Fish Use Clever Mating Trick [LiveScience 2007-11-15] Some fish
are able to get sex by faking out the females. Now scientists
have found a gene that helps them do so. The fish, known as
cichlids, are maternal mouthbrooders???the female scoops up eggs
in her mouth after she lays them. While collecting her eggs, the
female may mistake the yellow, oval-shaped markings on a male’s
fin as one of her own eggs and approaches the male. Once she
gets close enough to his anal fin, he then squirts sperm into
her egg-filled mouth. This form of mating ‘trickery’ works so
well that more than 80 percent of cichlid species evolved the
fake egg markings. Researchers at the University of Germany
identified the gene associated with the egg-like markings by
observing how the gene was expressed in distantly related
species, where such spots developed on the pectoral fins rather
than the anal fins. The researchers published their findings in
the online open access journal BMC Biology. "The two kinds of
independently evolved egg-du