Post by Xion Praeten on Jul 9, 2015 22:45:09 GMT -5
Yes. Natural Selection can happen very quickly. There are mass extinction events which can happen within a very short amount of time. Say there is only a tiny subset of humans that have an immunity to a specific disease and the bacteria, virus or prion which causes the disease is highly virulent and spreads quickly to all others within the species. The humans with that, say, point mutation encoding a receptor on the cell or a glycoprotein to which the bacteria/virus/prion attaches, will be more successful in passing on their genes (which includes the allele which grants immunity) to the next generation of humans, and thus that group will be selected for. That said, it is likely that the only difference between the survivors and those dead is the point mutation causing the encoded protein produced to form at least parts of receptors or glycoprotiens, et cetera, on the micro level to not allow for the attachment and subsequent passage of the microbiotic interloper's (in the case of a retrovirus) RNA and Reverse Transcriptase complexed with other enzymes through the phospholipid bilayer of the survivors' cells. The survivors will probably still have two eyes, two arms, two legs, intelligence, etc. Though, as you brought up, sometimes a point mutation or even autosomal mutation would run in a specific community (see Tay-Sachs). You could have a collapse of nearly an entire species, yet the environment has selected for only a small subset.
