  It has recently been noted that the relative prevalence of the various kinds
of epistasis varies along an adaptive walk. This has been explained as a result
of mean regression in NK model fitness landscapes. Here we show that this
phenomenon occurs quite generally in fitness landscapes. We propose a simple
and general explanation for this phenomemon, confirming the role of mean
regression. We provide support for this explanation with simulations, and
discuss the empirical relevance of our findings.
