Multiple modes of selection can influence the role of phenotypic plasticity in species' invasions: Evidence from a manipulative field experiment

In exploring the roles of phenotypic plasticity in the establishment and early evolution of invading species, little empirical attention has been given to the importance of correlational selection acting upon suites of functionally related plastic traits in nature. We illustrate how this lack of attention has limited our ability to evaluate plasticity's role during invasion and also, the costs and benefits of plasticity. We addressed these issues by transplanting clones of European-derived Plantago lanceolata L. genotypes into two temporally variable habitats in the species' introduced range in North America. Phenotypic selection analyses were performed for each habitat to estimate linear, quadratic, and correlational selection on phenotypic trait values and plasticities in the reproductive traits: flowering onset and spike and scape lengths. Also, we measured pairwise genetic correlations for our "colonists." Results showed that (a) correlational selection acted on trait plasticity after transplantation, (b) selection favored certain combinations of genetically correlated and uncorrelated trait values and plasticities, and (c) using signed, instead of absolute, values of plasticity in analyses facilitated the detection of correlational selection on trait value-plasticity combinations and their adaptive value. Based on our results, we urge future studies on species invasions to (a) measure correlational selection and (b) retain signed values of plasticity in order to better discriminate between adaptive and maladaptive plasticity.

Bacterial efflux inhibitors are widely distributed in land plants

ETHNOPHARMACOLOGICAL RELEVANCE

Secondary metabolites play a critical role in plant defense against disease and are of great importance to ethnomedicine. Bacterial efflux pumps are active transport proteins that bacterial cells use to protect themselves against multiple toxic compounds, including many antimicrobials. Efflux pump inhibitors from plants can block these efflux pumps, increasing the potency of antimicrobial compounds. This study demonstrates that efflux pump inhibition against the Gram-positive bacterial pathogen Staphylococcus aureus is widespread in extracts prepared from individual species throughout the land plant lineage. It therefore suggests a general mechanism by which plants used by indigenous species may be effective as a topical treatment for some bacterial infections.

AIM OF THE STUDY

The goal of this research was to evaluate the distribution of efflux pump inhibitors in nine plant extracts with an ethnobotanical use suggestive of an antimicrobial function for the presence of efflux pump inhibitory activity against Staphylococcus aureus.

MATERIALS AND METHODS

Plants were collected, dried, extracted, and vouchers submitted to the Herbarium of the University of North Carolina Chapel Hill (NCU). The extracts were analyzed by quantitative mass spectrometry (UPLC-MS) to determine the presence and concentration of flavonoids with known efflux pump inhibitory activity. A mass spectrometry-based assay was employed to measure efflux pump inhibition for all extracts against Staphylococcus aureus. The assay relies on UPLC-MS measurement of changes in ethidium concentration in the spent culture broth when extracts are incubated with bacteria.

RESULTS

Eight of these nine plant extracts inhibited toxic compound efflux at concentrations below the MIC (minimum inhibitory concentration) value for the same extract. The most active extracts were those prepared from Osmunda claytoniana L. and Pinus strobes L., which both demonstrated IC₅₀ values for efflux inhibition of 19 ppm.

CONCLUSIONS

Our findings indicate that efflux pump inhibitors active against Staphylococcus aureus are common in land plants. By extension, this activity is likely to be important in many plant-derived antimicrobial extracts, including those used in traditional medicine, and evaluation of efflux pump inhibition may often be valuable when studying natural product efficacy.

Two reproductive traits show contrasting genetic architectures in Plantago lanceolata

In many species, temperature-sensitive phenotypic plasticity (i.e., an individual's phenotypic response to temperature) displays a positive correlation with latitude, a pattern presumed to reflect local adaptation. This geographical pattern raises two general questions: (a) Do a few large-effect genes contribute to latitudinal variation in a trait? (b) Is the thermal plasticity of different traits regulated pleiotropically? To address the questions, we crossed individuals of Plantago lanceolata derived from northern and southern European populations. Individuals naturally exhibited high and low thermal plasticity in floral reflectance and flowering time. We grew parents and offspring in controlled cool- and warm-temperature environments, mimicking what plants would encounter in nature. We obtained genetic markers via genotype-by-sequencing, produced the first recombination map for this ecologically important nonmodel species, and performed quantitative trait locus (QTL) mapping of thermal plasticity and single-environment values for both traits. We identified a large-effect QTL that largely explained the reflectance plasticity differences between northern and southern populations. We identified multiple smaller-effect QTLs affecting aspects of flowering time, one of which affected flowering time plasticity. The results indicate that the genetic architecture of thermal plasticity in flowering is more complex than for reflectance. One flowering time QTL showed strong cytonuclear interactions under cool temperatures. Reflectance and flowering plasticity QTLs did not colocalize, suggesting little pleiotropic genetic control and freedom for independent trait evolution. Such genetic information about the architecture of plasticity is environmentally important because it informs us about the potential for plasticity to offset negative effects of climate change.

Natural selection contributes to geographic patterns of thermal plasticity in Plantago lanceolata

A long-standing debate in evolutionary biology concerns the relative importance of different evolutionary forces in explaining phenotypic diversification at large geographic scales. For example, natural selection is typically assumed to underlie divergence along environmental gradients. However, neutral evolutionary processes can produce similar patterns. We collected molecular genetic data from 14 European populations of Plantago lanceolata to test the contributions of natural selection versus neutral evolution to population divergence in temperature-sensitive phenotypic plasticity of floral reflectance. In P. lanceolata, reflectance plasticity is positively correlated with latitude/altitude. We used population pairwise comparisons between neutral genetic differentiation (F ST and Jost's D) and phenotypic differentiation (P ST) to assess the contributions of geographic distance and environmental parameters of the reproductive season in driving population divergence. Data are consistent with selection having shaped large-scale geographic patterns in thermal plasticity. The aggregate pattern of P ST versus F ST was consistent with divergent selection. F ST explained thermal plasticity differences only when geographic distance was not included in the model. Differences in the extent of cool reproductive season temperatures, and not overall temperature variation, explained plasticity differences independent of distance. Results are consistent with the hypothesis that thermal plasticity is adaptive where growing seasons are shorter and cooler, that is, at high latitude/altitude.

PARENTAL EFFECTS IN PLANTAGO LANCEOLATA L. I.: A GROWTH CHAMBER EXPERIMENT TO EXAMINE PRE- AND POSTZYGOTIC TEMPERATURE EFFECTS

In spite of the potential evolutionary importance of parental effects, many aspects of these effects remain inadequately explained. This paper explores both their causes and potential consequences for the evolution of life-history traits in plants. In a growth chamber experiment, I manipulated the pre- and postzygotic temperatures of both parents of controlled crosses of Plantago lanceolata. All offspring traits were affected by parental temperature. On average, low parental temperature increased seed weight, reduced germination and offspring growth rate, and accelerated onset of reproduction by 7%, 50%, 5%, and 47%, respectively, when compared to the effects of high parental temperature. Both pre- and postzygotic parental temperatures (i.e., prior to fertilization vs. during fertilization and seed set, respectively) influenced offspring traits but not always in the same direction. In all cases, however, the postzygotic effect was stronger. The prezygotic effects were more often transmitted paternally than maternally. Growth and onset of reproduction were influenced both directly by parental temperature as well as indirectly via the effects of parental temperature on seed weight and germination. Significant interactions between parental genotypes and prezygotic temperature treatment (G × E interactions) show that genotypes differ in their intergenerational responses to temperature with respect to germination and growth. The data suggest that temperature is involved in both genetically based and environmentally induced parental effects and that parental temperature may accelerate the rate of evolutionary change in flowering time in natural populations of P. lanceolata. The environmentally induced temperature effects, as mediated through G × (prezygotic) E interactions are not likely to affect the rate or direction of evolutionary change in the traits examined because postzygotic temperature effects greatly exceed prezygotic effects.

Multiple Plantago species (Plantaginaceae) modify floral reflectance and color in response to thermal change

PREMISE OF THE STUDY

Understanding how plant reproduction responds to temperature has become increasingly important because of global climate change. Temperature-sensitive plasticity in floral reflectance is likely involved in some of these responses. Such plasticity, which underlies thermoregulatory ability, affects reproductive success in Plantago lanceolata. To see whether other Plantago species also show thermal plasticity in reflectance, we measured plasticity in P. lagopus, P. coronopus, P. major, P. subulata, P. albicans, P. tomentosa, P. maritima, and P. weldenii.

METHODS

We induced plants to flower at two temperatures in growth chambers and recorded floral reflectance (362-800 nm).

KEY RESULTS

All species were thermally plastic in visible and near-IR regions. Species and populations differed in response. Some showed greater variation in reflectance at warm temperature, while the reverse was true for others. Plasticity was greatest in the P. lanceolata clade. Cosmopolitan species were not more plastic than were geographically restricted species.

CONCLUSIONS

The data suggest that (1) thermal plasticity is an ancestral trait for Plantago, (2) plasticities in visible and near-IR regions have evolved along different pathways within the genus, and (3) phylogenetic history partially explains this evolutionary divergence. Our data combined with those of previous studies suggest that global climate change will modify floral reflectance and color in many plant species. These modifications are likely to affect plant reproductive success.

Fitness effects of floral plasticity and thermoregulation in a thermally changing environment

To better understand the evolution of phenotypic plasticity and thermoregulation and their potential value for ectotherms in the face of global warming, we conducted field experiments to measure their effects on fitness and their association with reproductive phenology in Plantago lanceolata in a thermally variable environment. We measured the reproductive timing and success of genotypes varying in thermoregulation, as mediated by floral-reflectance plasticity. Results were consistent with the hypothesis that thermoregulation is more adaptive when thermally variable reproductive seasons are shorter and cooler. Strong thermoregulation/plasticity increased reproductive success during the cool portion of the reproductive season but not during the warm portion. Directional selection that favored strongly thermoregulating genotypes early in the season shifted to stabilizing selection that favored genotypes with weaker thermoregulation later in the season. Thermoregulation and reproductive phenology were negatively correlated. Although reproductive onset and duration were similar between genotypes, strong thermoregulators produced more and larger spikes (clutches) early; weak thermoregulators produced more spikes late. Results suggest that with atmospheric warming, the benefit of raising body temperature via thermoregulation when it is cool should decline in extant populations. The negative correlation between thermoregulation and phenology should accelerate the evolutionary shift toward thermoconformity, that is, reduced plasticity.

Floral reflectance, color, and thermoregulation: what really explains geographic variation in thermal acclimation ability of ectotherms?

Adaptive phenotypic plasticity in thermally sensitive traits, that is, thermal acclimation, generally increases with increasing latitude and altitude. The presumed explanation is that high-latitude/altitude organisms have evolved greater acclimation ability because of exposure to greater temperature fluctuations. Using a conceptual model of the thermal environment during the reproductive season, we tested this hypothesis against an alternative that plasticity is greater because of increased exposure to specific temperatures that strongly select for thermal acclimation. We examined geographic variation in floral reflectance/color plasticity among 29 European populations of a widespread perennial herb, Plantago lanceolata. Individuals partially thermoregulate reproduction through temperature-sensitive plasticity in floral reflectance/color. Plasticity was positively correlated with latitude and altitude. Path analyses support the hypothesis that the thermal environment mediates these geographic effects. Plasticity declined as seasonal temperature range increased, and it increased as duration of the growing season shortened and as the proportion of time exposed to temperatures favoring thermoregulation increased. Data provide evidence that floral reflectance/color plasticity is adaptive and that it has evolved in response not to the magnitude of temperature variation during the reproductive season but rather to the relative exposure to low temperatures, which favor thermoregulation.

Temperature-sensitive alternative oxidase protein content and its relationship to floral reflectance in natural Plantago lanceolata populations

In many plant species, the alternative respiratory pathway consisting of alternative oxidase (AOX) is affected by growth temperature. The adaptive significance of this temperature-sensitivity is unresolved. Here, leaf and spike (flower cluster) AOX protein content and spike/floral reflectance of genotypes from European Plantago lanceolata populations found in regions differing in reproductive season temperatures were measured. Cloned genotypes grown at controlled warm and cool temperatures were used to assess the natural within- and between-population variation in AOX content, temperature-sensitive phenotypic plasticity in content, and the relationship between AOX and temperature-sensitive floral/spike reflectance. AOX content and plasticity were genetically variable. Leaf AOX content, although greater at cool temperature, was relatively low and not statistically different across populations. Spike AOX content was greater than in leaves. Spike AOX plasticity differed significantly among populations and climate-types and showed significant negative correlation with floral reflectance plasticity, which also varied among populations. Genotypes with more AOX at cool than at warm temperature had greater floral reflectance plasticity; genotypes with relatively more AOX at warm temperature had less floral reflectance plasticity. The data support the hypothesis that plasticity of AOX content in reproductive tissues is associated with long-term thermal acclimatization.

Phenotypic plasticity, parental effects, and parental care in plants? I. An examination of spike reflectance in Plantago lanceolata (Plantaginaceae)

We explore the relationships among phenotypic plasticity, parental effects, and parental care in plants by presenting data from four experiments examining reflectance/color patterns in Plantago lanceolata. In three experiments, we measured spike (inflorescence) reflectance between 362 and 850 nm using a spectrophotometer with an integrating sphere. Experiments show that (1) spike reflectance changes seasonally within and outside the visible portion of the spectrum of radiant energy, (2) increasing ambient temperature causes an individual plant to produce flowering and fruiting spikes that reflect more/lighten in color (the greatest changes occur in the regions around 550 nm and between 750 and 850 nm, the visible and near-infrared regions, respectively), (3) responses are reversible, (4) genotypes within populations and populations from different latitudes differ in mean reflectance and degree of phenotypic plasticity. In a fourth experiment, we measured internal spike temperature. Darker spikes, those produced at lower temperature, got hotter than did lighter spikes in full sun. Thus, plants can partially thermoregulate reproduction and the embryonic development of their offspring. In light of a previous experiment, data suggest that thermoregulation produces adaptive parental effects and is a mechanism by which P. lanceolata provides parental care.

Parental effects in Plantago lanceolata L. III. Measuring parental temperature effects in the field

To determine the evolutionary importance of parental environmental effects in natural populations, we must begin to measure the magnitude of these effects in the field. For this reason, we conducted a combined growth chamber-field experiment to measure parental temperature effects in Plantago lanceolata. We grew in the field offspring of controlled crosses of chamber-grown parents subjected to six temperature treatments. Each treatment was characterized by a unique combination of maternal prezygotic (prior to fertilization), paternal prezygotic, and postzygotic (during fertilization and seed set) temperatures. Offspring were followed for three years to measure the effects of treatment on several life-history traits and population growth rate, our estimate of fitness. Parental treatment influenced germination, growth, and reproduction of newborns, but not survival or reproduction of offspring at least one year old. High postzygotic temperature significantly increased germination and leaf area at 17 weeks by approximately 35% and 2%, respectively. Probability of flowering and spike production in the newborn age class showed significant parental genotype x parental treatment interactions. High postzygotic temperature increased offspring fitness by approximately 50%. The strongest contributors to fitness were germination and probability of flowering and spike production of newborns. A comparison of our data with previously collected data for chambergrown offspring shows that the influence of parental environment on offspring phenotype is weaker but still biologically meaningful in the field. The results provide evidence that parental environment influences offspring fitness in natural populations of P. lanceolata and does so by affecting the life-history traits most strongly contributing to fitness. The data suggest that from the perspective of offspring fitness, natural selection favors parents that flower later in the flowering season in the North Carolina Piedmont when it is warmer. Genotypic-specific differences in response of offspring reproductive traits to parental environment suggest that parental environmental effects can influence the rate of evolutionary change in P. lanceolata.

CARBON INTEGRATION IN TWO PLANTAGO SPECIES

We measured the pattern of export of ¹⁴ C-assimilate from reproductive spikes and leaves subtending spikes in Plantago aristata and P. virginica. In P. arislata, little ¹⁴ carbon was exported to any other reproductive metamer (leaf + associated spike) from the leaf subtending a flowering spike. In P. virginica a large amount was exported. Thus, like clonal species, rosette species can vary in patterns of carbon integration among the repeated morphological subunits comprising an individual. When considered in the context of other studies, these data suggest that comparisons of carbon integration in species differing in morphological complexity would be useful in trying to understand the evolution of patterns of carbon integration in plants.

Nurses' knowledge, attitudes, and beliefs regarding organ and tissue donation and transplantation

The acute shortage of human organs and tissues for transplantation has been attributed in part to health professionals, including nurses, for their reluctance to recognize and refer suitable candidates for donation. In 1988, nurses' knowledge, attitudes, and beliefs regarding organ and tissue donation and transplantation were assessed using a 70-item questionnaire. Respondents included 1,683 nurses employed in 62 rural and urban hospitals in the Midwest. Only 365 respondents (21.7 percent) reported having requested tissue donations and 243 (14.4 percent) reported having requested organ donations. However, of those who requested tissue or organ donations, 270 (74 percent) obtained consents for tissues and 150 (61.7 percent) obtained consent for organ donations. Respondents were knowledgeable about organ and tissue donation (mean score of 7.5 on a 0 to 10 knowledge scale with 10 as highest) and reported attitudes and beliefs were moderately positive. Factors that were significantly correlated with the number of requests made for organs and tissues and the number of consents obtained included nurses' knowledge, attitudes, and beliefs about donation; nurses' perception of their own confidence in their ability to request tissues and organs; being a supervisor; and working in an emergency department.

Broadening the perspective of pica: literature review

Pica is an eating disorder that is manifested by a craving for oral ingestion of a given substance that is unusual in kind and or quantity. It is a long-standing practice that has far reaching implications for prevention and treatment--implications for public health as well as clinical personnel who work in settings where they have the potential for influencing health knowledge, attitudes, and behaviors of their patients. Pica practices also challenge researchers and social scientists whose work encompass development and refinement of models related to nutritional deficiencies. The body of literature on pica is so fragmented that it is difficult to find a precise summary of the knowns and unknowns about the condition. There is little consistency in defining pica, classifying substances ingested, identifying key characteristics of practicers, recommending treatment, or in projecting outcomes. This review presents a framework for understanding pica as a general practice, summarizes divergent reported hypotheses and conclusions, and illustrates that there is a need for more comprehensive studies of prevalence and incidence and use of deductive as well as inductive research processes.

Tapping patient satisfaction: a strategy for quality assessment

Participant satisfaction is an important measure of program effectiveness. In hospitals, patient satisfaction is a measure that is compatible with quality assurance. This article focuses on the revision, implementation and analysis of a patient satisfaction questionnaire that was designed as a tool for assessing the quality of non-physician encounters in a small hospital. The Patient Satisfaction Questionnaire (PSQ), which contained a 30-item rating scale, was designed to collect data about admissions, nursing care and seven other hospital services. The 686 PSQs that comprised a 4-month sample of 2156 instruments (31.8%) completed in a selected year were analyzed. Results show no less than 90% of patient ratings reflecting satisfaction. In addition, open-ended responses were overwhelmingly laudatory. The content and process of this collaborative effort demonstrate compatibility between research and management when goals and purposes are clearly delineated.