Evolution

A Hop, Skip, and a Jump

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Science  13 Aug 2010:
Vol. 329, Issue 5993, pp. 729
DOI: 10.1126/science.329.5993.729-a
CREDIT: ISTOCKPHOTO.COM
CREDIT: JOSÉ LUIS BARTHELD

Marsupial mammals bear their young much earlier than placental mammals and then nurture them in a maternal pouch. They split from the placental line more than 100 million years ago, and the evolutionary relationships among the Australasian (left) and South American (right) species have been debated. Nilsson et al. have performed genome-wide scans for retroposon integrations in the opossum and kangaroo genomes. A subset of the resulting loci was validated in 20 species from the seven marsupial orders, yielding 53 phylogenetically informative retroposon markers that root modern marsupials and demonstrate a clear separation between the South American and Australasian denizens. Furthermore, they support the view that the marsupial fauna of Australia was populated by a single Gondwanan migration event originating from what is today South America.

PLoS Biol. 8, e1000436 (2010).

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