Methods  DNA was isolated from blood samples collected at four separate locations.  Samples were Nanodropped to ensure proper concentrations of DNA.  PCR reactions were run using eight different microsatellite loci with fluorescent-labels (neutral genetic markers).  Gel electrophoresis was used to confirm a successful PCR reaction.  Genotyping was performed by Iowa State University DNA facility and scored using Genemapper.  Population parameters were calculated using Arlequin, Genepop, Genalex, and Structure.  In testing each locus for Hardy Weinberg equilibrium, locus TelCa3 was dropped from the project. Results  A total of 88 samples were successfully genotyped. (see Table 1)  One locus was dropped from analysis because it was out of Hardy Weinberg equilibrium in all four populations.  In comparing levels of genetic diversity, Stones (ST) had the lowest heterozygosity and fewest alleles.  Fst values were significantly different among many locations. Stones had the most genetic divergence. (Table2) Conclusions  We found significant genetic structure among the four populations.  This structure was significant within the lake as well as between Lake and Meadow locations.  The degree of structure was similar to the previous study on other locations around Eagle Lake.  Of the four populations, Stones is the most genetically distinct and also has the least genetic diversity. Future Directions 1.Extend the study to include four additional locations. 2.Determine if multiple paternity is present in garter snakes, and if so, to what extent. 3.Determine if the degree of multiple paternity in the studied populations of garter snakes is strongly linked to the life history traits defined by the differing ecotypes. Population genetics in western garter snakes Courtney Wolken¹, Megan Manes², Tonia Schwartz², Anne Bronikowski² ¹Newton High School, Newton, IA ²Department of Ecology, Evolution, and Organismal Biology Iowa State University, Ames, IA Literature cited 1.Manier, M.K. and Arnold S.J Ecological correlates of population genetic structure: a comparative approach using a vertebrate metacommunity.. Proc. R. Soc. B 2.Uller, T. and Olsson M Multiple paternity in reptiles: patterns and processes. Molecular Ecology Bronikowski, A. and Arnold S The evolutionary ecology of life-history variation in the garter snake Thamnophis elegans. Ecology 80. Acknowledgements  NSF Plant Genome Research Program  homepage.html Questions Previous research has identified morphological and physiological differences between the ecotypes (Lakeshore versus Meadow), based on common garden experiments. This variation has both a genetic and environmental basis. We address the following questions as the first step to understanding the genetic basis for these differences. 1.Do the populations vary in their amount of genetic diversity? 2. Are the populations genetically different? Introduction Eagle Lake, California provides habitats for two different ecotypes of terrestrial Gartner snake, Thamnophis elegans. Based on location they have evolved differing life history traits. Lakeshore ecotype: fast growth, early maturation, short lifespan, found at low elevations Meadow ecotype: slow growth, late maturation, long lifespan, found at higher elevations. sitecodeecotype sample size observed heterozygosity average # of alleles SummitSMM StonesSTL MerrillMLL GallatinGAL Mountain Meadow Lakeshore MLSTSMGA ML ST0.061** SM ** GA ***0.048*** Fig. 2. Graphical representation from Structure. SM ST ML GA Fig. 1: (TOP) Ecotypes of garter snake found at Eagle Lake. The checkered snake represents the Lake Shore ecotype, the black and yellow striped snake represents the Meadow Ecotype. (BOTTOM) Map of locations in the study. Red dots denote the lakeshore locations the blue dot denotes the mountain meadow location. ML GAL ST SM Table 2 Pairwise Fst values: ** indicates P-value < 0.01; *** indicates P-value <  Using Bayesian statistics, the program Structure was able to group the individuals into genetic populations (Fig. 2). Table 1. Sites, codes, ecotypes, sample sizes, and measures of genetic diversity for the studied locations. Ecotype refers to the habitat and snake phenotype. L denotes a Lakeshore habitat, M denotes a Meadow habitat