Many animals appear to be monogamous, with males and females forming pairs that can often last a lifetime. But the recent explosion in genetic analyses has revealed many of these so-called monogamous relationships to be a sham. While many animals might stay together and breed, they will often sneak off and cheat on their partners when they get a chance.
However (digo eu)
(…) the researchers believe they have found convincing evidence of an evolutionary chain of causation: changing the breeding pool size forced the mimic poison frog to change its system of parental care, with males and females working together. That then culminated in social and genetic monogamy. If the pools were bigger, the frogs wouldn't have to remain faithful, as they wouldn't be tied by their need to work together to raise their brood. "These frogs are truly devoted to their offspring, and to each other," says Dr Brown, who is now studying at Duke University in Durham, North Carolina, US.