Title: Verifying The Taxonomic Validity And Resolving The Subspecific Boundaries Of The Lomatium Foeniculaceum Complex
Program: Master of Science in Biology
Advisor: Dr. James Smith, Biological Sciences
Committee Members: Dr. Don Mansfield, Biological Sciences and Dr. Sven Buerki, Biological Sciences
Plant species in western North America historically have been delimited using morphological differences and geographic distribution of the species’ populations. Historically, the subspecies rank was relegated to populations that are geographically coherent but morphologically intergradient at areas of sympatry, resulting in doubts on the taxonomic validity and usefulness of the subspecific rank. The Lomatium foeniculaceum complex of the Perennial Endemic North American clade (PENA) of Apiaceae is present across much of the Great Plains and Intermountain Region, and as far north as northeast British Columbia. It is comprised of five subspecies and is the most widely distributed complex in the PENA clade. As delineated by previous taxonomic treatments, these infrataxa are separated by the presence or absence of variable characters such as petal ciliation, petal color, and involucel geometry. The Continental Divide has been used as a geographic barrier to separate the Great Plains taxa from species occurring in Idaho southward to New Mexico. Recent phylogenetic research has found that morphology alone in the PENA clade does not always reflect evolutionary history and is often misleading when used for species delimitation. Additionally, only a few samples of L. foeniculaceum have ever been included in recent phylogenetic analyses, and not all subspecies have been sampled. To study the species boundaries of all subspecies within the taxa, fifty populations of L. foeniculaceum were selected based on general distribution, and to include all named subspecies and areas where sympatry or peripatry of subspecies occurs. Target capture with the Angiosperm353 bait kit, next generation sequencing, and gene assembly with HybPiper and HybPhaser were employed to retrieve genes suitable for various phylogenetic analyses. Results from the maximum likelihood analysis (RAxML), pseudo-coalescent analysis (ASTRAL), coalescent analysis (STACEY), as well as results from ecological analyses and morphological measurements, support distinct clades for subspecies west of the Continental Divide. We find that samples associated with L. foeniculaceum subsp. daucifolium and L. foeniculaceum subsp. foeniculaceum occurring in the Great Plains do not form distinct clades congruent across all phylogenetic analyses and should be retained as subspecies. Phylogenetic analyses, in conjunction with herbarium collections, have allowed us to discover morphological characters that align with our phylogenetic results. Using the general lineage concept of species, along with support from various analyses, we propose the recognition of L. foeniculaceum subsp. inyoense, L. foeniculaceum subsp. fimbriatum, L. foeniculaceum subsp. macdougalii as distinct species, and the recognition of an undescribed species occurring mainly in Idaho.