The landscape of New Zealand is spectacular in its expression of the active tectonic processes that occur along the Pacific-Australian plate boundary. However, it is difficult to determine the geological history of development of the onshore topography because previous configurations in the evolution of that topography have been eroded.

Some of the native fauna carry a biological memory of the topographic environments in which they evolved, in their genetic makeup (DNA). Native freshwater fish are the most useful for this type of study. In particular, the genus Galaxias has numerous freshwater-limited species and populations that have been isolated by changes in the river drainage pattern.

The South Island vividly displays the resultant biological diversity and co-evolution of topography and fish. The genetic variations of the fish can be used to document the nature and timing of river capture events and mountain range growth, especially since the Plio-Pleistocene but with some extensions into the Miocene. Hence, these biological tools provide some new insights into the development of the onshore landscape since the submergence or near- submergence of the NZ landmass in the Oligocene. The biological memory approach to understanding topographic evolution could be extended to all endemic NZ fauna and flora for which suitable distribution and genetic data are available.