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Speciation only results in sub-species with less genetic variability than the original population had. Macro-evolution cannot happen with groups that continually sub-divide into groups with diminished potential for variation.
That process is the inverse of macro-evolution. It leads toward a genetic bottleneck.
The reproduction of individuals is the means by which genetic modifications are transmitted and spread in a population.
I was pointing out the fact that scientists do not stick with the biological definition in practice. It would be unreasonable to do so. There are many species that are capable of breeding with other species.
In the taxonomic system,a genus is a group of species that are structurally similar,even if they have not been seen to be related.
Phylogenetic research cannot show that there was ever reproductive relatedness between species.
We cannot know if there was common descent between species unless they have been seen to be reproductively compatible or if one group has been seen to emerge from another.
I said no because you did not describe macro-evolution. Your definition of genus was wrong anyway.
I know that it is not the process. I don't believe macro-evolution happened so I do not call it results either.
Speciation only results in sub-species with less genetic variability than the original population had. Macro-evolution cannot happen with groups that continually sub-divide into groups with diminished potential for variation.
That process is the inverse of macro-evolution. It leads toward a genetic bottleneck.
Evolution is explained with reference to changes of allele frequencies,but that is not the proper definition. Evolution refers to changes in physical form,not statistical changes of DNA.
I look at the supposed causes,as well as the supposed results. That is why I do not believe that macro-evolution happened. The supposed causes - natural selection and genetic mutation - cannot possibly lead to macro-evolution.
Macro-evolution cannot be shown to have happened,and it does not logically or biologically follow that populations will develop beyond the species level because of genetic isolation. It just does not happen that way.
It is wrong to extrapolate macro-evolution from the observed instances of speciation.
We can even do a sort of "genetic archeology" and find in species genes used by their ancestors that are not used today such as the genes for teeth in chickens or the GULO gene (which synthesizes vitamin C in most mammals) in humans and other hominids where it is non-functional.
The GULO gene is particularly interesting because hominids not only have a non-functional gene: it is non-functional for the same reason. There are a few other mammals that also have a non-functional GULO gene, but the reason for the lack of function is different.
One has to ask: what are the chances that structurally similar but non-related species would not only share a genetic defect, but the very same genetic defect, if they did not all inherit it from the same ancestor.
That raises some red flags for me, hard to imagine that selective pressure is going to allow a lot of divergence during the evolutionary process from chimpanzee/human common ancestry.
That raises some red flags for me, hard to imagine that selective pressure is going to allow a lot of divergence during the evolutionary process from chimpanzee/human common ancestry.
What these homology arguments never do is to take into consideration the inverse logic. If things in common are evidence for common ancestry then are differences a valid argument against?
Chromosome 8 in humans and chimpanzees diverge by about 2 million base pairs and over 2,000 genes according to these two maps. Perhaps there is an explanation I'm not aware of but if we are talking about direct comparisons of a single defunct gene perhaps the search should be expanded to include highly conserved genes involved in the development of the human brain from that of apes.
What, precisely, is a genetic bottleneck?
I think it is becoming clear to all that you are simply critiquing your own understanding of evolutionary theory, and that your own understanding of evolutionary theory is shallow if not outright wrong.
The reproduction of individuals is the means by which genetic modifications are spread to their descendants. But that doesn't make their descendants anything more than a variant group within the species. It doesn't account for change in the populations.
If you have in one generation 10 individuals born with a specific genetic change and each passes on that change to its descendants (and meanwhile 99% of the individuals are passing on their unchanged genes to their descendants) you get Mendelian balance, not an evolving population. You now have a population which is mostly in stasis (little to no physical change in form) with 10 different variants.
So reproduction alone does not account for evolution. You need a pattern of reproduction that allows one variant to become more common in the population. You need one of those individuals to have more descendants than others on a consistent (non-random) basis.
Good. Now, does speciation cause bottlenecks?
A variant group within a species is change in a population. Not change above the species level,but still change. Variance is change.
It depends upon the size of the population and the extent to which the descendants reproduce generation after generation. 10 individuals with variant genes can beget a hundred descendants,which in turn can beget a thousand. It isn't like there is a specific dividing line between a population in stasis and a population that is changing.
Whole populations exist as individuals that are reproduced and reproduce,so when variants become more common in a population it is ultimately due to reproduction.
Ah, but I did not speak of a variant group.
Variant individuals multiply through reproduction,and may become separated and reproductively isolated from the group they sprang from.The first instance of a variation necessarily occurs in an individual. How do we get from that to an identifiable variant group?
The "selective" process is secondary to reproduction,and it boils down to individual acts of reproduction.Note that two things have to happen.
1. The variation must be passed on to others in the population, but
2. it must be passed on preferentially to some and not others.
The pigmentation of hair is not enough to make a different species anyway.If it passed randomly through a population, there would be many individuals with that trait, but no variant group. (This is more or less the case with red hair--there is no one group of humans identified by red hair; but many groups of humans include some individuals with red hair.)
Evolution is not always about a population changing on the whole,it is often about one population branching and diverging from another. So if a large variant group of South American fruit flies is discovered in a different region from the group it sprang from,what is to prevent scientists from giving it a new species name?When I said "the other 99%" I implied that these 10 were one percent of the population. That means there are 990 others. Yes, these ten can beget a hundred descendants and those in turn a thousand. But the 990 can beget 9900 descendants and those in turn 99000. And what this means is that the variant genes now inherited by 1000 descendants are right where they were two generations back: at one percent in a population of 100,000.
This is not changing the population; this is not evolution.
The PROPORTION of variants increases as the numbers of the original group decreases through natural elimination (i.e. natural selection). But evolution is not always about an increase in proportion of variants or allele frequency. Evolution often refers to the BRANCHING of new species from prior ones,not to the transformation of species. The new variant group does not have to become the majority in the group it originated from to be called a new species. It can just be branched from the original group.But as you see above, (and as Mendel discovered) reproduction alone does not make variants more common. So how do they become more common?
You did. See post 322.
Variant individuals multiply through reproduction,and may become separated and reproductively isolated from the group they sprang from.
The "selective" process is secondary to reproduction,and it boils down to individual acts of reproduction.
The pigmentation of hair is not enough to make a different species anyway.
Evolution is not always about a population changing on the whole,it is often about one population branching and diverging from another. So if a large variant group of South American fruit flies is discovered in a different region from the group it sprang from,what is to prevent scientists from giving it a new species name?
The PROPORTION of variants increases as the numbers of the original group decreases through natural elimination (i.e. natural selection).
But evolution is not always about an increase in proportion of variants or allele frequency. Evolution often refers to the BRANCHING of new species from prior ones,not to the transformation of species. The new variant group does not have to become the majority in the group it originated from to be called a new species. It can just be branched from the original group.
Reproduction may not be the only reason why variants become more common,but reproduction is the reason they emerge from prior species in the first place,and why they increase in numbers.
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