Sister taxa with distinct phenotypes often occupy contrasting environments in parapatric ranges, yet we generally do not know whether trait divergence reflects spatially varying selection. We conducted a reciprocal transplant experiment to test whether selection favors "native phenotypes" in two subspecies of Clarkia xantiana (Onagraceae), an annual plant in California. For four quantitative traits that differ between subspecies, we estimated phenotypic selection in subspecies' exclusive ranges and their contact zone in two consecutive years. We predicted that in the arid, pollinator-scarce eastern region, selection favors phenotypes of the native subspecies parviflora: small leaves, slow leaf growth, early flowering, and diminutive flowers. In the wetter, pollinator-rich, western range of subspecies xantiana, we expected selection for opposite phenotypes. We investigated pollinator contributions to selection by comparing naturally pollinated and pollen-supplemented individuals. For reproductive traits and for subspecies xantiana, selection generally matched expectations. The contact zone sometimes showed distinctive selection, and in ssp. parviflora selection sometimes favored nonnative phenotypes. Pollinators influenced selection on flowering time but not on flower size. Little temporal variation in selection occurred, possibly because of plastic trait responses across years. Though there were exceptions and some causes of selection remain obscure, phenotypic differentiation between subspecies appears to reflect spatially variable selection.

California Agriculture - All Issues

Coastal fog affects many California plant species and can be critically important to species that experience periodic drought. Drought-deciduous species in particular rely on water availability to maintain their leaves during the summer. To determine fog water use in drought-deciduous plants, this study manipulated access to fog drip and measured the water relations of the common shrub, Artemisia californica, near Santa Barbara, CA. Measuring the stable isotope ratio of hydrogen and oxygen, this study found that A. californica uses fog water in the late summer months when fog is present. This additional water increased plant water content but had no effect on pre-dawn xylem pressure potential. While climatic variability inhibits reliable fog input to A. californica in Santa Barbara, this species can use fog water opportunistically and benefits from large fog events during the summer drought.

BackgroundAntimicrobial resistance (AMR) is a major threat to global public health. Medicinal plants have long been used as remedies for infectious diseases by native cultures around the world and have the potential for providing effective treatments for antibiotic-resistant infections. Rhamnus californica (Rhamnaceae) and Umbellularia californica (Lauraceae) are two indigenous California plant species historically used by Native Americans to treat skin, respiratory and gastrointestinal infections. This study aimed to assess the in vitro antimicrobial activity of methanolic extracts of leaves and bark of R. and U. californica against methicillin-resistant Staphylococcus aureus (MRSA) and other Gram-positive and Gram-negative bacteria.MethodsMethanolic extracts of leaves and bark of R. and U. californica were prepared by soxhlet extraction and evaluated for their antimicrobial activity against Bacillus cereus, Streptococcus pyogenes, Mycobacterium smegmatis, Staphylococcus aureus, MRSA, Escherichia coli and Pseudomonas aeruginosa using disc diffusion and minimal inhibitory concentration (MIC) assays. Chemical profiling of the extracts was performed using standard methods.ResultsAll extracts inhibited the growth of MRSA and other Gram-positive bacteria with MICs of 3.3-6.0 mg/ml. Gram-negative organisms were unaffected by these extracts. U. californica extracts (leaves and bark) had the lowest MIC values. Chemical profiling detected the presence of quinones, alkaloids, flavonoids, cardenolides, tannins and saponins in these extracts. Our study is the first to report the antimicrobial properties of R. and U. californica and illustrates their promising anti-MRSA potential.ConclusionsOur results give scientific credence to the traditional medicinal uses of these plants by the indigenous peoples of California. Further investigation of the secondary metabolites responsible for the antimicrobial activity of these extracts against MRSA is warranted.

S.P. Harrison (2013) – Plant and Animal Endemism in California

Continuing work on the flora of California after the publication of The Jepson Manual: Vascular Plants of California has led to the discovery of three new Monardella Benth. (Lamiaceae) subspecies: M. australis Abrams subsp. gabrielensis Elvin & A. C. Sanders, M. australis subsp. occidentalis Elvin, R. A. Burgess & A. C. Sanders, and M. sinuata Elvin & A. C. Sanders subsp. gerryi Elvin, A. C. Sanders & R. A. Burgess. Monardella australis subsp. gabrielensis occurs in the central and western San Gabriel Mountains of the Transverse Ranges, and M. australis subsp. occidentalis occurs on Pine Mountain Ridge in the Western Transverse Ranges and the San Rafael Mountains of the adjacent southern portion of the South Coast Ranges. The two new subspecies of M. australis are most similar to the autonymic subspecies, but both differ in their bract and leaf morphology, pubescence on the stems and calyces, stature, and distribution. Monardella sinuata subsp. gerryi occurs in the Las Posas and Camarillo Hills in the coastal plain of Ventura County in the South Coast Region. The new subspecies is most similar to M. sinuata subsp. sinuata but differs in its stem, leaf, bract, and glomerule size and in its pubescence, nutlets, and ecological setting. Monardella neglecta Greene is transferred to a new rank as a subspecies of M. purpurea Howell, as M. purpurea subsp. neglecta (Greene) Elvin & A. C. Sanders. It is a diminutive, glabrous, serpentine endemic on the Marin and Tiburon peninsulas in northern California. A taxonomic assessment of names within the M. villosa Benth. complex results in the synonymy of M. franciscana Elmer to M. villosa subsp. villosa. Monardella villosa subsp. subserrata (Greene) Epling is recognized as the upland and interior taxon in this species. A lectotype is designated for M. purpurea Howell and recognized for both M. franciscana Elmer and M. neglecta Greene.

The draft whole-genome sequence of “Candidatus Liberibacter solanacearum” strain R1, isolated from and maintained in tomato plants in California, is reported. The R1 strain has the genome size of 1,204,257 bp, G+C content of 35.3%, 1,101 predicted open reading frames, and 57 RNA genes.

Recent biogeographic and evolutionary studies have led to improved understanding of the origins of exceptionally high plant diversity in the California Floristic Province (CA-FP). Spatial analyses of Californian plant diversity and endemism reinforce the importance of geographically isolated areas of high topographic and edaphic complexity as floristic hot spots, in which the relative influence of factors promoting evolutionary divergence and buffering of lineages against extinction has gained increased attention. Molecular phylogenetic studies spanning the flora indicate that immediate sources of CA-FP lineages bearing endemic species diversity have been mostly within North America—especially within the west and southwest—even for groups of north temperate affinity, and that most diversification of extant lineages in the CA-FP has occurred since the mid-Miocene, with the transition toward summer-drying. Process-focused studies continue to implicate environmental heterogeneity at local or broad geographic scales in evolutionary divergence within the CA-FP, often associated with reproductive or life-history shifts or sometimes hybridization.

The potential for novel pests to attack indigenous plants can be examined in non-native ranges of these plants. We used perennial native New Zealand plant species growing in botanic gardens and on public spaces in southern California to explore new associations between these plants, the bacterium Xylella fastidiosa, and its vector, the invasive insect pest, Homalodisca vitripennis (the glassy-winged sharpshooter), both of which are not yet present in New Zealand. Further, we examined the biocontrol potential of egg parasitoids against H.vitripennis on New Zealand plant hosts in southern California. We make the case for the inclusion of biocontrol as an early-response strategy against H.vitripennis should this pest invade New Zealand, and outline the steps required to make biocontrol part of a rapid-response management plan should an incursion and localized establishment occur.

Preventing plant invasions or eradicating incipient populations is much less costly than confronting large well-established populations of invasive plants. We developed a preliminary determination of plants that pose the greatest risk of becoming invasive in California, primarily through the horticultural industry. We identified 774 species that are invasive elsewhere in Mediterranean climates but not yet invasive in California. From this list, we determined which species are sold through the horticulture industry, whether they are sold in California and whether they have been reported as naturalized in California. We narrowed the list to 186 species with the greatest potential for introduction and/or invasiveness to California through the horticultural trade. This study provides a basis for determining species to evaluate further through a more detailed risk assessment that may subsequently prevent importation via the horticultural pathway. Our results can also help land managers know which species to watch for in wildlands.

Huge Solar Plant in California versus Affordable Solar Appliances for the Poor

Studies of ecotypic differentiation in the California Floristic Province have contributed greatly to plant evolutionary biology since the pioneering work of Clausen, Keck, and Hiesey. The extent of gene flow and genetic differentiation across interfertile ecotypes that span major habitats in the California Floristic Province is understudied, however, and is important for understanding the prospects for local adaptation to evolve or persist in the face of potential gene flow across populations in different ecological settings. We used microsatellite data to examine local differentiation in one of these lineages, the Pacific Coast polyploid complex of the plant genus Grindelia (Asteraceae). We examined 439 individuals in 10 different populations. The plants grouped broadly into a coastal and an inland set of populations. The coastal group contained plants from salt marshes and coastal bluffs, as well as a population growing in a serpentine grassland close to the coast, while the inland group contained grassland plants. No evidence for hybridization was found at the single location where adjacent populations of the two groups were sampled. In addition to differentiation along ecotypic lines, there was also a strong signal of local differentiation, with the plants grouping strongly by population. The strength of local differentiation is consistent with the extensive morphological variation observed across populations and the history of taxonomic confusion in the group. The Pacific Clade of Grindelia and other young Californian plant groups warrant additional analysis of evolutionary divergence along the steep coast-to-inland climatic gradient, which has been associated with local adaptation and ecotype formation since the classic studies of Clausen, Keck, and Hiesey.

ULTIMATE TROUGH® - Fabrication, Erection and Commissioning of the World's Largest Parabolic Trough Collector

Supplementary data for: Field Testing Diorhabda elongata (Coleoptera: Chrysomelidae) From Crete, Greece, to Assess Potential Impact on Nontarget Native California Plants in the Genus Frankenia

Plant and animal endemism in California

Precipitation of calcium phosphate scale on reverse osmosis (RO) membranes continues to be a major challenge for wastewater recycling facilities. In most cases, antiscalant is dosed in combination with sulfuric acid because calcium phosphate solubility improves at lower pH. Several waste water RO plants in California that have attempted to reduce the costly acid dosing have experienced fast scale formation that has offset any savings with downtime and expensive cleaning chemicals. Online cleanings were attempted by reducing the pH to 6 for 1 week in order to reduce downtime; however, they did not fully restore flux in the tail elements and performance progressively declined over time. When these membranes were autopsied, silica was surprisingly the predominant deposit on the membrane surface, even though brine silica concentrations were only in the range of 130–160 ppm. An extensive study was conducted to simulate these conditions in a laboratory setting. Tests were conducted using various antiscalants av...

Spatially distinct communities can arise through interactions and feedbacks between abiotic and biotic factors. We suggest that, for plants, patches of infertile soils such as serpentine may support more distinct communities from those in the surrounding non-serpentine matrix in regions where the climate is more productive (i.e., warmer and/or wetter). Where both soil fertility and climatic productivity are high, communities may be dominated by plants with fast-growing functional traits, whereas where either soils or climate impose low productivity, species with stress-tolerant functional traits may predominate. As a result, both species and functional composition may show higher dissimilarity between patch and matrix in productive climates. This pattern may be reinforced by positive feedbacks, in which higher plant growth under favorable climate and soil conditions leads to higher soil fertility, further enhancing plant growth. For 96 pairs of sites across a 200-km latitudinal gradient in California, we found that the species and functional dissimilarities between communities on infertile serpentine and fertile non-serpentine soils were higher in more productive (wetter) regions. Woody species had more stress-tolerant functional traits on serpentine than non-serpentine soil, and as rainfall increased, woody species functional composition changed toward fast-growing traits on non-serpentine, but not on serpentine soils. Soil organic matter increased with rainfall, but only on non-serpentine soils, and the difference in organic matter between soils was positively correlated with plant community dissimilarity. These results illustrate a novel mechanism wherein climatic productivity is associated with higher species, functional, and landscape-level dissimilarity (beta diversity).

Transport hubs of international trade and tourism are sites of unprecedented long-distance dispersal of species and novel ecological interactions. In cases of invasive plants released from their specialist natural enemies, novel interactions with both resident enemies and new arrivals can accumulate and potentially reduce weed competitiveness. I present here one dramatic example of this, where an invasive woody weed in southern California is being rapidly controlled by an accidentally introduced genus-specialist herbivorous insect. The New Zealand native shrub/small tree, Myoporum laetum, is a long-time popular ornamental plant in California and has become an invasive woody weed. In 2005, a Myoporum-specific thrips, Klambothrips myopori, was discovered (and described) in California feeding on M. laetum leaves. Several searches have failed to find K. myopori in New Zealand and a population has recently been discovered in Tasmania, Australia, feeding on Myoporum insulare. In 5 years, K. myopori has killed off about half of southern Californian M. laetum with almost all surviving individuals being gradually defoliated. Inadequate border biosecurity has resulted in inadvertent biological control, in a rapid timeframe, caused by a novel enemy. Unfortunately, K. myopori has subsequently been accidentally transported from California to Hawaii where it is now killing off Hawaiian native Myoporum sandwicense. Transport hubs can both connect weeds with natural enemies and disperse those enemies more widely.

Abstract Understanding the novel ecological interactions that result from biological invasions is a critical issue in modern ecology and evolution as well as pest management. Introduced herbivorous insects may interact with native plants and indigenous natural enemies, creating novel tri‐trophic interactions. To help predict the potential outcomes of novel interactions, we investigated the behavioural and physiological responses of an indigenous generalist parasitoid (Habrobracon gelechiae) to an introduced generalist herbivore (the light brown apple moth, Epiphyas postvittana) and its new host plants in California. We first examined the parasitoid's host location and acceptance on a range of nine common host plants of the moth representing distinctly different geographic origins and morphologies (to examine the effect of a known toxic plant on the parasitoid's performance, an additional toxic plant species was also tested that the moth consumes in the laboratory but does not naturally attack). The parasitoid was able to locate the host larvae on all plants equally well, although clutch size was affected by host plant. We then determined fitness of the moth and the parasitoid on four representative plants. The moth larvae suffered higher mortality and a slower developmental rate on the known toxic plant than on the other three plants, but the parasitoid's fitness correlates did not differ between the host food plants. These results show a high level of plasticity in the indigenous generalist parasitoid in its ability to exploit the exotic host on a wide range of host plants, generating an invasion‐driven novel tri‐trophic interaction.

Dittrichia graveolens is a rapidly spreading invasive plant in California. While populations are observed primarily in disturbed areas, there is concern it may expand into adjacent undisturbed areas, particularly grasslands and riparian corridors. In a field experiment conducted in two successive years, we compared plant growth and phenological development of fall, winter, and spring sown seeds. Plants establish equally well in disturbed upland sites in both above and below average precipitation years but the absence of late spring rainfall negatively affected total plant biomass. In a greenhouse experiment, we compared growth in four light environments (100, 50, 27 and 9 % available light). Total plant growth decreased exponentially with decreasing light. This suggests that D. graveolens is not competitive in low light environments, such as woodlands and riparian forests. All plants flowered in early- to mid-September, coinciding with flowering in field grown plants, suggesting that photoperiod is the primary signal for reproductive growth. Using a minirhizotron system, we measured root growth over time in D. graveolens and three common California annual grassland species, two non-natives, Centaurea solstitialis and Bromus hordeaceus, and the native forb Holocarpha virgata. Root growth of D. graveolens began later in the season than the other species, reaching depths >1 m by late May. Roots of C. solstitialis and H. virgata reached >1 m earlier in the season. The temporal difference in root growth suggests that D. graveolens may be less competitive for soil moisture with other early season annuals than other deep-rooted broadleaf species found in grasslands.