Q45 - Predator-Specific Effects on Guppy Color-Pattern Evolution

Theoretical A Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license

Male guppies (Poecilia reticulata) show a complex color pattern polymorphism that varies with predation pressure, reflecting a balance between selection for crypsis by predators and selection for conspicuousness by sexual selection. Three experimental ponds were used to study this phenomenon, mimicking the real condition on the native habitat of the guppies and its predators, Rivulus hartii and Crenicichla alta. One pond has the control group while the other two ponds were added with one of the two predators. In the field, C. alta was observed to be more dangerous than R. hartii.

Figure 1. Figure 1.

Using the information and data, determine which of the statements are true or which are false.

A. The color pattern is responsible for the reduced fitness of P. reticulata.

B. Sexual selection for color pattern of the P. reticulata cannot be inferred from the data.

C. The color pattern of the P. reticulata may be advantagous in escaping R. hartii.

D. The two predators possibly use two different mechanisms to detect P. reticulata.

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Question reproduced from IBO 2016, Theoretical Paper A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)