Biology Commons^™

Genetic Basis For Sex Differences In Obesity And Lipid Metabolism, Jenny Link, Karen Reue

Biology

Men and women exhibit significant differences in obesity, cardiovascular disease, and diabetes. To provide better diagnosis and treatment for both sexes, it is important to identify factors that underlie the observed sex differences. Traditionally, sex differences have been attributed to the differential effects of male and female gonadal secretions (commonly referred to as sex hormones), which substantially influence many aspects of metabolism and related diseases. Less appreciated as a contributor to sex differences are the fundamental genetic differences between males and females, which are ultimately determined by the presence of an XX or XY sex chromosome complement. Here, we review …

Archelosaurian Color Vision, Parietal Eye Loss, And The Crocodylian Nocturnal Bottleneck, Christopher A. Emerling

Biology

Vertebrate color vision has evolved partly through the modification of five ancestral visual opsin proteins via gene duplication, loss, and shifts in spectral sensitivity. While many vertebrates, particularly mammals, birds, and fishes, have had their visual opsin repertoires studied in great detail, testudines (turtles) and crocodylians have largely been neglected. Here I examine the genomic basis for color vision in four species of turtles and four species of crocodylians, and demonstrate that while turtles appear to vary in their number of visual opsins, crocodylians experienced a reduction in their color discrimination capacity after their divergence from Aves. Based on the …

Northern Spotted Owl (Strix Occidentalis Caurina) Genome: Divergence With The Barred Owl (Strix Varia) And Characterization Of Light-Associated Genes, Christopher A. Emerling, Zachary R. Hanna, James B. Henderson, Jeffrey D. Wall, Jérôme Fuchs, Charles Runckel, David P. Mindell, Rauri C. K. Bowie, Joseph L. Derisi, John P. Dumbacher

Biology

We report here the assembly of a northern spotted owl (Strix occidentalis caurina) genome. We generated Illumina paired-end sequence data at 90× coverage using nine libraries with insert lengths ranging from ∼250 to 9,600 nt and read lengths from 100 to 375 nt. The genome assembly is comprised of 8,108 scaffolds totaling 1.26 × 109 nt in length with an N50 length of 3.98 × 106 nt. We calculated the genome-wide fixation index (F_ST) of S. o. caurina with the closely related barred owl (Strix varia) as 0.819. We examined 19 genes that …

Diet, Gonadal Sex, And Sex Chromosome Complement Influence White Adipose Tissue Mirna Expression, Jenny C. Link, Yehudit Hasin-Brumshtei, Rita M. Cantor, Xuqi Chen, Arthur P. Arnold, Aldons J. Lusis, Karen Reue

Biology

Background: MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression by targeting specific mRNA species for degradation or interfering with translation. Specific miRNAs are key regulators of adipogenesis, and are expressed at different levels in adipose tissue from lean and obese mice. The degree of lipid accumulation and distribution of white adipose tissue differs between males and females, and it is unknown whether sex differences in adipose tissue-specific miRNA expression may contribute to this dimorphism. Typically, sex differences are attributed to hormones secreted from ovaries or testes. However, the sex chromosome complement (XX versus XY) is also a …

Polypores And Genus Concepts In Phanerochaetaceae (Polyporales, Basidiomycota), Otto Miettinen, Viacheslav Spirin, Josef Vlasák, Bernard Rivoire, Soili Stenroos, David S. Hibbett

Biology

We explored whether DNA-phylogeny-based and morphology-based genus concepts can be reconciled in the basidiomycete family Phanerochaetaceae. Our results show that macromorphology of fruiting bodies and hymenophore construction do not reflect monophyletic groups. However, by integrating micromor-phology and re-defining genera, harmonization of DNA phylogeny and morphological genus concepts is possible in most cases. In the case of one genus (Phlebiopsis), our genetic markers could not resolve genus limits satisfactorily and a clear morphological definition could not be identified. We combine extended species sampling, microscopic studies of fruiting bodies and phylogenetic analyses of ITS, nLSU and rpb1 to revise genus concepts. Three …

Functional Trait Values, Not Trait Plasticity, Drive The Invasiveness Of Rosa Sp. In Response To Light Availability, Rebecca E. Drenovsky, Jennifer E. Murphy

Biology

PREMISE OF THE STUDY : Functional trait plasticity in resource capture traits has been suggested as an underlying mechanism promoting invasive species establishment and spread. Earlier studies on this mechanism treat invasiveness as a discrete characteristic (i.e., invasive vs. noninvasive) and do not consider the potential impacts of evolutionary history. In the present study, we used a continuous measure of invasiveness and a phylogenetic framework to quantify the relationship between functional trait expression, plasticity, and invasiveness in Rosa .

Marine Ecoregion And Deepwater Horizon Oil Spill Affect Recruitment And Population Structure Of A Salt Marsh Snail, Steven C. Pennings, Scott Zengel, Jacob Oehrig, Merryl Alber, T. Dale Bishop, Donald R. Deis, Donna Devlin, A. Randall Hughes, John J. Hutchens, Whitney M. Kiehn, Caroline R. Mcfarlin, Clay L. Montague, Sean Powers, C. Edward Proffitt, Nicolle Rutherford, Camille L. Stagg, Keith Walters

Biology

Marine species with planktonic larvae often have high spatial and temporal variation in recruitment that leads to subsequent variation in the ecology of benthic adults. Using a combination of published and unpublished data, we compared the population structure of the salt marsh snail, Littoraria irrorata, between the South Atlantic Bight and the Gulf Coast of the United States to infer geographic differences in recruitment and to test the hypothesis that the Deepwater Horizon oil spill led to widespread recruitment failure of L. irrorata in Louisiana in 2010. Size-frequency distributions in both ecoregions were bimodal, with troughs in the distributions consistent …

Reproductive Success Through High Pollinator Visitation Rates Despite Self Incompatibility In An Endangered Wallflower, Miranda K. Melen, Julie A. Herman, Jessica Lucas, Rachel E. O’Malley, Ingrid M. Parker, Aaron M. Thom, Justen B. Whittall

Biology

PREMISE OF THE STUDY: Self incompatibility (SI) in rare plants presents a unique challenge—SI protects plants from inbreeding depression, but requires a sufficient number of mates and xenogamous pollination. Does SI persist in an endangered polyploid? Is pollinator visitation sufficient to ensure reproductive success? Is there evidence of inbreeding/outbreeding depression? We characterized the mating system, primary pollinators, pollen limitation, and inbreeding/outbreeding depression in Erysimum teretifolium to guide conservation efforts.

METHODS: We compared seed production following self pollination and within- and between-population crosses. Pollen tubes were visualized after self pollinations and between-population pollinations. Pollen limitation was tested in the field. Pollinator …

Habitats Colonized By Non-Native Flowering Rush Butomus Umbellatus (Linnaeus, 1753) In The Niagara River, Usa, Matthew D. Gunderson, Kevin L. Kapuscinski, Derek P. Crane, John M. Farrell

Biology

During the summer of 2012, we first observed non-native flowering rush Butomus umbellatus (Linnaeus, 1753) in the upper Niagara River, NY, USA, where this species had previously been undocumented. In a 2013 study, Butomus was present at 33 of 161 (20%) submersed nearshore (≤ 3 m) sites surveyed. It was the species of greatest biomass at 27% of the sites where it was collected, and was observed growing at depths > 3 m. Butomus was disproportionately prevalent in the upper observed ranges of water depth and velocity. Butomus was also closely associated with coarse substrates, differing from canopy-forming species but not …

Malosma Laurina Dieback Associated With Fungal Induced Loss In Hydraulic Conductivity And Photosynthesis, Gabriella N. Palmeri, Shaquetta R. Reese, Helen I. Holmlund, Frank W. Ewers, Stephen D. Davis

Biology

Widespread Malosma laurina (Laurel Sumac) dieback is occurring throughout the Santa Monica Mountains. M. laurina is a keystone species within the SMM and its deep roots provide necessary slope stability to the hillsides; therefore, M. laurina’s health is of ecological importance. This study examines whether M. laurina dieback is associated with decreased stem water transport due to the prevalence of a pathogenic fungus within the water transport tissue. Stem samples from dieback and healthy control M. laurina were cultured for fungal growth. 100% of samples from water transport tissue from dieback adult plants contained a fungal pathogen from the …

Phenotypic Plasticity And Population Differentiation In Response To Salinity In The Invasive Cordgrass Spartina Densiflora, Rebecca E. Drenovsky, Brenda J. Grewell, Jesus M. Castillo, Meghan J. Skaer Thomason

Biology

Salinity and tidal inundation induce physiological stress in vascular plant species and influence their distribution and productivity in estuarine wetlands. Climate change-induced sea level rise may magnify these abiotic stressors and the physiological stresses they can cause. Understanding the potential of invasive plants to respond to predicted salinity increases will elucidate their potential niche breadth. To examine potential phenotypic plasticity and functional trait responses to salinity stress in the invasive cordgrass Spartina densiflora, we collected rhizomes from four invasive populations occurring from California to Vancouver Island, British Columbia on the Pacific Coast of North America. In a glasshouse common …

Nucleotide Interdependency In Transcription Factor Binding Sites In The Drosophila Genome, Jacqueline M. Dresch, Rowan G. Zellers, Daniel K. Bork, Robert A. Drewell

Biology

A long-standing objective in modern biology is to characterize the molecular components that drive the development of an organism. At the heart of eukaryotic development lies gene regulation. On the molecular level, much of the research in this field has focused on the binding of transcription factors (TFs) to regulatory regions in the genome known as cis-regulatory modules (CRMs). However, relatively little is known about the sequence-specific binding preferences of many TFs, especially with respect to the possible interdependencies between the nucleotides that make up binding sites. A particular limitation of many existing algorithms that aim to predict binding site …

Modeling Observed Animal Performance Using The Weibull Distribution, Travis J. Hagey, Jonathan B. Puthoff, Kristen E. Crandell, Kellar Autumn, Luke J. Harmon

Biology

To understand how organisms adapt, researchers must link performance and microhabitat. However, measuring performance, especially maximum performance, can sometimes be difficult. Here, we describe an improvement over previous techniques that only consider the largest observed values as maxima. Instead, we model expected performance observations via the Weibull distribution, a statistical approach that reduces the impact of rare observations. After calculating group-level weighted averages and variances by treating individuals separately to reduce pseudoreplication, our approach resulted in high statistical power despite small sample sizes. We fitted lizard adhesive performance and bite force data to the Weibull distribution and found that it …

Quantitative Perturbation-Based Analysis Of Gene Expression Predicts Enhancer Activity In Early Drosophila Embryo, Rupinder Sayal, Jacqueline M. Dresch, Irina Pushel, Benjamin R. Taylor, David N. Arnosti

Biology

Enhancers constitute one of the major components of regulatory machinery of metazoans. Although several genome-wide studies have focused on finding and locating enhancers in the genomes, the fundamental principles governing their internal architecture and cis-regulatory grammar remain elusive. Here, we describe an extensive, quantitative perturbation analysis targeting the dorsal-ventral patterning gene regulatory network (GRN) controlled by Drosophila NF-kB homolog Dorsal. To understand transcription factor interactions on enhancers, we employed an ensemble of mathematical models, testing effects of cooperativity, repression, and factor potency. Models trained on the dataset correctly predict activity of evolutionarily divergent regulatory regions, providing insights into spatial relationships …

Design For Mosquito Abundance, Diversity, And Phenology Sampling Within The National Ecological Observatory Network, D. Hoekman, Y. P. Springer, C. M. Barker, R. Barrera, M. S. Blackmore, W. E. Bradshaw, D. H. Foley, H. S. Ginsberg, M. H. Hayden, C. M. Holzapfel, S. A. Juliano, L. D. Kramer, S. L. Ladeau, Todd P. Livdahl, C. G. Moore, R. S. Nasci, W. K. Reisen, H. M. Savage

Biology

The National Ecological Observatory Network (NEON) intends to monitor mosquito populations across its broad geographical range of sites because of their prevalence in food webs, sensitivity to abiotic factors, and relevance for human health. We describe the design of mosquito population sampling in the context of NEON's long-term continental scale monitoring program, emphasizing the sampling design schedule, priorities, and collection methods. Freely available NEON data and associated field and laboratory samples, will increase our understanding of how mosquito abundance, demography, diversity, and phenology are responding to land use and climate change.

Erratum: In the paper by Hoekman et al. (“Design …

Tick-, Mosquito-, And Rodent-Borne Parasite Sampling Designs For The National Ecological Observatory Network, Yuri P. Springer, David Hoekman, Pieter T.J. Johnson, Paul A. Duffy, Rebecca A. Hufft, David T. Barnett, Brian F. Allan, Brian R. Amman, Christopher M. Barker, Roberto Barrera, Charles B. Beard, Lorenza Beati, Mike Begon, Mark S. Blackmore, William E. Bradshaw, Dustin Brisson, Charles H. Calisher, James E. Childs, Maria A. Diuk-Wasser, Richard J. Douglass, Rebecca J. Eisen, Desmond H. Foley, Janet E. Foley, Holly D. Gaff, Scott L. Gardner, Howard S. Ginsberg, Gregory E. Glass, Sarah A. Hamer, Mary H. Hayden, Brian Hjelle, Christina M. Holzapfel, Steven A. Juliano, Todd P. Livdahl

Biology

Parasites and pathogens are increasingly recognized as significant drivers of ecological and evolutionary change in natural ecosystems. Concurrently, transmission of infectious agents among human, livestock, and wildlife populations represents a growing threat to veterinary and human health. In light of these trends and the scarcity of long-term time series data on infection rates among vectors and reservoirs, the National Ecological Observatory Network (NEON) will collect measurements and samples of a suite of tick-, mosquito-, and rodent-borne parasites through a continental-scale surveillance program. Here, we describe the sampling designs for these efforts, highlighting sampling priorities, field and analytical methods, and the …

Src1 Is A Protein Of The Inner Nuclear Membrane Interacting With The Dictyostelium Lamin Ne81, Petros Batsios, Xiang Ren, Otto Baumann, Denis A. Larochelle, Ralph Gräf

Biology

The nuclear envelope (NE) consists of the outer and inner nuclear membrane (INM), whereby the latter is bound to the nuclear lamina. Src1 is a Dictyostelium homologue of the helix-extension-helix family of proteins, which also includes the human lamin-binding protein MAN1. Both endogenous Src1 and GFP-Src1 are localized to the NE during the entire cell cycle. Immuno-electron microscopy and light microscopy after differential detergent treatment indicated that Src1 resides in the INM. FRAP experiments with GFP-Src1 cells suggested that at least a fraction of the protein could be stably engaged in forming the nuclear lamina together with the Dictyostelium lamin …

Parent-Of-Origin Effects On Genome-Wide Dna Methylation In The Cape Honey Bee (Apis Mellifera Capensis) May Be Confounded By Allele-Specific Methylation, Emily J. Remnant, Alyson Ashe, Paul E. Young, Gabriele Buchmann, Madeleine Beekman, Michael H. Allsopp, Catherine M. Suter, Robert A. Drewell, Benjamin P. Oldroyd

Biology

Background: Intersexual genomic conflict sometimes leads to unequal expression of paternal and maternal alleles in offspring, resulting in parent-of-origin effects. In honey bees reciprocal crosses can show strong parent-of-origin effects, supporting theoretical predictions that genomic imprinting occurs in this species. Mechanisms behind imprinting in honey bees are unclear but differential DNA methylation in eggs and sperm suggests that DNA methylation could be involved. Nonetheless, because DNA methylation is multifunctional, it is difficult to separate imprinting from other roles of methylation. Here we use a novel approach to investigate parent-of-origin DNA methylation in honey bees. In the subspecies Apis mellifera capensis, …

Ectomycorrhizal Fungi Decompose Soil Organic Matter Using Oxidative Mechanisms Adapted From Saprotrophic Ancestors, Firoz Shah, César Nicolás, Johan Bentzer, Magnus Ellström, Mark Smits, Francois Rineau, Björn Canbäck, Dimitrios Floudas, Robert Carleer, Gerald Lackner, Jana Braesel, Dirk Hoffmeister, Bernard Henrissat, Dag Ahrén, Tomas Johansson, David S. Hibbett, Francis Martin, Per Persson, Anders Tunlid

Biology

Ectomycorrhizal fungi are thought to have a key role in mobilizing organic nitrogen that is trapped in soil organic matter (SOM). However, the extent to which ectomycorrhizal fungi decompose SOM and the mechanism by which they do so remain unclear, considering that they have lost many genes encoding lignocellulose-degrading enzymes that are present in their saprotrophic ancestors. Spectroscopic analyses and transcriptome profiling were used to examine the mechanisms by which five species of ectomycorrhizal fungi, representing at least four origins of symbiosis, decompose SOM extracted from forest soils. In the presence of glucose and when acquiring nitrogen, all species converted …

Transcriptome And Biochemical Analysis Of A Flower Color Polymorphism In Silene Littorea (Caryophyllaceae), Inés Casimiro-Soriguer, Eduardo Narbona, Mª L. Buide, José C. Del Valle, Justen B. Whittall

Biology

Flower color polymorphisms are widely used as model traits from genetics to ecology, yet determining the biochemical and molecular basis can be challenging. Anthocyanin-based flower color variations can be caused by at least 12 structural and three regulatory genes in the anthocyanin biosynthetic pathway (ABP). We use mRNA-Seq to simultaneously sequence and estimate expression of these candidate genes in nine samples of Silene littorea representing three color morphs (dark pink, light pink, and white) across three developmental stages in hopes of identifying the cause of flower color variation. We identified 29 putative paralogs for the 15 candidate genes in the …

Trait Responses Of Invasive Aquatic Macrophyte Congeners: Colonizing Diploid Outperforms Polyploid, Rebecca E. Drenovsky, Brenda J. Grewell, Meghan J. Skaer Thomason, C. J. Futrell, M. Iannucci

Biology

Understanding traits underlying colonization and niche breadth of invasive plants is key to developing sustainable management solutions to curtail invasions at the establishment phase, when efforts are often most effective. The aim of this study was to evaluate how two invasive congeners differing in ploidy respond to high and low resource availability following establishment from asexual fragments. Because polyploids are expected to have wider niche breadths than diploid ancestors, we predicted that a decaploid species would have superior ability to maximize resource uptake and use, and outperform a diploid congener when colonizing environments with contrasting light and nutrient availability. A …

Phylogenetic Relationships Of Dasyuromorphian Marsupials Revisited, Christopher A. Emerling, Michael Westerman, Carey Krajewski, Benjamin P. Kear, Lucy Meehan, Robert W. Meredith, Mark S. Springer

Biology

We reassessed the phylogenetic relationships of dasyuromorphians using a large molecular database comprising previously published and new sequences for both nuclear (nDNA) and mitochondrial (mtDNA) genes from the numbat (Myrmecobius fasciatus), most living species of Dasyuridae, and the recently extinct marsupial wolf, Thylacinus cynocephalus. Our molecular tree suggests that Thylacinidae is sister to Myrmecobiidae + Dasyuridae. We show robust support for the dasyurid intrafamilial classification proposed by Krajewski & Westerman as well as for placement of most dasyurid genera, which suggests substantial homoplasy amongst craniodental characters presently used to generate morphology-based taxonomies. Molecular dating with relaxed molecular clocks suggests that …

Inactivation Of Cone-Specific Phototransduction Genes In Rod Monochromatic Cetaceans, Christopher A. Emerling, Mark S. Springer, Noah Fugate, Rachna Patel, James Starrett, Phillip A. Morin, Cheryl Hayashi, John Gatesy

Biology

Vertebrate vision is mediated by two types of photoreceptors, rod and cone cells. Rods are more sensitive than cones in dim light, but are incapable of color discrimination because they possess only one type of photosensitive opsin protein (rod opsin = RH1). By contrast, cones are more important for vision in bright light. Cones also facilitate dichromatic color vision in most mammals because there are two cone pigment genes (SWS1, LWS) that facilitate color discrimination. Cone monochromacy occurs when one of the cone opsins (usually SWS1) is inactivated and is present in assorted subterranean, nocturnal, and aquatic mammals. Rod monochromacy …

Osteopontin Ablation Ameliorates Muscular Dystrophy By Shifting Macrophages To A Proregenerative Phenotype, Sylvia Vetrone, Joana Capote, Irina Kramerova, Leonel Martinez, Elisabeth R. Barton, H. Lee Sweeney, M. Carrie Miceli, Melissa J. Spencer

Biology

In the degenerative disease Duchenne muscular dystrophy, inflammatory cells enter muscles in response to repetitive muscle damage. Immune factors are required for muscle regeneration, but chronic inflammation creates a profibrotic milieu that exacerbates disease progression. Osteopontin (OPN) is an immunomodulator highly expressed in dystrophic muscles. Ablation of OPN correlates with reduced fibrosis and improved muscle strength as well as reduced natural killer T (NKT) cell counts. Here, we demonstrate that the improved dystrophic phenotype observed with OPN ablation does not result from reductions in NKT cells. OPN ablation skews macrophage polarization toward a pro-regenerative phenotype by reducing M1 and M2a …

The Importance Of Having Two X Chromosomes, Jenny Link, Arthur P. Arnold, Karen Reue, Mansoureh Eghbali, Eric Vilain, Xuqi Chen, Negar Ghahramani, Yuichiro Itoh, Jingyuan Li, Tuck Ngun, Shayna M. Williams-Burris

Biology

Historically, it was thought that the number of X chromosomes plays little role in causing sex differences in traits. Recently, selected mouse models have been used increasingly to compare mice with the same type of gonad but with one versus two copies of the X chromosome. Study of these models demonstrates that mice with one X chromosome can be strikingly different from those with two X chromosomes, when the differences are not attributable to confounding group differences in gonadal hormones. The number of X chromosomes affects adiposity and metabolic disease, cardiovascular ischaemia/reperfusion injury and behaviour. The effects of X chromosome …

Use Of The Non-Radioactive Sunset Method To Detect Decreased Protein Synthesis In Proteasome Inhibited Arabidopsis Roots, Doug Van Hoewyk

Biology

Background: In eukaryotic cells, the proteasome maintains homeostasis by selectively degrading regulatory and misfolded proteins, and in doing so contributes to the amino acid pool. Inhibition of the proteasome in yeast and human cells decreases de novo protein synthesis. However, it is not know if proteasome inhibition in plants similarly suppresses protein synthesis. To address this gap in plant biology, protein synthesis in Arabidopsis roots was estimated using SUface SEnsing of Translation (SUnSET) techniques. This non-radioactive method has been validated in animal cells, but has not yet been applied to plants. The goal of this study was to investigate the …

Draft Genome Sequence Of The White-Rot Fungus Obba Rivulosa 3a-2, Otto Miettinen, Robert Riley, Kerrie Barry, Dan Cullen, Ronald P. De Vries, Matthieu Hainaut, Annele Hatakka, Bernard Henrissat, Kristiina Hildén, Rita Kuo, Kurt Labutti, Anna Lipzen, Miia R. Mäkelä, Laura Sandor, Joseph W. Spatafora, Igor V. Grigoriev, David S. Hibbett

Biology

We report here the first genome sequence of the white-rot fungus Obba rivulosa (Polyporales, Basidiomycota), a polypore known for its lignin-decomposing ability. The genome is based on the homokaryon 3A-2 originating in Finland. The genome is typical in size and carbohydrate active enzyme (CAZy) content for wood-decomposing basidiomycetes.

Rt-Qpcr Demonstrates Light-Dependent Atrbcs1a And Atrbcs3b Mrna Expressions In Arabidopsis Thaliana Leaves, Ming-Mei Chang, Anna Li, Robert Feissner, Talal Ahmad

Biology

Reverse transcription quantitative polymerase chain reaction (RT-qPCR) is widely used in diagnosis and research to determine specific mRNA expressions in cells. As RT-qPCR applications increase, it’s necessary to provide undergraduates hands-on experience of this modern technique. Here, we report a 3-week laboratory exercise using RT-qPCR to demonstrate the light-dependent expressions of AtRBCS1A and AtRBCS3B genes encoding two Arabidopsis thaliana small subunits of the ribulose 1,5-bisphosphate carboxylase/ oxygenase (Rubisco). In the first week, students purified and quantified total RNA from leaves of A. thaliana pretreated in the dark for 96 hr and untreated controls. In the second week, RNA samples were …

Premature Seed Germination And High Seedling Mortality In A Chaparral Shrub (Adenostoma Fasciculatum) Caused By Severe Drought In Calfiornia, Lexe Evans, Teal Speece, Stephen D. Davis

Biology

The Santa Monica Mountains (SMM) represents one of five Mediterranean-type environments in the world. With sustained summer droughts, this ecosystem is prone to frequent wildfires, a phenomenon that has affected the SMM with regularity once every 32 years. Adenostoma fasciculatum (chamise), is a chaparral shrub well adapted to wildfire cycles because typically its seeds are triggered to germinate by high fire temperatures, smoke, and charate. In the winter of 2015, we were surprised to discover seedlings of A. fasiculatum emerging at an unburned chaparral site without the occurrence of fire. We hypothesized that drought induced canopy dieback at some microsites, …

Recent Dieback In A Keystone Chaparral Species Is Caused By A Fungal Pathogen, Botryosphaeria Dothidea, Adriana Borges, Frida Morales, Emily Pierce, Mariah Taylor

Biology

Due to the recent drought in Southern California, the abundance of a keystone species, Malosma laurina, within the Santa Monica Mountains (SMM) has been dwindling. This species has a rooting depth that exceeds 13 m, so it typically has little difficulty tapping into the water table. Recently, this species has undergone extensive dieback, which might be attributed to the unprecedented drought in California and predisposition fungal pathogen Botryosphaeria. dothidea. While this fungi appears to be innocuous to M. laurina when the plant is healthy, it is more susceptible to invasion under water stress due to the dry and …