From an article in Wired, another example of the fascinating intricacy of evolution:
"...It’s an incredibly bizarre system,” said study co-author Michael Goodisman, a Georgia Institute of Technology sociobiologist who described the trick Feb. 2 in Proceedings of the Royal Society B. “A queen produces males that are completely unrelated to her, that have none of her genetic material.”
Longhorn crazy ants, or Paratrechina longicornis, are so widespread that scientists don’t even know where they first came from. They form series of connected colonies, called “supercolonies,” that greatly disrupt ecosystems they invade, including human farms and homes.
To discover how crazy ant queens deal with a shortage of mates, Goodisman’s team formed 21 laboratory colonies, each with one queen and some workers. After three months, the researchers collected pupae of workers, males and queens, then analyzed their DNA.
Workers had one set of genes each from both mother and father, as normal. But females were exact copies of their queen mother, while males were clones of their fathers.
Because both the queens’ offspring are genetically unrelated, they can mate with one another without the consequences of inbreeding.
“It’s cheating, in a genetic sense, but this weird system allows [crazy ants] to overcome severe restrictions,” said evolutionary geneticist Jürgen Gadau of Arizona State University, who wasn’t involved in the study..."