Abstract

Behavioral observations have suggested that Channel Catfish, Ictalurus punctatus, spawn as monogamous pairs and that males alone provide subsequent care to the resulting embryos and fry. However, genetic monogamy is quite uncommon in fish and is not necessarily correctly predicted by apparent social interactions. Here we develop and employ seven microsatellite loci to address biological parentage and the genetic mating system in a natural population of I. punctatus. A total of 175 progeny and their respective attendant males were genotyped from five nests. Results indicate that each male had mated with only one female in his nest. Additionally, one nest contained a second group of full sibs unrelated to the attendant male and his mate who proved to be the biological parents of all other progeny within that nest. This instance probably represents either a case of nest piracy by the attendant male or perhaps our inadvertent sampling of progeny from two closely adjacent nests. In any event, our findings help confirm a rare suspected example of genetic monogamy in a fish species with uniparental offspring care.