Abstrakt
With the rise of Mendelism the course of evolutionary biology was set for decades. The majority of evolutionary models are based on the assumption of particulate inheritance.
However, this does not necessarily apply to cultural evolution, which appears to be significant in our species. In our study we try to solve the conundrum of evolution in systems with non-particulate inheritance by using computer simulations.
In presented models we created a theoretical population consisting of individuals exhibiting a quantitative trait. In this population the individual fitness is computed as a difference between the trait value and a previously set optimum.
Surviving individuals pair at random giving rise to the next generation. The average trait value of offspring is equal to the parental average and individual descendants are normally distributed around this value.
Therefore a small proportion of them exhibit a higher or lower trait value than both of their parents. When Darwin came up with his theory, some objections against it were based on the assumption of blending (i.e. non-particulate) inheritance.
However, our results clearly show that non-particulate inheritance does not pose a problem for natural selection to be a constitutional evolutionary force. According to our simulations the variability among individuals rises when all of them are far from the hypothetical optimum which leads to higher impact of directional selection.
When the peak in adaptive landscape is reached by some individuals, the variability starts to decline and that heightens the stabilizing selection effect. This relationship may be crucial because even a minor initial variability could lead to an extreme variability in only a few generations, where natural selection can effectively operate on unevenly adapted entities/individuals.