Figure 14.

Male–male sexual competition enhances male competitiveness and male-induced harm. (A) Scanning electron micrograph of male C. elegans (Bar, 50 µm; picture by H.S. and A. Thomas). Sixty generations of experimental evolution under high male–male competition (indicated by High Comp., with three replicate lines called ABC) leads to increased sperm size (B) and thus male sperm competitiveness; to longer spicule insertion time (D) and thus mating duration; and also to increased killing of mated hermaphrodites (C). Graphs from Palopoli et al. (2015).