Mutations would eventually lead to the extinction of a species

A note: I shall abbreviate my points C1, C2, C3, etc, and shall abbreviate Muted’s points P1, P2, P3, etc. Though not in this round for the latter. I would also note that I believe my opponent is describing Muller’s ratchet. C1: Many mutations are only ‘harmful’ or ‘beneficial’ in regards to the environment. For instance, a variation in the CCR5 receptor increases the risk of a nasty case of malaria, but decreases the risk of various other diseases—for instance, AIDS (in fact, a significant percentage of the Caucasian population is immune to AIDS as a result of the Black Death)[1]. If mutation X confers vulnerability to disease Y but resistance to disease Z, it will be selected against in areas with disease Y and without disease Z, selected for in areas with disease Z but not disease Y, and either selected for or selected against (depending on which disease is more predominant/severe/affected by the mutation) in areas with both disease Y and disease Z. Now, deliberately moving to a place with fewer harmful diseases might be evidence of planning and intelligence, but deliberately moving isn’t necessary. If a species has a large population and a large range, different phenotypes or genotypes may ‘migrate’ over generations to areas where they are more suited. C2. Relatively few mutations are deleterious. Nachman and Crowell estimated about three deleterious mutations out of one hundred seventy-five in each generation of humans[2]. C3: Labs have bred many, many generations of various species, ranging from bacteria to fruit flies. Many of these organisms have extremely short reproductive cycles. In the lack of conscious effort to prevent such populations from going extinct, we face the question of why they haven’t. If we can expect humans to go extinct within the next five thousand years due to mutations and natural selection, why do we not see fruit fly cultures regularly dropping dead because of mutations and natural selection? Why do we not see cricket cultures, or flour beetle cultures, or guppy populations, dropping dead? Now, one might argue that all these populations have one thing in common: They are captive, and humans interfere with their evolution. However, this objection misses two points. Firstly, humans are perfectly willing to interfere in their own evolution. If we are to going extinct, we are probably going to put up quite a fight—far more of a fight than we would put up to save a fruit fly culture. Secondly, there are wild populations of fruit flies, and flour beetles, and guppies, and crickets, and we do not see them going extinct for these reasons. A second objection would be that fast reproduction rates allow this to be avoided. I would like more detail on how this would work. C4: Not all of the genome is actually used—junk DNA is famous here. A mutation here would, indeed, be a mutation, but would be truly neutral, since the DNA is not ‘useful’. Various hypotheses have been put forth that would have ‘junk DNA’ be of some use, but since .1% of the mouse genome was deleted without apparent effect on the phenotype, we can safely say that enough is useless[3]. C5: Recombination. Sexual reproduction and horizontal gene transfer allows Muller’s ratchet to be avoided. For such a deletion mutation to be carried into the offspring, both parents would have to have the same deletion mutation. Otherwise recombination would deal with the problem[4]. Indeed, this has been demonstrated using experimental evidence. A population of ciliates decreased due to Muller’s ratchet. When they were allowed to have sex, the ratchet stopped[5]. 1. http://en.wikipedia.org... 2. http://www.talkorigins.org... 3. M.A. Nobrega, Y. Zhu, I. Plajzer-Frick, V. Afzal and E.M. Rubin (2004). "Megabase deletions of gene deserts result in viable mice". Nature 431 (7011): 988–993. Bibcode 2004Natur.431..988N. doi:10.1038/nature03022. PMID 15496924. 4. http://www.talkorigins.org... 5. http://www.talkorigins.org...