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That is an important question. No informed scientist would assert that the process of change or speciation is not an important part of biology. But the process is not easy to observe, and if experience is any teacher, it is not occurring today at an observable rate. That this may not have been so in the past is attested to by many observations including the occurrence of nearly 600 species of the fruitfly Drosophila found in the Hawaiian Islands and nowhere else. As to the observation of new species forming today, Lynn Margulis has the following to say:
“In nearly thirty years of work, the Grants have recorded some extraordinary changes in population structures and morphology. They have documented strong responses on the population and on the species level to the obvious selection pressures of wet and dry. They recorded changes in beak size along with alterations in the ability of these oral tools to crack open seeds. The differences in beak sizes between two highly selected groups of finches have gone from no difference (0 percent) to 6 percent. New work on birds by Mayr and Diamond (20010 shows unequivocal correlation of bird species with the geographical isolation on Melanesian islands. Yet here’s the rub: Speciation, the details of the appearance of any given new species of bird, whether Ecuadorian or Melanesian, has not been documented. The differences in beak measurements between the six distinguishable species of ground-dwelling finches is about 15 percent. No changes of this magnitude, correlated with other traits that would produced a newly named species of the Galapagos finch, were seen by the Grants—or anyone else. The Darwinian paradigm is operating exactly as it should: Different traits (whether within species or among species) are varying in prevalence according to the demands of the environment. Obviously, the genes that would produce these traits are varying in like fashion. But there is no evidence whatsoever that this process is leading to speciation. Speciation, whether in the remote Galapagos, in the laboratory cages of drosophilosophers, or in the crowded sediments of the paleontologists, stil lhas never been directly traced. The closest science has come to observing and recording the actual speciation in animals is the work of Theodosius Dobzhansky in Drosophila paulistorium fruit flies. But even here, only reproductive isolation, not a new species, appeared. The reproductive isolation occurred where a fully fertile population living at moderate temperatures became two populations—one cold-dwelling and the other warm-dwelling.” (Lynn Margulis, Dorion Sagan, Acquiring Genomes: A Theory of the Origins of the Species, pg. 31-32 (Basic Books, 2003))
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