Researchers recently found a “remarkable lack of diversity” among sperm whale populations. They were able to trace the mitochondrial DNA of more than 1,000 sperm whales back to a single female tens of thousands of years ago. They’re calling this individual “Eve.”
Mitochondrial DNA is inherited from the maternal side and is useful for studying long-term patterns because it evolves slowly compared to other genetic markers.
The researchers aren’t sure yet where Eve came from, but they are certain that her descendants shaped global population structure.
“Sperm whales have been in the fossil record for some 20 million years, so the obvious question is how one maternal lineage could be so successful that it sweeps through the global population and no other lineages survive? At this point, we can only speculate about the reasons for this success, but evolutionary advances in feeding preferences and social strategies are plausible explanations,” Scott Baker, co-author of the study and associate director of Oregon State’s Marine Mammal Institute, explained in a news release.
The researchers note that female sperm whales tend to stay in one area, which could contribute to the patterns seen in the species’ mtDNA.
Though, according to Baker, there is some concern that “this very strong local fidelity may slow expansion of the species following whaling. The Sri Lanka sperm whales, for example, don’t seem to mix with the Maldives whales, thus local anthropogenic threats could have a negative impact on local populations.”
While sperm whales were never driven to the brink of extinction, they do face many threats as the oceans continue to change. These findings could help decision-makers better manage sperm whale populations and make more effective conservation decisions.
To learn more:
- Read the OSU news release: “Eve” and descendants shape global sperm whale population structure
- Read the study abstract: What influences the worldwide genetic structure of sperm whales (Physeter macrocephalus)?
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