Following tetraploidy in an Arabidopsis ancestor, genes were removed preferentially from one homeolog leaving clusters enriched in dose-sensitive genes

^aNumber of non-retained genes in the a or b homeolog.

^bFractionation bias as the ratio of the homeolog with the greater number of non-retained genes over the other homeolog of the pair.

^cTwo-tailed negative binomial probability of getting the observed fractionation bias under the assumption that the expected is the bias of 1 (equal gene loss from either homeolog), where ***, **, and * are as in Table 1.

^dEvery gap size from one to 20 was used to tabulate the occurrence of gaps on either the longer a homeolog (Gaps on a) or shorter b homeolog (Gaps on b).

^eRepresents the two-tailed negative binomial probability of getting the observed gaps, where ***, **, and * are as in Table 1.