Does Evolution occur because of changes to allele frequencies in populations?

 

 Claim: Evolution occurs because changes to allele frequencies in populations results in phenotypic changes. Accruing phenotypic changes result in new genotypes (a distinguishable variety of a species). Accruing genotypic changes ultimately result in the arival of a fundamentally different kind of organism.

Example: Changing allele frequencies in a species will result in new phenotypes (varieties with a differing trait). Accruing phenotypic changes (existing traits) will ultimately result in a fundamentally different type of organisms (genus or family) - i.e. fish evolving into land-dwelling creatures that are not fish.

Response:

1. Changes to allele frequency causes variation in how many copies of existing genes are present in a population. Changing how frequently existing information is present in a population does not introduce the new information evolution would require. The arival of new traits, new features, and ultimately a fundamentally different type of organism, cannot be explained by including or excluding existing information. Example: It would not be possible to produce the instructions for the assembly of a motorcycle by including or excluding the various instructions for the assembly of a bicycle.
2. Changing allele frequencies in populations creates increased heterozygosity (commonality in a population) of some alleles while reducing heterozygosity of others over time. ^1 , 3  Instead of introducing new features, it causes existing traits to become lost or increasingly common, which is not a mechanism for evolutionary change, since no new information is created.
3. Changing allele frequency continuously results in certain genes becoming recessive and no longer expressed in a given population, which constitutes a loss of information. ¹  This is the opposite of evolution, since evolution would require a continuous input of new genetic information, for which there is no biological mechanism - i.e. mutation does not generate new genetic information.
4. Changes to allele frequency is a mechanisms for genomic entropy by causing a loss of heterozygosity for healthy alleles, while making mutated alleles to become common in large populations, thereby causing disease-promoting genes to become increasingly common in that population. There is no mechanism for evolutionary change in genomic entropy

Definition of Allele Frequency

L. Silver, in Encyclopedia of Genetics, 2001: "Allele frequency (also called gene frequency) is the term used to describe the fraction of gene copies that are of a particular allele in a defined population. Let us consider, for example, a population of 100 diploid individuals. Each individual carries two copies of each gene, so there are a total of 200 gene copies in the population of 100 people. Now let us say that 20 individuals in this population are heterozygous for allele A (with a second allele of some other type), and 5 individuals are homozygous for allele A. Each homozygote would contribute two copies of the allele toward the total fraction, while each heterozygote would only contribute one copy toward the total fraction. So the total number of A alleles in the population would be 20 + 10, for a total of 30. The allele frequency would be this number divided by the total number of gene copies (30/200) to yield 0.15, which is the allele frequency. Allele frequencies can always be determined in this way when the numbers of homozygotes and heterozygotes in a population are known. When heterozygotes cannot be distinguished because an allele expresses a recessive trait, it is still possible to use Hardy-Weinberg statistics (see Population Genetics) to estimate the allele frequency if certain assumptions about breeding practices are made."

Sources

1. "Suppose that a particular allele shifts frequency at random for a number of generations, eventually becoming very rare, with perhaps only one copy in the population. If the individual carrying this allele does not pass it on to any offspring or fails to have any offspring, the allele will be lost to the population. Once lost, the allele is gone from the population forever. In this light, drift causes the loss of genetic variation over time. All populations are subject to this process, with smaller populations more strongly affected than larger ones." - Biology Reference, Population Genetics


2. "It is widely understood that a mutational allele arises as a single copy - which is, therefore, on the verge of its own extinction. When a new mutation enters a population, its frequency is just one copy in a population of 2n (with n being the population's size). Therefore, most mutational alleles are rapidly lost due to genetic drift within just a few generations (Rupe and Sanford 2013)." - ADAM AND EVE, DESIGNED DIVERSITY, AND ALLELE FREQUENCIES, Sanford, J., R. Carter, W. Brewer, J. Baumgardner, B. Potter, and J. Potter. 2018. Adam and Eve, designed diversity, and allele frequencies. In Proceedings of the Eighth International Conference on Creationism, ed. J.H. Whitmore, pp. 200-216. Pittsburgh, Pennsylvania: Creation Science Fellowship


3. "Over a long period of time, this selective pressure will change the frequency of appearance of certain gene forms, and the traits they control will become commoner or rarer in the population." - Hardy-Weinberg law, Encyclopaedia Britanica


4. "Over two-thirds of hereditary hearing loss cases are diagnosed as nonsyndromic hearing loss (NSHL), in which the hearing loss phenotype is the only feature observed without additional symptoms. Since 2015, application of NGS technology to discovering novel genetic causes of NSHL enabled identification of 16 additional genes, whose variants have been linked to NSHL development, and currently, approximately a hundred genes are implicated in the disease. However, genetic heterogeneity and phenotypic variability of NSHL makes precise interpretation of variants identified by NGS a challenge. Furthermore, it is technically difficult to examine the pathogenic impact of some gene variants associated with NSHL, such as those of MYO15A and CDH23, because of very large gene sizes and the absence of relevant functional tests in vitro." - Systematic evaluation of gene variants linked to hearing loss based on allele frequency threshold and filtering allele frequency


5. "We identified 36 significantly mutated genes, but these could only partly account for the quanta of LOH in the samples. Using our own and TCGA data we then evaluated five possible models to explain the selection for non-random accumulation of LOH in ovarian cancer genomes: 1. Classic two-hit hypothesis: high frequency biallelic genetic inactivation of tumour suppressor genes. 2. Epigenetic two-hit hypothesis: biallelic inactivation through methylation and LOH. 3. Multiple alternate-gene biallelic inactivation: low frequency gene disruption. 4. Haplo-insufficiency: Single copy gene disruption. 5. Modified two-hit hypothesis: reduction to homozygosity of low penetrance germline predisposition alleles." - Loss of heterozygosity: what is it good for? August 2015, BMC Medical Genomics (a part of Springer Nature)