zerinus wrote:Wrong as usual. This is a classic example of "natural selection," which does not translate into "evolution" (as explained in by blog). The very image supplied belies the claim. The caption under the image says: "A mating pair of peppered moths." If the two different kinds of moths are mating, that means that they still belong to the same species. The actual species has not changed. No "evolution" has taken place.
Your response indicates that you believe natural selection and evolution are different processes. That is simply not the case. Here are fairly standard definitions for the two terms, which you apparently do not yet fully understand.
Evolution is the process that results in new species.
Natural selection is the mechanism by which evolution occurs.
You will find that the terms for the process and the mechanism are often used synonymously. When you try to claim that natural selection and evolution are distinct terms, one having no relationship to the other, you just look silly.
Let's look at the part of the process represented by the moth example. As described upthread, ecological speciation is primed, or initiated, by epigenetic (gene expression) effects in response to changes in the environment. These can lead to physical changes in the genome of a population over time and thus eventually become heritable. If you read the article on the pepper moth, you would know that, in this case, the difference in color was caused by a genetic mutation. So the expressed portions of the genomes of the black moth population are already different than those of the oreo milkshake colored moth population.
When a sufficient number of non-lethal mutations occur in one population as compared to another, that mutation-carrying population will eventually comprise a new sub-species (perhaps having a different appearance, different breeding behaviors, fewer predators, different ecological niches, etc.) The accumulation of mutations different from those in the original population is normally associated with adaptation to a new or different environment.
zerinus wrote:A black cat and a white cat is still a cat.
Are white polar bears and brown bears different species? What about white polar bears and black and white (or red) panda bears? According to your stated understanding, they are all bears, so they would not be different species.
Here are the facts. While they both are in the order Ursidae, polar bears and panda bears are completely separate species and not genetically related. Panda bears are genetically related most closely to raccoons (panda bears and raccoons have a common ancestor).
Except for a few hybrids found in specific parts of Alaska, polar bears are a separate species of animal and are not genetically related to brown bears.
So, the animals you call bears are comprised of at least three distinct species. In fact, last time I checked, there were at least 8 genetically distinct species of bears here on Earth. In terms of cats, domestic cats (Felis catus) are a species separate from bobcats (Lynx rufus).
zerinus wrote:Now if a wolf came into town, and started eating the white cats, and left the black ones alone, so that the white cats became scarce, and the black ones became more common; and the black ones started to breed among themselves and produce more and more black cats; does that mean that the cats have "evolved" to become a different species? How ridiculous is that?
Think about what you have just learned regarding moths, bears, and cats. Think about their respective ecological niches and predators, then you tell me.
