Research is exploring the complex interactions between sperm competition and postmating female mortality, with studies investigating various factors such as sperm viability, genetic factors, and seminal fluid proteins. The studies involve different species, including Drosophila, lamprey, and Chinook salmon, and examine the effects of sperm competition on female fertility and mortality. The findings suggest that multiple factors, including genetic compatibility and sexual selection, may influence the outcomes of sperm competition and female postmating mortality.