We examine an analytical model of selection against the deleterious effects of transposable element
(TE) insertions in Drosophila, focusing attention on the asymptotic and dynamic characteristics.
With strong selection the only asymptotically stable equilibrium point corresponds to extinction of
the TEs. With very weak selection a stable and realistic equilibrium point can be obtained. The
dynamics of the system is fast for strong selection and slow, on the human time scale, for weak
selection. Hence weak selection acts as a force that contributes to the stabilization of mean TE
copy number. The consequence is that under weak selection, and ‘out-of-equilibrium’ situation can
be maintained for a long time in populations, with mean TE copy number appearing stabilized.