Female accessory gland fluid promotes sperm survival in yellow dung flies

Female and male reproductive traits co-evolve through pre- post-copulatory sexual selection conflict. Although males typically transfer many sperm during copulation, only a small proportion reach the fertilization site because females often actively or passively reduce number in their tract. Males may accessory substances to protect ejaculates against female selective processes, which benefits but can harm females. In turn, use gland fluids control paternity storage. yellow dung flies ( Scathophaga stercoraria ) have paired glands that produce involved egg laying. One proposed function for these is spermicide. Alternatively, fluid help keep alive avoid failure encourage competition. Using flies, we investigated interaction of with vitro . Significantly more remained when exposed compared buffer (63% vs. 44%). We conclude nourish rather than kill sperm, although nourishment as consistent cryptic choice