An intervening variable facilitates a better understanding of the relationship between the independent and dependent variables when the variables appear to not have a definite connection. They are studied by means of operational definitions and have no existence apart.
Difference between Microevolution and Macroevolution. â¢ Micro evolution refers to visible changes in a population of the same species over a period of time. â¢ Macroevolution is what evolution is as described by the theory of evolution by Darwin.
This is why many authors use the term macroevolution to mean large-scale evolution. However, just like anagenetic speciation, large-scale is an arbitrary and often subjective term, and the objective meaning of macroevolution is evolution at or above the level of species [note 2].