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Clarkia xantiana (Onagraceae)

The major focus of research in my lab concerns the evolutionary ecology of reproduction, life history and geographic distribution in the California “wildflower” Clarkia xantiana

    Adaptation and the determinants of geographic distribution - publications

Anderson JT, Eckhart VM, Geber MA (2015) Experimental studies of selection and adaptation in Clarkia xantiana (Onagraceae). III. Phenotypic selection across a subspecies border. Evolution 69: 2249-2261.

Thuiller W, Münkemüller T, Schiffers KH, Georges D, Dullinger S, Eckhart VM, Edwards TC, Gravel D, Kunstler G, Merow C, Moore K, Piedallu C, Vissault S, Zimmerman NE, Zurell D, Schurr FM (2014) Does probability of occurrence relate to population dynamics? Ecography 37: 1155-1166.

Schiffers K, Schurr FM, Travis JMJ,  Duputié M, Eckhart VM, Lavergne S, McInerny G, Moore KA, Pearman PB, Thuiller W, Wüest RO, Holt RD (2014) Landscape structure and genetic architecture jointly impact rates of niche evolution. Ecography 37: 1218-1229.

Gould BA, Moeller DA, Eckhart VM, Tiffin P, Fabio E, Geber MA (2014)  Local adaptation and range boundary formation in response to complex environmental gradients across the geographic range of Clarkia xantiana ssp. xantiana. Journal of Ecology 102:95-107.

Moeller DA. Geber MA, Eckhart VM, Tiffin P (2012) Reduced pollinator service and elevated pollen limitation at the geographic range limit of an annual plant. Ecology 93:136-1048.

Kramer AHC, Montgomery DA, Eckhart VM, Geber, MA (2011) Environmental and dispersal controls of an annual plant’s distribution: How similar are patterns and apparent processes at two spatial scales? Plant Ecology 212: 1887-1899.

Eckhart VM, Geber MA, Morris WF, Tiffin P, Fabio ES, Moeller DA (2011) The geography of demography: Long-term demographic studies and species distribution models reveal a species border limited by adaptation. American Naturalist 178: S26-S43.

Eckhart VM, Singh I, Louthan AM, Keledjian AJ, Chu A, Moeller DM, Geber MA (2010) Plant-soil water relations and             the species border of Clarkia xantiana ssp. xantiana (Onagraceae). International Journal of Plant Sciences                     171:749-760. pdf (JSTOR)

Geber MA, Eckhart VM. (2005) Experimental studies of selection and adaptation in Clarkia xantiana (Onagraceae).                 II. Fitness variation across a subspecies border. Evolution 59:521-531. pdf (JSTOR)

Eckhart VM, Geber MA, McGuire C (2004) Experimental studies of selection and adaptation in Clarkia xantiana                     (Onagraceae). I. Sources of phenotypic variation across a subspecies border. Evolution 58:59-7. pdf (JSTOR)

Eckhart VM, Geber (MA 1999) Character variation and geographic distribution of Clarkia xantiana                                             (Onagraceae): Flowers and phenology distibguish two subspecies. Madrono 46:117-125.

    student projects

  • Howland, Maddie. 2014. Physiology and niche dimensions of co-occurring congeners, Clarkia speciosa ssp. polyantha and Clarkia xantiana ssp. xantiana
  • Jennison, Kevin. 2011. Spatial ecology of niche divergence of co-occurring congeners, Clarkia speciosa ssp. polyantha and Clarkia xantiana ssp. xantiana
  • Kircher, Bonnie. 2011. Microsite control of the performance of co-occurring congeners, Clarkia speciosa ssp. polyantha and Clarkia xantiana ssp. xantiana
  • Kramer, Heather Anu. 2008. Micro-scale controls of distribution and performance in Clarkia xantiana ssp. xantiana.
  • Montgomery, David. 2008. Niche modeling of the meso and macro distribution of Clarkia xantiana ssp. xantiana.
  • Chu, Anna. 2007. Soil compaction and texture controls on the local range limits of Clarkia xantiana ssp. xantiana.
  • Keledjian, Amanda. 2007. Water status of Clarkia xantiana ssp. xantiana: regional versus local controls of species borders.
  • Louthan, Allison. 2006. Edaphic characteristics and the range limit of Clarkia xantiana ssp. xantiana.
  • Singh, Indrani. 2006. Water relations and the species border of Clarkia xantiana ssp. xantiana.
  • Lindahl, Amy. 1998-1999. Experimental evidence of a trade-off between stress avoidance and competitive ability in annual plants.

    Pollination biology (breeding systems and flower color) - publications


Hart GM, Eckhart VM. 2010. Ecological separation in foraging schedule and food type between pollinators of the                 California wildflower Clarkia xantiana ssp. xantiana. Journal of Pollination Ecology 2:13-20. pdf (JPE)

Eckhart VM, Rushing NS, Hart GM, Hansen JD. 2006. Frequency-dependent pollinator foraging in polymorphic                         Clarkia xantiana ssp. xantiana populations: implications for flower colour evolution and pollinator                                 interactions. Oikos 112:412-421. pdf (Wiley)

Fausto JA Jr, Eckhart VM, Geber MA. 2001. Reproductive assurance and the evolutionary ecology of self-pollination             in Clarkia xantiana (Onagraceae). American Journal of Botany 88:1794-1800. pdf (JSTOR)

    student projects


  • Phillips, Daniele. 2014. Biochemistry of tannins and anthocyanins in C. xantiana fruits.
  • Lankiewicsz, Tom. 2012. qPCR protocol development for dihydroflavonol-4 reductase expression analysis.
  • Shannon, Laura. 2006-2007. Gene regulation underlying a flower-color polymorphism in Clarkia xantiana.
  • Lundberg, Matthew. 2005. Expression studies of anthocyanin biosynthesis in Clarkia xantiana flowers.
  • Cram, Jacob. 2004. Natural selection on two flower color polymorphisms in Clarkia xantiana ssp. parviflora.
  • Vigeland, Christine. 2004. Development and biochemistry of flower color in Clarkia xantiana.
  • Carter, Daniel. 2003. Petal spots in Clarkia xantiana (Onagraceae) are associated with reduced palatability to grasshoppers.
  • Carter, Daniel. 2003. Analysis of fine-scale spatial variation in the petal spot polymorphism in Clarkia xantiana (Onagraceae): Inbreeding produces finer, more variable structure.
  • Hart, Georgia M. 2003. Sources of variation in pollinator service to Clarkia xantiana (Onagraceae).
  • McCord, Aleia. 2002. Geostatiscal analysis of geographic variation in Clarkia xantiana (Onagraceae).
  • Brummel, Rachel M. 2002. Natural selection on flower color polymorphism in Clarkia xantiana (Onagraceae).
  • Marsh, Naomi. 2002. Opposing forms of frequency-dependent foraging choices in the pollinators of Clarkia xantiana (Onagraceae)
  • Cooper, Elizabeth. 2001. Genetic analysis of breeding system and subspecies differences in Clarkia xantiana(Onagraceae).
  • Fausto, James. 1998-2000. Reproductive assurance and the evolution of autogamy in Clarkia xantiana(Onagraceae).
  • Hansen, Joseph. 1999-2000. The maintenance of a flower-color polymorphism in Clarkia xantiana(Onagraceae). II. Field studies of selection on petal spotting.
  • La Grange, Ceanatha. 1999-2000. The maintenance of a flower-color polymorphism in Clarkia xantiana(Onagraceae). III. Quantitative genetics of petal spotting and herbivore resistance.
  • Southard, Sheryl. 1999. Flowers and stress: Flower size and water relations of Clarkia xantiana(Onagraceae).
  • Twieg, Elizabeth. 1998. The maintenance of a flower-color polymorphism in Clarkia xantiana(Onagraceae). I. Geographic and subspecies variation in morph frequencies.
  • Watkins, Stephen. 1997, 1998 Developmental basis of self-pollination in Clarkia xantiana(Onagraceae).