Recognition of cryptic biodiversity has rapidly accelerated in step with improvements in molecular methodology. The resulting taxonomic decisions can have significant implications for downstream conservation applications, yet standards by which to implement conservation of cryptic species are lacking. This session will include case studies of cryptic biodiversity in the California Floristic Province and how this knowledge can be successfully integrated into conservation initiatives, as well as perspectives on best practices.
SESSION CHAIRS Aaron Sims1, Ash Gill 2,3
1California Native Plant Society, Sacramento, CA, United States. 2Oregon Flora Project, Corvallis, OR, United States. 3SWCA Environmental Consultants, Portland, OR United States
Aaron Sims
California Native Plant Society
Aaron is responsible for directing and managing the status review process for additions and changes to the CNPS Rare Plant Inventory (RPI) and the California Natural Diversity Database (CNDDB), updating and maintaining the RPI, and developing and overseeing rare plant research and field projects throughout the state. He received a degree in Ecology and Systematic Biology with an emphasis in Botany from Cal Poly, San Luis Obispo, where he also assisted with David Keil’s Field Botany course for five consecutive years. Aaron has 19 years of professional botany experience, with prior work in environmental consulting and as an ecologist for the San Luis Obispo Coast District of California State Parks, where he performed rare plant and vegetation surveys, prescribed fire management, and GIS specialties. In his free time, he enjoys being a dad, baking, dancing, and spending time outside snowboarding, kayaking, botanizing, and photographing wildflowers.
Ash Gill
Oregon Flora Project
Ash is a plant systematist based in Portland, Oregon. She is currently the taxonomic editor at the Oregon Flora Project, and a consulting wetland scientist. Ash's interests include bryophytes, sedges, cryptic species, and strengthening the connection between systematics based research and applied plant conservation. When she isn't botanizing she can be found climbing, skiing, and backpacking in the mountains of the west.
19.1 The Navarretia Puzzle: Unraveling Phylogeny, Species Limits, and Conservation in Vernal Pools
Hannah Kang, Dr. Leigh A. Johnson
Brigham Young University, Provo, UT, United States
Description Over 90% of California’s vernal pools have disappeared due to habitat loss, yet these ephemeral wetlands remain hotspots of biodiversity and endemism. Navarretia (Polemoniaceae) includes both state and federally listed species and exemplifies the challenges of conserving cryptic plant groups. This genus has undergone rapid evolutionary radiation, producing species with blurred boundaries and limited phylogenetic resolution, making species limits especially difficult to define.
This uncertainty has profound implications for conservation: accurate taxonomy underpins recovery plans, legal protections, and ecological management. Previous studies have highlighted the difficulty of resolving relationships within the Navarretia leucocephala complex, a group restricted to vernal pools primarily in California. My research expands on this foundation by combining extensive field collections across the species’ range with cutting-edge genomic tools (RADseq) to generate higher-resolution data. This approach allows me to clarify evolutionary relationships and refine species boundaries more effectively than past studies.
By addressing these long-standing taxonomic uncertainties, my work not only advances our understanding of California’s unique flora but also provides critical tools for conserving one of the state’s most threatened ecosystems.
Presenter Bios
Hannah Kang
Brigham Young University
Hannah Kang graduated from the University of California, Davis with a B.S. in Plant Biology and worked as a field and consulting botanist before beginning her doctoral studies. She is currently pursuing a Ph.D. in the Johnson Lab at Brigham Young University, where her research focuses on systematics of the genus Navarretia, with a particular emphasis on resolving species boundaries within the Navarretia leucocephala complex.
19.2Cryptic Lineages, Morphological Stasis, and Mycoheterophy in Pityopus californicus
Ash Gill1,2, Dr. John Freudenstein3
1Oregon Flora Project, Corvallis, OR, United States. 2SWCA Environmental Consultants, Portland, OR, United States. 3Ohio State University, Columbus, OH, United States
Description Understanding the evolutionary processes leading to the formation of cryptic lineages is increasingly of interest as efforts continue to reconcile such lineages to established species concepts. Parasitic plants offer compelling case studies on this topic due to their severe morphological reductions and obligate reliance on other organisms for establishment and survival. Here, we examined Pityopus, a monotypic genus of mycoheterotrophic plants in Ericaceae that parasitize ectomycorrhizal fungi. Our goal was to investigate whether molecular divergence in this group is deserving of species-level recognition and whether lineage formation is related to the parasitic lifestyle. By integrating field samples with herbarium specimens, we assembled a representative dataset from across the range of this rare taxon for genomic and morphological analysis. Our findings reveal four discrete lineages of Pityopus in morphological stasis with range overlap, and a wider array of host affiliates than previously known. Due to the lack of clear diagnostic features, we fail to delimit any new species in Pityopus, but acknowledge the presence of cryptic lineages that should be conserved. We also demonstrate the efficacy of DNA barcoding for lineage identification. This study provides an example of morphologically similar yet reproductively isolated cryptic lineages that persist in sympatry.
Presenter Bios
Ash Gill
Oregon Flora Project
Ash is a plant systematist based in Portland, Oregon. She is currently the taxonomic editor at the Oregon Flora Project, and a consulting wetland scientist. Ash's interests include bryophytes, sedges, cryptic species, and strengthening the connection between systematics based research and applied plant conservation. When she isn't botanizing she can be found climbing, skiing, and backpacking in the mountains of the west.
19.3 Conservation Genomics of the Endangered Santa Cruz Island Rockcress (Sibara filifolia) Brassicaceae
Dr. May B. Roberts1, Dr. C. Matt Guilliams1, Kai Pessanha1, Seth Kauppinen1, Nicole Desnoyers2, Dr. Kristen Hasenstab-Lehman1
1Santa Barbara Botanic Garden, Santa Barbara, CA, United States. 2Naval Base Coronado, San Diego, CA, United States
Description The Channel Islands archipelago, located along the Southern California coast, is often referred to as the “Galapagos of North America” due to the high number of species found nowhere else on earth. Sibara filifolia Greene (Brassicaceae), or Santa Cruz Island rockcress, is one such endemic plant. This small annual, first described from Santa Cruz Island, is currently only known from a few restricted sites on San Clemente and Santa Catalina islands. Its rarity is tied to the long history of ranching and non-native herbivores. To inform archipelago-wide conservation and restoration efforts, we analyzed genomic data (ddRADseq) from over 200 individuals from both islands to assess 1) genetic differentiation between islands and 2) genetic health of populations in terms of genetic diversity, inbreeding, and gene flow. Our analyses reveal strong evidence for island-level divergence with both island populations showing low genetic diversity and indications of moderate to high inbreeding. We found that gene flow is high on Catalina Island but very restricted on San Clemente Island. These results complement recent morphometric, greenhouse, and pollination studies that also found significant differences by island, strengthening the case that the two islands may represent distinct evolutionary units to be managed separately. We discuss implications of these findings for conservation of Sibara filifolia and present recommendations for land managers and restoration practitioners. We demonstrate the functionality of genomics as a useful tool in conservation, and we also show that there are likely more taxa waiting to be identified in this biodiversity hotspot.
Presenter Bios
Dr. May B. Roberts
Santa Barbara Botanic Garden
May Roberts is the Plant Genetics Lab Manager at the Santa Barbara Botanic Garden where it has been a botanical joy for her to work on projects helping to answer important native plant conservation questions.
19.4 Nomenclature and Geographic Distribution of Bush Lupines of Mainland Southern California
Dr. Daniel S. Cooper
Resource Conservation District of the Santa Monica Mountains, Calabasas, CA, United States
Description Lupines (Lupinus spp.) include a diverse array of woody shrubs, subshrubs, perennial herbs, and annuals that have long provided identification challenges in California. For the woody shrubs and subshrubs (“bush lupines”), few consistent characters are known that can reliably distinguish obvious species and varieties, and multiple names have been applied for the same populations over time. Here we summarize distribution patterns of southern California mainland populations of bush lupines, discuss their nomenclatural history, and suggest how existing names could be better applied to reflect their distribution and characteristics. We suggest applying a “morphogroup” approach, which acknowledges a high level of taxonomic uncertainty that has made it impossible to confidently name all populations. We suggest recognizing four morphogroups in total, with two along the immediate coast (L. arboreus and L. chamissonis), and two inland. While the near-coastal morphogroups are distinctive and easily separable, inland populations are not. However, they may be generally split into woody/trunked shrubs found in lowlands and lower foothills, and suffrutescent subshrubs in montane and desert-edge habitats. Using specimen records and photographs uploaded to the community science platform iNaturalist, we show how populations in the latter two morphogroups occur as biogeographically separated “subgroups”, all of which we aggregate into existing varieties of Lupinus albifrons. We discuss threats to these populations, recommending that the subgroup “hallii” (currently treated as Lupinus albifrons var. hallii) be afforded increased conservation attention, given its small range in a rapidly urbanizing region and its narrow habitat requirements.
Presenter Bios
Dr. Daniel S. Cooper
Resource Conservation District of the Santa Monica Mountains
Dan is a Principal Conservation Biologist at the Resource Conservation District of the Santa Monica Mountains, and a Lecturer at UCLA (Institute of the Environment and Sustainability) and CSU Long Beach (Biological Sciences). Through research and independent consulting, he spent more than 20 years conducting surveys and drafting reports in the region, and co-authored a landmark conservation analysis for the Santa Monica Mountains Coastal Zone for L.A. Co. Department of Regional Planning in 2014. His "Griffith Park Connectivity Study" was the first to document the mountain lion that became known as P-22.
19.5 Impacts of Hybridization on Rare Species Management: A Case Study in Castilleja mollis (Orobanchaceae)
Dr. Kristen E. Hasenstab-Lehman1, Dr. C. Matt Guilliams1, Caitlin Hazelquist1, Dr. Diane Thomson2
1Santa Barbara Botanic Garden, Santa Barbara, CA, United States. 2Scripps College, Claremont, CA, United States
Description Hybridization, a process by which distantly related taxa exchange genetic material, can impact rare plants. On one hand, conservation managers must contend with potential impacts of hybridization that might drive rare taxa to extinction through processes like genetic or demographic swamping. Conversely, and controversially, some conservationists have argued that hybridization should be used as a tool to enhance adaptive potential of rare taxa, especially in the face of climate change. We examine these issues through studies of the Federally Endangered Castilleja mollis Pennell (Orobanchaceae). This perennial hemiparasite is endemic to the northern Channel Islands, historically found on Santa Rosa and San Miguel islands. Presently, it is restricted to stabilized dunes and marine terraces of Santa Rosa Island’s Carrington Point and Jaw Gulch. Grazing damage from historic ranching, increasing annual temperatures and aridity, and suspected hybridization with Castilleja affinis in parts of its extant range may be contributing to the decline of C. mollis. The Jaw Gulch site is assumed to have mostly genetically intact C. mollis, but putative hybrids of C. mollis and C. affinis have been noted at increasing frequency at Carrington Point. With hybridization posing a potential and increasing threat to C. mollis, we used genomic evidence to examine if and for how long these processes have occurred on Santa Rosa Island. We also present micro and macro morphological evidence to better identify hybrids in the field. We discuss practical implications for managing a naturally hybridizing rare species into the future.
Presenter Bios
Dr. Kristen E. Hasenstab-Lehman
Santa Barbara Botanic Garden
Kristen Hasenstab-Lehman, Ph.D., is a plant systematist, a botanist, and has been the conservation geneticist at Santa Barbara Botanic Garden since 2017. She integrates field studies, molecular tools, and histological techniques to document biodiversity and to understand the interplay of ecological and evolutionary effects on plants of conservation concern. After earning a master’s degree at San Diego State University working on the mysteries of the genus Cryptantha, Kristen earned her doctorate in botany at Claremont Graduate University at California Botanic Garden (formerly Rancho Santa Ana Botanic Garden). She worked at the Smithsonian National Museum of Natural History managing the plant DNA barcoding lab. She has worked with California’s native plants since 2006.
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The mission of the California Native Plant Society is to protect California’s native plants and their natural habitats, today and into the future, through science, education, stewardship, gardening, and advocacy.
DateFriday, February 6
