A study suggests that modern baleen whales follow similar migratory pathways as their ancestors. Baleen whales tend to feed in cool, high-latitude waters during summer before returning to warm waters to breed in winter, and researchers have hypothesized that migration is integral to the evolution of baleen whales. Although fossil records of baleen whales' migration history are limited, whale barnacles can provide a record of the whales' migration cycles by preserving the oxygen isotopic (δ18O) signature of the whales' movements. Larry D. Taylor and colleagues compared the oxygen isotope composition of modern whale barnacle shells from Alaska and California to fossilized Pleistocene-age barnacle shells from California and Panama. Both the prehistoric and modern specimens exhibited δ18O profiles with a wide range of values, indicating time spent in varied waters, as well as a continuous progression between the 18O-enriched and 18O-depleted values, suggesting that barnacles grow throughout the whales' migration. The δ18O profiles of the fossil barnacles exhibited signatures of a summer feeding season and winter breeding season, mirroring the migration patterns of the modern specimens. The findings suggest that baleen whale migration patterns have been similar for hundreds of millennia, and that the Pacific coast of Panama has served a meeting point for several whale subpopulations for at least 270,000 years, according to the authors.
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Article #18-08759: "Isotopes from fossil coronulid barnacle shells record evidence of migration in multiple Pleistocene whale populations," by Larry D. Taylor, Aaron O'Dea, Timothy J. Bralower, and Seth Finnegan.
MEDIA CONTACT: Larry D. Taylor, University of California, Berkeley, CA; tel: 903-649-3724; email: larry.taylor@berkeley.edu
Proceedings of the National Academy of Sciences