Twists and turns Quote by Ed Yong

““John McCutcheon has worked out the origins of this weird hierarchy-and it's almost unbelievable in its twists and turns. It begins with Tremblaya, the first of the two bacteria to colonise mealybugs. It became a permanent resident and, like many insect symbionts, it lost genes that were important for a free-living existence. In the cosy confines of its new host, it could afford to get by with a more streamline genome. When Moranella joined this two-way symbiosis, Tremblaya could afford to lose even more genes, in the surety that the new arrival would pick up the slack. As long as a gene exists in one of the partners, the others can afford to lose it. These types of gene transfer are different to those that turned nematodes, into plant parasites, or those that sprinkled antibiotic genes into tick genomes. Here, the recipients don't gain beneficial abilities. Here, HGT is more about evacuating bacterial genes from a capsizing ship. It preserves genes that would otherwise be lost to the inevitable decay that afflicts symbiont genomes.””

— Ed Yong