[b said:
Quote[/b] ]but how does that prove speciation this is one group that is decendent from one single female. this gives no gentic diversity,
ok. The single female thing is to show that it was because of mutations. All the offspring of that female were the same species as the wild ones because the feamle was cought from the wild.
[b said:
Quote[/b] ] and where does it say that after they would not longer cross that they were still inter-fertile? i dont see that anywhere.
huh?
[b said:
Quote[/b] ] also what about the wild population it came from can it still breed with that, if so no speciation, since the wild populations still seem to be able to cross sucessfully
no it can't breed with the wild population! that's the whole point. When they tried to cross a lab population with the wild population, they produced INFERTILE MALES only.
who the hell cares if the wild populations are able to cross sucessfully?? that is completely irrelevant. Whole species don't evolve, populations do. The lab population became another species from the wild population.
ok... let me translate what it says.
Dobzhansky and Pavlovsky (1971) reported a speciation event that occurred in a laboratory culture of Drosophila paulistorum
[D and P. had one species become another in a laboratory. The one in the laboratory was a different species than the wild one]
sometime between 1958 and 1963. The culture was descended from a single inseminated female that was captured in the Llanos of Colombia.
[showing that speciation wasn't because of hybrids between different subspecies. The offspring all came from the same species and what made them different species were mutations]
In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan.
[when they started, the lab population was able to have fertile offspring with the wild population, showing they were indeed the same species]
From 1963 onward crosses with Orinocan strains produced only sterile males.
[after a while, when the laboratory population was crossed with the wild population, the offspring were only STERILE males, showing that even though they may have been the same species, they were changing]
Initially no assortative mating or behavioral isolation was seen between the Llanos strain and the Orinocan strains. Later on Dobzhansky produced assortative mating (Dobzhansky 1972).
[at first, the wild population and the lab population were able to interbreed just fine, except they didn't have fertile offspring (previous statement)... but then the lab population and the wild population did not want to mate]
so at first the lab population and the wild population were the same species. Then the lab and wild populations couldn't have fertile offspring but COULD mate. Then they could neither have fertile offspring nor could they mate.
And how do you know the lab population could mate within itself? because the experiment lasted years, the lab population only came from a single female, and if they couldn't interbreed within themselves they would have died.
understand now?