upolu males rare 2005, common 2007. 2006- 21 m and 33 f in Savaii. 14 f- all produced male progeny, 2006 1:1. 2001- 3/64 had males. lack of male killing in 2006 as there was a high egg hatch rate. 2006- salelologa, close to upolu, 1:1 nearly complete, no heterogeneity btw broods, high egg hatch rate. sagone- shift more incomplete, distant from upolu, 3/6 no sons, median egg hatch rate 77%. previous strain not replaced- host suppressor genes. mutation spread fast. gene rescues males. when males uncommon, females mate more.