How did rainbow smelt invade the Great Lakes? Testing Bergstedtâ€™s 1983 multipleintroduction hypothesisNick Sard1, Yue Shi2, Brian Weidel3, and Wes Larson21 Biological Sciences Department, SUNY Oswego, Oswego, New York 2 Wisconsin Cooperative Fishery Research Unit, College of Natural Resources, University of Wisconsin Stevens Point, Stevens Po int, Wisconsin 3 United States Geological Survey, Great Lakes Science Center, Lake Ontario Biological Station, Oswego NY, 13126Backgroundâ€¢Some invasive species rapidly adapt to novel environments despite associated founder effects during the initial colonization phase.1â€¢P ossible if sufficient genetic variation is generated (e.g., via multiple introductions ).2â€¢In the Great Lakes, rainbow s melt (Osmerus mordax ) originally invaded Lake Michigan following unintended migration from a stocked population in Crystal Lake.â€¢R emaining Great Lakes were subsequently colonized in a r elatively sequential order.3â€¢First observation of r ainbow smelt in Lake Ontario was six years prior to that of Lake Erie.â€¢Lake Ontario may have been established by an anadromous strain originally stocked into the Finger Lakes.4â€¢Evidence for the rapid evolution of distinct, semelparous and iteroparous, rainbow smelt ecotypes in Canadian lakes.5â€¢This invasion provides a natural experiment to test if multiple introductions occurred and if so, to investigate the potential evolution of different ecotypes.Objectivesâ€¢Determine if Lake Ontario was founded independently from the upper Great Lakes.â€¢Test for outlier loci that may be associated with adaption.General methodsâ€¢Extracted and normalized DNAs from rainbow smelt collected from Lake Superior (n=18), Lake Michigan (n=24), Lake Huron (n=21), Lake Erie (n=24), and Lake Ontario (n=43).â€¢Prepared restrictionsite associated DNA libraries.6â€¢Sequenced libraries on a HiSeqX and data processed with STACKS.7â€¢A total of 13,186 single nucleotide polymorphisms (SNPs) were genotyped.â€¢SNPs were used to characterize genomic variation within and among collections.â€¢Within â€“ estimated heterozygosity, private sites, segregating sites, and FIS.â€¢Among â€“ estimated pairwise FST,principle components analysis (PCA).Preliminary results1) Genetic variation in collections supports the multiple-introduction hypothesis for Lake Ontarioâ€¢Expected heterozygosity among all collections were similar.â€¢Lake Ontario had the highest number of private sites.â€¢Negative FISin Lakes Ontario and Erie may indicate outbreeding.Future workâ€¢Perform a meristic and geometric morphometric analysis of rainbow smelt heads collected from Lake Ontario.â€¢Create a genotyping by sequencing panel to genotype more rainbow smelt from within Lake Ontario.â€¢Map loci against the E uropean s melt g enome.References1.Roman, J. and Darling, J.A., 2007. Paradox lost: genetic diversity and the success of aquatic invasions. Trends in ecology & evolution, 22(9), pp.454 -464.2.Brown, J.E. and Stepien, C.A., 2009. Invasion genetics of the Eurasian round goby in North America: tracing sources and spread patterns. Molecular Ecology , 18(1), pp.64 -79.3.Emery, L. 1985. Review of fish introduced into the Great Lakes, 1819 -1974. Great Lakes Fishery Commission Technical Report, volume 45.4.Bergstedt , R.A., 1983. Origins of rainbow smelt in Lake Ontario. Journal of Great Lakes Research, 9 (4), pp.582 -583.5.Saint -Laurent, R., Legault , M. and Bernatchez , L., 2003. Divergent selection maintains adaptive differentiation despite high gene flow between sympatric rainbow smelt ecotypes ( Osmerus mordax Mitchill ). Molecular Ecology , 12(2), pp.315-330.6.Ali, O.A., Oâ€™Rourke, S.M., Amish, S.J., Meek, M.H., Luikart , G., Jeffres , C. and Miller, M.R., 2016. RAD capture (Rapture): flexible and efficient sequence -based genotyping. Genetics , 202(2), pp.389 -400.7.Catchen , J., Hohenlohe, P.A., Bassham , S., Amores , A. and Cresko , W.A., 2013. Stacks: an analysis tool set for population genomics. Molecular ecology , 22(11), pp.3124-3140. AcknowledgementsWe thank Tim Oâ€™Brian, USGS, for collecting rainbow smelt tissue samples from Lake Huron. We also thank Chelsea May , OMNRF, for collecting tissue samples from Lake Erie. Finally, SUNY Oswegoâ€™s Faculty Scholarly and Creative Activity Grant for funding the library preparations for this project.2) Pairwise estimates of genetic differentiation suggest Lakes Ontario and Erie are distinct from other Great Lakesâ€¢Comparisons among Lakes Superior, Michigan, and Huron suggested genetic differentiation was small (01%).â€¢Lakes Ontario and Erie were 56% different from the other Great Lakes.3) Multivariate statistics corroborate results based on population genetics theoryâ€¢PC1 clearly separated Lake Ontario and Lake Erie from Lakes Superior, Michigan, and Huron.â€¢PC2 separated Lake Superior from Lakes Huron and Michigan.Table 1. Summary statistics describing genetic variation observed in rainbow smelt within each Great Lake. Figure 3 . Principle Components Analysis using 13,186 SNPs genotyped in rainbow smelt collected from all five Great Lakes. Figure 2 . Pairwise FSTestimates among Great Lakes collections of rainbow smelt. Figure 4 . Principle Components Analysis of 13,186 SNPs genotyped in rainbow smelt collected from Lakes Ontario and Erie. Want to learn more? Check out my websiteCorresponding author: n email@example.com Lake HepS S F IS Ontario 0.244 73 11835 0.03 Erie 0.249 32 11455 0.02 Huron 0.236 13 11086 0.00 Michigan 0.232 22 11245 0.00 Superior 0.233 52 10539 0.00 Heâ€“ expected heterozygosity; pS â€“ number of private sites; S â€“ number of segregating sites; and FISâ€“ Wrightâ€™s inbreeding coefficient4) Most samples from Lakes Ontario and Erie cluster togetherâ€¢PCA of just Lake Ontario and Lake Erie samples indicated a few Lake Ontario individuals were different. Figure 1 . Map of first sightings of rainbow smelt in each Great Lake.