A MICROSATELLITE ASSESSMENT OF SNEAKED FERTILIZATIONS AND EGG THIEVERY IN THE FIFTEENSPINE STICKLEBACK

Attempts by males to steal fertilizations from other males are common in many species. In some sticklebacks, males also are known to steal e ggs from the nests of rivals and to carry them back to their own nests . However, the genetic consequences of these nest-raiding behaviors se ldom have been investigated. Here we assess genetically the prevalence of sneaked fertilizations and egg stealing, and we describe the matin g system in a natural population of the fifteenspine stickleback. Six microsatellite markers were developed and employed to assay a total of 1307 embryos from 28 nests. Guardian males and all nest-holding males in the local area also were genotyped for two to six loci. Analysis o f male genotypes and those of embryos revealed that five of the 28 nes ts (18%) contained progeny from sneaked fertilizations, and that four of the 24 nests (17%) with resident males contained stolen egg clutche s. Comparisons of the composite DNA genotypes of nest-holding males ag ainst those of inferred sneakers implicated one nest holder as the sne aker of a nest seven meters from his own. Also, the genetic data demon strated that nests of males frequently contain eggs from multiple fema les. The multilocus genotypes of inferred mothers indicated that femal es mate with multiple males, sometimes over distances greater than one kilometer.