AUTHORS: Alexandra Johnson, South Dakota State University Department of Natural Resource Management; Hannah Mulligan, South Dakota State University Department of Natural Resource Management; Amber Ruskell-Lamer, Southeastern Community College; Jim Lamer, Illinois Natural History Survey; Alison A. Coulter, South Dakota State University Department of Natural Resource Management
ABSTRACT: The invasive bighead and silver carp are known for their ability to quickly establish new populations in naive water bodies. Determining cost effective and efficient management strategies for managing these carp can reduce populations and improve ecosystem health. At low density areas (i.e., invasion fronts), silver carp and bighead carp readily hybridize and produce offspring with enhanced survival and dispersal capabilities. However, subsequent hybrid generations display reduced body condition which may prevent them from invading new areas. Understanding the hybridization of silver and bighead carp can therefore provide insights to their spread and subsequently allow for more efficient use of management resources. Genetic testing is costly, and therefore determining how many hybrids exist in a location may be hindered by available resources. The objectives of this research are to 1) Use photographs to analyze body shape differences among bighead carp, silver carp, and their hybrids via geometric morphometrics and 2) Use correlated genetic and morphologic data to create a classification system to determine the hybrid type from body shape. Morphometric photographs of 2,795 bighead and silver carp with varying degrees of hybridization have been collected and genetically analyzed for hybrid type. In a subset of photographs per genetic group (silver, bighead, hybrid), we will place a series of landmarks on different body features using the program TpsDig2. The distances between landmarks will then be imported into MorphoJ software to quantify the body shape of each individual (known as geometric morphometric analysis). The geometric morphometric data paired with the results from the genetic analysis will then be used to create a classification tree that groups genetic types based on body shape. Results will ultimately identify whether morphology can be used to distinguish hybrid types which can help to reduce resource limitations for managing these invasive species.
