Table 1. Previous studies that have identified signatures of positive selection in the Drosophila piRNA machinery.

Study	Species	Test of Neutrality	Genes w/significant tests	Genes w/non-significant tests
Lee and Langley [44]	mel and/or sim	MK test	armi, aub, krimper, spn-E, vasa	ago3, hen1, mael, piwi, rhino, squash, zuc
Vermaak et al. [45]	mel, sim	Sliding window dN/dS, MK test	rhino	N/A
	mel to pseudo	PAML: M1 vs M2, M7 vs. M8	rhino	N/A
Lewis et al. [46]	Nematocera, Brachycera	PAML: M8a vs M8	N/A	ago3, piwi/aub
Heger and Ponting [47]	mel, sim, yak, ere, ana	SLR	spn-E	N/A
Obbard et al. [49]	mel, sim	MK test	aub, armi	N/A
Kolaczkowski et al. [50]	mel	SweepFinder	armi, aub, hen1, piwi, rhino, spn-E, squash, zuc	ago3, krimper, mael
	12 species	PAML: Branch-sites	aub, krimper, spn-E, squash, zuc	ago3, armi, mael, hen1, piwi, rhino
Obbard et al. [48]	mel, sim	MK test	armi, aub, piwi, mael, spn-E	ago3, zuc, squash, hen1, krimper
Simkin et al. [52]	mel	Polymorphism	aub, armi, rhino, spn-E, vasa, zuc	ago3, krimper, piwi, squash
	mel,sim	MK test	aub, armi, krimper, spn-E, vasa	ago3, piwi, rhino, squash, zuc
	mel, sim, sech, yak, ere, ana	PAML: M7 vs. M8	ago3, aub, piwi, rhino	armi, krimper, spn-E, squash, vasa, zuc