A landmark environmental law looks ahead.

In late December 1973, the United States enacted what some would come to call "the pitbull of environmental laws." In the 50 years since, the formidable regulatory teeth of the Endangered Species Act (ESA) have been credited with considerable successes, obliging agencies to draw upon the best available science to protect species and habitats. Yet human pressures continue to push the planet toward extinctions on a massive scale. With that prospect looming, and with scientific understanding ever changing, Science invited experts to discuss how the ESA has evolved and what its future might hold. -Brad Wible.

A comparative case study of the accommodation of students with disabilities in online and in-person degree programs.

Fully online degree programs are an increasingly important part of the higher education ecosystem. Among the many challenges raised by the growth of fully online courses and degree programs is the question: Are institutions providing online students with disabilities accommodations that are comparable to those provided to students in traditional in-person degree programs? To explore this question, we compared students in a fully online biology degree program to students in the equivalent in-person degree program at a large research university. For each group, we assessed the frequency with which students register with the disability resource center, the range of specific accommodations provided, and course grades. Results show that students in the in-person program were nearly 30% more likely to be enrolled with the disability resource center, and that students in the online program were offered a narrower range of accommodations. However, in relative terms (i.e., compared to students without disabilities in their degree program), online students with disabilities perform better than in-person students with disabilities.

Challenges in cybersecurity: Lessons from biological defense systems.

Defending against novel, repeated, or unpredictable attacks, while avoiding attacks on the 'self', are the central problems of both mammalian immune systems and computer systems. Both systems have been studied in great detail, but with little exchange of information across the different disciplines. Here, we present a conceptual framework for structured comparisons across the fields of biological immunity and cybersecurity, by framing the context of defense, considering different (combinations of) defensive strategies, and evaluating defensive performance. Throughout this paper, we pose open questions for further exploration. We hope to spark the interdisciplinary discovery of general principles of optimal defense, which can be understood and applied in biological immunity, cybersecurity, and other defensive realms.

Online biology degree program broadens access for women, first-generation to college, and low-income students, but grade disparities remain.

Online education has grown rapidly in recent years with many universities now offering fully online degree programs even in STEM disciplines. These programs have the potential to broaden access to STEM degrees for people with social identities currently underrepresented in STEM. Here, we ask to what extent is that potential realized in terms of student enrollment and grades for a fully online degree program. Our analysis of data from more than 10,000 course-enrollments compares student demographics and course grades in a fully online biology degree program to demographics and grades in an equivalent in-person biology degree program at the same university. We find that women, first-generation to college students and students eligible for federal Pell grants constitute a larger proportion of students in the online program compared to the in-person mode. However, the online mode of instruction is associated with lower course grades relative to the in-person mode. Moreover, African American/Black, Hispanic/Latinx, Native American, and Pacific Islander students as well as federal Pell grant eligible students earned lower grades than white students and non-Pell grant eligible students, respectively, but the grade disparities were similar among both in-person and online student groups. Finally, we find that grade disparities between men and women are larger online compared to in-person, but that for first-generation to college women, the online mode of instruction is associated with little to no grade gap compared to continuing generation women. Our findings indicate that although this online degree program broadens access for some student populations, inequities in the experience remain and need to be addressed in order for online education to achieve its inclusive mission.

Comment on "Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity".

Scheele et al (Reports, 29 March 2019, p. 1459) bring needed attention to the effects of amphibian infectious disease. However, the data and methods implicating the disease chytridiomycosis in 501 amphibian species declines are deficient. Which species are affected, and how many, remains a critical unanswered question. Amphibians are imperiled; protective actions require public support and robust science.

Protection of wetlands as a strategy for reducing the spread of avian influenza from migratory waterfowl.

Highly pathogenic avian influenza (HPAI) H5N1 has led to the death or destruction of millions of domesticated and wild birds and caused hundreds of human deaths worldwide. As with other HPAIs, H5N1 outbreaks among poultry have generally been caused by contact with infected migratory waterfowl at the interface of wildlands and human-dominated landscapes. Using a case-control epidemiological approach, we analyzed the relation between habitat protection and H5N1 outbreaks in China from 2004 to 2017. We found that while proximity to unprotected waterfowl habitats and rice paddy generally increased outbreak risk, proximity to the most highly protected habitats (e.g., Ramsar-designated lakes and wetlands) had the opposite effect. Protection likely involves two mechanisms: the separation of wild waterfowl and poultry populations and the diversion of wild waterfowl from human-dominated landscapes toward protected natural habitats. Wetland protection could therefore be an effective means to control avian influenza while also contributing to avian conservation.

Safe CRISPR: Challenges and Possible Solutions.

Applications of CRISPR in human health and in gene drives are at the forefront of biological research as tools. This technology will affect humankind and our environment, so as this technology pushes forward, the design and implementation of safety measures is imperative. Novel technologies and forethought in various applications of CRISPR are essential for using this technology safely. Here, we review environmental and health-related safety concerns associated with using CRISPR and ways proposed to minimize risk.

Gene drives in our future: challenges of and opportunities for using a self-sustaining technology in pest and vector management.

Gene drives are systems of biased inheritance that enhance the likelihood a sequence of DNA passes between generations through sexual reproduction and potentially throughout a local population and ultimately all connected populations of a species. Gaps in our knowledge of gene drive systems prompted the US National Institutes of Health (NIH) and the Foundation for the NIH to ask the US National Academies of Sciences, Engineering, and Medicine (NASEM) to convene an expert panel to provide an independent, objective examination of what we know about gene drive systems. The report, "Gene drives on the horizon: Advancing science, navigating uncertainty, and aligning research with public values," outlines our understanding of the science, ethics, public engagement, governance, and risk assessment pertaining to gene drive research. Researchers have studied naturally occurring gene drive systems for more than a century. While CRISPR/Cas9 was not the first molecular tool considered to create an engineered gene drive, the advent of the CRISPR/Cas9 technology for gene editing gave a renewed impetus to developing gene drives in the laboratory for eventual release in the field. Recent experiments demonstrate that a CRISPR/Cas9-based gene drive can spread a targeted gene throughout nearly all of laboratory populations of yeast, fruit flies, or mosquitoes. Applying this basic science, there are proposals to use gene drive modified organisms to address such things as eradication of insect-borne infectious diseases and conservation of threatened and endangered species. Gene drives could potentially support agriculture by reversing pesticide and herbicide resistance in insects and weeds, and by control of damaging, invasive species. A major recommendation of the NASEM report is that there is insufficient evidence at this time to support release of gene-drive modified organisms into the environment. Importantly, the committee also recognized that the potential benefits of gene drives for basic and applied research are significant and justify proceeding with laboratory research and controlled field trials. This review summarizes highlights of the NASEM report with its focus on using the CRISPR/Cas9 genome-editing technology to develop gene drive modified organisms.

Times from Infection to Disease-Induced Death and their Influence on Final Population Sizes After Epidemic Outbreaks.

For epidemic models, it is shown that fatal infectious diseases cannot drive the host population into extinction if the incidence function is upper density-dependent. This finding holds even if a latency period is included and the time from infection to disease-induced death has an arbitrary length distribution. However, if the incidence function is also lower density-dependent, very infectious diseases can lead to a drastic decline of the host population. Further, the final population size after an epidemic outbreak can possibly be substantially affected by the infection-age distribution of the initial infectives if the life expectations of infected individuals are an unbounded function of infection age (time since infection). This is the case for lognormal distributions, which fit data from infection experiments involving tiger salamander larvae and ranavirus better than gamma distributions and Weibull distributions.

Do fatal infectious diseases eradicate host species?

In simple SI epidemic and endemic models, three classes of incidence functions are identified for their potential to be associated with host extinction: weakly upper density-dependent incidences are never associated with host extinction. Power incidences that depend on the number of susceptibles and infectives by powers strictly between 0 and 1 are associated with initial-constellation-dependent host extinction for all parameter values. Homogeneous incidences, of which frequency-dependent incidence is a very particular case, and power incidences are associated with global host extinction for certain parameter constellations and with host survival for others. Laboratory infection experiments with salamander larvae are equally well fitted by power incidences and certain upper density-dependent incidences such as the negative binomial incidence and do not rule out homogeneous incidences such as an asymmetric frequency-dependent incidence either.

Phylogenetic patterns of trait and trait plasticity evolution: Insights from amphibian embryos.

Environmental variation favors the evolution of phenotypic plasticity. For many species, we understand the costs and benefits of different phenotypes, but we lack a broad understanding of how plastic traits evolve across large clades. Using identical experiments conducted across North America, we examined prey responses to predator cues. We quantified five life-history traits and the magnitude of their plasticity for 23 amphibian species/populations (spanning three families and five genera) when exposed to no cues, crushed-egg cues, and predatory crayfish cues. Embryonic responses varied considerably among species and phylogenetic signal was common among the traits, whereas phylogenetic signal was rare for trait plasticities. Among trait-evolution models, the Ornstein-Uhlenbeck (OU) model provided the best fit or was essentially tied with Brownian motion. Using the best fitting model, evolutionary rates for plasticities were higher than traits for three life-history traits and lower for two. These data suggest that the evolution of life-history traits in amphibian embryos is more constrained by a species' position in the phylogeny than is the evolution of life history plasticities. The fact that an OU model of trait evolution was often a good fit to patterns of trait variation may indicate adaptive optima for traits and their plasticities.

Economic growth, urbanization, globalization, and the risks of emerging infectious diseases in China: A review.

Three interrelated world trends may be exacerbating emerging zoonotic risks: income growth, urbanization, and globalization. Income growth is associated with rising animal protein consumption in developing countries, which increases the conversion of wild lands to livestock production, and hence the probability of zoonotic emergence. Urbanization implies the greater concentration and connectedness of people, which increases the speed at which new infections are spread. Globalization-the closer integration of the world economy-has facilitated pathogen spread among countries through the growth of trade and travel. High-risk areas for the emergence and spread of infectious disease are where these three trends intersect with predisposing socioecological conditions including the presence of wild disease reservoirs, agricultural practices that increase contact between wildlife and livestock, and cultural practices that increase contact between humans, wildlife, and livestock. Such an intersection occurs in China, which has been a "cradle" of zoonoses from the Black Death to avian influenza and SARS. Disease management in China is thus critical to the mitigation of global zoonotic risks.

Disentangling host, pathogen, and environmental determinants of a recently emerged wildlife disease: lessons from the first 15 years of amphibian chytridiomycosis research.

The amphibian fungal disease chytridiomycosis, which affects species across all continents, recently emerged as one of the greatest threats to biodiversity. Yet, many aspects of the basic biology and epidemiology of the pathogen, Batrachochytrium dendrobatidis (Bd), are still unknown, such as when and from where did Bd emerge and what is its true ecological niche? Here, we review the ecology and evolution of Bd in the Americas and highlight controversies that make this disease so enigmatic. We explore factors associated with variance in severity of epizootics focusing on the disease triangle of host susceptibility, pathogen virulence, and environment. Reevaluating the causes of the panzootic is timely given the wealth of data on Bd prevalence across hosts and communities and the recent discoveries suggesting co-evolutionary potential of hosts and Bd. We generate a new species distribution model for Bd in the Americas based on over 30,000 records and suggest a novel future research agenda. Instead of focusing on pathogen "hot spots," we need to identify pathogen "cold spots" so that we can better understand what limits the pathogen's distribution. Finally, we introduce the concept of "the Ghost of Epizootics Past" to discuss expected patterns in postepizootic host communities.

We must teach more effectively: here are four ways to get started.

Research on how people learn shows that teaching using active learning is more effective than just lecturing. We outline four concrete ways instructors can begin to apply active learning in their teaching: backward instruction design; expecting students to learn more than facts; posing "messy" problems for students to solve; and expecting students to talk, write, and collaborate. Each tactic is supported with references demonstrating its efficacy and advice and links to resources for getting started with active learning.

Commentary: tempo of evolutionary change in ecological systems.

As ecology and evolutionary biology developed during the 20th century one thing that frustrated an integration of research programs in these areas was the assumption that ecological and evolutionary processes operated on very different time scales. In 1961 the ecologist Lawrence Slobodkin reflected this assumption in his distinction between "evolutionary time" and "ecological time." This commentary reflects on the four papers in this Special Section that advance our understanding of the history of research at the intersection of phenotypes, genotypes, ecology, and evolution using plants as study organisms. Early in the 20th century at least some researchers, especially in agricultural systems, were already using observations and experiments to show how natural selection could operate over relatively short time periods and small spatial scales. These four studies offer a more nuanced view of the history of our understanding of the rate of phenotypic change via natural selection and the use of experiments to study evolutionary change. They illuminate the route that has led to the current presumption that in many cases ecological and evolutionary processes may indeed operate on similar, not dissimilar, time scales.