Floral Color Properties of Serpentine Seep Assemblages Depend on Community Size and Species Richness

Functional traits, particularly those that impact fitness, can shape the ecological and evolutionary relationships among coexisting species of the same trophic level. Thus, examining these traits and properties of their distributions (underdispersion, overdispersion) within communities can provide insights into key ecological interactions (e.g., competition, facilitation) involved in community assembly. For instance, the distribution of floral colors in a community may reflect pollinator-mediated interactions between sympatric plant species, and the phylogenetic distribution of color can inform how evolutionary contingencies can continue to shape extant community assemblages. Additionally, the abundance and species richness of the local habitat may influence the type or strength of ecological interactions among co-occurring species. To evaluate the impact of community size and species richness on mechanisms shaping the distribution of ecologically relevant traits, we examined how floral color (defined by pollinator color vision models) is distributed within co-flowering assemblages. We modeled floral reflectance spectra of 55 co-flowering species using honeybee (Apis mellifera) and syrphid fly (Eristalis tenax) visual systems to assess the distributions of flower color across 14 serpentine seep communities in California. We found that phylogenetic relatedness had little impact on the observed color assemblages. However, smaller seep communities with lower species richness were more overdispersed for flower color than larger, more species-rich communities. Results support that competitive exclusion could be a dominant process shaping the species richness of flower color in smaller-sized communities with lower species richness, but this is less detectable or overwhelmed by other processes at larger, more speciose communities

Peripheral lymph nodes contain migratory and resident innate lymphoid cell populations

Tissue residency is considered a defining feature of the innate lymphoid cell (ILC) populations located within mucosal and adipose tissues. ILCs are also present within all lymphoid tissues, but whether ILCs migrate between lymphoid and nonlymphoid sites and in what context is poorly understood. To determine whether migratory ILCs exist within peripheral lymph nodes (LNs), we labeled all cells within the brachial LN (bLN) of transgenic mice expressing a photoconvertible fluorescent protein by direct exposure to light. Tracking of cellular changes in the labeled LN revealed the gradual migration of new ILCs into the tissue, balanced by egress of ILCs dependent on sphingosine-1-phosphate receptors. Most of the migratory ILCs were ILC1s, entering LNs directly from the circulation in a CD62L- and CCR7-dependent manner and thus behaving like conventional natural killer (cNK) cells. Upon egress, both ILC1s and cNK cells were found to recirculate through peripheral LNs. A distinct population of migratory ILC2s were detected in the LN, but most of the ILC3s were tissue resident. Functionally, both migratory and resident ILC1s within LNs were able to rapidly produce IFN-γ to support the generation of robust TH1 T cell responses after immunization. Thus, migratory and resident ILC populations exist within peripheral LNs, with ILC1s, akin to cNK cells, able to traffic into these tissues where they can contribute to the initiation of adaptive immunity

Specialized Peptidoglycan Hydrolases Sculpt the Intra-bacterial Niche of Predatory Bdellovibrio and Increase Population Fitness

Bdellovibrio are predatory bacteria that have evolved to invade virtually all Gram-negative bacteria, including many prominent pathogens. Upon invasion, prey bacteria become rounded up into an osmotically stable niche for the Bdellovibrio, preventing further superinfection and allowing Bdellovibrio to replicate inside without competition, killing the prey bacterium and degrading its contents. Historically, prey rounding was hypothesized to be associated with peptidoglycan (PG) metabolism; we found two Bdellovibrio genes, bd0816 and bd3459, expressed at prey entry and encoding proteins with limited homologies to conventional dacB/PBP4 DD-endo/carboxypeptidases (responsible for peptidoglycan maintenance during growth and division). We tested possible links between Bd0816/3459 activity and predation. Bd3459, but not an active site serine mutant protein, bound β-lactam, exhibited DD-endo/carboxypeptidase activity against purified peptidoglycan and, importantly, rounded up E. coli cells upon periplasmic expression. A ΔBd0816 ΔBd3459 double mutant invaded prey more slowly than the wild type (with negligible prey cell rounding) and double invasions of single prey by more than one Bdellovibrio became more frequent. We solved the crystal structure of Bd3459 to 1.45 Å and this revealed predation-associated domain differences to conventional PBP4 housekeeping enzymes (loss of the regulatory domain III, alteration of domain II and a more exposed active site). The Bd3459 active site (and by similarity the Bd0816 active site) can thus accommodate and remodel the various bacterial PGs that Bdellovibrio may encounter across its diverse prey range, compared to the more closed active site that “regular” PBP4s have for self cell wall maintenance. Therefore, during evolution, Bdellovibrio peptidoglycan endopeptidases have adapted into secreted predation-specific proteins, preventing wasteful double invasion, and allowing activity upon the diverse prey peptidoglycan structures to sculpt the prey cell into a stable intracellular niche for replication

The Positive Impact of Conservation Action

Governments recently adopted new global targets to halt and reverse the loss of biodiversity. It is therefore crucial to understand the outcomes of conservation actions. We conducted a global meta-analysis of 186 studies (including 665 trials) that measured biodiversity over time and compared outcomes under conservation action with a suitable counterfactual of no action. We find that in two-thirds of cases, conservation either improved the state of biodiversity or at least slowed declines. Specifically, we find that interventions targeted at species and ecosystems, such as invasive species control, habitat loss reduction and restoration, protected areas, and sustainable management, are highly effective and have large effect sizes. This provides the strongest evidence to date that conservation actions are successful but require transformational scaling up to meet global targets

Hellfire and Grey Drones: An Empirical Examination of the Effectiveness of Targeted Killings

This study examines the effectiveness of the United States’ targeted killing program. Specifically, do targeted killings work as an effective program for combating global terrorism? This thesis is divided into parts. The first section provides a brief introduction to targeted killings. The second part consists of an examination of targeted killings as an essentially contested concept, arguing that targeted killings can be defined in a manner consistent with the scientific enterprise. The third section contains a thorough review of the literature on targeted killings, demonstrating that there is a dearth of works investigating the actual effectiveness of targeted killings. The fourth portion outlines the methodologies chosen for this endeavor – a combination of quantitative and quantitative methodologies. The fifth part provides the descriptive and predictive results of the statistical analyses conducted in the course of this study. It is found that the statistical data provides mixed results concerning the effectiveness of targeted killings. The sixth section contains the qualitative data uncovered in the authors’ research. The qualitative information provides strong support to the view that targeted killings are an effective method for combating terrorist groups. The final chapter consists of an analysis of the results, thoughts on future research and methodologies, and policy recommendations

The influence of militant group structure and inter-militant competition upon the effectiveness of targeted killings

Are targeted killings an effective strategy for combating militant groups? I add to the literature by accounting for variation in militant group structure and competition among militant groups as conditioning effects on the likely effectiveness of targeted killings. I do this cross-nationally by examining four cases: Colombia, Israel, Russia, and the United States (in the Afghanistan- Pakistan theater of operations). A dataset was constructed for each state’s program, containing information on militant attacks, targeted killings, and other relevant variables. Each case was examined between the years 2004 and 2011, using the day as the unit of analysis (N of 2922 observations in each case), and zero-inflated negative binomial regression (ZINB) as the statistical test. I found that the effectiveness of targeted killings was dependent upon the structure of militant groups and the existence of competition among militant groups (on the same side of a conflict). Specifically, targeted killings were less effective against decentralized organizations and under the conditions of inter-militant group competition; while targeted killings were more likely to be effective against centralized organizations that did not face competition

Alaska Resource Development: Issues of the 1980s

Exact publication date is unknown, estimated to be some time in the 1980s.The research on which this book was based was performed under a special grant by the Andrew W. Mellon FoundationYe

Sex in a material world: why the study of sexual reproduction and sex-specific traits should become more nutritionally-explicit

International audienceRecent advances in nutritional ecology, particularly arising from Ecological stoichiometry and the Geometric framework for nutrition, have resulted in greater theoretical coherence and increasingly incisive empirical methodologies that in combination allow for the consideration of nutrient-related processes at many levels of biological complexity. However, these advances have not been consistently integrated into the study of sexual differences in reproductive investment, despite contemporary emphasis on the material costs associated with sexually selected traits (e.g. condition-dependence of exaggerated ornaments). Nutritional ecology suggests that material costs related to sex-specific reproductive traits should be linked to quantifiable underlying differences in the relationship between individuals of each sex and their foods. Here, we argue that applying nutritionally-explicit thought to the study of sexual reproduction should both deepen current understanding of sex-specific phenomena and broaden the tractable frontiers of sexual selection research. In support of this general argument, we examine the causes and consequences of sex-specific nutritional differences, from food selection and nutrient processing to sex-specific reproductive traits. At each level of biological organization, we highlight how a nutritionally-explicit perspective may provide new insights and help to identify new directions. Based on predictions derived at the individual level, we then consider how sex-specific nutrient limitation might influence population growth, and thus potentially broader patterns of life history evolution, using a simple population dynamics model. We conclude by highlighting new avenues of research that may be more accessible from this integrative perspective

Floral spectral reflectance data for: Floral color properties of serpentine seep assemblages depend on community size and species richness

Legend (also included in datasheet header) -- \u27filename\u27: code for specific spectral file; \u27species\u27: plant species; \u27Internal_contrast_estimated\u27: whether internal contrast was estimated for species; \u27Internal_contrast_detail\u27: detailed location of spectra collection on floral unit; \u27spectrometer\u27: spectrometer model (USB2000+ , USB4000, Jaz, Ocean Optics, Dunedin, FL USA); \u27integration_time_microseconds\u27: given in microseconds (range of 50-250 milliseconds, which is 50,000-250,000 microseconds); \u27number_spectra_averaged\u27: ranges from 10-30 scans; \u27boxcar_smoothing_width\u27: ranges 3-25 nanometers; \u27number_pixels_processed\u27: number of pixels processed per spectral measurement; \u27columns at 300-700\u27: binned reflectance values as percentages (%), binned to 1-nm intervals;,Functional traits, particularly those that impact fitness, can shape the ecological and evolutionary relationships among coexisting species of the same trophic level. Thus, examining these traits and properties of their distributions (underdispersion, overdispersion) within communities can provide insights into key ecological interactions (e.g., competition, facilitation) involved in community assembly. For instance, the distribution of floral colors in a community may reflect pollinator-mediated interactions between sympatric plant species, and the phylogenetic distribution of color can inform how evolutionary contingencies can continue to shape extant community assemblages. Additionally, the abundance and species richness of the local habitat may influence the type or strength of ecological interactions among co-occurring species. To evaluate the impact of community size and species richness on mechanisms shaping the distribution of ecologically relevant traits, we examined how floral color (defined by pollinator color vision models) is distributed within co-flowering assemblages. We modeled floral reflectance spectra of 55 co-flowering species using honeybee (Apis mellifera) and syrphid fly (Eristalis tenax) visual systems to assess the distributions of flower color across 14 serpentine seep communities in California. We found that phylogenetic relatedness had little impact on the observed color assemblages. However, smaller seep communities with lower species richness were more overdispersed for flower color than larger, more species-rich communities. Results support that competitive exclusion could be a dominant process shaping the species richness of flower color in smaller-sized communities with lower species richness, but this is less detectable or overwhelmed by other processes at larger, more speciose communities.,Spectra were collected using either an internal pulsed-xenon light source (Jaz, Ocean Optics, Dunedin, FL USA) or a deuterium-halogen light source (DH-2000-BAL (Ocean Optics, Dunedin, FL USA) with a Spectralon white standard (Labsphere, North Sutton, NH) and dark correction to measure percent reflectance from 300-700 nanometers, which is the general range of color perception by many flower-visiting insects, including bees and flies. Floral tissue was illuminated with a collimated beam oriented normal to the floral surface, and spectra were collected by a probe positioned at a 45-degree azimuth, composed of a collimating lens and optical fiber (fiber diameter = 400 microns) connected to the spectrophotometer. We utilized SpectraSuite version 2.0.162 software for capturing spectral data (Ocean Optics, Dunedin, FL USA). Spectra were collected with an integration time ranging from 50-250 milliseconds, a boxcar smoothing width ranging 3-25 nanometers, and with a range of 10-30 average spectral scans (species-specific details of these parameters are included in datasheet). In collection of floral spectra, at least one single petal of the floral unit was measured for each flowering species, or in the instance that a single petal was too small to cover the entire sampling area, multiple petals were overlaid to provide enough surface for the spectrometer to collect a reflectance reading. Within each floral unit, if there was a noticeable change in coloration in the human vision color spectrum or morphological component (e.g.: petal v. labellum), reflectance readings were obtained from various portions across the floral unit. We also searched for any change in ultraviolet reflectance range across the floral display area by viewing live spectrometer reflectance output while moving across the floral tissue surface. Any noted differences within a floral unit for each species is included in datasheet