
$begingroup$
You've cited the same citation that I've cited. I'm not arguing that it is a tautology, I just wanted to know the definition, and all of your responses were great. Thanks
$endgroup$
– Zuhair Al-Johar
7 hours ago
add a comment |
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2 Answers
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2 Answers
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$begingroup$
Official definition
Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly?
I don't think there is such concept as an "official definition" of any concept in science. There are common ones though.
The three definitions you cite
Let's go through your three definitions
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
This is probably the most common definition.
Natural selection, process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype, or genetic constitution.
Part of the phrasing is about the consequence of the process rather than the process itself. The part that describes the process itself is "selectively reproducing changes in its genotype, or genetic constitution." which is a rather unusual phrasing and I would argue is slightly vague. I personally prefer the first one.
Note that while most authors refer to natural selection as the fitness differential, it is not impossible to refer to natural selection as the resulting change in allele frequency. I have never seen cases where this semantic difference matters though.
Natural selection, then, can be defined as the differential reproduction of alternative hereditary variants, determined by the fact that some variants increase the likelihood that the organisms having them will survive and reproduce more successfully than will organisms carrying alternative variants.
I have never encounter the expression "alternative hereditary variants". I think the author made it up. It sounds like the author tried to avoid the term "allele" by replacing it with "alternative hereditary variants". The author also seem to have tried to avoid the term "fitness" by replacing it with "likelihood that the organisms having them will survive and reproduce more successfully".
But overall the definition sounds correct to me. There is an important difference between the first and the third definition is that in the first definition, it emphasizes the fact that the genetic elements that explain fitness variance is doing so via its effect on the phenotype. The third definition just ignores the phenotype. As such, I would consider the first definition more complete (and more compact).
Natural Selection is a mechanism of evolution that leads to non-random spread of genes due to the effect that genes have on reproductive success
Here, the definition is again very much based on the consequence of the process rather than the process itself. Only "due to the effect that genes have on reproductive success" refers to the actual process of natural selection.
I don't really like the term "random" here as the concept of randomness is somewhat unpleasant to define outside of a well define model. I don't really like the term "genes" either because selection doesn't only act on genes (but can act at any locus) and because sounds like the term "allele" would be more appropriate even if the phrasing would still remain unclear.
So in short, shame on us, the StackExchange definition is pretty bad!
Mathematical modelling
You might want also to consider as a definition the mathematical modelling of the process. In absence of genetic drift (assuming infinite population size), assuming a bi-allelic locus with alleles a and A, one can model (haploid) selection as
$$p_{t+1} = frac{P_t W_a}{P_t W_a + (1-P_t) W_A}$$
, where $P_t$ is the frequency of the allele a at time $t$. $W_a$ and $W_A$ are the fitness of the genotype with alleles a and A, respectively. Of course, you can extend this model to any kind of ploidy and any number of alleles. You can also extend this model to include genetic drift (typically done via the use of diffusion equations or via branching patterns).
For more information about these mathematical modelling, please have a look at an intro book in evolutionary genetics (see here for book recommendation).
answered 8 hours ago
Remi.bRemi.b
58.8k8108195
$endgroup$
add a comment |
$begingroup$
Official definition
Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly?
I don't think there is such concept as an "official definition" of any concept in science. There are common ones though.
The three definitions you cite
Let's go through your three definitions
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
This is probably the most common definition.
Natural selection, process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype, or genetic constitution.
Part of the phrasing is about the consequence of the process rather than the process itself. The part that describes the process itself is "selectively reproducing changes in its genotype, or genetic constitution." which is a rather unusual phrasing and I would argue is slightly vague. I personally prefer the first one.
Note that while most authors refer to natural selection as the fitness differential, it is not impossible to refer to natural selection as the resulting change in allele frequency. I have never seen cases where this semantic difference matters though.
Natural selection, then, can be defined as the differential reproduction of alternative hereditary variants, determined by the fact that some variants increase the likelihood that the organisms having them will survive and reproduce more successfully than will organisms carrying alternative variants.
I have never encounter the expression "alternative hereditary variants". I think the author made it up. It sounds like the author tried to avoid the term "allele" by replacing it with "alternative hereditary variants". The author also seem to have tried to avoid the term "fitness" by replacing it with "likelihood that the organisms having them will survive and reproduce more successfully".
But overall the definition sounds correct to me. There is an important difference between the first and the third definition is that in the first definition, it emphasizes the fact that the genetic elements that explain fitness variance is doing so via its effect on the phenotype. The third definition just ignores the phenotype. As such, I would consider the first definition more complete (and more compact).
Natural Selection is a mechanism of evolution that leads to non-random spread of genes due to the effect that genes have on reproductive success
Here, the definition is again very much based on the consequence of the process rather than the process itself. Only "due to the effect that genes have on reproductive success" refers to the actual process of natural selection.
I don't really like the term "random" here as the concept of randomness is somewhat unpleasant to define outside of a well define model. I don't really like the term "genes" either because selection doesn't only act on genes (but can act at any locus) and because sounds like the term "allele" would be more appropriate even if the phrasing would still remain unclear.
So in short, shame on us, the StackExchange definition is pretty bad!
Mathematical modelling
You might want also to consider as a definition the mathematical modelling of the process. In absence of genetic drift (assuming infinite population size), assuming a bi-allelic locus with alleles a and A, one can model (haploid) selection as
$$p_{t+1} = frac{P_t W_a}{P_t W_a + (1-P_t) W_A}$$
, where $P_t$ is the frequency of the allele a at time $t$. $W_a$ and $W_A$ are the fitness of the genotype with alleles a and A, respectively. Of course, you can extend this model to any kind of ploidy and any number of alleles. You can also extend this model to include genetic drift (typically done via the use of diffusion equations or via branching patterns).
For more information about these mathematical modelling, please have a look at an intro book in evolutionary genetics (see here for book recommendation).
answered 8 hours ago
Remi.bRemi.b
58.8k8108195
$endgroup$
add a comment |
$begingroup$
Official definition
Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly?
I don't think there is such concept as an "official definition" of any concept in science. There are common ones though.
The three definitions you cite
Let's go through your three definitions
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
This is probably the most common definition.
Natural selection, process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype, or genetic constitution.
Part of the phrasing is about the consequence of the process rather than the process itself. The part that describes the process itself is "selectively reproducing changes in its genotype, or genetic constitution." which is a rather unusual phrasing and I would argue is slightly vague. I personally prefer the first one.
Note that while most authors refer to natural selection as the fitness differential, it is not impossible to refer to natural selection as the resulting change in allele frequency. I have never seen cases where this semantic difference matters though.
Natural selection, then, can be defined as the differential reproduction of alternative hereditary variants, determined by the fact that some variants increase the likelihood that the organisms having them will survive and reproduce more successfully than will organisms carrying alternative variants.
I have never encounter the expression "alternative hereditary variants". I think the author made it up. It sounds like the author tried to avoid the term "allele" by replacing it with "alternative hereditary variants". The author also seem to have tried to avoid the term "fitness" by replacing it with "likelihood that the organisms having them will survive and reproduce more successfully".
But overall the definition sounds correct to me. There is an important difference between the first and the third definition is that in the first definition, it emphasizes the fact that the genetic elements that explain fitness variance is doing so via its effect on the phenotype. The third definition just ignores the phenotype. As such, I would consider the first definition more complete (and more compact).
Natural Selection is a mechanism of evolution that leads to non-random spread of genes due to the effect that genes have on reproductive success
Here, the definition is again very much based on the consequence of the process rather than the process itself. Only "due to the effect that genes have on reproductive success" refers to the actual process of natural selection.
I don't really like the term "random" here as the concept of randomness is somewhat unpleasant to define outside of a well define model. I don't really like the term "genes" either because selection doesn't only act on genes (but can act at any locus) and because sounds like the term "allele" would be more appropriate even if the phrasing would still remain unclear.
So in short, shame on us, the StackExchange definition is pretty bad!
Mathematical modelling
You might want also to consider as a definition the mathematical modelling of the process. In absence of genetic drift (assuming infinite population size), assuming a bi-allelic locus with alleles a and A, one can model (haploid) selection as
$$p_{t+1} = frac{P_t W_a}{P_t W_a + (1-P_t) W_A}$$
, where $P_t$ is the frequency of the allele a at time $t$. $W_a$ and $W_A$ are the fitness of the genotype with alleles a and A, respectively. Of course, you can extend this model to any kind of ploidy and any number of alleles. You can also extend this model to include genetic drift (typically done via the use of diffusion equations or via branching patterns).
For more information about these mathematical modelling, please have a look at an intro book in evolutionary genetics (see here for book recommendation).
answered 8 hours ago
Remi.bRemi.b
58.8k8108195
$endgroup$
Official definition
Is there an official definition of natural selection that is adopted by biologists nowadays? and what is that definition exactly?
I don't think there is such concept as an "official definition" of any concept in science. There are common ones though.
The three definitions you cite
Let's go through your three definitions
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype.
This is probably the most common definition.
Natural selection, process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype, or genetic constitution.
Part of the phrasing is about the consequence of the process rather than the process itself. The part that describes the process itself is "selectively reproducing changes in its genotype, or genetic constitution." which is a rather unusual phrasing and I would argue is slightly vague. I personally prefer the first one.
Note that while most authors refer to natural selection as the fitness differential, it is not impossible to refer to natural selection as the resulting change in allele frequency. I have never seen cases where this semantic difference matters though.
Natural selection, then, can be defined as the differential reproduction of alternative hereditary variants, determined by the fact that some variants increase the likelihood that the organisms having them will survive and reproduce more successfully than will organisms carrying alternative variants.
I have never encounter the expression "alternative hereditary variants". I think the author made it up. It sounds like the author tried to avoid the term "allele" by replacing it with "alternative hereditary variants". The author also seem to have tried to avoid the term "fitness" by replacing it with "likelihood that the organisms having them will survive and reproduce more successfully".
But overall the definition sounds correct to me. There is an important difference between the first and the third definition is that in the first definition, it emphasizes the fact that the genetic elements that explain fitness variance is doing so via its effect on the phenotype. The third definition just ignores the phenotype. As such, I would consider the first definition more complete (and more compact).
Natural Selection is a mechanism of evolution that leads to non-random spread of genes due to the effect that genes have on reproductive success
Here, the definition is again very much based on the consequence of the process rather than the process itself. Only "due to the effect that genes have on reproductive success" refers to the actual process of natural selection.
I don't really like the term "random" here as the concept of randomness is somewhat unpleasant to define outside of a well define model. I don't really like the term "genes" either because selection doesn't only act on genes (but can act at any locus) and because sounds like the term "allele" would be more appropriate even if the phrasing would still remain unclear.
So in short, shame on us, the StackExchange definition is pretty bad!
Mathematical modelling
You might want also to consider as a definition the mathematical modelling of the process. In absence of genetic drift (assuming infinite population size), assuming a bi-allelic locus with alleles a and A, one can model (haploid) selection as
$$p_{t+1} = frac{P_t W_a}{P_t W_a + (1-P_t) W_A}$$
, where $P_t$ is the frequency of the allele a at time $t$. $W_a$ and $W_A$ are the fitness of the genotype with alleles a and A, respectively. Of course, you can extend this model to any kind of ploidy and any number of alleles. You can also extend this model to include genetic drift (typically done via the use of diffusion equations or via branching patterns).
For more information about these mathematical modelling, please have a look at an intro book in evolutionary genetics (see here for book recommendation).
answered 8 hours ago
Remi.bRemi.b
58.8k8108195
edited 40 mins ago
answered 8 hours ago
Remi.bRemi.b
58.8k8108195
answered 8 hours ago
Remi.bRemi.b
58.8k8108195
answered 8 hours ago
Remi.bRemi.b
58.8k8108195
58.8k8108195
add a comment |
add a comment |
$begingroup$
I've adapted your definitions to another process that I think will be less controversial to you.
Eating is the intake of food by taking into the mouth, chewing, and swallowing.
Eating, the process that results in digestion by taking in food and chewing and then swallowing.
Eating, then, can be defined as the intake and digestion of food items, determined by the fact that organisms take in foods to the mouth and then chew and swallow them leading to digestion of those foods into nutrients used by that organism.
If you look up dictionary definitions of the verb "to eat" you will also get a variety of answers, but there is no controversy about what "eating" is: it's a concept you learn and agree on. Some of the definitions reach further, mentioning digestion. Some focus on the "just eating" part. However, they all agree with each other, there is no conflict. In fact, a lot of the words are just rearrangements of the same words into different grammatical constructs.
All of the definitions you cite are reasonable descriptions of the term; all of the sources you cite also go further into those definitions to describe the whole process. You should focus on that whole process rather than trying to find fault in the definition. Natural selection is not a tautology, and arguments that it is are misguided.
answered 8 hours ago
Bryan Krause♦Bryan Krause
19.3k23254
$endgroup$
$begingroup$
You've cited the same citation that I've cited. I'm not arguing that it is a tautology, I just wanted to know the definition, and all of your responses were great. Thanks
$endgroup$
– Zuhair Al-Johar
7 hours ago
add a comment |
$begingroup$
I've adapted your definitions to another process that I think will be less controversial to you.
Eating is the intake of food by taking into the mouth, chewing, and swallowing.
Eating, the process that results in digestion by taking in food and chewing and then swallowing.
Eating, then, can be defined as the intake and digestion of food items, determined by the fact that organisms take in foods to the mouth and then chew and swallow them leading to digestion of those foods into nutrients used by that organism.
If you look up dictionary definitions of the verb "to eat" you will also get a variety of answers, but there is no controversy about what "eating" is: it's a concept you learn and agree on. Some of the definitions reach further, mentioning digestion. Some focus on the "just eating" part. However, they all agree with each other, there is no conflict. In fact, a lot of the words are just rearrangements of the same words into different grammatical constructs.
All of the definitions you cite are reasonable descriptions of the term; all of the sources you cite also go further into those definitions to describe the whole process. You should focus on that whole process rather than trying to find fault in the definition. Natural selection is not a tautology, and arguments that it is are misguided.
answered 8 hours ago
Bryan Krause♦Bryan Krause
19.3k23254
$endgroup$
$begingroup$
You've cited the same citation that I've cited. I'm not arguing that it is a tautology, I just wanted to know the definition, and all of your responses were great. Thanks
$endgroup$
– Zuhair Al-Johar
7 hours ago
add a comment |
$begingroup$
I've adapted your definitions to another process that I think will be less controversial to you.
Eating is the intake of food by taking into the mouth, chewing, and swallowing.
Eating, the process that results in digestion by taking in food and chewing and then swallowing.
Eating, then, can be defined as the intake and digestion of food items, determined by the fact that organisms take in foods to the mouth and then chew and swallow them leading to digestion of those foods into nutrients used by that organism.
If you look up dictionary definitions of the verb "to eat" you will also get a variety of answers, but there is no controversy about what "eating" is: it's a concept you learn and agree on. Some of the definitions reach further, mentioning digestion. Some focus on the "just eating" part. However, they all agree with each other, there is no conflict. In fact, a lot of the words are just rearrangements of the same words into different grammatical constructs.
All of the definitions you cite are reasonable descriptions of the term; all of the sources you cite also go further into those definitions to describe the whole process. You should focus on that whole process rather than trying to find fault in the definition. Natural selection is not a tautology, and arguments that it is are misguided.
answered 8 hours ago
Bryan Krause♦Bryan Krause
19.3k23254
$endgroup$
I've adapted your definitions to another process that I think will be less controversial to you.
Eating is the intake of food by taking into the mouth, chewing, and swallowing.
Eating, the process that results in digestion by taking in food and chewing and then swallowing.
Eating, then, can be defined as the intake and digestion of food items, determined by the fact that organisms take in foods to the mouth and then chew and swallow them leading to digestion of those foods into nutrients used by that organism.
If you look up dictionary definitions of the verb "to eat" you will also get a variety of answers, but there is no controversy about what "eating" is: it's a concept you learn and agree on. Some of the definitions reach further, mentioning digestion. Some focus on the "just eating" part. However, they all agree with each other, there is no conflict. In fact, a lot of the words are just rearrangements of the same words into different grammatical constructs.
All of the definitions you cite are reasonable descriptions of the term; all of the sources you cite also go further into those definitions to describe the whole process. You should focus on that whole process rather than trying to find fault in the definition. Natural selection is not a tautology, and arguments that it is are misguided.
answered 8 hours ago
Bryan Krause♦Bryan Krause
19.3k23254
edited 7 hours ago
answered 8 hours ago
Bryan Krause♦Bryan Krause
19.3k23254
answered 8 hours ago
Bryan Krause♦Bryan Krause
19.3k23254
answered 8 hours ago
Bryan Krause♦Bryan Krause
19.3k23254
19.3k23254
$begingroup$
You've cited the same citation that I've cited. I'm not arguing that it is a tautology, I just wanted to know the definition, and all of your responses were great. Thanks
$endgroup$
– Zuhair Al-Johar
7 hours ago
add a comment |
$begingroup$
You've cited the same citation that I've cited. I'm not arguing that it is a tautology, I just wanted to know the definition, and all of your responses were great. Thanks
$endgroup$
– Zuhair Al-Johar
7 hours ago
$begingroup$
You've cited the same citation that I've cited. I'm not arguing that it is a tautology, I just wanted to know the definition, and all of your responses were great. Thanks
$endgroup$
– Zuhair Al-Johar
7 hours ago
$begingroup$
You've cited the same citation that I've cited. I'm not arguing that it is a tautology, I just wanted to know the definition, and all of your responses were great. Thanks
$endgroup$
– Zuhair Al-Johar
7 hours ago
add a comment |
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$begingroup$
I think it's unrealistic to expect to find word-for-word congruence b/w definitions from multiple sources. All your definitions still describe the same phenomenon conceptually. From a broader viewpoint, no 2 textbooks (or at least few) define "simpler" biological concepts the same (e.g., even the word cell). The same can be said of common non-scientific words (e.g., see dictionary.com, OED, Merriam-Webster, etc. for any given word). In conclusion, there is no "official" wording for this definition or most definitions. This is why bio instruction emphasizes learning concepts not words...
$endgroup$
– theforestecologist♦
8 hours ago
$begingroup$
Then there's the definition which pops up when you hover your cursor over the tag "natural-selection" at the bottom of this question.
$endgroup$
– mgkrebbs
7 hours ago
$begingroup$
@mgkrebbs, oh yes, thanks, i didn't notice that really. I'll add it.
$endgroup$
– Zuhair Al-Johar
7 hours ago
1
$begingroup$
Of all the definitions, I think the SE tag one is possibly the worst. Maybe @Remi.b would take a stab at editing it, if you agree?
$endgroup$
– Bryan Krause♦
7 hours ago
$begingroup$
As to whether it's a tautology: it's a tautology that the most fecund phenotypes will have more offspring, but it's not a tautology that there are more fecund phenotypes, or that heredity occurs, or that what qualifies as fit varies slowly (in fact, it might not). Nor is it a tautology that this is where adaptation comes from (or even primarily where it does), or that drift isn't also an important mechanism (which it is). These are all issues where evidence is key.
$endgroup$
– J.G.
5 hours ago