and that's another thing.
what demonstrated evidence is there that says a species "forks"?
I was referring to the inapplicability of "rat to dog" as far as the cladistic trees of phyla are concerned. Gene flow is sequential at the fork in speciation, not tip-to-tip across distant branches. The rest (rat to dog) sounds like Dr. Frankenstein's School of Animal Husbandry.
As for 'demonstratable' evidence, the simplest is the one you gave, the fruit fly.
i realize it's logical to assume it does but what if it's some kind of chrysalis phenomenon?
If you mean metamorphosis--in the context of creating a new phenotype, there's no parallel. The closest would be embryonic development, a primitive process related to metamorphosis, but it doesn't affect the genome.
Since the fruit fly is easily persuaded to mutate, it's the more convenient teaching aid.
darwins finches?
doesn't apply because they are all finches.
(They are not true finches.) Darwin's finches do not interbreed; they are each a new species. It was this issue that plagued Darwin: how could highly differentiated non-interbreeding groups descend from a common breeding pair? He compared this to the possible ways artificial selection was known to work, and inferred that nature was doing effectively the same thing, only per the Malthus model, survival of the fittest.
So, yes, Darwin's finches are the prime example of this. In this case the fork has 13 or 14 prongs.
the stated article alludes to the lack of data but i supposed lewin lied about that too.
This characterization is only valid in the proper context. If you oversimplify and generalize enough, then it becomes the creationist argument that the Theory of Evolution is flatly false. What's better is to try to understand the discussion in its proper context and to try to delve into the science a little. Consider first your aversion to the teaching of evolution as "accumulation of gradual changes". Take a timeline or the geologic eras, and, starting with cyanobacteria, find what the fossil record tells us about the approximate dates of first candidate ancestor of each of the major taxa. You will get something like this:
3.6 billion years of simple cells (prokaryotes),
3.4 billion years of cyanobacteria performing photosynthesis,
2 billion years of complex cells (eukaryotes),
1 billion years of multicellular life,
600 million years of simple animals,
555 million years of arthropods (ancestors of insects, arachnids and crustaceans),
550 million years of complex animals,
500 million years of fish and proto-amphibians,
475 million years of land plants,
400 million years of insects and seeds,
360 million years of amphibians,
300 million years of reptiles,
200 million years of mammals,
150 million years of birds,
130 million years of flowers,
66 million years since the dinosaurs died out,
20 million years since the appearance of the family Hominidae (great apes)
2.5 million years since the appearance of the genus Homo (human predecessors)
200,000 years since the appearance of anatomically modern humans,
25,000 years since the disappearance of Neanderthal traits from the fossil record.
13,000 years since the disappearance of Homo floresiensis from the fossil record.
This is a highly reduced way of evaluating the fossil record, common for the school books. Is there evidence of gradualism here? Is the data lacking? It's quite evident what has happened on Earth when viewing all of evolution at lowest magnification. The mere succession of forms over time is ample data for declaring macro scale gradualism. But if instead of avoiding the science you were to delve into it and ask yourself: when did the first vestiges of each of the major human body parts first appear? . . . you will find gradualism on an entirely different level. The eye begins with the cyanobacteria's photosynthetic cells. By the time of algae (cell colonies) the photo receptor becomes delegated to a cell or cell cluster - because by then cells have acquired the ability to specialize even though they carry the same DNA. They
diverge into two functional types belonging to one "body", and they do it by signalling. But signalling becomes the mode of fertilization when sexual reproduction appears. It also gives root to primitive nervous processes in Cnidaria (jellies). But then worms take that to a higher level by tying the nerves to a CPU, a very primitive brain called "ganglia", on primitive spinal cords. Worms also introduce a coelum (gut) and this stages the process for all higher forms, and is seen in homologue during early embryonic development in a process called gastrulation. Fish have first vertebra, and their air sacs (for controlling buoyancy) are filled through nares--precursors to nostrils-- while their fins are precursors to legs. Fish brains are advanced enough to support relatively high level instincts. (Have you seen the goldfish shooting hoops to get fed?) The amphibians bridge the world of water and dry land and begin as tadpoles. Reptiles have true lungs and better adapted eggs, birds have the first helpless young, and the tendency to pair bond, etc. etc. I'll stop here even though I've done it no service by this level of reduction.
But I hope you get my point. You can't read that article in a vacuum. You have to read it in the context of biology. And when that's in place, it has to be read in the context of genetics/genomics. The scattered distribution of specimens from the fossil record, and the discussions about how it complicates the explanation of micro- to macro evolution, are all moot in this level of analysis. All that's required is that it be taken in proper context and balanced against all of the evidence, not just the very specific interpretation you have in mind. Here we can see through the lens of gradualism merely by reviewing the wealth of "data" available from the fossil record at the macro level, and using those reference points in evolutionary development to mark the pages of our biology books--and then the picture is startlingly clear. We got here from the ancestors of the cyanobacteria. It's all a complete windfall of random events and the particularities of chemistry, geology and climate.
All of this--and a whole lot more--is going on in nature, so we have to present it in the classrooms. Just remember - it's not just the teaching of evolution, but of evolutionary biology. The difference is in the details.