Small-brained female guppies aren’t drawn to attractive males

Female guppies with smaller brains can distinguish attractive males, but they don't recognise them as being more appealing or choose to mate with them, according to a new study by UCL and Stockholm University researchers. The study, published in Nature Ecology & Evolution , adds weight to the link between mate preference and cognitive ability. "One of the biggest decisions a female guppy has to make in its life is choosing who to mate with. It is very important, so you might think they would all prefer a single most attractive male," said one of the study's senior authors, Professor Judith Mank (UCL Genetics, Evolution & Environment). "But we found that it takes a certain amount of brain-power to size up an attractive mate." The research team studied female Trinidadian guppies in two groups differentiated by brain size and mating preferences. The fish were exposed to males that were either colourful with long tails, which are more commonly attractive to females, or males that were less colourful. The researchers allowed the female fish to evaluate the males, keeping the fish in separate tanks so exposure was only visual.