Freezing polar oceans—a great place for fish species formation

A study involving researchers at the ARC Centre of Excellence for Coral Reef Studies (based at James Cook University) and the University of Michigan—including ARC Discovery Early Career Researcher Award (DECRA) recipient, Dr Peter Cowman—has analysed the evolutionary relationships between fish species and found that the fastest rates of species formation have occurred at the highest latitudes and in the coldest ocean waters.

The researchers examined the relationship between latitude, species richness and the rate of new species formation among marine fishes by assembling a time-calibrated ‘evolutionary tree’ of all 31,526 ray-finned fish species, then focused their analysis on marine species worldwide.

They found that the fastest rates of new species formation occurred in Antarctic icefish and their relatives. Other temperate and polar groups with exceptionally high speciation rates include snailfish, eelpouts and rockfish.

The results are surprising considering the adaptions fish like the icefish require to live in the coldest Antarctic waters, and challenge the widely-held idea that the tropics serve as an evolutionary cradle for marine fish diversity.

	Over the past several million years, cool-water and polar ocean fishes formed new species twice as fast as the average species of tropical fish.

 

Image: Icefish uk. Credit: Wikipedia commons.