Walking Stick Head Width
Two measures of head width (head.width) for each of 25 walking sticks
(Timema cristinae).
A data frame with 50 observations on the following 2 variables.
a factor with levels 1-25
a numeric vector
Nosil, P. and B.J. Crespi. 2006. Experimental evidence that predation promotes divergence in adaptive radiation. Proceedings of the National Academy of Sciences (USA) 103: 9090-9095.
aggregate(head.width ~ specimen, data=WalkingStickHeads, mean) -> WS histogram(~ head.width, WS)
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