Evolution sometimes forces two species to survive together. Researchers have discovered that a beetle has outsourced a key metabolic function to a bacterium in its gut, while the bacterium has lost most of its genes and evolved one of the world's tiniest known genomes.

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Evolution sometimes forces two species to survive together. Researchers have discovered that a beetle has outsourced a key metabolic function to a bacterium in its gut, while the bacterium has lost most of its genes and evolved one of the world's tiniest known genomes.