Sexual Selection Lab

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1) Hypothesis [2 marks]
|An isopod’s body length and speed affect its chances of predator avoidance. |

2) Plausible reason why/how each independent variables affect the dependent variable. [2 marks]
|An isopod’s body length, specifically if it is short, will allow it to move faster. If an isopod has low speed it will not likely avoid predators as |
|much as an isopod which moves fast. |

3) Prediction(s): [2 marks]
|If an isopod’s body length and speed have an effect on its chances of predator avoidance, then some traits will be better adapted to the environment |
|and as a result, would increase the isopod frequency and those traits will be passed on to subsequent generations. |

4) Null Hypothesis: [1 mark]
|Body length and an isopod’s speed have no affect on its chances of predator avoidance. |

5) Prediction of Null Hypothesis: [1 mark]
|If an isopod’s body length and speed have no affect on its chances of predator avoidance, then there will be no change to frequency since those traits |
|will not be passed on to subsequent generations because they provide no advantage in regards to fitness and predator avoidance. |

6) Results and Conclusions:
a) Figures 1 (for size) & 2( for speed): Inserted on page 2. [7 marks, 3.5 marks per figure]

b) Isopod length and success against predation: [3 marks]
|The mean average for isopod length in the initial population is 12.8mm. The mean average for isopod length in the survivor population is 13.8mm. The |
|selection intensity is 1 mm. There is a slight shift towards longer isopods. Looking at the figure 1, the isopods with a body length between 12.1 mm- |
|15.0 mm produced the most survivors after predation. Surprisingly, those with a body length between 15.1mm-18.0 mm initially had a low population, but |
|after predation, they had an increased number of survivors. Taking this into account, my hypothesis was incorrect because the longer the body length, |
|the increase number of survivors you will observe after predation. |

c) Isopod speed and success against predation: [3 marks]
|The mean average for isopod speed in the initial population is 0.91 cm/s. The mean average for isopod speed in the survivor population is about 1.28 |
|cm/s. The selection intensity is 0.37 cm/s. There is a slight shift towards faster isopods in the surviving population. Looking at figure 2, the |
|isopod’s who had a sprint speed between 0.0 cm/s – 0.05 cm/s had the highest amount of predator avoidance in the survivor population. Yet again, the |
|isopods who had a sprint speed between 2.6 cm/s and 3.0 cm/s had an increased number of survivors (> than initial population). Also, those isopods who |
|had sprint speeds between 1.6 cm/s and 2.0 cm/s had the same rate of survivors as the initial population. Analyzing these results, my hypothesis is |
|somewhat correct because those who ran the fastest (0.0 cm/s – 0.05 cm/s) produced the highest number of survivors after predation. |

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[pic]

Figure 1. Frequency distribution of isopod body length prior to and after being exposed to a black spoon as the predator.

Figure 2. Frequency distribution of isopod sprint speed before and after being placed on a plastic race track and measuring its speed on an interval of 10 seconds.

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7) Primary Literature Search:
a) Citation: [1 mark]
|1. Zidar, P., Hribar, M., Žižek, S. & Štrus, J. Behavioural response of terrestrial isopods (Crustacea: Isopoda) to pyrethrins in soil or food. Eur. J.|
|Soil Biol. 51, 51-55 (2012). |

b) Relevance to lab experiment: [1 mark]
|Discusses changes to an isopod’s behavior when exposed to different environment. Might explain why the isopods behaved a certain way in the lab. |

8) Communication (TO BE COMPLETED BY YOUR TA) [2 marks]:
Your TA will evaluate your assignment as follows:
|Poor (0.5) |Average (1) |Good (1.5) |Excellent (2) |
|Poor syntax, grammar, sentence | | |Excellent syntax, grammar, sentence|
|structure and flow throughout. |Some issues with syntax, grammar, |Minimal issues with syntax, |structure and flow throughout. |
|(…It is very difficult to |sentence structure and flow. |grammar, sentence structure and |(… Everything is clear, concise, |
|understand what you are trying to | |flow. |and easy to read.) |
|say.) | | | |

Final Mark: _______ /25

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