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. Author manuscript; available in PMC: 2013 Aug 1.
Published in final edited form as: Evolution. 2012 Apr 16;66(8):2484–2497. doi: 10.1111/j.1558-5646.2012.01630.x

Figure 1. The diversity of altruistic strategies and their evolutionary response to model parameters.

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Survival altruism (solid black line), fecundity altruism (solid gray line), resource-enhancement altruism (dashed black line), and resource-efficiency altruism (dashed black line), with survival trade-offs (fecundity trade-offs not shown). The horizontal dotted line at Selection Gradient = 0.04 is the value for (br − c), which is “Hamilton’s rule” for survival or fecundity altruism in the absence of resource competition. Note that resource-enhancement and resource-efficiency altruism have identical first order effects on fitness, which is why the plots show three instead of four curves. Column 1 gives results for Type I functional responses (x = 1, y = 0), Column 2 for Type II responses (x = 1, y = 1), and Column 3 for Type III responses (x = 2, y = 1). Note also that fecundity altruism cannot evolve under these parameter values with a Type I response, so that a gray line does not appear in Column 1. Parameter values for all curves are b = 0.1, c = 0.01, and r = 0.5. Unless used as the independent variable for a given graph, the remaining parameter values are S = v = f = TD = 0.5.