Scientists have discovered mountains play a bigger role in the diversity of fresh water fish species than previously thought.
A new study from the University of Otago has brought together 15 years of research looking at the relationship between mountain geology and the impact it has on fresh water fish species.
Scientists analysed the river catchments from six main tectonic zones and found when mountains lifted up it created more species of fish.
Co-author Professor Jon Waters said the study was the clearest link he had seen.
"One thing that really struck me about this work is how you can have one mountain range coming up but that one event geologically can isolate a whole lot of different bunches of species so it's like you have a whole lot of different types of animal and they can have their population sort of cut in half by these mountains coming up."
Prof Waters said New Zealand was the best place for such research because it was constantly moving and changing.