AIM: To what degree do predation and sexual selection affect guppy coloration?
Hypothesis: If there are 90 predators in the guppy inhabitation with major number of colorful guppies,
then the level of guppy coloration will change to camouflaged/dark colors over 5 generations because
predators mostly prey the bright colored guppies that are easy to spot.
Data Collection:
Flashy Fish: Quantitative Data
Predator types and numbers:30 Rivulus, 30 Acara, 30 cichlid
Initial guppy population: Mostly Bright
First Trial:
Starting Number of Guppies:
103 Guppies
Brightest: 35% (35 Guppies)
Bright: 33% (33 Guppies)
Drab: 22% (22 Guppies)
Drabbest: 10% (10 guppies)
Number of Weeks: 1
Number of Generations: 2
After 5 Generations
Number of Guppies: 172 guppies
Brightest: 23% (40 Guppies)
Bright: 43% (74 guppies)
Drab: 17% (29 Guppies)
Drabbest: 17% (29 Guppies)
Number of Weeks: 65
Number of Generations: 5
Qualitative Data:
The percentage of major guppy colors changed from brightest to Bright over 5 generations. The
sex selection somehow kept the brightest guppies alive, but after few generations guppies started
to evolve and became adapted to the nature.
Second Trial:
Starting Number of Guppies: 109
Brightest: 43% (47 Guppies)
Bright: 26% (28 Guppies)
Drab: 22% (24 Guppies)
Drabbest: 9% (10 Guppies)
Number of Generations: 2
Number of Weeks: 1
After 5 Generations
Number of Guppies: 216
Brightest: 18% (39 Guppies)
Bright: 25% (54 Guppies)
Drab: 37% (80 Guppies)
Drabbest: 20% (43 Guppies)
Number of Weeks: 89
Qualitative Data:
The guppies had more frequent reproduction than the first experiment. But this experiment also
showed how the major bright guppies slowly started to evolve into a state of being camouflaged.
The starting percentage of Bright – Brightest guppies was 69% but in the end, the Drab –
Drabbest colors took majority of the guppies.
Processing and presenting data:
Percentage of Guppy Coloration - Trial 1 Generation 1
40%
35%
30%
25%
20%
Percentage of Guppy Coloration Trial 1 - Generation 1
15%
10%
5%
0%
Brightest
Bright
Drab
Drabbest
Percentage of Guppy Coloration - Trial 1 After 5 Generations
50%
45%
40%
35%
30%
25%
Percentage of Guppy Coloration
- Trial 1 - After 5 Generations
20%
15%
10%
5%
0%
Brightest
Bright
Drab
Drabbest
Percentage of Guppy Coloration - Trial 2 Generation 1
50%
45%
40%
35%
30%
25%
Percentage of Guppy Coloration
- Trial 2 - Generation 1
20%
15%
10%
5%
0%
Brightest
Bright
Drab
Drabbest
Percentage of Guppy Coloration - Trial 2 After 5 generations
40%
35%
30%
25%
20%
Percentage of Guppy Coloration
- Trial 2 - After 5 generations
15%
10%
5%
0%
Brightest
Bright
Drab
Drabbest
Trial 1 (After 5 generations):
Number of brightest guppies: 40
Number of drabbest guppies: 29
Took 65 weeks
Trial 2 (After 5 generations):
Number of brightest Guppies: 39
Number of drabbest guppies: 43
Took 89 Weeks
The more time it takes for the experiment to be done, the number of the drabbest guppies
increase due to natural selection.
Conclusion:
Conclusion – 1: The guppy coloration changes due to predators and sexual selection into a
drabber guppy.
Conclusion – 2: The bright - Brightest guppies were the major amount of guppies in the
inhabitation but after 5 generations, most of the brightest guppies disappeared either into bright
or drab guppy’s category. The bright guppy took 43% (34 guppies more than brightest guppies)
of the guppy population in the first experiment and the drab guppy took 37% (41 more guppies
than the brightest) of the guppy population in the next experiment.
Conclusion – 3: The result doesn’t fit my hypothesis as well as it could have, because 5
generations were too short to see the guppies adapt to the nature. There were very small changes
to the guppies, which were the change in the brightest guppy section. The brightest guppies
became the ‘bright guppies’ and the bright guppies became the drab guppies. If this experiment
continued, my hypothesis would have supported the results.
Conclusion – 4: Natural selection and Sexual selection is a factor to highly think of in these
kinds of experiments on animal’s coloration and phenotypes. Natural selection in this case means
the predators that eat guppies. Being bright considering this factor is a very dangerous thing. The
predators can spot them easily when they are bright. But considering sexual selection, being
colorful and flashy is a must-have factor to mate with other guppies. Considering 2 of these
factors, the coloration of guppies is very complicated. The colorful guppies can reproduce more
than the drabber ones, but they have more chance of being hunted down. This means that drabber
ones would survive, and although they can’t reproduce as much as the colorful ones, they will
start to increase in number and soon be the major population in the guppy inhabitation.
Evaluation:
The hypothesis was not valid because the experiment wasn’t able to reach the goals I set in the hypothesis.
The goal of hypothesis was that there was a big change to the guppies throughout the 5 generations, but
only 5 generations didn’t help.
Weakness and Improvement:
Weakness
Improvement
Different numbers of guppies
The numbers of guppies in these 2 same experiments were
different. This factor can be changed or be stayed, but there must
be a reasonable answer to why there are changes to the numbers
of guppies.
Not realistic environment
The environment could have been more realistic, the predator
could have had different habits on eating. Or there could have
been other factors like plague, fishing and etcs. Maybe there can
be a better program to run this.
2 same experiments tried
There could have been a different experiment that I could
compare to instead of doing the same experiment again. The
results were different but it could have been more interesting to
do a different one.