Influence of alternate reproductive tactics and pre- and postcopulatory sexual selection on paternity and offspring performance in a lizard
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Sexual selection theory predicts different optima for multiple mating in males and females. We used mating experiments and genetic paternity testing to disentangle pre- and postcopulatory mechanisms of sexual selection and alternate reproductive tactics in the highly promiscuous lizard Eulamprus heatwolei. Both sexes mated multiply: 30–60 % of clutches were sired by two to four fathers, depending on the experiment. Larger males sired more offspring when we allowed male contest competition: 52 % of large males but only 14 % of small males sired at least one offspring. In the absence of male contest competition, females mated promiscuously and there was no large male advantage: 80 % of large males and 90 % of small males sired at least one offspring, and there was no evidence for last-male precedence. Multiple mating did not yield obvious direct or indirect benefits to females. E. heatwolei represents a complex system in which males attempt to improve their fertility success by limiting rivals from access to females and through adopting alternate reproductive tactics. Conversely, females exhibit no obvious precopulatory mate choice but may influence fitness through postcopulatory means by either promoting sperm competition or through cryptic female choice. Our results support the hypothesis that female multiple mating in nonavian reptiles is best explained by the combined effect of mate encounter frequency and high benefits to males but low costs to females.
KeywordsMating system Reproductive success Sexual selection Polygynandry Promiscuity Behavior Lizard
We are indebted to Megan Head and Paul Doughty for their help with the field and experimental work and Christine Hayes, Ian Scott, and Matt Morgan for their help with the molecular lab work. This research was supported by an Australian Research Council grant to JSK.
All work was with the approval of the Australian National University Animal Experimentation Ethics Committee (F.BTZ.01.99) and with research permits from Environment ACT (permit number LT1999008).
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