From the popularity of authoritarian political leaders to the under-representation of women in boardrooms, leadership is an important theme in current human social affairs. Leadership is also a ...prominent research topic in the biological, social, and cognitive sciences. However, these active literatures have evolved somewhat independently and there is a need for synthesis. A comparative-evolutionary approach can integrate seemingly divergent perspectives by making a distinction between two leadership styles, prestige and dominance, that have contrasting expressions, functions, histories, and neural and developmental pathways. The distinction may help to resolve various scientific puzzles, such as: (i) opposing views on the different functions and expressions of leadership; (ii) the appeal of dominance-style leaders; and (iii) sex biases in leadership emergence in modern society.
Eastern and Western philosophers have long recognized the difference between prestige-style and dominance-style leaders.Leadership is an active research area in the social, cognitive, and biological sciences, but there has been limited synthesis among these fields. Recognition that there are two leader types can assist with this integration and generate new ideas for a comparative analysis.Dominance- and prestige-based hierarchies emerge early in development; children use a variety of social and physical cues to learn about different social hierarchies.Leadership is a crucial but under-recognized force in the evolution of human cooperation, aiding the transition from small-scale to large-scale societies.Current male-biased leadership systems result, in part, from evolved follower preferences for dominance-style leaders in the face of intense competition within and between groups.
Abstract
We present a moderate-resolution spectrum of the peculiar Type II supernova (SN) iPTF14hls taken on day 1153 after discovery. This spectrum reveals the clear signature of shock interaction ...with dense circumstellar material (CSM). We suggest that this CSM interaction may be an important clue for understanding the extremely unusual photometric and spectroscopic evolution seen over the first 600 d of iPTF14hls. The late-time spectrum shows a double-peaked intermediate-width H α line indicative of expansion speeds around 1000 km s−1, with the double-peaked shape hinting at a disc-like geometry in the CSM. If the CSM were highly asymmetric, perhaps in a disc or torus that was ejected from the star 3–6 yr prior to explosion, the CSM interaction could have been overrun and hidden below the SN ejecta photosphere from a wide range of viewing angles. In that case, CSM interaction luminosity would have been thermalized well below the photosphere, potentially sustaining the high luminosity without exhibiting the traditional observational signatures of strong CSM interaction (narrow H α emission and X-rays). Variations in density structure of the CSM could account for the multiple rebrightenings of the light curve. We propose that a canonical 1 × 1051 erg explosion energy with enveloped CSM interaction as seen in some recent SNe, rather than an entirely new explosion mechanism, may be adequate to explain the peculiar evolution of iPTF14hls.
In 1964, W. D. Hamilton proposed a novel solution to the long-standing evolutionary puzzle: why do individuals cooperate? Hamilton predicted that, if individuals possess the ability to discriminate ...on the basis of kinship, then they should gain inclusive fitness benefits by biasing helpful behaviour towards relatives and harmful behaviour away from them. The possibility that kin selection might favour social evolution has now inspired five decades of active research. Here, I synthesize this evidence for social mammals. First, I report on the methodological advances that allow for pedigree construction, and review the evidence for maternal and paternal kin discrimination. Second, I recognize that a substantial body of evidence for the evolution of cooperative breeding via kin selection exists, and then focus on the potential for kin selection to favour less well understood, yet equally salient, targets of selection: social partner choice, coalition formation and social tolerance (withholding aggression). I find that kin selection favours remarkably similar patterns of nepotism in primate and nonprimates with respect to these short-lived social acts. Although social alliances among maternal and paternal kin are common in mammalian societies, kinship largely fails to protect individuals from aggression. Thus, an individual's closest associates and allies, many of whom are kin, are most often an individual's closest competitors within mammalian social groups. Taken together, these findings highlight the value of Hamilton's holistic approach in simultaneously considering the direct benefits of competition and the indirect fitness benefits of cooperation. Despite major empirical advances since the inception of kin selection theory, future tests using newly available molecular and statistical methods in combination with longitudinal behavioural data are required to partition the relative contributions of direct and indirect fitness on the lifetime inclusive fitness. Such approaches will elucidate the relative influences of evolutionary and ecological forces favouring social evolution across the mammalian lineage of social mammals.
•W. D. Hamilton's (1964) kin selection theory has now inspired five decades of research.•Inclusive benefits of short-lived social acts have been largely overlooked for social mammals.•Kinship promotes associations and coalitions, but rarely tolerance in primates and nonprimates.•Context-dependent costs (competition) and benefits (cooperation) are both important.•Longitudinal data should be combined with new methods to elucidate lifetime fitness consequences.
The effect of Ocean Acidification (OA) on marine biota is quasi-predictable at best. While perturbation studies, in the form of incubations under elevated pCO(2), reveal sensitivities and responses ...of individual species, one missing link in the OA story results from a chronic lack of pH data specific to a given species' natural habitat. Here, we present a compilation of continuous, high-resolution time series of upper ocean pH, collected using autonomous sensors, over a variety of ecosystems ranging from polar to tropical, open-ocean to coastal, kelp forest to coral reef. These observations reveal a continuum of month-long pH variability with standard deviations from 0.004 to 0.277 and ranges spanning 0.024 to 1.430 pH units. The nature of the observed variability was also highly site-dependent, with characteristic diel, semi-diurnal, and stochastic patterns of varying amplitudes. These biome-specific pH signatures disclose current levels of exposure to both high and low dissolved CO(2), often demonstrating that resident organisms are already experiencing pH regimes that are not predicted until 2100. Our data provide a first step toward crystallizing the biophysical link between environmental history of pH exposure and physiological resilience of marine organisms to fluctuations in seawater CO(2). Knowledge of this spatial and temporal variation in seawater chemistry allows us to improve the design of OA experiments: we can test organisms with a priori expectations of their tolerance guardrails, based on their natural range of exposure. Such hypothesis-testing will provide a deeper understanding of the effects of OA. Both intuitively simple to understand and powerfully informative, these and similar comparative time series can help guide management efforts to identify areas of marine habitat that can serve as refugia to acidification as well as areas that are particularly vulnerable to future ocean change.
The American Heart Association, in conjunction with the National Institutes of Health, annually reports the most up-to-date statistics related to heart disease, stroke, and cardiovascular risk ...factors, including core health behaviors (smoking, physical activity, diet, and weight) and health factors (cholesterol, blood pressure, and glucose control) that contribute to cardiovascular health. The Statistical Update presents the latest data on a range of major clinical heart and circulatory disease conditions (including stroke, congenital heart disease, rhythm disorders, subclinical atherosclerosis, coronary heart disease, heart failure, valvular disease, venous disease, and peripheral artery disease) and the associated outcomes (including quality of care, procedures, and economic costs).
The American Heart Association, through its Epidemiology and Prevention Statistics Committee, continuously monitors and evaluates sources of data on heart disease and stroke in the United States to provide the most current information available in the annual Statistical Update with review of published literature through the year before writing. The 2023 Statistical Update is the product of a full year's worth of effort in 2022 by dedicated volunteer clinicians and scientists, committed government professionals, and American Heart Association staff members. The American Heart Association strives to further understand and help heal health problems inflicted by structural racism, a public health crisis that can significantly damage physical and mental health and perpetuate disparities in access to health care, education, income, housing, and several other factors vital to healthy lives. This year's edition includes additional COVID-19 (coronavirus disease 2019) publications, as well as data on the monitoring and benefits of cardiovascular health in the population, with an enhanced focus on health equity across several key domains.
Each of the chapters in the Statistical Update focuses on a different topic related to heart disease and stroke statistics.
The Statistical Update represents a critical resource for the lay public, policymakers, media professionals, clinicians, health care administrators, researchers, health advocates, and others seeking the best available data on these factors and conditions.
Effective conservation requires rigorous baselines of pristine conditions to assess the impacts of human activities and to evaluate the efficacy of management. Most coral reefs are moderately to ...severely degraded by local human activities such as fishing and pollution as well as global change, hence it is difficult to separate local from global effects. To this end, we surveyed coral reefs on uninhabited atolls in the northern Line Islands to provide a baseline of reef community structure, and on increasingly populated atolls to document changes associated with human activities. We found that top predators and reef-building organisms dominated unpopulated Kingman and Palmyra, while small planktivorous fishes and fleshy algae dominated the populated atolls of Tabuaeran and Kiritimati. Sharks and other top predators overwhelmed the fish assemblages on Kingman and Palmyra so that the biomass pyramid was inverted (top-heavy). In contrast, the biomass pyramid at Tabuaeran and Kiritimati exhibited the typical bottom-heavy pattern. Reefs without people exhibited less coral disease and greater coral recruitment relative to more inhabited reefs. Thus, protection from overfishing and pollution appears to increase the resilience of reef ecosystems to the effects of global warming.
Community structure and assembly are determined in part by environmental heterogeneity. While reef-building corals respond negatively to warming (i.e. bleaching events) and ocean acidification (OA), ...the extent of present-day natural variability in pH on shallow reefs and ecological consequences for benthic assemblages is unknown. We documented high resolution temporal patterns in temperature and pH from three reefs in the central Pacific and examined how these data relate to community development and net accretion rates of early successional benthic organisms. These reefs experienced substantial diel fluctuations in temperature (0.78°C) and pH (>0.2) similar to the magnitude of 'warming' and 'acidification' expected over the next century. Where daily pH within the benthic boundary layer failed to exceed pelagic climatological seasonal lows, net accretion was slower and fleshy, non-calcifying benthic organisms dominated space. Thus, key aspects of coral reef ecosystem structure and function are presently related to natural diurnal variability in pH.
Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied ...dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC) release were assessed for several common benthic reef organisms from the backreef habitat. We assessed microbial community response to dissolved exudates of each benthic producer by measuring bacterioplankton growth, respiration, and DOC drawdown in two-day dark dilution culture incubations. Experiments were conducted for six benthic producers: three species of macroalgae (each representing a different algal phylum: Turbinaria ornata--Ochrophyta; Amansia rhodantha--Rhodophyta; Halimeda opuntia--Chlorophyta), a mixed assemblage of turf algae, a species of crustose coralline algae (Hydrolithon reinboldii) and a dominant hermatypic coral (Porites lobata). Our results show that all five types of algae, but not the coral, exuded significant amounts of labile DOC into their surrounding environment. In general, primary producers with the highest rates of photosynthesis released the most DOC and yielded the greatest bacterioplankton growth; turf algae produced nearly twice as much DOC per unit surface area than the other benthic producers (14.0±2.8 µmol h⁻¹ dm⁻²), stimulating rapid bacterioplankton growth (0.044±0.002 log10 cells h⁻¹) and concomitant oxygen drawdown (0.16±0.05 µmol L⁻¹ h⁻¹ dm⁻²). Our results demonstrate that benthic reef algae can release a significant fraction of their photosynthetically-fixed carbon as DOC, these release rates vary by species, and this DOC is available to and consumed by reef associated microbes. These data provide compelling evidence that benthic primary producers differentially influence reef microbial dynamics and biogeochemical parameters (i.e., DOC and oxygen availability, bacterial abundance and metabolism) in coral reef communities.
ABSTRACT
SN 2017hcc was remarkable for being a nearby and strongly polarized superluminous Type IIn supernova (SN). We obtained high-resolution Echelle spectra that we combine with other spectra to ...investigate its line-profile evolution. All epochs reveal narrow P Cygni components from pre-shock circumstellar material (CSM), indicating an axisymmetric outflow from the progenitor of 40–50 km s−1. Broad and intermediate-width components exhibit the classic evolution seen in luminous SNe IIn: symmetric Lorentzian profiles from pre-shock CSM lines broadened by electron scattering at early times, transitioning at late times to multicomponent, irregular profiles coming from the SN ejecta and post-shock shell. As in many SNe IIn, profiles show a progressively increasing blueshift, with a clear flux deficit in red wings of the intermediate and broad velocity components after day 200. This blueshift develops after the continuum luminosity fades, and in the intermediate-width component, persists at late times even after the SN ejecta fade. In SN 2017hcc, the blueshift cannot be explained as occultation by the SN photosphere, pre-shock acceleration of CSM, or a lopsided explosion of CSM. Instead, the blueshift arises from dust formation in the post-shock shell and in the SN ejecta. The effect has a wavelength dependence characteristic of dust, exhibiting an extinction law consistent with large grains. Thus, SN 2017hcc experienced post-shock dust formation and had a mildly bipolar CSM shell, similar to SN 2010jl. Like other superluminous SNe IIn, the progenitor lost around 10 M⊙ due to extreme eruptive mass-loss in the decade before exploding.
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