Abstract
Cultural traits lack the phenotype-genotype duality of biological systems and can be of a non-particulate nature. However, several objections are questioning the validity of selection in systems with non-particulate inheritance.
Consequent to this, the majority of models of cultural evolution employ discrete traits. Here, using computer simulations, we studied adaptation in systems with non-particulate inheritance.
Our models are based on theoretical population consisting of individuals exhibiting a non-particulate quantitative trait. Survival and reproductive success of an individual was set to be dependent on the difference between the trait value and the previously set optimum.
Individuals paired at random gave rise to the next generation. The average trait value of offspring was equal to parental average trait value; individual descendants were normally distributed around this value.
A small proportion of them therefore exhibited a higher/lower trait value than both of their parents. According to our simulations, the variability between individuals rises when the population is far from the optimum and declines rapidly when the peak in adaptive landscape is reached by some individuals.
These patterns emerge regardless of most model parameters. However, we also observed that a population stabilized around a certain suboptimal value, when the effects of directional selection were outweighed by decreasing variability caused by small proportion of offspring exceeding parental trait range.
Our results convincingly show that non-particulate inheritance does not constitute a major problem for adaptation by the means of selection.