30 species known. Both believed that the mechanism responsible for the change paralleled breeder selection. Remember, Mendel 's work wasn't started. Progression of species occurred gradually over prolonged intervals of time - Phyletic Gradualism. Stephen Gould and Niles Eldridge recognized that the fossil record depicts the appearance of new groups suddenly in strata where there is no evidence of any imperfection in the geologic record.
Speciation occurs at the periphery of the population.
Rates of Evolution and Extinction Adaptive Radiation Rapid expanses in species number of species from some ancestral adaptive condition. Adaptive expresses the idea that new species are functionally related to new ways of life. May be preceded by adaptive breakthroughs. Read what the California Academy of Sciences BioForum had to say about the topic of Evolution in their Panel Discussion. Recently, the Kansas Board of Education voted to exclude Evolution from the state's science curriculum.