Cannabalism and Survival of the Fittest

I´m sure when you were younger your mother sighed exasperatedly "that´s why some animals eat their young" but Marion Mehlis of the University of Bonn in Germany has proven that the three spined Stickleback makes very precise decisions when it comes to eating its offspring. Mehlis concluded that male Sticklebacks that guard the eggs after fertilization eat only the eggs that are fertilized by another male. Sticklebacks are notorious for "sneak fertilizations" but apparently the males have evolved a sense of whose eggs are whose. Researchers speculate that the fish must use some type of odor to determine his own eggs when the paternal genes are activated during development.

The study replaced different percentages of the clutches of male Sticklebacks, including 100% of the eggs, and every time, the male ate all the eggs that he did not fertilize. This goes back to the idea of fitness, in which an animal´s ability to produce more offspring and leave behind more of its genome is the ultimate goal. The fish would be wasting valuable energy and time raising offspring with another competitor´s genes. Darwin, of course, is the father of the "survival of the fittest.

Spencer Castro

New York Times
http://www.nytimes.com/2010/04/27/science/27obcannibal.html?ref=science