=COUNTIF(A2:A5,A2)+COUNTIF(A2:A5,A3) Counts the number of apples (the value in A2), and oranges (the value in A3) in cells A2 through A5. The result is 3. This formula uses COUNTIF twice to specify multiple criteria, one criteria per expression. You could also use the COUNTIFS function.
Punctuated equilibrium. Definition. noun. A theory that describes an evolutionary change happening rapidly and in brief geological events in between the long periods of stasis (or equilibrium). The theory is based on the stasis in fossil records, and when phenotypic evolution occurs, it is localized in rare, rapid events of branching speciation.
Punctuated equilibrium can be accommodated within the classical neo-Darwinian synthesis as an end-member of the spectrum of possible evolutionary events that lead to the appearance of new species. But it's not the only possible mode of speciation: it is one possible mode. There's no intrinsic reason that evolutionary change should occur only in small populations, and there's no evidence that populations that have undergone marked evolutionary change are any smaller than those that are stable.