LEKKING WITHOUT A PARADOX IN THE BUFF-BREASTED SANDPIPER

Females in lek-breeding species appear to copulate with a small subset of the available males. Such strong directional selection is predicte d to decrease additive genetic variance in the preferred male traits, yet females continue to mate selectively, thus generating the lek para dox. In a study of buff-breasted sandpipers (Tryngites subruficollis), we combine detailed behavioral observations with paternity analyses u sing single-locus minisatellite DNA probes to provide the first eviden ce from a lek-breeding species that the variance in male reproductive success is much lower than expected. In 17 and 30 broods sampled in tw o consecutive years, a minimum of 20 and 39 males, respectively, sired offspring. This low variance in male reproductive success resulted fr om effective use of alternative reproductive tactics by males, females mating with solitary males off leks, and multiple mating by females. Thus, the results of this study suggests that sexual selection through female choice is weak in buff-breasted sandpipers. The behavior of ot her lek-breeding birds is sufficiently similar to that of buff-breaste d sandpipers that paternity studies of those species should be conduct ed to determine whether leks generally are less paradoxical than they appear.