The Impact of Predators on Guppy Coloration

Adult male guppies use brightly colored patches to attract female mates. When adult guppies are preyed upon by predators like the pike-cichlid, which feeds only on adult guppies, populations with these predators tend to have less brightly colored adults compared to populations without such predators. In contrast, populations with no adult guppy predators are likely to exhibit more brightly colored adults due to the advantage in mating and reproductive success that these bright colors provide.

The Role of Predators in Guppy Coloration

Predators play a crucial role in shaping the coloration of adult male guppies. When predators selectively target and consume adult guppies based on their coloration, it creates a selective pressure that influences the survival and reproduction of the guppy population. The presence or absence of predators like the pike-cichlid can significantly impact the proportion of brightly colored adult guppies within a population.

Adaptation to Predation Pressure

Populations of guppies with predators like the pike-cichlid that specifically target brightly colored adults are more likely to exhibit a decrease in the frequency of these color traits over generations. This is because individuals with less conspicuous coloration have a higher chance of surviving and reproducing in the presence of such predators. On the other hand, in populations without these predators, brightly colored males have a mating advantage and are more likely to pass on their genes to the next generation.

Impact of Predator Diversity

When a population of guppies is introduced to a new predator such as the killifish, which feeds on juvenile guppies, it can lead to changes in coloration within the population. In this scenario, where killifish are the primary threat, the selective pressure may favor the survival of brightly colored adult males, as predators primarily target juvenile guppies. Over time, this could result in a higher occurrence of brightly colored males in the population due to their mating advantage and increased reproductive success.

Conclusion

The interplay between predators and guppy coloration highlights the intricate relationship between predator-prey dynamics and evolutionary adaptations. The coloration of adult male guppies is not merely ornamental but has significant implications for survival and reproductive success in the face of predation. Understanding how predators influence guppy coloration provides valuable insights into the mechanisms driving natural selection and the evolutionary strategies employed by prey species to cope with predation pressure.