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This is a model about showing various movements of turtles and comparing them by how much height they travel...the turtle with the most height in total/highest average height wins!

The real-life context of this model could be of different variations on motion in hiking or some other outdoor adventure sport.

Start out with no predators. This will show the same trends as in the Non-Selective version.

Now add a predator (or predators)- how do predators affect the mean and distribution of trait values? How do they affect diversity?

This demonstrates selection. Prey with higher trait values are more likely to survive long enough to reproduce. This creates a shift in the trait value distribution toward the higher end of the range and increases the mean value. It also creates a slight drop in diversity, as a disproportionate number of prey have high trait values.

Try again with more predators. Does selection happen faster? Using the TRAIT-VALUE-DISTRIBUTION chooser, set up two populations with different initial trait values. Is one favored? Do they evolve at the same rate?

Note that mean trait values never stabilize all the way at the maximum value, as you might expect. This is due to the right-wall effect (some offspring of prey with a trait value of 9 will die, as they

To start, the model has the SETUP MODEL button which initializes the model. The height of the highest peak (maxheight) is random every time.

There is a slider button that says NUMBER, meaning the number of peaks that are generated when you SETUP MODEL. Slide the bar back and forth to eiher decrease or increase the number of peaks.

The START MODEL (1-STEP) button moves the model through one 'tick' of progress.

The START MODEL (INFINITE) button moves the model continously.

A HEIGHT OF THE HIGHEST PEAK monitor is given for the observer.

TURTLE 1 TOTAL HEIGHTS REACHED is a monitor which states the (increasing) sum of heights that Turtle 1 travels at each peak. The same goes for TURTLE 2 TOTAL HEIGHTS REACHED.

TURTLE 1 AVG is a monitor that gives the average of total height traveled divided by the ticks progressed. The same goes for TURTLE 2 AVG.

Finally, there is some graphical representation of the data collected. Two graphs are shown on the interface: 'turtle1' graph which plots ticks on the x axis and the height traveled at each respective tick on the y axis. The same design applies to the 'turtle2' graph.