Sex and the Single Guppy: Simulation

1. If being flashy and colorful attracts predators, why do you think guppies are so colorful?

To attract a mate. To blend in coral reefs. They could also have ravenous appetites, or high reproduction rates. This would allow populations to sustain themselves.

2. After viewing the guppy gallery, pick the fish you find most interesting. What is the fish’s scientific name, origin and average size? Describe the coloration of the fish you chose.

Brazilian guppy, poecilia reticulata, 3.5 cm

3. After viewing the predator gallery, pick the fish you find most interesting. What is the fish’s common name, scientific name, and origin?

Pike cichlid, Crenichla alta, 30cm, Trinidad and Latin America

4. View the guppy’s habitats, what habitat conditions would affect the predator populations?
A natural dam because then the predators would restrict upstream movement.

Endler’s Discovery and Variations of Guppy’s in Pools

5. Who is John Endler? What did he study and where did he study it?

He, an evolutionary biologist, studied the variation in guppies in Trinidad.

6. For each of the three stream areas, describe the guppy coloration:

Pool 1: Blue and orange splotches on their sides, with bright coloration and large spots.

Pool 2: Average coloration, with medium-sized spots.

Pool 3: Average coloration with small spots.


7. Develop your own hypothesis about guppy coloration. The hypothesis should answer the questions: Why do guppies in different areas of the stream have difference in coloration? (You can choose from the list on the simulation, or make up your own)

I believe all of the guppies need to balance the predators in the area (by becoming more drab), and need to pass on their genes (with causes more vivacity), so more predators will cause more drabness, and more females and less predators


Guppy Simulation

Guppy Simulation

% of Brightest Guppies
(10 generations) % of Bright Guppies
(10 generations) % of Drab Guppies
(10 generations) % of DrabbestGuppies
(10 generations)
Trial 1
Guppy: Even Mix
Predators: 30 Rivulus 60 20 13 7
Trial 2
Guppy: Even Mix
Predators: 30 Rivulus, 30 Acara 10 60 30 0
Trial 3
Guppy: Even Mix
Predators: 30 Rivulus, 30 Acara, 30 Cichlid 0 0 23 77
Trial 4
Guppy: Mostly Bright
Predators: 30 Rivulus 85 9 3 2
Trial 5
Guppy: Mostly Drab
Predators: 30 Rivulus, 30 Acara, 30 Cichlid 0 1 0 99

Summary
8. Describe how predators influence guppy coloration.
Obviously, the more predators there are, the more drably colored guppies survive which allows the passing on of traits.


9. Was your hypothesis correct, use your data to justify your answer.
Yes. As more varieties of predators were introduced, then more were drab. If only rivulii were introduced, then the bright guppies would become completely dominant.


10. What does it mean that “male guppies live in a crossfire between their enemies and their would be mates”?
It means that they have to choose between attracting the best mate through best color, or trying to stay alive with a drab color to evade predators.

11. Why do you think guppies in different areas of the stream have different coloration?
Because some physical features restrict larger predators. In one case, the area above a dam is very safe because of the loss of chance of going upstream.

12. What would happen to mostly drab guppies that were placed in a stream with very few predators?

They would either become colorful because of being able to attract better mates, or have their population completely explode. The latter would occur only if the physical features allowed.

13. What would happen to brightly colored guppies that were placed in a stream with many predators?

They would quickly fade away because of being so noticeably ostentatious. Unless drab guppies also existed, the guppy population would completely fade away.