Morphological Comparison of Southern Appalachian Brook Trout (Salvelinus fontinalis) Relegated to Allopatric Headwater Streams in Great Smoky Mountains National Park

Weathers, Thomas

Brook Trout (Salvelinus fontinalis) from geographically isolated headwater streams in Great Smoky Mountains National Park present an idealistic phylogenetic modeling opportunity to differentiate phenotypic relatedness. Through the configuration of a landmark truss network, shape analysis comprised of individual static landmarks allowed me to examine phenotypic variance of individual isolated Brook Trout populations. For this investigation, I analyze the affects sex, elevation, and flow aspects have upon morphomertics and meristics to Brook Trout populations from the French Broad/Pigeon Watershed. Here I examined twenty-three morphometric and ten meristic characters, constructed a landmark truss network for multiple statistical examinations. Minimal Polygon Clusters were generated by plotting the retained largest contributing Principle Components of variance from to illustrate phenotypic variance amongst populations. Analysis of Variance (ANOVA) was utilized to compare covariate means of retained Principle Components. Populations that did not exceed critical alpha values under ANOVA testing conditions of P < 0.05, for morphometric and meristic characters, were considered unique phenotypic polymorphisms. To further examine affects sex, elevation, aspect and locality had upon Brook Trout morphomertics and meristics; Nonmetric Multidimensional Scaling (NMDS) ordination plots were generated using PC-ORD™ 6 with greatest vectors of similarity influence. Lastly, phenotype characters where used to construct two cladograms used to disseminate phylogenetic relatedness of “southern Appalachian” Brook Trout populations from the French Broad/Pigeon Watershed. My findings indicate high variation in Brook Trout shape analysis as represented by low p-values (<0.0001 to 0.1267) from all ANOVA results. Meristic counts displayed greater continuity of outward expression similarities as represented by p-values ranging from (<0.0001 to 0.669) across all ANOVA results. Here I provide significant evidence that the observed shape variation of unblocked Brook Trout analyzed is an artifact of sexual dimorphism coupled with phenotypic plasticity. Thus resulting in Brook Trout from geographically isolated streams retaining similar but measureable divergent phenotypes presumably derived from no more than two common ancestral forms.