Models fit to TE polymorphism data.

Models containing the full set of independent variables and their second order interactions were fit to log-transformed population frequencies of polymorphic TE insertions (full models). For the reduced models, we started with the full model containing family (rather than order) as a factor, and dropped or retained independent variables using AIC as the criteria (reduced models), with either the recombination rate or the centromere proximal, normal recombining or telomere proximal regions (TEC) used to indicate recombination environment. In a separate analysis, we fit models to the subset of data from the 11 families with age estimates and more than 30 insertions. We started with all the terms in the full model (with order as the taxonomic level), as well as the rank age estimates and second order interactions with age. The terms in the models are indicated by ‘+’ in the table; terms not tested are indicated by ‘−’.