For my dissertation topic I am investigating the evolutionary relationships in Pectis, a genus of ~85 species in the Sunflower family (Asteraceae). These plants have an interesting distribution across dry habitats of southwest North America, Mexico, the Caribbean and South America.

Species of the genus are also known to utilize C4 photosynthesis. C4 photosynthesis is an adaptation that has allowed plants to persist in very hot environments in which water availability is low and the soil is poor. Although only 3% of plant species have C4 photosynthesis, they dominate vast areas of the Neotropics, and account for one-third of the world’s primary productivity. The success of C4 plants is widely attributed to their novel photosynthetic pathway, because it allows them to grow, and often flourish, where their C3 relatives cannot. One of the most intriguing questions in evolutionary biology is what makes one lineage succeed and diversify while its sister lineages do not. Do certain morphological novelties promote speciation, and can we see evidence of this in especially diverse groups? A novel trait that confers the ability to exploit a new environment can spur speciation via adaptive radiation. In such cases, the trait is termed a key innovation. Classic examples of key innovations are floral nectar spurs in Columbines and phytophagy (eating plants instead of meat) in insects. C4 photosynthesis has attributes of a key innovation, but no one yet has tested its relation to speciation rates. I will use Pectis to test the link between C4 photosynthesis and accelerated speciation rates. It has been assumed that Pectis is a C4 genus and Porophyllum (<30 ssp., its proposed closest relative), is a C3 genus, but of their combined ~115 species, only 32 have been surveyed for photosynthetic pathway.

The objectives of my study are to: a) determine the photosynthetic pathways of the remaining 83 Pectis and Porophyllum species; b) infer, using nuclear and chloroplast DNA, the evolutionary relationships between and among the two genera; c) combine the evolutionary history with the photosynthetic data to compare speciation rates between C3 and C4 species in the group; and d) use the inferred evolutionary history (the phylogeny) to test specific hypotheses regarding taxonomy, biogeography, and the evolution of C4 photosynthesis in Pectis.

M.S., San Francisco State University, 2005. Advisor: Dr. Bob Patterson

For my Master's thesis I inferred the evolutionary relationships in two sections of the genus Phacelia (Boraginaceae). There are 175 species of Phacelia, 89 of which grow in California. I studied the species in sections Whitlavia and Gymnobythus. These are very showy flowers that, for the most part, grow in deserts and dryer areas of California.

Phacelia Sect. Gymnobythus
Phacelia grandiflora	Phacelia viscida

Phacelia Sect. Whitlavia
Phacelia minor	Phacelia longipes	Phacelia nashiana	Phacelia parryii	Phacelia campanularia