Species Distribution and Biogeography
At the end of this lab, students should know...
View the full transcript and gain access to JoVE Lab Manual videos
Q1: How do you set up the island cups for a colonization and extinction simulation?
Label six red cups and six blue cups numbered 1-6 with permanent marker. Arrange them on a table with rims touching, alternating colors to create a large island. Pour 100 mL of water into each cup to prevent tipping. For small islands, use only six cups of one color. This physical setup models island habitats for studying species colonization dynamics.
Q2: What role does distance play in the colonization simulation?
Distance from the throwing line affects colonization rates. The far-large island trial uses a 2-meter distance, while the near-large island trial uses 1 meter. Increased distance makes it harder to throw Ping-Pong balls into cups, simulating how remote islands receive fewer colonizing species. This demonstrates how geographic isolation influences species arrival and establishment.
Q3: How does island size influence colonization and extinction in this simulation?
Large islands use 12 cups (six red, six blue), while small islands use only six cups of one color. Larger islands provide more habitat area, potentially supporting more colonizing species and experiencing lower extinction rates. Small islands have limited space, making them more vulnerable to species loss. This models real biogeographic patterns where island size affects biodiversity.
Q4: What is the purpose of using colored dice in the extinction simulation?
Red and blue dice represent extinction events for species on large islands, while unmarked dice are used at small island stations. Rolling a die determines which species goes extinct during each time step. This random process simulates stochastic extinction, where species disappear unpredictably due to environmental factors or chance events.
Q5: Why is the class divided into groups of three for this lab?
Each group member has a specific role: data recorder tracks results, colonization simulator throws Ping-Pong balls to represent arriving species, and extinction simulator rolls dice to determine extinctions. This division of labor ensures efficient data collection and allows students to focus on different aspects of the colonization-extinction process simultaneously.
Q6: How do Ping-Pong balls represent colonizing species in this experiment?
Ping-Pong balls thrown from a measured distance simulate propagules or individuals attempting to colonize island cups. Successfully landing in a cup represents successful colonization. The number of balls thrown and landing reflects colonization rates, allowing students to observe how species accumulate on islands over time and how distance affects immigration success.
Q7: What ecological concepts does this simulation demonstrate about island biogeography?
The simulation models colonization and extinction dynamics that determine species diversity on islands. By varying island size and distance, students observe how these factors influence species accumulation. This hands-on approach demonstrates population growth exponential logistic growth patterns and helps students understand why remote or small islands support fewer species than large, nearby islands.