Gray whales a model in climate adaptation

In the time since California gray whales existed, the Earth has gone through more than 40 cycles of warming and cooling. Many species have been impacted and have even died out, but the gray whale has persisted for 250 million years. How did the gray whale survive?

The gray whales, it turns out, may be a model in how a species can adapt and change during dramatic swings in the Earth’s climate. In the modern era, whaling has been the biggest threat to the gray whale survival, and in fact the species has rebounded to 22,000 individuals from a low of 1,000 in the past 75 years of conservation. But prior to human arrival, the whales faced dramatic changes in its feeding grounds due to climate change.

Photo: NOAA

During the last Ice Age (150,000-200,000 years ago), the expanding glaciers drew down sea levels and eliminated 60 percent of the Bering Sea Platform, where the whales go to feed off a shallow shelf of seafloor sediment that contains worms and amphipods. The habitat destruction must have been devastating to the whales, unless they were resourceful enough to find something else to eat.

DNA evidence suggests their numbers did not suffer a population crash. According to a new study out of University of California at Berkeley and published last week in the journal PLoS ONE,  the whales likely began feeding off herring and krill. The population may have reached as high as 170,000 during that time, but only with an expanded diet, said David Lindberg, evolutionary biologist and co-author of the paper.

A switch in diet is also being observed among some gray whales today under rising temperatures. Gray whales may be more adaptive than other mammals and birds in the Bering Sea, which is an especially productive summer ecosystem.

A historical understanding of species and their ability to adapt may be crucial to predicting how they will fare in today’s climate change.