Widespread evidence for horizontal transfer of transposable elements across Drosophilagenomes

Table 2 Estimates of the fraction of orthologous TE families that display significantly lower K_S values than expected assuming vertical transmission and near-neutrality of synonymous sites

	Dm-Dy	Ds-Dy	Dm-Ds	Pooled
LTR RTs
low K_S	14.0	6.0	13.0	33.0
N	30	18	32	80.0
F	0.47	0.33	0.41	0.41
Non-LTR RTs
low K_S	1.0	0.0	1.0	2.0
N	12	9	13	34.0
F	0.08	0.00	0.08	0.06
DNA-transposons
low K_S	0.0	1.0	1.0	2.0
N	1	1	3	5.0
F	0.00	1.00	0.33	0.40
Pooled across TEs
low K_S	15.0	7.0	15.0	37.0
N	43	28	48	119.0
F	0.35	0.25	0.31	0.31

Dm-Dy: between-species pairwise comparisons of insertions that belong to orthologous families from D. melanogaster and D. yakuba, and so on. Low K_S: numbers of families that display a level of synonymous divergence (K_S) lower than the 2.5% quantile of the distribution of K_S values for the nuclear genes of the hosts. N: number of orthologous families analyzed. F: fraction of families with lower K_S than expected under neutral assumptions.

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