Current Research 2

Saturday, October 22 at 10:00-11:40 am, Oak Room

*note alternate instance of this session – Saturday at 8am

Session Description: This students-only session provides a venue to highlight research that focuses on the California flora. A number of topics will be explored in this session, including plant taxonomy, rare plant biology, and plant ecology of both native and invasive plant species.

Session Chairs: Dena Grossenbacher (California Polytechnic State University, San Luis Obispo, San Luis Obispo, CA, USA) and Natalie Love (California Polytechnic State University, San Luis Obispo, San Luis Obispo, CA, USA)

39.1    Saving the rare northern island mallow on Anacapa Island

Stephanie Calloway (California Polytechnic State University, San Luis Obispo, San Luis Obispo, CA, USA), Jenn Yost (California Polytechnic State University, San Luis Obispo, San Luis Obispo, CA, USA)

The northern island mallow, Malva assurgentiflora subsp. assurgentiflora, is a rare shrub endemic to Anacapa and San Miguel Islands – two of California’s Channel Islands located off the coast of southern California. Grazing by introduced herbivores drastically degraded Anacapa Island’s ecosystems. While introduced herbivores were removed from Anacapa nearly two decades ago, many species have failed to recover, including Malva. Naturally occurring Malva on Anacapa are presumed extirpated. Fortunately, prior to extirpation, biologists collected seeds that were used to create a new population on East Anacapa Island, where ~1,000 individuals were planted in a restoration site managed by the National Park Service. In the years following restoration, however, the new population has failed to produce recruits. This alarming lack of recruitment puts Malva at risk of future declines. The overall goal of this research was to learn more about Malva’s recruitment dynamics on Anacapa Island and the potential impact of the Anacapa deer mouse – a known seed predator of Malva. In 2020, we began research on Anacapa Island to track the fate of Malva fruits, seeds, and seedlings (pre-dispersal seed predation, post-dispersal seed predation, germination, seedling survival, and establishment) under deer mouse included and excluded conditions. Deer mice removed ~70% of non-dispersed fruits from reproductive Malva before they were able to mature to viable fruits, compared to treatments where deer mice were excluded from fruits, where 100% of fruits matured to viable fruits. Deer mice removed ~50% of dispersed fruits during spring trials compared to 100% in Fall trials as deer mouse densities increased. Germination only occurred in treatments where deer mice were completely excluded from sewed seeds. However, ~95% of seedlings died due to lack of water, regardless of deer mouse exposure, showing that water availability may be more important for seedling survival than deer mouse predation.

39.2    Rushes in California – evolutionarily distinct groups?

Reed Kenny (University of California, Davis, Davis, CA, USA)

Morphological similarity in the family Juncaceae does not necessarily reflect evolutionary relatedness. Previous molecular systematic studies have shown that several genera of South American cushion plants share a closest common ancestor with two groups of Juncus species. These are Juncus section Graminifolii, a group of perennial Juncus species with flat, grass-like leaves with centers of diversity in North America and South Africa, and section Caespitosi, a group of annual Juncus species found in North America and the Cape region of South Africa. Here I present evidence suggesting that North American species in section Graminifolii are not most closely related to South African species in section Graminifolii. Rather, my evidence indicates that North American species in section Graminifolii are more closely related to North American species in section Caespitosi than to South African species in section Graminifolii. Additionally, it suggests that North American Caespitosi and Graminifolii share a closest common ancestor with the South American cushion plants and that South African Graminifolii are more distantly related. Over the summer of 2021 I collected specimens of Juncus species classified as section Caespitosi or Graminifolii that are found in California and began DNA extraction and sequencing. Phylogenies built using my sequences of the ITS region indicate the above relationships. I will continue to sequence additional gene regions to verify these patterns, as well as seek to obtain sequence data for more species, such as South African species in section Caespitosi. My results suggest that there may have been parallel evolution of an annual life form in North America and South Africa from an ancestral grass leaved form. This work may also prove informative about the process of rapid morphological divergence that occurred in the South American cushion plant clade.

39.3    Genome-wide association analyses reveal genes putatively adapted to local climate in a California wildflower, Calochortus venustus

Adriana I. Hernandez (School of Integrative Plant Science, Section of Plant Biology, and the L.H. Bailey Hortorium, Cornell University, Ithaca, NY, USA), Chelsea D. Specht (School of Integrative Plant Science, Section of Plant Biology, and the L.H. Bailey Hortorium, Cornell University, Ithaca, NY, USA)

A key goal of biology is to understand how biodiversity is driven and maintained across natural, heterogeneous, and changing landscapes. One approach is to examine the molecular basis of adaptation to local climate through high-throughput genotype and environmental data. Most studies have focused on model genetic or cultivated organisms, guaranteeing extensive genome coverage and/or a controlled set of phenotypes under analysis such as for agricultural applications. This project leverages a highly polymorphic wildflower in the genus Calochortus, C. venustus, to identify and to interpret the genetic mechanisms underlying local climatic adaptation across California’s diverse and unique habitats utilizing genotype-environment associations, a type of genome-wide association analysis. Over 94,700 genetic markers were used to test associations between 174 genotypes and nine climatic variables known to influence growth, phenology, and distribution of California’s native plants, such as annual precipitation and temperature seasonality, which are also expected to change under the global climate crisis. Despite gene flow between individuals of different floral phenotypes and between populations, we find evidence of ecological specialization at the molecular level, including genes known from model systems to regulate cold stress, heat, water deprivation, salt stress, and root development. Single nucleotide polymorphisms that evolved across independent transects show parallel trends in allelic similarity across latitudes indicating adaptation to northern climates, and/or divergent genetic evolution across longitude suggesting adaptation to either coastal or inland habitats. These results highlight the importance of understanding how these climatic variables affect local adaptation to temperature and precipitation at the molecular level.

39.4    Close relatives in sympatry: is there evidence of gene flow between species of Linanthus?

Ioana Anghel (University of California, Los Angeles, Los Angeles, CA, USA), Felipe Zapata (University of California, Los Angeles, Los Angeles, CA, USA)

The majority of the 25 species in the genus Linanthus occur in a geographically diverse area characterized by exceptional plant endemism. Half of the putative sister species overlap in range and seven species pairs co-flower and co-occur at a locally sympatric scale. Most species have a short life cycle, flowering and seeding in a span of a few weeks, before the hot dry summers characterizing the California desert climate. These geographic, phenological, and life cycle traits make it likely that co-occurring species interact ecologically, potentially competing for resources and pollinators, with ample opportunities for interspecific gene flow. With much of the diversification estimated at less than seven million years old, it is plausible that reproductive isolation between species is incomplete. Indeed, previous phylogenetic work has shown that clades of species are poorly resolved, and several species are not monophyletic. These inconsistencies in previous phylogenetic analyses may indicate misidentification due to error, limitations of traditional taxonomic methods, or a reticulated pattern of divergence. To determine whether there is evidence of gene flow between any of the lineages or between populations that occur in sympatry, I sequenced multiple individuals per species, including many individuals from localities with multiple co-occurring species of Linanthus. Using target capture and RAD data, I reconstruct the evolutionary relationships in the genus and investigate patterns of admixture across populations. 

39.5    Natural history and demography of the imperiled redwood forest specialist, Pedicularis dudleyi (Dudley’s Lousewort)

Anjum K. Gujral (San Francisco State University, University of California, Davis, CA, USA)

Dudley’s Lousewort is a rare plant endemic to central California. The species distribution is limited to populations in the Santa Cruz Mountains and Monterey County, both of which are associated with redwood forests in coastal California. The ecology, reproductive biology, and demography of Pedicularis dudleyi were not well known; however, both populations appear to be in steep decline. In this study, we aimed to determine whether pollination, seed dispersal, and seed germination were important limiting factors for population growth of P. dudleyi at Portola Redwoods State Park, one of two known populations. We conducted a full census of the population, pollinator and seed disperser observations, a litter removal experiment, and a greenhouse seed germination study. The results of the population census confirm an extremely small population size (<500 reproductive individuals) at Portola Redwoods State Park. Field observations confirm pollination by native bees (Bombus spp.) as well as seed predation and potentially seed dispersal by yellowjackets (Vespula alascensis). Litter removal and germination tests reveal poor recruitment and seed germination. Combining age class data from the census, poor overall recruitment in the litter removal trial and poor seed germination, we infer that establishment of new individuals and populations is a primary threat to the population and should be the focus of future management goals.