This effectively means that populations of organisms must have reached a certain measurable level of difference to be recognised as subspecies. Dean Amadon proposed in 1949 that subspecies would be defined according to the seventy-five percent rule which means that 75% of a population must lie outside 99% of the range of other populations for a given defining morphological character or a set of characters. The seventy-five percent rule still has defenders but other scholars argue that it should be replaced with ninety or ninety-five percent rule. COUNT 5
QSN1 What must organisms have a measurable level of to be seen as a subspecies? ANS1 difference QSN2 Who proposed subspecies be defined by the seventy-five percent rule? ANS2 Dean Amadon QSN3 What year did Dean Amadon make his proposal? ANS3 1949 QSN4 The 75% rule states how much of a population must lie outside the range of other populations for a defining set of characters? ANS4 99% QSN5 Many scholars argue what should be replaced with a ninety or ninety-five percent rule? ANS5 The seventy-five percent rule