>_< please don't compare animal and plant genetics, they function so very differently it's not fair... and I'm not even going to go into the K9 thing because there are too many conflicting views and it will just start another fight on the subject (but you should know that most K9's are starting to be reclassified as being the same species w/ different subspecies).
...However, you are very correct that speciation can occur quickly. In plants more so than in animals. This is because as soon as a plant's chromosome number increases evenly by poliploidation (is that a word?) or by single chromosomes doubling up, it is instantly a new species. You can start with a hybrid, or you can have a single species just double up. However, the new species may not be very different from the parent plant/plants. Usually polyploidy are bigger, and that’s about it. However, the sudden level of redundant data means mutations that would normally be lethal are compensated for thus leaving the DNA open for more change. DNA mutation occurs at a steady rate, but the number of non-lethal mutations will greatly increase meaning natural selection has more material to work with. Eventually, you can get the extra genes so distorted they won't recognize the original cross’s chromosomes. This means you have a population that has completely separated from the parent plants and no new accidents are going to make a new member of this species because they can't interbreed. Does that make sence?
Now here is how you get slower speciation. Same thing is happening, but remember these plants are all still very similar looking. It take several "technically" new species to show up before you can compare the end product back to the original and say, those are different plants at a glance. The more diverse the range of appearances, the further away from each other the groups have gone. Eventually transitional species die out and what you have left are a bunch of different but related species. AKA, what I believe Tamlin was referring to was the processes of creating dramatically different species adapted to a range of habitats with highly unique genes in addition to common roots way way way back.
Evolution can be fast, but the evolution of one part of a population while another stays the same or takes a different root is very slow.
Long term species diversity
1. isolate
2. mutate
3. disturbances/competition
Evolution of a species (This is your Domestic Dog, their genetic sequence is relatively unaltered, it is only the alleles that have changed. K9’s happen to have an incredibly adaptive set of DNA which is why so many phenotypes have arisen both in domestic and wild types. AKA they don’t NEED to become a new species to adapt to new environments… same for small cats. Gene Example: 1 gene determines snout shape and length in dogs. It’s an on-off switch that is timer based. The sooner it is turned off, the shorter and blockier the snout, the longer is it left on the longer and skinner and pointier the snout. 1 gene, big difference! This is also our variants of plants, a white vs. pink flower, fat vs. thin leaves etc.)
1. mutate
2. disturbances/competition
I luv genetics, sorry if I got boring there.