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 paternalcare of both eggs and chicks. This pattern of care typicallyleads to the potential rate of reproduction of males being lowerthan that of females. Hence, operational sex-ratio theory predictsthat each male should be under strong selection to avoid beingcuckolded. A male should, therefore, guard his female partner(s)from extrapair copulation attempts by other males. Furthermore,the sexual conflict theory of copulation behavior predicts thatin species with extensive paternal care the male should controlthe temporal pattern of copulations—copulations shouldoccur both frequently and throughout the prelaying period. Wetested these predictions in the Eurasian dotterel (Charadriusmorinsllus), in which the male usually provides all the parentalcare. In accordance with the first prediction, male dotterelsdid "guard" their pair-female prior to egg-laying. Contraryto the second prediction, however, copulations were not frequentand did not occur throughout the pre-laying phase-despite frequentsolicitation by the female, copulations only occurred immediatelyprior to egg-laying. Nevertheless, male-initiated courtshipwas both coincident with the pattern of copulations and morelikely than female-initiated courtship to result in copulation.Our results do, therefore, appear to agree with the centralprediction of the sexual conflict theory that males should controlthe pattern of copulations. We suggest that male dotterels willcopulate only after several days of being paired because theyface a duel risk of cuckoldry from both extrapair copulationand rapid mate switching. We tested the realized incidence ofcuckoldry using DNA fingerprinting. Only 4.6% (2/44) of chickswere not the genetic offspring of the caring male correspondingto 9.1% (2/22) broods affected. The rate of extrapair paternityin the dotterel is, therefore, relatively low compared to thatin many other avian species. We conclude that male dotterelssuccessfully protect their paternity of the brood for whichthey care through a combined strategy of mate guarding and strategictiming of copulations.