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Female great white sharks stay at home while males go gallivanting on the
high seas, reports a team led by Andrew Martin of the University of Colorado at
Boulder in this week鈥檚 Nature. They looked at the DNA of two shark
populations鈥攐ne off the coast of South Africa and another near Australia
and New Zealand. Mitochondrial DNA, which is passed down from mothers to their
offspring, was different in the two groups, suggesting that the females hadn鈥檛
intermingled. But nuclear DNA, which contains a male contribution, was
indistinguishable in the two groups. The finding suggests great whites have a
lifestyle more like that of whales and dolphins than fish.