Abalone Evolution Unravels


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Posted by on September 15, 2004 at 01:23:15:

With the initial goal of relocating a species of endangered sea otters, researchers stumbled upon a solution to the mystery of evolutionary survival in abalone.

Over two decades ago, David Lindberg, chair of the UC Berkeley Department of Integrative Biology, facilitated a project to relocate a group of sea otters from central to southern California, in an attempt to bring them to a safer environment.

However, the move was questionable. Lindberg and his team were afraid that moving the otters to southern California might endanger the survival of abalone living there, which the otters would feed upon.

But the team discovered that there was no need to fear the abalone becoming the otter’s mid-morning snack.

According to researchers, the abalone and the otter evolved around the same time in California, and both were able to survive together. The abalone were even able to evolve from their usual size of 50 millimeters into a size equivalent to that of a salad bowl, becoming too big to hide in crevices to protect themselves from animals like the sea otter.

Researchers found out how the evolution was possible.

Lindberg and his team went back in time to follow the evolution of the abalone, and found the formation of the Antarctic Ice Sheet during the Cenozoic era led to the beginning of the abalone’s migration and increase in size.

“The cooling of the South Pole produced new temperate habitats and increased productivity in the region. Abalone are one of the groups that appear to have expanded their ranges into this new habitat over evolutionary time” said Lindberg.

The cooling of the South Pole also led to an increase of macroalgae for the abalone to feed upon. This increase is what Lindberg believes caused the abalone’s growth in size.

“High productivity of kelps in the North Pacific produces lots of drift kelp—kelp that breaks off and drifts around in the water. Any time you have been down to the beach and seen that smelly pile of rotting kelp covering the sand, you are looking at potential abalone food” Lindberg said.

Thus, instead of having to leave their safety zone and go out in search of food, the abalone are able to stay in hiding and have the drift-kelp come to them. As a result, the abalone are able to grow freely without becoming consumed.

The researchers encountered one grievance during the project, however. They found a lack of abalone in South America and off of the Chilean coast, which posed a problem since the team had evidence that there should have been traces of abalone living in the region.

Biologists Discover Evolutionary History of Abalone During Otter Relocation

By SILVIA CHIANG
Contributing Writer
Wednesday, September 15, 2004Lindberg later found that El Nino had caused the abalone’s food source to disappear, causing the abalone to die from starvation.

Lindberg still hopes to one day travel back to the Chilean coast to conduct further research.

“I would very much like to go back to Chile and search for abalone fossils in the Pleistocene deposits in the northern part of the country. The implications are many, but primarily they point out the importance of understanding ecological interactions in an evolutionary context. This is especially important when we try to ‘restore’ habitats and species to ‘natural’ conditions” Lindberg said.



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