What is it about?
We used genome sequencing methods to trace the family tree of 175 sperm whales from around the world. We found unique branches of the tree in the Atlantic and Pacific oceans, showing isolation of these populations over tens of thousands of years. We also learned that sperm whales were probably excluded from the North Atlantic Ocean during the ice ages, and were able to re-colonize it from a smaller population in the Pacific Ocean starting about 100,000 years ago.
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Why is it important?
The sperm whale is an endangered large whale species that was heavily exploited by commercial whaling during the 19th and 20th century. As highly mobile, deep-diving predators, sperm whales are usually found far from land and are difficult to study and count. Our genetic studies demonstrate that there are multiple populations of sperm whales, some of which have been isolated for a long time, and should be managed separately to ensure appropriate protection and recovery.
Perspectives
It was surprising to me to think that a large, mobile, deep-water predator like the sperm whale could have been excluded from an entire ocean basin, but past climate change has caused more extreme changes in the smaller Atlantic Ocean than in the Pacific, and could have drastically changed the abundance and availability of sperm whale prey species. This suggests that future climate change could also have drastic and unpredictable effects on sperm whales.
Dr Phillip A Morin
Southwest Fisheries Science Center
Read the Original
This page is a summary of: Demography or selection on linked cultural traits or genes? Investigating the driver of low mtDNA diversity in the sperm whale using complementary mitochondrial and nuclear genome analyses, Molecular Ecology, May 2018, Wiley,
DOI: 10.1111/mec.14698.
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