Residence time determines invasiveness and performance of garlic mustard (Alliaria petiolata) in North America.

While biological invasions have the potential for large negative impacts on local communities and ecological interactions, increasing evidence suggests that species once considered major problems can decline over time. Declines often appear driven by natural enemies, diseases or evolutionary adaptations that selectively reduce populations of naturalised species and their impacts. Using permanent long-term monitoring locations, we document declines of Alliaria petiolata (garlic mustard) in eastern North America with distinct local and regional dynamics as a function of patch residence time. Projected site-specific population growth rates initially indicated expanding populations, but projected population growth rates significantly decreased over time and at the majority of sites fell below 1, indicating declining populations. Negative soil feedback provides a potential mechanism for the reported disappearance of ecological dominance of A. petiolata in eastern North America.

The importance of space, time, and stochasticity to the demography and management of Alliaria petiolata.

As population modeling is increasingly called upon to guide policy and management, it is important that we understand not only the central tendencies of our study systems, but the consequences of their variation in space and time as well. The invasive plant Alliaria petiolata (garlic mustard) is actively managed in the United States and is the focus of a developing biological control program. Two weevils (Coleoptera: Curculionidae: Ceutorhynchus) that reduce fecundity (C. alliariae) and rosette survival plus fecundity (C. scrobicollis) are under consideration for release pending host specificity testing. We used a demographic modeling approach to (1) quantify variability in A. petiolata growth and vital rates and (2) assess the potential for single- or multiple-agent biocontrol to suppress growth of 12 A. petiolata populations in Illinois and Michigan studied over three plant generations. We used perturbation analyses and simulation models with stochastic environments to estimate stochastic growth rates (lambda(S)) and predict the probability of successful management using either a single biocontrol agent or two agent species together. Not all populations exhibited invasive dynamics. Estimates of lambda(S) ranged from 0.78 to 2.21 across sites, while annual, deterministic growth (lambda) varied up to sevenfold within individual sites. Given our knowledge of the biocontrol agents, this analysis suggests that C. scrobicollis alone may control A. petiolata at up to 63% of our study sites where lambda >1, with the combination of both agents predicted to succeed at 88% of sites. Across sites and years, the elasticity rankings were dependent on lambda. Reductions of rosette survival, fecundity, or germination of new seeds are predicted to cause the greatest reduction of lambda in growing populations. In declining populations, transitions affecting seed bank survival have the greatest effect on lambda. This contrasts with past analyses that varied parameters individually in an otherwise constant matrix, which may yield unrealistic predictions by decoupling natural parameter covariances. Overall, comparisons of stochastic and deterministic growth rates illustrate how analyses of individual populations or years could misguide management or fail to characterize complex traits such as invasiveness that emerge as attributes of populations rather than species.

Zinc dyshomeostasis is linked with the loss of mucolipidosis IV-associated TRPML1 ion channel.

Chelatable zinc is important in brain function, and its homeostasis is maintained to prevent cytotoxic overload. However, certain pathologic events result in intracellular zinc accumulation in lysosomes and mitochondria. Abnormal lysosomes and mitochondria are common features of the human lysosomal storage disorder known as mucolipidosis IV (MLIV). MLIV is caused by the loss of TRPML1 ion channel function. MLIV cells develop large hyperacidic lysosomes, membranous vacuoles, mitochondrial fragmentation, and autophagic dysfunction. Here, we observed that RNA interference of mucolipin-1 gene (TRPML1) in HEK-293 cells mimics the MLIV cell phenotype consisting of large lysosomes and membranous vacuoles that accumulate chelatable zinc. To show that abnormal chelatable zinc levels are indeed correlated with MLIV pathology, we quantified its concentration in cultured MLIV patient fibroblast and control cells with a spectrofluorometer using N-(6-methoxy-8-quinolyl)-p-toluene sulfonamide fluorochrome. We found a significant increase of chelatable zinc levels in MLIV cells but not in control cells. Furthermore, we quantified various metal isotopes in whole brain tissue of TRPML1(-/-) null mice and wild-type littermates using inductively coupled plasma mass spectrometry and observed that the zinc-66 isotope is markedly elevated in the brain of TRPML1(-/-) mice when compared with controls. In conclusion, we show for the first time that the loss of TRPML1 function results in intracellular chelatable zinc dyshomeostasis. We propose that chelatable zinc accumulation in large lysosomes and membranous vacuoles may contribute to the pathogenesis of the disease and progressive cell degeneration in MLIV patients.

Differences in the temporal dynamics of phenotypic selection among fitness components in the wild.

The balance of selection acting through different fitness components (e.g. fecundity, mating success, survival) determines the potential tempo and trajectory of adaptive evolution. Yet the extent to which the temporal dynamics of phenotypic selection may vary among fitness components is poorly understood. Here, we compiled a database of 3978 linear selection coefficients from temporally replicated studies of selection in wild populations to address this question. Across studies, we find that multi-year selection through mating success and fecundity is stronger than selection through survival, but varies less in direction. We also report that selection through mating success varies more in long-term average strength than selection through either survival or fecundity. The consistency in direction and stronger long-term average strength of selection through mating success and fecundity suggests that selection through these fitness components should cause more persistent directional evolution relative to selection through survival. Similar patterns were apparent for the subset of studies that evaluated the temporal dynamics of selection on traits simultaneously using several different fitness components, but few such studies exist. Taken together, these results reveal key differences in the temporal dynamics of selection acting through different fitness components, but they also reveal important limitations in our understanding of how selection drives adaptive evolution.

Consequences of parameterization and structure of applied demographic models: a comment on Pardini et al. (2009).

Correcting the problems in the model of A. petiolata presented in Pardini et al. (2009) changes its dynamics and thus the management recommendations. As with any model, our revised model's-management predictions are conditional on model parameterization. Thus, managers should carefully consider at what spatial scales it is appropriate to infer management recommendations given the data used to build the model (e.g., is a management plan developed from a population in Missouri equally relevant to populations in Georgia, Maine, and Oregon?). In agreement with PDCK's conclusions, we found their A. petiolata study population to exhibit complex dynamics (two-point cycling) at lower efficacies of either rosette or adult management, and stable equilibria at higher management efficacies. This could have important implications for A. petiolata management techniques such as biological control if the biocontrol agents' population dynamics are dependent on A. petiolata density. While the predictions generated in our reanalysis represent an improvement over the original model, they should be tempered by the limited scope of the data used to parameterize the model. Running the model through previously published parameter ranges results in qualitatively different dynamics than those predicted in PDCK. Because of the tremendous spatiotemporal variability in A. petiolata demographic rates and the species' large geographical range, more general management recommendations will only arise from a larger set of demographic data that has greater coverage in space and time. Our revision of the model of Pardini et al. (2009) should therefore be considered as a subset of many possible models of A. petiolata population dynamics.

The tissue-specific expression of TRPML2 (MCOLN-2) gene is influenced by the presence of TRPML1.

Mucolipidosis type IV is a lysosomal storage disorder caused by the loss or dysfunction of the mucolipin-1 (TRPML1) protein. It has been suggested that TRPML2 could genetically compensate (i.e., become upregulated) for the loss of TRPML1. We thus investigated this possibility by first studying the expression pattern of mouse TRPML2 and its basic channel properties using the varitint-waddler (Va) model. Here, we confirmed the presence of long variant TRPML2 (TRPML2lv) and short variant (TRPML2sv) isoforms. We showed for the first time that, heterologously expressed, TRPML2lv-Va is an active, inwardly rectifying channel. Secondly, we quantitatively measured TRPML2 and TRPML3 mRNA expressions in TRPML1-/- null and wild-type (Wt) mice. In wild-type mice, the TRPML2lv transcripts were very low while TRPML2sv and TRPML3 transcripts have predominant expressions in lymphoid and kidney organs. Significant reductions of TRPML2sv, but not TRPML2lv or TRPML3 transcripts, were observed in lymphoid and kidney organs of TRPML1-/- mice. RNA interference of endogenous human TRPML1 in HEK-293 cells produced a comparable decrease of human TRPML2 transcript levels that can be restored by overexpression of human TRPML1. Conversely, significant upregulation of TRPML2sv transcripts was observed when primary mouse lymphoid cells were treated with nicotinic acid adenine dinucleotide phosphate, or N-(2-[p-bromocinnamylamino]ethyl)-5-isoquinoline sulfonamide, both known activators of TRPML1. In conclusion, our results indicate that TRPML2 is unlikely to compensate for the loss of TRPML1 in lymphoid or kidney organs and that TRPML1 appears to play a novel role in the tissue-specific transcriptional regulation of TRPML2.

Considering weed management as a social dilemma bridges individual and collective interests.

Weeds pose severe threats to agricultural and natural landscapes worldwide. One major reason for the failure to effectively manage weeds at landscape scales is that current Best Management Practice guidelines, and research on how to improve such guidelines, focus too narrowly on property-level management decisions. Insufficiently considered are the aggregate effects of individual actions to determine landscape-scale outcomes, or whether there are collective practices that would improve weed management outcomes. Here, we frame landscape-scale weed management as a social dilemma, where trade-offs occur between individual and collective interests. We apply a transdisciplinary system approach-integrating the perspectives of ecologists, evolutionary biologists and agronomists into a social science theory of social dilemmas-to four landscape-scale weed management challenges: (i) achieving plant biosecurity, (ii) preventing weed seed contamination, (iii) maintaining herbicide susceptibility and (iv) sustainably using biological control. We describe how these four challenges exhibit characteristics of 'public good problems', wherein effective weed management requires the active contributions of multiple actors, while benefits are not restricted to these contributors. Adequate solutions to address these public good challenges often involve a subset of the eight design principles developed by Elinor Ostrom for 'common pool social dilemmas', together with design principles that reflect the public good nature of the problems. This paper is a call to action for scholars and practitioners to broaden our conceptualization and approaches to weed management problems. Such progress begins by evaluating the public good characteristics of specific weed management challenges and applying context-specific design principles to realize successful and sustainable weed management.

Confronting herbicide resistance with cooperative management.

BACKGROUND: Resistance of pathogens and pests to antibiotics and pesticides worldwide is rapidly reaching critical levels. The common-pool-resource nature of this problem (i.e. whereby the susceptibility to treatment of target organisms is a shared resource) has been largely overlooked. Using herbicide-resistant weeds as a model system, we developed a discrete-time landscape-scale simulation to investigate how aggregating herbicide management strategies at different spatial scales from individual farms to larger cooperative structures affects the evolution of glyphosate resistance in common waterhemp (Amaranthus tuberculatus). RESULTS: Our findings indicate that high-efficacy herbicide management strategies practiced at the farm scale are insufficient to slow resistance evolution in A. tuberculatus. When best practices were aggregated at large spatial scales, resistance evolution was hindered; conversely, when poor management practices were aggregated, resistance was exacerbated. Tank mixture-based strategies were more effective than rotation-based strategies in most circumstances, while applying glyphosate alone resulted in the poorest outcomes. CONCLUSIONS: Our findings highlight the importance of landscape-scale cooperative management for confronting common-pool-resource resistance problems in weeds and other analogous systems. © 2018 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Soil-mediated eco-evolutionary feedbacks in the invasive plant Alliaria petiolata.

Ecological and evolutionary processes historically have been assumed to operate on significantly different time-scales. We know now from theory and work in experimental and model systems that these processes can feed back on each other on mutually relevant time-scales.Here, we present evidence of a soil-mediated eco-evolutionary feedback on the population dynamics of an invasive biennial plant, Alliaria petiolata.As populations age, natural selection drives down production of A. petiolata's important antimycorrhizal allelochemical, sinigrin. This occurs due to density-dependent selection on sinigrin, which is favoured under interspecific, but disfavoured under intraspecific, competition.We show that population stochastic growth rates (λS) and plant densities are positively related to sinigrin concentration measured in seedling roots. This interaction is mediated by sinigrin's positive effect on seedling and summer survival, which are important drivers of λS.Together, these illustrate how the evolution of a trait shaped by natural selection can influence the ecology of a species over a period of just years to decades, altering its trajectory of population growth and interactions with the species in the soil and plant communities it invades.Our findings confirm the predictions that eco-evolutionary feedbacks occur in natural populations. Furthermore, they improve our conceptual framework for projecting future population growth by linking the variation in plant demography to a critical competitive trait (sinigrin) whose selective advantages decrease as populations age.

Managing the evolution of herbicide resistance.

BACKGROUND: Understanding and managing the evolutionary responses of pests and pathogens to control efforts is essential to human health and survival. Herbicide-resistant (HR) weeds undermine agricultural sustainability, productivity and profitability, yet the epidemiology of resistance evolution - particularly at landscape scales - is poorly understood. We studied glyphosate resistance in a major agricultural weed, Amaranthus tuberculatus (common waterhemp), using landscape, weed and management data from 105 central Illinois grain farms, including over 500 site-years of herbicide application records. RESULTS: Glyphosate-resistant (GR) A. tuberculatus occurrence was greatest in fields with frequent glyphosate applications, high annual rates of herbicide mechanism of action (MOA) turnover and few MOAs field(-1) year(-1) . Combining herbicide MOAs at the time of application by herbicide mixing reduced the likelihood of GR A. tuberculatus. CONCLUSIONS: These findings illustrate the importance of examining large-scale evolutionary processes at relevant spatial scales. Although measures such as herbicide mixing may delay GR or other HR weed traits, they are unlikely to prevent them. Long-term weed management will require truly diversified management practices that minimize selection for herbicide resistance traits.

Pyomyositis: a fatal case in a healthy teenager.

Pyomyositis is a common disease in the tropics that is reported with increasing frequency in the United States. We describe an unusually fulminant, fatal case in a previously healthy adolescent male. This case illustrates the clinical progression of pyomyositis from localized muscle infection to disseminated disease, and highlights the importance of considering this rare diagnosis in any stage of occult sepsis.

Evidence for gravity's influence on molecules at a solid-solution interface.

Yoshimoto et al. [Anal. Chem. 2002, 74, 4306-4309] reported that a quartz crystal microbalance or QCM changed its response to sucrose solutions according to its angle of immersion. The effect was tentatively attributed to gravity-caused stress on the viscous interface between the oscillator and the bulk solution. The present work reports results from QCM experiments carried out so that any effect of gravity on the interfacial region would be magnified. This permitted use of a lower-frequency, less-sensitive QCM. Molecules of DNA were tethered to a functionalized QCM surface and then extended in steps, via sandwich hybridization, to produce DNA of uniform and known length. This feature allowed both the effect of QCM immersion angle and the relationship between frequency and molecular length to be investigated simultaneously. Comparison of acoustic wave damping at 0 degrees and 180 degrees immersion angles offers compelling evidence that the interfacial region expands when the active face of the QCM is down and contracts when it is up. This is apparently a consequence of the interfacial region being more dense than the bulk solution. The results are consistent with (a) slow gravity-driven movement of molecules away from a down-facing QCM, (b) rapid hybridization-driven movement away from an up-facing QCM, and (c) a QCM frequency response that decreases according to a simple exponential function of the tethered molecules' radius of gyration.