Table A1 . Parameters and varables used in the model.

Parameters
a, b	Selection coefficient against P elements through synergistic epistasis
d	Proportional reduction of P-element transposition rate in homozygotes of host beneficial allele
h	Dominance coefficient for host beneficial allele
u0	P-element transposition rate per copy per generation in dysgenic cross
u1	P-element transposition rate per copy per generation in nondysgenic cross
nHD	Maximum number of new P-element insertions an individual can tolerate before becoming completely sterile
Variables
n	P-element copy number in a given individual
m	Mean copy number of P element of parents
u	P-element transposition rate per copy per generation
δ	Proportional reduction of P-element transposition rate due to the host genotype
rt	Proportion of individuals with P cytotype in the population at generation t
lt	Allele frequency of the host beneficial allele in the population at generation t
μt	Average P-element copy number among individuals with P cytotype at generation t
${\bar{W}}_t$	Mean fitness of the population at generation t
s	Selection coefficient against host nonbeneficial allele