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Hot Guppies?

photo by Silvana Gericke

photo by Silvana Gericke

In a recent article from Nature, researchers observed mating patterns in guppies. While most guppies are plain in color, a few male guppies are vibrant and have interesting color variation. In the lab at Weill Cornell Medical College, it was seen that these colorful males father the most offspring. This is due to negative frequency-dependent selection, or the “rare-male effect“. Because the colorful male guppies are rare, they are attractive to female guppies looking for a mate. The variation in color is an effect from the guppies’ genes. Theoretically, these color variations were supposed to be “normal” a long time ago, because of Darwin’s Theory of Evolution. Rather than conforming to the common pattern, the few males that are colorful show bright colors and diverse patterns. Apparently this is due to the rare male effect. Female guppies simply prefer rare guppies and do not care for the pattern.

Although the results prove this theory in the lab, the researchers were doubtful that this happened in a natural setting. Therefore, the scientists went to Trinidad to see the guppies in their wild setting. They collected the colorful males, numbered them and then released them. Next, they waited for the guppies to mate and then counted their offspring. They did this twice. The first brood showed that the rare male effect was present, but the second did not. The researchers questioned, even though the effect was present in the first brood of offspring, the staying power of this effect. The scientists believed that the effect’s purpose was to prevent insect, which hinders the evolution of the fish.

Why are the mating patterns of guppies so important? What can they help us with in future research?

Here are some articles to further your knowledge in mating patterns and evolution



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1 Comment

  1. biolivcious

    It was very interesting that the rare male effect was not present in both generations. This system of attractiveness based on color and patterns, is what is commonly know both in the wild and in society as “peacocking”. Here is an article that correlates car choice with desirability in men, just like the rare male effect does for fish:

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