Females butterflies can smell if a male butterfly is inbred

The mating success of male butterflies is often lower if they are inbred. But how do female butterflies know which males to avoid? New research reveals that inbred male butterflies produce significantly less sex pheromones, making them less attractive to females.

If animals (and humans) breed with a relative their offspring will be inbred and more likely to have genetic disorders. Because of these disorders inbred males are often weaker and, for instance, less able to defend the nest or provide food for their youngsters. To make sure her offspring will have the highest chance of survival and reproduction, females are expected to avoid mating with a weak inbred male. That is, if she is able to recognize who is inbred and who is not.