Parentage and nest guarding in the Tessellated Darter (Etheostoma olmstedi) assayed by microsatellite markers (Perciformes : Percidae)

parental investment as manifested through extended parental care of young p resumably enhances the reproductive success of the custodial parent. In the Tessellated Darter (Etheostoma olmstedi), the primary caregivers are breed ing males on the nest. However, prior field observations on nesting darters seem suggestive of behaviors that are more difficult to interpret evolutio narily. These include tending clutches that may have been fertilized by oth er males and appropriating nests from smaller courting males. To address su ch possibilities genetically, we assayed six microsatellite loci in 16 nest -tending males and the embryos from their associated clutches. In most case s, a guardian male had shed nearly all of the embryos in his nest. However, in one nest, a guardian male had been cuckolded, and in two other nests, a n attendant male guarded embryos that were not his own presumably resulting from nest takeovers. From direct genotypic counts, a mean of at least 3.2 mothers contributed to the progeny in a nest, and computer simulations sugg est that the true maternal number may be substantially higher.