Types of Selection



Name __________________________ Pd

Types of Selection and… Snakes!

A group of snakes were all placed into environments that had differing selective pressures. Read the data tables below and graph each snake in its environment. From the graph, determine what type of selection is being portrayed: directional, stabilizing or disruptive. (NOTE: Each graph should have 2 lines… one for each year. Color code them!!)

1. Snakes placed on an island where there are many red-tailed hawks that hunt for the snakes from the sky.

|Number |Snake Length (cm) |

|of Snakes | |

| |2 |4 |6 |8 |10 |12 |14 |

|Year |1990|2 |

2. Snakes placed on an island where there is one size of burrow available to the snakes to live in.

| |24 | |

| |24 | |

|Number |Snake Length (cm) |

|of Snakes | |

| |2 |4 |6 |8 |10 |12 |14 |

|Year |1990 |

| |2 |4 |6 |8 |10 |12 |14 |

Year |1990 |4 |7 |12 |16 |11 |6 |2 | | |1998 |1 |2 |2 |8 |18 |21 |9 | |

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Type of Selection:

Summarize what happened to the snakes:

Type of Selection:

Summarize what happened to the snakes:

Type of Selection:

Summarize what happened to the snakes:

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