Table 1

Parameters and variables used in this study.

w

Individual fitness

r

Relatedness between any two randomly selected individuals in the group

s

Individual cost to cooperator growth in the group

k

Number of individuals in a group (an inverse measure of kin selection)

c

Individual cost to cooperator dispersal

e

Individual cost to cheater dispersal

Q

Impact of sedentary cheaters on the individual fitness of group members (via consumption of the public good)

P

Impact of sedentary cooperators on the individual fitness of group members (via production of the public good)

n

Relative frequency of cooperators in the group (1-n is the proportion of cheaters)

z

Relative frequency of cheaters dispersing

y

Relative frequency of cooperators dispersing

d

Overall investment in dispersal. d = yn + z(1-n)

Φ

Overall cooperation with respect to the public good. Φ = n*(1-y*)+(1-n*)z*

σ

Association between dispersal and cooperation. σ = y/(y+z)

Hochberg et al. BMC Evolutionary Biology 2008 8:238   doi:10.1186/1471-2148-8-238