Well, the thing is, you ASSUME that they further variation because that's what the current ToE says. All variation is ASSUMED to be the result of mutations. There is no evidence that that is so, it is merely assumed.
Not all nucleotide variation in a population is attributed to mutation under the modern evolutionary synthesis, but much variation is indeed the result of mutation. Remember this?
Here's a look at the mean values of nucleotide diversity of the various gull taxa (the closer these values are to 1, the greater the amount of nucleotide diversity):
Larus canus: .00380
L. argentatus: .00418 L. hyperboreus: .00383
L. schistisagus: .00300 L. glaucescens: .00329 L. glaucoides: .00500
Once again, this pattern reveals absolutely no trend towards decreased genetic diversity in daughter populations. But why do we think this diversity is the result of mutation after the origin of the species? Because:
1. This nucleotide diversity data comes from nuclear intron sequences, and there is no evidence that there has been significant gene flow among nuclear DNA genes in various Larus species (see Pons et al., 2014).
2. If this nucleotide diversity was the result of significant gene flow, then it would totally confuse any molecular phylogenetic construction of the Larus species. For if there has been significant gene flow among nuclear regions -- enough to account for this diversity -- then that gene flow would result in multiple shared polymorphisms among divergent Larus taxa. And, this in turn, would lead to weird, conflicting branching patterns in molecular phylogenies of these taxa -- which we don't observe. In other words, the best explanation for this nucleotide diversity is mutation.
First, archaeological and census evidence indicates that the Sardinian population (which goes back thousands of years) never grew beyond about 300,000 individuals until around 1728, when the population began to grow rapidly (see Calò et al., 2008).
Second, sequence analysis of Sardinian mitochondrial DNA also suggests that this population was initially a small “bottleneck” but has experienced growth over time (Di Rienzo and Wilson, 1991). This is further corroborated by research on allelic richness and heterozygosity, which can indicate population growth from an initial, smaller population (Cornuet and Luikart, 1996). So we have here multiple lines of independent evidence for a small founding population on Sardinia, which was followed by population growth.
There is, moreover, compelling genetic evidence from nuclear DNA polymorphisms, mitochondrial DNA sequences, and other markers that the Sardinian population has been isolated with no gene flow from outside the island (Di Rienzo et al., 1994).
Now, for the clincher. In a beautiful piece of genomics research, Caramelli and colleagues (2007) analyzed mtDNA D-loop sequences (which are basically the most variable regions of the human genome) from ancient Sardinians who lived between 3,430 and 2,700 years ago (the DNA was extracted from teeth using a highly rigorous laboratory approach). The diversity of these sequences was then compared to the mtDNA of present-day Sardinians.
The haplotype diversity (a way to measure genetic diversity, and a form of heterozygosity) of the ancient population was 0.83, compared to a haplotype diversity of .96 for modern Sardinians (the larger the number, the greater the diversity). Revealingly, too, was the discovery that the average number of indels (a form of mutation) between sequences from the ancient population was a low 1.43, whereas the mean value for indels between modern Sardinian sequences was 4.68. This neatly demonstrates, again, that the modern Sardinian population has increased in genetic diversity, despite being isolated. The study by Caramelli and colleagues also provides evidence for clear genetic continuity between the ancient population and the modern Sardinian population, indicating a lack of gene flow from the “outside” world.
In the late 1800s, the northern elephant seal population hit an all-time low, with numbers dipping below a mere 100 individuals. However, the northern elephant seal’s population size has recovered, and now has over 175,000 individuals.
This situation, then, allows an empirical test of the expectations of your argument. In an analysis of mtDNA sequences, Weber et al. (2000) sought to compare the genetic diversity of northern elephant seals prior to their bottleneck, during the bottleneck, and after the bottleneck when the population recovered.
Like other studies referenced in this response, the control region of the mitochondrial genome was used, given the highly variable nature of this genomic region. In other words, changes in nucleotide and haplotype diversity would show up most clearly in the D-loop region of mtDNA.
So what were the results (from Table 1 of Weber et al., 2000)?
Haplotype Diversity, Elephant Seal Population DNA from 1892: 0.00 Haplotype Diversity, Elephant Seal Population DNA from 1980: 0.53
Nucleotide Diversity, Elephant Seal Population DNA from 1892: 0.0000 Nucleotide Diversity, Elephant Seal Population DNA from 1980: 0.0086
What do these results tell us? Both haplotype diversity and nucleotide diversity of modern northern elephant seals are significantly higher than that of the elephant seal population from 1892, when the population hit an all-time low. And unlike heterozygosity, which is not necessarily the result of novel mutations, nucleotide diversity is the result of mutations introducing new DNA changes throughout the population. Furthermore, in recent history, the northern elephant seal population has not been subjected to gene flow from other species, so the only way these observations can be explained is through mutations.
Re: Desperate evolutionists desperately need proof
...before becoming a full time missionary...
Well, that figures.
I heard about these dark moths adapting for survival maybe twenty years ago.... or was it thrity years ago, before becoming a full time missionary...and that dementia of evolutionists is still being touted as a proof of evolution. Give us a scientific break.
Desperate evolutionists will twist anything. Chaleleons change colour via their oringial design, all sorts of animals are given the ability to blend into their environment, (Which came first the flounders eyes on only one side or their method of hiding in the sand at the bottom.... The Lord created them in one go, they did not evolve by shifting their eyes to one side, they didn;t evolve their colours, they were GIVEN.
Moths that get darker, are still moths.
One thing I've learned is that, in general, the more emotionally-laden a post is, the most vacuous it is in terms of intellectual content. You have a fervent outpouring of emotion in each post, but you don't take the time to step back and think. You're proselytizing here, instead of openly engaging in a discussion. You need to learn how to listen.
We have, on the one hand, independently converging lines of evidence for the theory of evolution. The moth example demonstrates how fit alleles can become fixed in a population; extended over multiple generations, this means that phenotypes can emerge which are radically different from the original, ancient parent population.
We know that this happens, because of the concordance of molecular phylogenetic evidence, paleontology, and more. We know from population genetics that new alleles can arise as a result of mutations, and that each allele has a degree of fitness; alleles with sufficient fitness get fixed in the population. And the process is repeated over time.
You need to calm down, and get to work and show me exactly where my thinking is wrong. But no, all you can do is preach, preach, preach -- like the missionary you are. That's fine for proponents of Western colonialism, but if you're going to talk about biology and science, then you need to adopt a communication framework that goes beyond preaching and missionizing.
Races are not different because of their color.
Race is a social construct, not a meaningful biological method of taxonomy and classification. Do you know what empirically confirmed this? Evolutionary genomics.