Positive
Frequency-Dependent Selection
A plant species occurs in two
flower color forms (morphs), red and blue. Pollinator
insect species are attracted preferentially to the rarer,
standout morph, therefore, each morph has higher fitness
when rare (e.g., Wblue
2 while f(blue)
0 and Wred 1
while f(red) 1) [top].
[Bottom] Optimal population fitness occurs when both morphs
are maintained at intermediate frequency: any deviation is
corrected back towards the equilibrium. Positive
frequency-dependent selection stabilizes and maintains intra-population
variation.
Compare dynamics with
negative frequency-dependent selection in S&R2019
Fig 4.11.
[note to self: curves are backwards, swap 4.11
& 4.12 ?]