Bare Bones Biology 203 – Gary’s Question #3, Genetics

The process of evolution results in a change in the gene pool over time so that each species separately and the entire ecosystem, if it can respond to its environment, can stay alive. The ability to respond to the internal and external environment is the definition of being alive and of being a Life form, whether a cell, or an individual organism or a species or the entire Biosystem. That the Biosystem is a life form is not an opinion; it is a fact, or if you prefer, a definition.

140506-flowers-asc_8951SsIt’s also true that inheritable mutations are not altogether random, but we are not talking about mutations here, we are taling about evolution, and as I tried to explain previously in this series (Bare Bones Biology 201 – Genotypes, Phenotypes and Evolution), evolution works on the phenotype, not the primarily the genotype. The genotype is all the genes in one individual organism: the phenotype is the sum of the physical characteristics of an individual organism: Evolution is a change in the gene pool of a species (not an individual, that is impossible) over generations of time: the gene pool is all the genes in all the individuals of the species or of the ecosystem.

The process of natural selection, which is part of evolution, selects FOR survival and reproduction of phenotypes that function well in the environment. If and only if that genotype is heritable, then the entire gene pool may be change to favor one gene or, much more likely, a combination of genes, that are best suited to whatever environment is operating at any given time.

It makes no difference to evolution whether or not mutations occur, what those mutations may be and whether or not mutations are random. Evolution does not select genes; evolution selects phenotypes that function well within the Biosystem at any given time and place.

The function of the genes has primarily to do with the survival of the individual and of the species, and it is two-fold. First, the genes turn on and off during growth, development and survival in response to cues from the environment. These actions are studied by cell biologists, physiologists, developmental biologists. This level of activity is what you referred to as epigenetics – that is how genes know what is happening in and around your body so they can activate the appropriate responses. This is how we stay alive, day to day. It does not change the genes; in fact the basic function of the genes is to not change but to provide the information necessary for the organism to respond to environment, and the second function of the genes is to pass on all of that information to the next generation without changing the genes but reorganizing them, so that each individual has a slightly different phenotype. The variability of the phenotype is the connection between the genes and the process of evolution.

The most common kind of genomic variability is recombination of genes. Recombination ensures that every individual organism in a species is slightly different from every other organism in that species. Another way that variability is generated is by mutation.

140506-flowers-asc_8953SsGiven that every cell in the body has a full set of genes, and all these genes are copied billions of times, it is not surprising that mistakes (mutations) occasionally occur. It would be surprising if they did not. Some of the mutations can be passed on to the next generation. Therefore every organism does have a small percentage of mutations and every species carries a large number of mutations in its gene pool; should any of these ever become useful to the survival phenotype of the species – evolution will select for those mutations.

This whole story of nested processes is the language of Life, as it has been created. Unlike the languages of man the Language of Life is completely honest, and yet it is far, far more mysterious and empowering and glorious than the concept of personhood, which places God and his works subordinate to the narrow mind of man.

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This is not yet the end of the story. I’ll talk about punctuated equilibrium next week.

This is Bare Bones Biology a production of FactFictionFancy and KEOS radio 89.1, in Bryan, Texas.

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