The Columbine Adaptive Radiation

 

 

 


The recent radiation of the columbines in the Northern Hemisphere has generated over 75 species. A monophyletic clade of 25 species are restricted to North America and northern Mexico. Not only does this clade represent a rapid diversification event, it is also characterized by a spectacular range of floral diversity and habitat types. My labs research seeks to explain the origin and maintenance of this diversity from a comparative phylogenetic perspective. 

1. Phylogenetics

  • We developed a method for identifying phylogenetially informative nuclear introns in non-model taxa by anchoring a primer in the 3'-UTR using a cDNA library (PDF).

 

  • Using an approximate molecular clock for the nuclear ribosomal ITS region, we can test age-based hypotheses about divergence times when no internal calibration is available (PDF).

 

  • An AFLP phylogeny for the North American columbines.

 

2. Character Evolution

  • Convergent origins of hummingbird and hawkmoth pollination syndromes
    • click here to see Anna's Hummingbird on A. formosa in an experimental array at UCSB
    • click here to see a hawkmoth (Hyles lineata) on A. pubescens in the eastern Sierra (movie by Ji Yang)
  • Increasing spur lengths support the pollinator shift model (Wasserthal 1997)
  • Habitat diversification is also highly convergent
 

Justen B. Whittall

Biology Department

Santa Clara University

500 El Camino Real 

Santa Clara, CA 95053 USA