The Use of Fluorescent Randomly Amplified Polymorphic DNA Markers to Identify Hybrids: A Case Study Evaluating the Origins of Saugeye following the Cessation of Stocking in an Ohio Reservoir

Abstract

Hybridization and introgression continue to gain recognition as important issues in the management and conservation of native fishes. It is often necessary to identify hybrids in natural populations and to distinguish among individuals of various hybrid categories. Molecular methods are important for these purposes, and it is valuable if researchers have a range of molecular methods to apply, since each method has unique advantages and disadvantages. The determination of the best class of marker for a particular study depends on various factors, including the goals of the study, the resolution required, and the genomic and marker information already available for the taxa of interest. We modified a protocol to generate fluorescent randomly amplified polymorphic DNA (FRAPD) markers for hybridization studies. To our knowledge, this type of marker has not previously been used for hybrid identification. To demonstrate the utility of the modified methods, FRAPD markers were used to evaluate potential reproduction by saugeye (female walleye Sander vitreus × male sauger Sander canadensis) in a central Ohio reservoir. Our approach successfully generated a battery of diagnostic genetic markers that were used to test the hypothesis that young-of-year saugeye were later-generation offspring of saugeye cohorts previously stocked into the reservoir. Alternatively, the fish may have been immigrant first-generation saugeye from other sources. Data obtained from the FRAPD markers provided strong support favoring the alternative hypothesis. These methods provide a very useful tool for distinguishing between pure parentals and various classes of hybrid individuals, both in Sander spp. and in other taxa, offering a powerful and easily developed alternative to other molecular methods of generating informative genetic markers for hybridization studies.

Received September 20, 2011; accepted April 5, 2012

ACKNOWLEDGMENTS

Funding for this project was provided by the Sport Fish Restoration Project. We thank the Ohio Division of Wildlife and the Ohio River Valley Water Sanitation Commission and Dylan Sickles of the Indiana Department of Natural Resources East Fork State Fish Hatchery for field assistance and both Kevin Page and Rich Zweifel for helpful comments and discussions pertaining to this study.