Michael wrote:Yes. Because if we start manipulating science for political purposes (not that it doesn't happen, but it would be much worse if we flat our approved of it), then what will be left of science? We have to separate our bias/desires from achieving a truthful understanding of the world.
This is true, but it is also true that scientific conventions -- nomenclature, for example -- do change as a function of time. IMO this is very different from falsifying data or falsifying an experimental result. The DNA profiles of P.r.r., P.f.f and P.f.s should be similar/different by a measurable amount, and that result -- the data-- should not change even if we label them differently. Taxonomy is a tool of science, it is not the science itself.
If the P. r. robustus Cape Parrot can be considered to be a different species from the P. r. fuscicollis based on some discrete differences (such as hue of plumage, weight, and beak size), then we have to entirely rethink the concept of a species.
The discrete difference is the DNA profile. I have found numerous references to degree of commonality in DNA in a group compared to degree of differentiation of those profiles in a different group as being used to reevaluate species classifications in animals other than the Cape Parrot. I cannot find a solid guideline as to how this discriminator is applied but IMO it is actually more quantifiable and less subjective than the interbreeding discriminator. It could not have been proposed at the time the interbreeding discriminator was proposed. I don't see anything inherently wrong with it. The idea is to have a way to quantify a unique group. The devil is of course in the details, but it should be possible to have a viable definition.
At this rate, we will soon be calling people of different races a different species too.
Well, now you are putting a very fine point on it. But I think the range in human DNA is very small, less than 1%. I can't find a number for the genetic difference between P.r and P.f but I would assume it was considerably greater than that for the argument to carry weight.
I have heard a suggestion that there is no such thing as a species, that every individual is their own species.
That's obviously going too far. I would think most scientists would agree that's going too far. You could just as well argue any individual has cells of several species, because mutations may occur... Sure every individual has unique DNA, but you CAN do commonality statistics and do something usefulo with that. Just because it is possible to define a meaningless discriminator using DNA does not mean that it is impossible to define a meaningful one.
You cannot violate the taxonomic principles by changing the definition of a species but then still labeling it a species.
As far as I can tell, there is no ironclad taxonomic "code". The driving principle is to rationally classify living things by grouping them according to their similarity. Utilizing genetic information to do that is IMO no violation of the principle -- creatures do often get reclassified when new information surfaces. Really "species" was the only level that ever had a common observational definition suggested as a razor -- and it doesn't apply to plants, only animals. Maybe we have a better discriminator for uniqueness now -- that was truly the intent of the system in the first place, to organize and name things in accordance with their similarities and uniquenesses.
If they want to create a new organization system of categorizing living things where genetics (or something else) rather than reproductive viability defines a species, then they can do so without breaking the existing system.
I think "they" already have. The only thing that "breaks" the current system is strict adherence to the interbreeding criterion. I'm open to arguments that just because interbreeding is possible, if a population is sufficiently isolated to have developed a unique genetic signature, interbreeding would in fact never naturally occur and that unique population is sufficiently unique to be worthy of calling a different species. I've found references to several other proposed reclassification based on genetic diversity -- in elephants and in worms, specifically. It is not just a Cape Parrot issue.
How do you feel about poor old Pluto? Seriously, that's another thing we all learned in school was a FACT, and now that we know a bit more about the taxonomy of our solar system, we realize it is really more similar to a whole host of other things just like it, and less similar to the other planets. Because of where it is, it was the first thing "like it" that we discovered. But over time, that was insufficient to allow it to be considered unique. This seem very analogous to me. The science was never bent or broken, but the definitions were refined based on data, and a mistake that was made a long time ago was corrected, causing much trauma. But now that we are finding planets around other stars right and left, the definition of "planet" needed to be reevaluated and made clearer.
BTW I have a strong feeling that Scotty is a Grey Headed Cape Parrot while Truman is a Brown Necked.
It should be possible to figure that out, but I don't have his breeder info and he isn't banded or chipped. The seller keeps promising me to dig it out, but she seems sufficiently disorganized that I may never know. She says he came from EB Cravens, and EB confirms he sold her some chicks, so... I don't know if he has only Grey Heads or Brown Necks or both. Certainly from a distance Scotty's head and neck seem quite silvery but if you look very closely there is maroon blended into the feathers giving a brownish tinge.... I can take some closeups if you want.
