evolutionary rate The amount of evolutionary change that occurs in a given unit of time. This is often difficult to determine, for several reasons: for example, should the unit of time be geological or biological (the number of generations)? How should morphological change in unrelated groups be compared? In practice it is necessary to adopt a pragmatic approach, such as the number of new genera per million years. See also darwin.

evolutionary rate The amount of evolutionary change that occurs in a given unit of time. This is often difficult to determine, for several reason: for example, should the unit of time be geological or biological (the number of generations)? How should morphological change in unrelated groups be compared? In practice it is necessary to adopt a pragmatic approach, such as the number of new genera per million years. See also DARWIN.

evolutionary rate Amount of evolutionary change that occurs in a given unit of time. This is often difficult to determine, for several reasons: e.g. should the unit of time be geological or biological (the number of generations)? How should morphological change in unrelated groups be compared? In practice it is necessary to adopt a pragmatic approach, such as the number of new genera per million years. See also DARWIN.

evolutionary rate Amount of evolutionary change that occurs in a given unit of time. This is often difficult to determine, for several reasons. For example, should the unit of time be geologic or biological (the number of generations)? How should morphological change in unrelated groups be compared? In practice it is necessary to adopt a pragmatic approach, such as the number of new genera per million years.