Phylogeny/DNA Barcoding
For our project to succeed, we must first produce an accurate phylogeny for all vascular plant species native or introduced to Wisconsin. This will provide the crucial framework for analyzing how evolutionary relationships have affected trait evolution, community assembly and structure, and changes in abundance. No such tree yet exists.
Photo: ©2012 Tyler Schappe
Despite the obvious value of molecular phylogenetics for investigating the questions outlined, only one study to date (Kress et al. 2009) has taken this approach. Deriving a phylogeny for the entire vascular flora will maximize the range of questions we can address and (via branch lengths) the power of our tests. Sequencing all species will also: contribute materially to producing a molecular phylogeny for the vascular flora of North America, provide an important diagnostic identification tool (Barcodes Database), and enhance future efforts to analyze taxa not part of this project.
We are extracting, amplifying and sequencing plastid genes from fresh material and herbarium specimens representing the 2572 vascular plant species (1889 native, 683 introduced) in Wisconsin (Wetter et al. 2001). For this, we need molecular markers that vary adequately among taxa, are short enough to be amplified and sequenced easily, and are used extensively in other studies. Use of plastid genes avoids problems with fungal contamination and provides sequences that can be aligned with confidence. The Consortium for the Barcode of Life (CBOL, PI Cameron, founding member) confronted the same issues and identified two partial plastid genes (rbcL and matK) as most suitable. We thus propose to sequence these loci (ca. 550 bp each) to reconstruct the phylogeny. Our State Herbarium (WIS) lists all plant taxa here (WisFLORA 2010), with species pages and links to the USDA PLANTS Database (USDA 2010). More than 330,000 specimens from the state are databased and geo-referenced.