• In Aquilegia, the loss of floral anthocyanins is often associated with the shift from hummingbird to hawkmoth pollination. This has occurred at least 7x in the North American columbine clade. Using the repeated instances of this loss-of-function adaptation, we tested the degree of convergence at the biochemical and gene expression levels. It appears that the first half of the anthocyanin biosynthetic pathway is constrained from being lost at both the biochemical and gene expression levels. Why is this? Maybe there are intermediates in the pathway that serve other functions, thereby constraining these early genes from being lost during shifts from hummingbird to hawkmoth pollination syndromes (PDF & Science's Editor's Choice)

2. Ecological Pleitropy

• The columbine results described above stimulated a broader survey of floral traits that may be constrained by non-pollinator agents of selection. Specifically, Sharon Strauss and I found that in taxa with floral anthocyanin polymorphisms, the pigmented morph has higher fitness in more stressful environments (both biotic and abiotic) (PDF). 

• I am currently following this up with two studies of correlated changes in flower color and edaphic tolerance such as the purple/white corolla polymorphism in Collinsia sparsiflora (Veronicaceae) that is found on and off serpentine and flower color polymorphisms in Arctic Mustards.  In Collinsia sparsiflora, non-serpentine populations harbor mostly white flowered morphs, immediately adjacent serpentine grasslands are restricted to almost entirely purple morphs. This work is in collaboration with Jessica Wright and Maureen Stanton.

• In the Arctic Mustards Parrya and Cardamine, flower color polymorphisms may provide insights into constraints on the adaptability of polar genomes. It has been long thought that polar environments are not particularly conducive to rapid adaptation. Yet, the existence of flower color polymorphisms into the Arctic Circle suggests otherwise. In collaboration with Matt Carlson (Univ. of Alaska Anchorage), my lab is examining the molecular basis for these color polymorphisms and comparing the roles of pollinators and non-pollinator agents of selection (i.e. temperature, moisture availability, herbivores, etc.) on the persistence of these color polymorphisms. This work is complemented with metabolomic and whole genome microarray techniques co-opted from the closely related model plant, Arabdiopsis thaliana, to better understand patterns of genomic variation and constraint along a transect into the Arctic circle of Alaska.

  
  

  Brief project summary

• Click here for a list of degenerate primers for amplifying the core anthocyanin biosynthetic pathway loci and two regulatory genes based on an angiosperm wide alignment. If you try them out and they work, let me know.