where the upper asymptote, c , is the distance from the initial
trait mean measured in standard deviations of the initial phenotype
distribution (at initialisation, VT = 1). We set
this to two across all simulations. The rate at which the environmental
suitability moves each generation is defined by a ’flattening constant’,m . An individual’s realised phenotypic value
(zi ) is referenced against this optimum value,vt, at each timestep to calculate the
individual’s fitness as a function of time.