Follow-Ups to Answer from Expert David Haas

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Mikael wrote at 2006-11-06 23:44:10
I may be able to add something to that...



The Talkorigins site has a list of observed cases of speciation at http://www.talkorigins.org/faqs/faq-speciation.html



Here's one of the more unambiguous of cases, a speciation event in fruit fly:

" 5.3.1 Drosophila paulistorum



Dobzhansky and Pavlovsky (1971) reported a speciation event that occurred in a laboratory culture of Drosophila paulistorum sometime between 1958 and 1963. The culture was descended from a single inseminated female that was captured in the Llanos of Colombia. In 1958 this strain produced fertile hybrids when crossed with conspecifics of different strains from Orinocan. From 1963 onward crosses with Orinocan strains produced only sterile males. 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)."



Also, there is the very interesting case of the salamader species Ensatina eschscholtzi, which is a ring species - it essentially is a live documentation of a speciation event. Ring species are species that change along a a ring-shaped range they inhabit, so that the populations of the species going along the ring change gradually, untill, when the ring ends meet, the "end" populations that meet are so different from each other that little or no mating occurs.



Ring species are great, because they allow us to whitness evolution without having to spend thousands of years observing - the intermediate populations being still alive.



There's a site on the above mentioned species at http://www.santarosa.edu/lifesciences2/ensatina2.htm



In Ensatina eschscholtzi, it appears that the ends are so far differentiated, that, quoting from the site mentioned above: "...In fact, by analyzing electrophoretic separations of selected enzymes and studying DNA patterns, the two subspecies klauberi and eschscholtzi are different species by every definition."  

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