Abstract Detail

Floristics & Taxonomy

Riley, Reece [1], Waselkov, Katherine [2].

A Phylogeny of the Western North American Wildflower Genus Helianthella.

This project aims to establish a phylogeny of the plant genus Helianthella (little sunflowers) and place it within its taxonomic subtribe in the family Asteraceae. Helianthella are wildflowers with perennial taproots and annual flowers with basal rosettes of leaves. They are distributed along the mountains of western North America, from southern Canada to northern Mexico, with some highly geographically restricted species in California and Mexico. This genus has gone understudied for many decades, with its last major taxonomic treatment being a monograph in 1952. The relationships among the 11 species within Helianthella, and the relationship of the genus to the four other genera in the taxonomic subtribe Enceliinae, are unknown. The nuclear regions ETS and ITS and three chloroplast regions have been sequenced and analyzed thus far. First, phylogenies were constructed using the Bayesian inference software MrBayes, separately for nuclear and chloroplast data, then these phylogenies were combined with distribution data to infer the biogeographic history of the genus using the program RASP. The resulting data have revealed a history of hybridization between the northernmost species H. uniflora and its neighboring taxa, as well as among taxa in the Central US. All phylogenies support two major clades within the genus, one containing all of the exclusively Mexican Helianthella and one containing the rest of the genus, as well as the monophyly of the genus as a whole. Helianthella californica was found to be non-monophyletic due to the presence of a neighboring species within its clade, so further taxonomic work will need to be done to resolve the conflict. The placement of Helianthella among its neighboring genera also remains contentious. These analyses have provided many insights into the history of the genus that were not possible when last it was studied.

1 - 4710 E Thomas Ave, Fresno, CA, 93702, United States
2 - California State University, Fresno, Department of Biology, 2555 East San Ramon Ave, M/S SB73 , Fresno, CA, 93740, USA

Keywords:
Helianthella
Enceliinae
ETS
ITS
Asteraceae
Incomplete Lineage Sorting
hybridization
Phylogenies.

Presentation Type: Oral Paper
Number: F&T II004
Abstract ID:779
Candidate for Awards:None