Similarly, the difference between the cytochrome c of a bacterium and yeast, wheat, moth, tuna, pigeon, and horse ranges from 64% to 69%.
Together with the work of Emile Zuckerkandl and Linus Pauling, the genetic equidistance result directly led to the formal postulation of the molecular clock hypothesis in the early 1960s.
Since fish diverges from the main stem of vertebrate evolution earlier than either birds or mammals, the cytochrome c of both mammals and birds should be equally different from the cytochrome c of fish.
Proboscideans from these localities comprise 11 families, 27 genera, and 53 species.First Appearance Datum (FAD) and Last Appearance Datum (LAD) for each species were plotted in 1-million-year intervals.Three periods of diversification were noted, the first in the Oligocene, the second in the early-middle Miocene, and the last in the Pliocene.Three ecomorphological categories based on dental functional morphology were identified in each of the three periods, suggesting that these are stable categories through time.The assumption that climate and environmental change are the driving forces behind evolution is prevalent in studies of adaptation and diversification.
However, there are other forces at work that may be equally responsible for evolutionary change, those involving biotic interaction and competition.
When calibrated with the few well-documented fossil branch points (such as no Primate fossils of modern aspect found before the K-T boundary), this led Sarich and Wilson to argue that the human-chimp divergence probably occurred only ~4-6 million years ago.
developed the neutral theory of molecular evolution, which predicted a molecular clock. mutations with no effect on fitness) in a new individual be .
In this paper, a summary of the African proboscidean record is presented as a means to examine overall trends in diversity and adaptation.
Specimens from 175 localities in East, Central, and Southern Africa were entered into a locality database.
Bill Sanders offered comments and additional information on species.