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Keywords:

  • marsupial;
  • mating behaviour;
  • sperm competition;
  • reproduction;
  • copulation;
  • Antechinus agilis

Abstract

Antechinus agilis mate within a 2–3 week, highly synchronized period each year, with copulation consisting of short bouts of thrusting interrupted by longer bouts of rest during which time the male remains mounted. In the laboratory, mating can last as long as 8–12 h without any break in intromission, with captive paired animals generally copulating once per day (Woolley, 1966a, b). The mating programme used in this study examines the effects on copulatory behaviour of changing: (1) timing of access relative to ovulation; (2) order of mating; (3) the delay between the first and second males' mating access. The total mount time was divided into quarters and the changes in behavioural patterns assessed by examining changes in the frequency of five key activities; thrusting, pelvic side-to-side movements, walking, female resistance, and dismounts. No significant differences were observed in the time from initial pairing to first mount regardless of mating order or time of mating, nor was the total time mounted significantly affected by mating order. Significant reductions in the total time mounted were evident, however, for those males mating closer to the time of ovulation. The behavioural strategies associated with copulation in A. agilis significantly enhance arguments for equality between males and females in determining overall mating strategies.