Late Cretaceous ammonoids show that drivers of diversification are regionally heterogeneous

Palaeontologists have long sought to explain the diversification of individual clades to whole biotas at global scales. Advances in our understanding of the spatial distribution of the fossil record through geological time, however, has demonstrated that global trends in biodiversity were a mosaic of regionally heterogeneous diversification processes. Drivers of diversification must presumably have also displayed regional variation to produce the spatial disparities observed in past taxonomic richness. Here, we analyse the fossil record of ammonoids, pelagic shelled cephalopods, through the Late Cretaceous, characterised by some palaeontologists as an interval of biotic decline prior to their total extinction at the Cretaceous-Paleogene boundary. We regionally subdivide this record to eliminate the impacts of spatial sampling biases and infer regional origination and extinction rates corrected for temporal sampling biases using Bayesian methods. We then model these rates using biotic and abiotic drivers commonly inferred to influence diversification. Ammonoid diversification dynamics and responses to this common set of diversity drivers were regionally heterogeneous, do not support ecological decline, and demonstrate that their global diversification signal is influenced by spatial disparities in sampling effort. These results call into question the feasibility of seeking drivers of diversity at global scales in the fossil record

Nacre tablet thickness records formation temperature in modern and fossil shells

Nacre, the iridescent outer lining of pearls and inner lining of many mollusk shells, is composed of periodic, parallel, organic sheets alternating with aragonite (CaCO_3) tablet layers. Nacre tablet thickness (TT) generates both nacre's iridescence and its remarkable resistance to fracture. Despite extensive studies on how nacre forms, the mechanisms controlling TT remain unknown, even though they determine the most conspicuous of nacre's characteristics, visible even to the naked eye. Thermodynamics predicts that temperature (T) will affect both physical and chemical components of biomineralized skeletons. The chemical composition of biominerals is well-established to record environmental parameters, and has therefore been extensively used in paleoclimate studies. The physical structure, however, has been hypothesized but never directly demonstrated to depend on the environment. Here we observe that the physical TT in nacre from modern and fossil shallow-water shells of the bivalves Pinna and Atrina correlates with T as measured by the carbonate clumped isotope thermometer. Based on the observed TT vs. T correlation, we anticipate that TT will be used as a paleothermometer, useful to estimate paleotemperature in shallow-water paleoenvironments. Here we successfully test the proposed new nacre TT thermometer on two Jurassic Pinna shells. The increase of TT with T is consistent with greater aragonite growth rate at higher T, and with greater metabolic rate at higher T. Thus, it reveals a complex, T-dependent biophysical mechanism for nacre formation

ENM2020 : A FREE ONLINE COURSE AND SET OF RESOURCES ON MODELING SPECIES NICHES AND DISTRIBUTIONS

The field of distributional ecology has seen considerable recent attention, particularly surrounding the theory, protocols, and tools for Ecological Niche Modeling (ENM) or Species Distribution Modeling (SDM). Such analyses have grown steadily over the past two decades-including a maturation of relevant theory and key concepts-but methodological consensus has yet to be reached. In response, and following an online course taught in Spanish in 2018, we designed a comprehensive English-language course covering much of the underlying theory and methods currently applied in this broad field. Here, we summarize that course, ENM2020, and provide links by which resources produced for it can be accessed into the future. ENM2020 lasted 43 weeks, with presentations from 52 instructors, who engaged with >2500 participants globally through >14,000 hours of viewing and >90,000 views of instructional video and question-and-answer sessions. Each major topic was introduced by an "Overview" talk, followed by more detailed lectures on subtopics. The hierarchical and modular format of the course permits updates, corrections, or alternative viewpoints, and generally facilitates revision and reuse, including the use of only the Overview lectures for introductory courses. All course materials are free and openly accessible (CC-BY license) to ensure these resources remain available to all interested in distributional ecology.Peer reviewe

Challenges in Designing a National Surveillance Program for Inflammatory Bowel Disease in the United States:

This review describes the history of US government funding for surveillance programs in IBD, provides current estimates of the incidence and prevalence of inflammatory bowel diseases (IBD) in the United States (US), and enumerates a number of challenges faced by current and future IBD surveillance programs. A rationale for expanding the focus of IBD surveillance beyond counts of incidence and prevalence, in order to provide a greater understanding of the burden of IBD, disease etiology and pathogenesis, is provided. Lessons learned from other countries are summarized, as well as potential resources that may be used to optimize a new form of IBD surveillance in the US. A consensus recommendation on the goals and available resources for a new model for disease surveillance are provided. This new model should focus upon “surveillance of the burden of disease,” including 1) natural history of disease and 2) outcomes and complications of the disease and/or treatments

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Data from: PaleoENM: applying ecological niche modeling to the fossil record

Ecological niche modeling (ENM) is a quantitative approach to predict species’ abiotic requirements. It is a correlative technique, requiring geographically explicit information on species occurrences and the suites of environmental conditions experienced at each occurrence point. The output of these models is a set of environmental suitability rules that can be projected geographically and through time to test biogeographic, ecologic, and evolutionary hypotheses. Although developed by biologists and used extensively in the modern, ENM is in its early stages of application to the deep-time fossil record (hence PaleoENM). In part its limited use in the fossil record thus far reflects the methodological challenge of constructing paleoenvironmental layers needed for PaleoENM analysis, whereas in the modern these layers are available from large public databases (e.g., WorldClim). This paper provides a contextual and methodological framework for appropriately applying PaleoENM, including best practices for developing species occurrence and paleoenvironmental data sets for PaleoENM analyses

Data from: PaleoENM: applying ecological niche modeling to the fossil record

Ecological niche modeling (ENM) is a quantitative approach to predict species’ abiotic requirements. It is a correlative technique, requiring geographically explicit information on species occurrences and the suites of environmental conditions experienced at each occurrence point. The output of these models is a set of environmental suitability rules that can be projected geographically and through time to test biogeographic, ecologic, and evolutionary hypotheses. Although developed by biologists and used extensively in the modern, ENM is in its early stages of application to the deep-time fossil record (hence PaleoENM). In part its limited use in the fossil record thus far reflects the methodological challenge of constructing paleoenvironmental layers needed for PaleoENM analysis, whereas in the modern these layers are available from large public databases (e.g., WorldClim). This paper provides a contextual and methodological framework for appropriately applying PaleoENM, including best practices for developing species occurrence and paleoenvironmental data sets for PaleoENM analyses

Data from: An analysis of the impacts of Cretaceous Oceanic Anoxic Events on global molluscan diversity dynamics

Oceanic Anoxic Events (OAEs) are contemporaneous with 11 of the 18 largest Phanerozoic extinction events, but the magnitude and selectivity of their paleoecological impact remains disputed. OAEs are associated with abrupt, rapid warming and increased CO2 flux to the atmosphere, thus insights from this study may clarify the impact of current anthropogenic climate change on the biosphere. We investigated the influence of the Late Cretaceous Bonarelli Event (OAE2; Cenomanian – Turonian stage boundary; ~ 94 Ma) on generic- and species-level molluscan diversity, extinction rates, and ecological turnover. Cenomanian – Turonian results were compared with changes across all Cretaceous stage boundaries, some of which are coincident with less severe OAEs. We found increased generic turnover, but not species-level turnover, associated with several Cretaceous OAEs. The absence of a species-level pattern may reflect species occurrence data that are too temporally coarse to robustly detect patterns. Five hypotheses of ecological selectivity relating anoxia to survivorship were tested across stage boundaries with respect to faunality, mobility and diet using generalized linear models. Increasingly benthic taxa were consistently selected against throughout the Cretaceous regardless of the presence or absence of OAEs. These results suggest that: (1) the Cenomanian – Turonian boundary (OAE2) was associated with a decline in mollusk diversity, and increase in extinction rate, that was significantly more severe than Cretaceous background levels; and (2) no differential ecological selectivity was associated with OAE-related diversity declines among the variables tested here