A phenomenon called mate-choice copying, which takes place not only with Guppies: A number of studies on human mate selection suggest that we might also engage in our fair share of mate-choice copying when faced with our version of having to choose between the brightly colored vs. However, until recently only relatively little was known about the mechanisms that guide this type of mate-copying behavior.Surprising, given the potentially quite fascinating influence this type of behavior may possess for the evolution of sexually selected traits in populations.
The pictures that each participant was given to rate were specifically photographed for this study, and they typically showed either a single man or woman, or a man and women together.
In the case that a man and women were shown together, the researchers played around with Photoshop a little, so that each male and each female model would appear on exactly three different "couples-pictures" in the study's photo-database.
On one of these couples-pictures, the model was matched with a highly attractive person, on another the match was a moderately attractive person, and on the third matching was performed with a less attractive person.
Yorzinski and Platt now wanted to see whether attractiveness ratings, and even the invited rater's reported willingness to engage in a romantic relationship with the photographed models, would be influenced by whether pictures showed models on their own, or together with another person (since the study included all reported heterosexuals, couples pictures always included two opposite sex models).
Guppies are small fish with brains of only a few millimeters in width, and so one wouldn't expect them to make complex mating decisions: Take for example the typical female Guppy who has to choose between two males; one a little drab, the other brightly colored.
For the typical female this situation presents a simple - practically hard-wired - call, and she will generally choose the brightly colored male.This is simply how things work in the Guppies' underwater world.(Note: Fish are much smarter than we usually give them credit for, so I'm cringing a little at my own use of the term "hard-wired" here...don't take it too literal).Things do change sometimes in Guppy-world, however.For example, if another female enters the picture and, for some unspecified reason, this other female seems to favor the drab male.When this happens, our typical Guppy female will often change her mate preference based on the simple observation that another female is actually mating with the previously undesired male.