April 23, 2010

Genetic Research Suggests Multiple Orca Species

Experts from the National Oceanic and Atmospheric Administration (NOAA) have discovered genetic evidence that there are multiple species of killer whales.

Lead researcher Phillip Morin and his colleagues at the NOAA's Southwest Fisheries Science Center in La Jolla, California, took tissue samples from 139 orcas from the North Atlantic, the North Pacific, and Antarctica. By analyzing the mitochondria of each, they confirmed the existence at least three distinct killer whale species.

According to Maggie Fox of Reuters, "Researchers had suspected this may be the case--the distinctive black-and-white or gray-and-white mammals have subtle differences in their markings and also in feeding behavior." They apparently also have different eating habits, as one hunts Antarctic seals and another preys on fish, according to what Morin told Fox.

The NOAA study was published in the April 22 edition of Genome Research.

"The genetic makeup of mitochondria in killer whales, like other cetaceans, changes very little over time, which makes it difficult to detect any differentiation in recently evolved species without looking at the entire genome," Morin said in a statement. "But by using a relatively new method called highly parallel sequencing to map the entire genome of the cell's mitochondria from a worldwide sample of killer whales, we were able to see clear differences among the species."

Orcas are currently not recognized as an endangered species, except in specific areas. Based on these new findings, however, that could all change. If the whales are reclassified, each of the new species might be eligible for protection status, which would aid efforts to protect them from habitat loss, fisheries, pollution, or other threats that could harm the marine mammals.

"Establishing appropriate taxonomic designations will greatly aid in understanding the ecological impacts and conservation needs of these important marine predators," the researchers note in the abstract accompanying their paper. "We predict that phylogeographic mitogenomics will become an important tool for improved statistical phylogeography and more precise estimates of divergence times."


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