Polyploidy is an important factor in the evolution and ecology of flowering plants. A better understanding of the kind and degree of morphological differentiation among ploidy levels within a species can help explain further how polyploidy affects biodiversity. How widespread is the impact of ploidy across the phenotype of a species? Which aspects of morphology vary, and do they vary consistently? How does ploidy relate to overall morphological diversity? Do ploidy levels have detectable phenotypic profiles? Finally, are there morphological differences between populations, potentially due to environment or evolutionary changes since formation apparent in natural populations? I assessed morphological variation within Arizona phlox, Phlox amabilis. This species of conservation concern is endemic to Arizona, and prior work has detected diploid, tetraploid, and hexaploid populations. I sampled 11 populations of P. amabilis, covering a large portion of the species’ range. A wide array of morphological features, including characters that described cell size, overall habit, leaf dimensions, and floral dimensions, were measured for up to 25 plants at each population. Significant differences were detected in 15 out of 27 characters using mixed GLM. A large amount of overall morphological variation is explained by the differences between ploidy levels, and each ploidy level can be described by a specific multivariate phenotype with 95% accuracy. Finally, although overall structuring was influenced by ploidy, differences among populations still contributed a high degree of variation in the morphospace of Phlox amabilis. This morphological assessment will be integrated with ecological and genetic data to build a more complete understanding of the interplay between these factors and ploidy in Phlox amabilis.
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