The Role of Menopause in Killer Whales
Author Information
Author(s): Ward Eric J, Parsons Kim, Holmes Elizabeth E, Balcomb Ken C III, Ford John K B
Hypothesis
What is the evolutionary significance of menopause in killer whales?
Conclusion
Oldest killer whale mothers appear to produce calves with higher survival rates, but there is little support for menopause providing fitness benefits to mothers or grandmothers.
Supporting Evidence
- Oldest mothers (> 35) had a small positive impact on calf survival.
- Calves born to older mothers had higher estimated survival rates than those born to younger mothers.
- Grandmothers did not appear to impact calf or juvenile survival.
Takeaway
Killer whale moms who are older might be better at taking care of their babies, but having grandmothers around doesn't seem to help the babies survive.
Methodology
Longitudinal sightings data were collected from two populations of killer whales over 30 years, tracking reproductive performance and survival.
Limitations
Data on birth defects, stillbirths, or mortality risk to pregnant females is not available.
Participant Demographics
Killer whales from two distinct populations in Washington State and British Columbia.
Digital Object Identifier (DOI)
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