STRATEGIC PATERNITY ASSURANCE IN THE SEX-ROLE REVERSED EURASIAN DOTTEREL (CHARADRIUS-MORINELLUS) - BEHAVIORAL AND GENETIC-EVIDENCE

Sex role reversal in birds is usually associated with paternal care of both eggs and chicks. This pattern of Andrew Dixon care typically lea ds to the potential rate of reproduction of males being lower than tha t of females. Hence, operational sex-ratio theory predicts that each m ale should be under strong selection to avoid being cuckolded. A male should, therefore, guard his female partner(s) from extrapair copulati on attempts by other males. Furthermore, the sexual conflict theory of copulation behavior predicts that in species with extensive paternal care the male should control the temporal pattern of copulations-copul ations should occur both frequently and throughout the prelaying perio d. We tested these predictions in the Eurasian dotterel (Charadrius mo rinellus), in which the male usually provides all the parental care. I n accordance with the first prediction, male dotterels did ''guard'' t heir pair-female prior to egg-laying. Contrary to the second predictio n, however, copulations were not frequent and did not occur throughout the pre-laying phase-despite frequent solicitation by the female, cop ulations only occurred immediately prior to egg-laying. Nevertheless, male-initiated courtship was both coincident with the pattern of copul ations and more likely than female-initiated courtship to result in co pulation. Our results do, therefore, appear to agree with the central prediction of the sexual conflict theory that males should control the pattern of copulations. We suggest that male dotterels will copulate only after several days of being paired because they face a duel risk of cuckoldry from both extrapair copulation and rapid mate switching. We tested the realized incidence of cuckoldry using DNA fingerprinting . Only 4.6% (2/44) of chicks were not the genetic offspring of the car ing male corresponding to 9.1% (2/22) broods affected. The rate of ext rapair paternity in the dotterel is, therefore, relatively low compare d to that in many other avian species. We conclude that male dotterels successfully protect their paternity of the brood for which they care through a combined strategy of mate guarding and strategic timing of copulations.