ERA

Journal Articles (Biological Sciences)

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  1. Effect of water stress and plant defense stimulation on monoterpene emission from a historical and a new pine host of the mountain pine beetle [Download]

    Title: Effect of water stress and plant defense stimulation on monoterpene emission from a historical and a new pine host of the mountain pine beetle
    Creator: Lusebrink, Inka
    Description: The mountain pine beetle (Dendroctonus ponderosae, MPB) has killed millions of lodgepole pine (Pinus contorta) trees in Western Canada and recent range expansion has resulted in attack of jack pine (Pinus banksiana) in Alberta. Establishment of MPB in the Boreal forest will require use of jack pine under a suite of different environmental conditions than it typically encounters in its native range. Lodgepole and jack pine seedlings were grown under controlled environment conditions and subjected to either water deficit or well watered conditions and inoculated with Grosmannia clavigera, a MPB fungal associate. Soil water content, photosynthesis, stomatal conductance and emission of volatile organic compounds (VOCs) were monitored over the duration of the six-week study. Monoterpene content of bark and needle tissue was measured at the end of the experiment. β-Phellandrene, the major monoterpene in lodgepole pine, was almost completely lacking in the volatile emission profile of jack pine. The major compound in jack pine was α-pinene. The emission of both compounds was positively correlated with stomatal conductance. 3-Carene was emitted at a high concentration from jack pine seedlings which is in contrast to monoterpene profiles of jack pine from more southern and eastern parts of its range. Fungal inoculation caused a significant increase in total monoterpene emission in water deficit lodgepole pine seedlings right after its application. By four weeks into the experiment, water deficit seedlings of both species released significantly lower levels of total monoterpenes than well-watered seedlings. Needle tissue contained lower total monoterpene content than bark. Generally, monoterpene tissue content increased over time independent from any treatment. The results suggest that monoterpenes that play a role in pine-MPB interactions differ between lodgepole and jack pine, and also that they are affected by water availability.
    Subjects: Pinus cortorta, Pinus banksiana, VOCs, Monoterpenes, Tree defense, Grosmannia clavigera, Mountain pine beetle
    Date Created: 2011
  2. The lodgepole x jack pine hybrid zone in Alberta, Canada: A stepping stone for the mountain pine beetle on its journey east across the Boreal forest? [Download]

    Title: The lodgepole x jack pine hybrid zone in Alberta, Canada: A stepping stone for the mountain pine beetle on its journey east across the Boreal forest?
    Creator: Lusebrink, Inka
    Description: Historical data show that outbreaks of the tree killing mountain pine beetle are often preceded by periods of drought. Global climate change impacts drought frequency and severity and is implicated in the range expansion of the mountain pine beetle into formerly unsuitable habitats. Its expanded range has recently reached the lodgepole × jack pine hybrid zone in central Alberta, Canada, which could act as a transition from its historical lodgepole pine host to a jack pine host present in the boreal forest. This field study tested the effects of water limitation on chemical defences of mature trees against mountain pine beetle-associated microorganisms and on beetle brood success in lodgepole × jack pine hybrid trees. Tree chemical defences as measured by monoterpene emission from tree boles and monoterpene concentration in needles were greater in trees that experienced water deficit compared to well-watered trees. Myrcene was identified as specific defensive compound, since it significantly increased upon inoculation with dead mountain pine beetles. Beetles reared in bolts from trees that experienced water deficit emerged with a higher fat content, demonstrating for the first time experimentally that drought conditions benefit mountain pine beetles. Further, our study demonstrated that volatile chemical emission from tree boles and phloem chemistry place the hybrid tree chemotype in-between lodgepole pine and jack pine, which might facilitate the host shift from lodgepole pine to jack pine.
    Subjects: Mountain pine beetle, Range expansion, Drought, Tree defences, Beetle condition
    Date Created: 2013
  3. The genetic signature of rapid range expansions: How dispersal, growth and invasion speed impact heterozygosity and allele surfing [Download]

    Title: The genetic signature of rapid range expansions: How dispersal, growth and invasion speed impact heterozygosity and allele surfing
    Creator: Goodsman, Devin W.
    Description: As researchers collect spatiotemporal population and genetic data in tandem, models that connect demography and dispersal to genetics are increasingly relevant. The dominant spatiotemporal model of invasion genetics is the stepping-stone model which represents a gradual range expansion in which individuals jump to uncolonized locations one step at a time. However, many range expansions occur quickly as individuals disperse far from currently colonized regions. For these types of expansion, stepping-stone models are inappropriate. To more accurately reflect wider dispersal in many organisms, we created kernel-based models of invasion genetics based on integrodifference equations. Classic theory relating to integrodifference equations suggests that the speed of range expansions is a function of population growth and dispersal. In our simulations, populations that expanded at the same speed but with spread rates driven by dispersal retained more heterozygosity along axes of expansion than range expansions with rates of spread that were driven primarily by population growth. In addition, mutations that initially occurred at the fronts of expanding population waves reached higher mean abundances in waves driven by wider dispersal kernels than in waves traveling at the same speed but driven by high demographic growth rates. In our models based on random assortative mating, surfing alleles remained at relatively low frequencies and surfed less often compared to previous results based on stepping-stone simulations with asexual reproduction.
    Subjects: Dispersal, Genetic diversity, Heterozygosity, Invasion, Range expansion
    Date Created: 2014
  4. Factors influencing flight capacity of the mountain pine beetle (Coleoptera: Curculionidae: Scolytinae) [Download]

    Title: Factors influencing flight capacity of the mountain pine beetle (Coleoptera: Curculionidae: Scolytinae)
    Creator: Evenden, Maya L.
    Description: The mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae) is the most damaging pest of mature pine (Pinaceae) in western North America. Although mountain pine beetles have an obligate dispersal phase during which adults must locate a new host for brood production, dispersal is a poorly understood aspect of its ecology. This flight mill study was designed to test the effects of beetle size, sex, and age on flight capacity. Energy use during flight was assessed through measurements of weight before and after flight and fat content of flown versus control beetles. The mean flight distance achieved by mountain pine beetles varied between 2.12 and 5.95 km over the 23-h bioassay, but the longest total flight of an individual beetle was >24 km. Beetle preflight weight influenced flight initiation, flight distance, and duration. Bigger beetles are more likely to fly and once in flight fly longer and farther than smaller beetles. There was no direct effect of beetle sex on flight capacity. Flight capacity of beetles declined with age postemergence. Although individual flight capacity was variable, flight velocity was relatively constant between 1.55 and 1.93 km/h. Lipids are used to power flight in mountain pine beetles, as lipid content was lower in beetles flown on the flight mills compared with beetles that did not fly. Flight distance was negatively correlated with beetle postflight lipid content. The baseline flight capacity data revealed in this study have implications for understanding the population dynamics of this eruptive forest pest.
    Subjects: Mountain pine beetle, Dendroctonus ponderosae, Pinaceae, Flight
    Date Created: 2014
  5. A species-diagnostic SNP panel for discriminating lodgepole pine, jack pine, and their interspecific hybrids [Download]

    Title: A species-diagnostic SNP panel for discriminating lodgepole pine, jack pine, and their interspecific hybrids
    Creator: Cullingham, Catherine I.
    Description: Accurate stock identification is important for forest management, yet this can be a challenge for tree species that hybridize naturally. Species discriminating molecular markers provide a means to identify stock with high accuracy. In Canada, lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia) and jack pine (P. banksiana Lamb) form a large hybrid zone in Alberta and Northwest Territories; within this hybrid zone, the identification of parentals and hybrids is difficult due to an overlap in morphological characteristics. Pure and hybrid ancestry can be resolved using microsatellite markers, but these are difficult and costly to type. We have developed a panel of SNP markers using 454 transcriptome sequence data that are more cost effective, easier to score and have greater discriminating power for differentiating species than microsatellites. Our SNP panel provides accurate and cost efficient forest seed stock identification and will thereby facilitate reforestation and our pipeline can be applied to other hybrid systems globally.
    Subjects: Pinus banksiana, Pinus contorta, SNP, Seed stock, Lodgepole pine, Jack pine
    Date Created: 2013
  6. Global and comparative proteomic profiling of overwintering and developing mountain pine beetle, Dendroctonus ponderosae (Coleoptera: Curculionidae), larvae [Download]

    Title: Global and comparative proteomic profiling of overwintering and developing mountain pine beetle, Dendroctonus ponderosae (Coleoptera: Curculionidae), larvae
    Creator: Bonnett, Tiffany
    Description: BACKGROUND: Mountain pine beetles, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae), are native to western North America, but have recently begun to expand their range across the Canadian Rocky Mountains. The requirement for larvae to withstand extremely cold winter temperatures and potentially toxic host secondary metabolites in the midst of their ongoing development makes this a critical period of their lives. RESULTS: We have uncovered global protein profiles for overwintering mountain pine beetle larvae. We have also quantitatively compared the proteomes for overwintering larvae sampled during autumn cooling and spring warming using iTRAQ methods. We identified 1507 unique proteins across all samples. In total, 33 proteins exhibited differential expression (FDR < 0.05) when compared between larvae before and after a cold snap in the autumn; and 473 proteins exhibited differential expression in the spring when measured before and after a steady incline in mean daily temperature. Eighteen proteins showed significant changes in both autumn and spring samples. CONCLUSIONS: These first proteomic data for mountain pine beetle larvae show evidence of the involvement of trehalose, 2-deoxyglucose, and antioxidant enzymes in overwintering physiology; confirm and expand upon previous work implicating glycerol in cold tolerance in this insect; and provide new, detailed information on developmental processes in beetles. These results and associated data will be an invaluable resource for future targeted research on cold tolerance mechanisms in the mountain pine beetle and developmental biology in coleopterans.
    Subjects: Mountain pine beetle, Insect proteomics, Ferritin, 2-deoxyglucose, Cold tolerance, Overwintering
    Date Created: 2012
  7. The Genomes of Oryza sativa: A History of Duplications [Download]

    Title: The Genomes of Oryza sativa: A History of Duplications
    Creator: Yu, Jun
    Subjects: Biological Sciences , Genetics, Cell Biology , Evolutionary Biology , genomes
    Date Created: 2005/02
  8. Ankylosaurid dinosaur tail clubs evolved through stepwise acquisition of key features [Download]

    Title: Ankylosaurid dinosaur tail clubs evolved through stepwise acquisition of key features
    Creator: Arbour, Victoria M.
    Description: Ankylosaurid ankylosaurs were quadrupedal, herbivorous dinosaurs with abundant dermal ossifications. They are best known for their distinctive tail club composed of stiff, interlocking vertebrae (the handle) and large, bulbous osteoderms (the knob), which may have been used as a weapon. However, tail clubs appear relatively late in the evolution of ankylosaurids, and seemed to have been present only in a derived clade of ankylosaurids during the last 20 million years of the Mesozoic Era. New evidence from mid Cretaceous fossils from China suggests that the evolution of the tail club occurred at least 40 million years earlier, and in a stepwise manner, with early ankylosaurids evolving handle-like vertebrae before the distal osteoderms enlarged and coossified to form a knob.
    Subjects: Ankylosauria, Ankylosauridae, Cretaceous, Dinosauria
  9. Identifying non-invasible habitats for marine copepods using temperature-dependent R0. [Download]

    Title: Identifying non-invasible habitats for marine copepods using temperature-dependent R0.
    Creator: Rajakaruna, H.
    Description: If a non-indigenous species is to thrive and become invasive it must first persist under its new set of environmental conditions. Net reproductive rate (R 0) represents the average number of female offspring produced by a female over its lifetime, and has been used as a metric of population persistence. We modeled R 0 as a function of ambient water temperature (T) for the invasive marine calanoid copepod Pseudodiaptomus marinus, which is introduced to west coast of North America from East Asia by ship ballast water. The model was based on temperature-dependent stage-structured population dynamics given by a system of ordinary differential equations. We proposed a methodology to identify habitats that are non-invasible for P. marinus using the threshold of R 0(T) < 1 in order to identify potentially invasible habitats. We parameterized the model using published data on P. marinus and applied R 0(T) to identify the range of non-invasible habitats in a global scale based on sea surface temperature data. The model predictions matched the field evidence of species occurrences well.
    Subjects: stage-structured population models, marine copepods, net reproductive rate, ordinary differential equations, temperature, Pseudodiaptomus marinus, habitat suitability, ecological modeling, habitat invasibility, invasive species
  10. Allozyme survey and relationships of Limnoporus Stal species (Heteroptera: Gerridae) [Download]

    Title: Allozyme survey and relationships of Limnoporus Stal species (Heteroptera: Gerridae)
    Creator: Sperling, F. A. H.
    Description: Five species of Limnoporus Stål (L. canaliculatus [Say], L. dissortis [Drake and Harris], L. nearcticus [Kelton], L. notabilis [Drake and Hottes], and L. rufoscutellatus [Latreille]) were each sampled at 20 electrophoretic loci. Twofold differences among species in mean heterozygosity appear to be unrelated to presence of wing dimorphism. Low heterozygosity in some populations within species may reflect geographic isolation. There were substantial differences in allele frequency among, but not within, species. Limnoporus rufoscutellatus from western Europe and L. nearcticus from Alaska were the most similar pair of species, with a Nei’s standard genetic identity that is generally found only between populations of the same species. Limnoporus canaliculatus was the most divergent species, and the relationship among L. dissortis, L. notabilis, and the L. rufoscutellatus – L. nearcticus pair is resolved as a trichotomy.
    Subjects: Allozyme survery, Limnoporus Stal