The Effects of Phenotypes on Predatory Selection Pressure
Faith Farmer BIOL 107-512 10/15/15
Introduction
The purpose of this experiment is to evaluate how different phenotypes influence predation patterns in Dottus variegatus. In nature, observations of animals such as insects and predatory birds indicate that predators select against organisms with phenotypes that do not blend in with their environment. In this lab, dots and their colors represent the species Dottus variegatus and the different phenotypes.
Depending on the conclusion of the experiment, selection pressure for or against phenotype may improve or prevent reproductive success (fitness) and survival. The hypothesis being tested is that brighter phenotypes will experience negative …show more content…
Ten differing phenotypes of Dottus variegatus will be placed randomly in a colorful board to simulate a population in its environment. The total population includes 100 organisms with 10 representing members of each phenotype. The predator will decimate 25% of the population. Based on which colors experienced high or low levels of predation, the hypothesis that brighter colors will be selected against is tested. The ‘predator’ looks away while another person randomly scatters the 100 dots. The ‘predator’ will quickly turn to the board and select a dot, then turn away and give the selected dot to a third person for data recording. The process is repeated until 25 members of Dottus variegatus are …show more content…
Column A shows the amount of each color ‘eaten’ by the predator. The colors with larger numbers in column A experienced negative selection pressure. Column B shows the expected number of each phenotype to be collected based on chance probability. The equation used to get the value 2.5 is as follows:
Number expected = Total number collected (25) / number of phenotypes (10)
Column C shows the number of organisms with each phenotype that survived predation. The number in column A was subtracted from 10 to get this value.
Brighter members of Dottus variegatus were ‘eaten’ in higher quantities than those that blended with the environment, which evaded predation better. 50% or less of the phenotypes for dark pink, red, or purple survived predation, while 100% of the pale pink, pale green, pale yellow, and pale blue survived predation. Blue, yellow, and red had an intermediate survival rate of 70% -90%. These result support the hypothesis.
Observed # - Expected #
A-B from Table 1 (Observed # - Expected #)^2 (Observed # - Expected #)^2
Expected #
-1.5 2.25 .9
2.5 6.25 2.5
.5 0.25 .1
3.5 12.25 4.9
-0.5 .25 .1
-2.5 6.25 2.5
-2.5 6.25 2.5
5.5 30.25 12.1
-2.5 6.25
Faith Farmer BIOL 107-512 10/15/15
Introduction
The purpose of this experiment is to evaluate how different phenotypes influence predation patterns in Dottus variegatus. In nature, observations of animals such as insects and predatory birds indicate that predators select against organisms with phenotypes that do not blend in with their environment. In this lab, dots and their colors represent the species Dottus variegatus and the different phenotypes.
Depending on the conclusion of the experiment, selection pressure for or against phenotype may improve or prevent reproductive success (fitness) and survival. The hypothesis being tested is that brighter phenotypes will experience negative …show more content…
Ten differing phenotypes of Dottus variegatus will be placed randomly in a colorful board to simulate a population in its environment. The total population includes 100 organisms with 10 representing members of each phenotype. The predator will decimate 25% of the population. Based on which colors experienced high or low levels of predation, the hypothesis that brighter colors will be selected against is tested. The ‘predator’ looks away while another person randomly scatters the 100 dots. The ‘predator’ will quickly turn to the board and select a dot, then turn away and give the selected dot to a third person for data recording. The process is repeated until 25 members of Dottus variegatus are …show more content…
Column A shows the amount of each color ‘eaten’ by the predator. The colors with larger numbers in column A experienced negative selection pressure. Column B shows the expected number of each phenotype to be collected based on chance probability. The equation used to get the value 2.5 is as follows:
Number expected = Total number collected (25) / number of phenotypes (10)
Column C shows the number of organisms with each phenotype that survived predation. The number in column A was subtracted from 10 to get this value.
Brighter members of Dottus variegatus were ‘eaten’ in higher quantities than those that blended with the environment, which evaded predation better. 50% or less of the phenotypes for dark pink, red, or purple survived predation, while 100% of the pale pink, pale green, pale yellow, and pale blue survived predation. Blue, yellow, and red had an intermediate survival rate of 70% -90%. These result support the hypothesis.
Observed # - Expected #
A-B from Table 1 (Observed # - Expected #)^2 (Observed # - Expected #)^2
Expected #
-1.5 2.25 .9
2.5 6.25 2.5
.5 0.25 .1
3.5 12.25 4.9
-0.5 .25 .1
-2.5 6.25 2.5
-2.5 6.25 2.5
5.5 30.25 12.1
-2.5 6.25