PATERNITY DISPLACEMENT IN THE GRASSHOPPER EYPREPOCNEMIS-PLORANS

Three types of double crosses were carried out to investigate sperm co mpetition in the grasshopper Eyprepocnemis plorans. Maximum likelihood estimation of paternity probability showed a high degree of second ma le sperm precedence (P2 = 90%). The results also showed that: (i) a si ngle copulation may be enough for an efficient paternity displacement; (ii) males do not use sperm plugs, but they mate for a prolonged peri od of time to resist further copulation; and (iii) successive paternit y displacements may be seen in the same female. The mechanisms control ling sperm competition in E. plorans, and the evolutionary implication s of this phenomenon are discussed.