PRF/J: A Molecular Systematic Study of Chromosomal, Phytochemical, and Morphological Evolution in Calycadenia (Asteraceae)

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Molecular studies of phenotypic evolution within the Californian-endemic, annual genus Calycadenia are proposed. Unusual and well-resolved patterns of chromosomal, flavonoid, and morphological evolution among these ca. 12 species and 30 races or forms make Calycadenia a model system for examining questions of broad systematic significance. Integrated chloropast DNA and nuclear DNA restriction site polymorphism analyses are proposed to determine patterns and relative timing of evolutionary divergence of these taxa and accompanying phenotypic characters. Issues addressed by this study would include (1) the role of selection in chromosome evolution, (2) the relationship between evolutionary divergence and chromosome pairing, (3) the extent of evolutionary parallelism in complex anatomical features, (4) the possible origin from within Calycadenia of two highly-distinctive monotypic genera (Osmadenia and Blepharipappus) and their accompanying suites of unique phenotypic characters, and (5) the taxinomic validity of a proposed-endangered species, C.fremontii. This study would be among the first to integrate extensive phylogenetically-informative data from cytogenetics, phytochemistry, and morphology with evolutionary data from diverse nucleotide sequences in both chloroplast and nuclear DNA. Preliminary chloroplast DNA restriction site data revealed an ideal level of interspecific variation for conducting molecular phylogenetic analysis in this group. //