The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Michael Foote - One of the best experts on this subject based on the ideXlab platform.
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association between geographic range and initial survival of mesozoic Marine Animal genera circumventing the confounding effects of temporal and taxonomic heterogeneity
Paleobiology, 2017Co-Authors: Kathleen A Ritterbush, Michael FooteAbstract:We investigate the association between geographic range and survival in Mesozoic Marine Animal genera. Previous work using data from the Paleobiology Database (paleobiodb.org) demonstrated greater survivorship overall among Phanerozoic genera that were widespread during their stage of first appearance, but this relationship did not hold during the Mesozoic. To explore this unexpected result, we consider geographic range in conjunction with temporal variation in survival and variation in survival among higher taxa. Because average range and average survival are negatively correlated among stages, for reasons that are still unclear, and because the data are heavily influenced by cephalopods, which include many wide-ranging and short-lived genera, the effect of geographic range on survival is obscured in the aggregate data. Thus, range is not a significant predictor of survival when data are analyzed in aggregate, but it does have a significant effect when variation in average range and average survival among stages and classes is taken into account. The best-fitting models combine range with both temporal and taxonomic heterogeneity as predictive factors. Moreover, when we take stage-to-stage variation into account, geographic range is an important predictor of survival within most classes. Cephalopod genera must be more widespread than genera in other classes for geographic range to significantly increase odds of survival, and factoring in survival heterogeneity of superfamilies further increases model fit, demonstrating a nested nature in the sensitivity of range and taxonomic aggregation.
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environmental controls on geographic range size in Marine Animal genera
Paleobiology, 2014Co-Authors: Michael FooteAbstract:Here I test the hypothesis that temporal variation in geographic range size within genera is affected by the expansion and contraction of their preferred environments. Using occurrence data from the Paleobiology Database, I identify genera that have a significant affinity for carbonate or terrigenous clastic depositional environments that transcends the Database's representation of these environments during the stratigraphic range of each genus. These affinity assignments are not a matter of arbitrarily subdividing a continuum in preference; rather, genera form distinct, nonrandom subsets with respect to environmental preference. I tabulate the stage-by-stage transitions in range size within individual genera and the stage-by-stage changes in the extent of each environment. Comparing the two shows that genera with a preference for a given environment are more likely to increase in geographic range, and to show a larger average increase in range, when that environment increases in areal extent, and likewise for decreases in geographic range and environmental area. Similar results obtain for genera with preferences for reefal and non-reef settings. Simulations and subsampling experiments suggest that these results are not artifacts of methodology or sampling bias. Nor are they confined to particular higher taxa. Genera with roughly equal preference for carbonates and clastics do not have substantially broader geographic ranges than those with a distinct affinity, suggesting that, at this scale of analysis, spatial extent of preferred environment outweighs breadth of environmental preference in governing geographic range. These results pertain to changes over actual geologic time within individual genera, not overall average ranges. Recent work has documented a regular expansion and contraction when absolute time is ignored and genera are superimposed to form a composite average. Environmental preference may contribute to this pattern, but its role appears to be minor, limited mainly to the initial expansion and final contraction of relatively short-lived genera.
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determinants of early survival in Marine Animal genera
Paleobiology, 2013Co-Authors: Michael Foote, Arnold I MillerAbstract:Genera by their very nature are expected to be monotypic and geographically and environmentally restricted at their origin, and most genera do not endure past their stage of first appearance. At the same time, those genera that do endure have a capacity to expand greatly in geographic range, environmental breadth, and species richness. Here we ask what it is that allows some genera and not others to survive past their inception. Using occurrence data from the Paleobiology Database, we find that initial geographic range has the strongest effect on survival, followed by environmental breadth, with the effect of species richness weaker on average. The effect of geographic range is strongest if measured as the distances spanned by the occurrences of a genus rather than the number of distinct areas in which a genus lives. We document substantial secular variation in selectivity of early survival. The most striking aspect of this variation is that survival is only weakly selective among genera that first appear during the Mesozoic. By following genera beyond their stage of first appearance, we find that selectivity with respect to all factors becomes systematically stronger as cohorts age and genera become more differentiated in range, breadth, and richness. This may help account for a previously identified statistical effect of genus age on the chances of survival.
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extinction and quiescence in Marine Animal genera
Paleobiology, 2007Co-Authors: Michael FooteAbstract:If last appearances of Marine Animal genera are taken as reasonable proxies for true extinctions, then there is appreciable global extinction in every stage of the Phanerozoic. If, instead, backsmearing of extinctions by incomplete sampling is explicitly taken into consideration, a different view of extinction emerges, in which the pattern of extinction is much more volatile and in which quiescent time spans—with little or no global extinction for several million years—are punctuated by major extinction events that are even more extreme than is generally thought. Independent support for this alternative view comes from analysis of genus occurrence data in the Paleobiology Database, which agrees with previous estimates of sampling probability and implies that offsets between extinction and last appearance of one or more stages are quite probable.
Christoffer Moesgaard Albertsen - One of the best experts on this subject based on the ideXlab platform.
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generalizing the first difference correlated random walk for Marine Animal movement data
Scientific Reports, 2019Co-Authors: Christoffer Moesgaard AlbertsenAbstract:Animal telemetry data are often analysed with discrete time movement models. These models are defined with regular time steps. However, telemetry data from Marine Animals are observed irregularly. To account for irregular data, a time-irregularised first-difference correlated random walk model with drift is introduced. The model generalizes the commonly used first-difference correlated random walk with regular time steps by allowing irregular time steps, including a drift term, and by allowing different autocorrelation in the two coordinates. The model is applied to data from a ringed seal collected through the Argos satellite system, and is compared to related movement models through simulations. Accounting for irregular data in the movement model results in accurate parameter estimates and reconstruction of movement paths. Further, the introduced model can provide more accurate movement paths than the regular time counterpart. Extracting accurate movement paths from uncertain telemetry data is important for evaluating space use patterns for Marine Animals, which in turn is crucial for management. Further, handling irregular data directly in the movement model allows efficient simultaneous analyses of several Animals.
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generalizing the first difference correlated random walk for Marine Animal movement data
arXiv: Quantitative Methods, 2018Co-Authors: Christoffer Moesgaard AlbertsenAbstract:Animal telemetry data are often analysed with discrete time movement models assuming rotation in the movement. These models are defined with equidistant distant time steps. However, telemetry data from Marine Animals are observed irregularly. To account for irregular data, a time-irregularised first-difference correlated random walk model with drift is introduced. The model generalizes the commonly used first-difference correlated random walk with regular time steps by allowing irregular time steps, including a drift term, and by allowing different autocorrelation in the two coordinates. The model is applied to data from a ringed seal collected through the Argos satellite system, and is compared to related movement models through simulations. Accounting for irregular data in the movement model results in accurate parameter estimates and reconstruction of movement paths. Measured by distance, the introduced model can provide more accurate movement paths than the regular time counterpart. Extracting accurate movement paths from uncertain telemetry data is important for evaluating space use patterns for Marine Animals, which in turn is crucial for management. Further, handling irregular data directly in the movement model allows efficient simultaneous analysis of several Animals.
Silvia Franzellitti - One of the best experts on this subject based on the ideXlab platform.
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human pharmaceuticals in the Marine environment focus on exposure and biological effects in Animal species
Environmental Toxicology and Chemistry, 2016Co-Authors: Elena Fabbri, Silvia FranzellittiAbstract:Marine waters have been poorly investigated for the occurrence of pharmaceutical contamination. Recent data confirm that pharmaceuticals occur widely in Marine and coastal environments; therefore, assessment of potential risk to Marine species needs further efforts. The present study represents the first extensive review of pharmaceutical contamination in Marine environments addressing the effects on the Marine biota analyzed at the molecular, cellular, and individual levels. Because pharmaceuticals differ from conventional pollutants, being designed to interact with specific physiological pathways at low doses, the most recent evidence on modes of action and physiological alterations on Marine Animal species are discussed. Data on spatial distributions of pharmaceuticals in waters and sediments, as well as bioaccumulation rates, are also presented. The present review also seeks to expand knowledge of how the quality of coastal and Marine environments could be efficiently monitored to anticipate possible health and environmental risks.
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human pharmaceuticals in the Marine environment focus on exposure and biological effects in Animal species
Environmental Toxicology and Chemistry, 2016Co-Authors: Elena Fabbri, Silvia FranzellittiAbstract:Marine waters have been poorly investigated for the occurrence of pharmaceutical contamination. Recent data confirm that pharmaceuticals occur widely in Marine and coastal environments; therefore, assessment of potential risk to Marine species needs further efforts. The present study represents the first extensive review of pharmaceutical contamination in Marine environments addressing the effects on the Marine biota analyzed at the molecular, cellular, and individual levels. Because pharmaceuticals differ from conventional pollutants, being designed to interact with specific physiological pathways at low doses, the most recent evidence on modes of action and physiological alterations on Marine Animal species are discussed. Data on spatial distributions of pharmaceuticals in waters and sediments, as well as bioaccumulation rates, are also presented. The present review also seeks to expand knowledge of how the quality of coastal and Marine environments could be efficiently monitored to anticipate possible health and environmental risks. Environ Toxicol Chem 2016;35:799–812. © 2015 SETAC
Heike K. Lotze - One of the best experts on this subject based on the ideXlab platform.
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Twenty-first-century climate change impacts on Marine Animal biomass and ecosystem structure across ocean basins.
Global change biology, 2018Co-Authors: Andrea Bryndum-buchholz, Derek P. Tittensor, Julia L. Blanchard, William W. L. Cheung, Marta Coll, Eric D. Galbraith, Simon Jennings, Olivier Maury, Heike K. LotzeAbstract:Climate change effects on Marine ecosystems include impacts on primary production, ocean temperature, species distributions, and abundance at local to global scales. These changes will significantly alter Marine ecosystem structure and function with associated socio‐economic impacts on ecosystem services, Marine fisheries, and fishery‐dependent societies. Yet how these changes may play out among ocean basins over the 21st century remains unclear, with most projections coming from single ecosystem models that do not adequately capture the range of model uncertainty. We address this by using six Marine ecosystem models within the Fisheries and Marine Ecosystem Model Intercomparison Project (Fish‐MIP) to analyze responses of Marine Animal biomass in all major ocean basins to contrasting climate change scenarios. Under a high emissions scenario (RCP8.5), total Marine Animal biomass declined by an ensemble mean of 15%–30% (±12%–17%) in the North and South Atlantic and Pacific, and the Indian Ocean by 2100, whereas polar ocean basins experienced a 20%–80% (±35%–200%) increase. Uncertainty and model disagreement were greatest in the Arctic and smallest in the South Pacific Ocean. Projected changes were reduced under a low (RCP2.6) emissions scenario. Under RCP2.6 and RCP8.5, biomass projections were highly correlated with changes in net primary production and negatively correlated with projected sea surface temperature increases across all ocean basins except the polar oceans. Ecosystem structure was projected to shift as Animal biomass concentrated in different size‐classes across ocean basins and emissions scenarios. We highlight that climate change mitigation measures could moderate the impacts on Marine Animal biomass by reducing biomass declines in the Pacific, Atlantic, and Indian Ocean basins. The range of individual model projections emphasizes the importance of using an ensemble approach in assessing uncertainty of future change.
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recovery of Marine Animal populations and ecosystems
Trends in Ecology and Evolution, 2011Co-Authors: Heike K. Lotze, Marta Coll, Anna M Magera, Christine A Wardpaige, Laura AiroldiAbstract:Many Marine populations and ecosystems have experienced strong historical depletions, yet reports of recoveries are increasing. Here, we review the growing research on Marine recoveries to reveal how common recovery is, its magnitude, timescale and major drivers. Overall, 10–50% of depleted populations and ecosystems show some recovery, but rarely to former levels of abundance. In addition, recovery can take many decades for long-lived species and complex ecosystems. Major drivers of recovery include the reduction of human impacts, especially exploitation, habitat loss and pollution, combined with favorable life-history and environmental conditions. Awareness, legal protection and enforcement of management plans are also crucial. Learning from historical recovery successes and failures is essential for implementing realistic conservation goals and promising management strategies.
George R. Pettit - One of the best experts on this subject based on the ideXlab platform.
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Marine Animal and terrestrial plant anticancer constituentsa
2015Co-Authors: George R. PettitAbstract:Abstract- Substantial advances in improving human cancer treatment continue to require discovery and development of new and curative anticancer drugs. Our recent (1989-93) progress in discovery and development of new anticancer drugs derived from Marine Animal and terrestrial plant biosynthetic products has been reviewed. Special emphasis was placed upon the bryostatin (1,2), dolastatin (4-6), halichondrin (15), halistatin (16,17), spongistatin (18-20), cephalostatin (7-14) and pancratistatin (34) series of potentially useful anticancer drugs. Real advances in improving human cancer treatment require discovery and development of new and curative anticancer drugs, and we are sharply focused on those objectives. To follow is a 1989-93 review of research progress aimed at discovery of structurally unique and promising anticancer drugs. The summary begins with a historical overview and then places major emphasis on our discoveries of the very important bryostatin (1, ref. l), dolastatin (4,6, ref. 2), halichondrin (15, ref. 3), halistatin (16,17, ref
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Marine Animal and terrestrial plant anticancer constituents
Pure and Applied Chemistry, 1994Co-Authors: George R. PettitAbstract:Substantial advances in improving human cancer treatment continue to require discovery and development of new and curative anticancer drugs. Our recent (1989-93) progress in discovery and development of new anticancer drugs derived from Marine Animal and terrestrial plant biosynthetic products has been reviewed. Special emphasis was placed upon the bryostatin (1,2), dolastatin (4-6), halichondrin (15), halistatin (16,17), spongistatin (18-20), cephalostatin (7-14) and pancratistatin (34) series of potentially useful anticancer drugs. Real advances in improving human cancer treatment require discovery and development of new and curative anticancer drugs, and we are sharply focused on those objectives. To follow is a 1989-93 review of research progress aimed at discovery of structurally unique and promising anticancer drugs. The summary begins with a historical overview and then places major emphasis on our discoveries of the very important bryostatin (1, ref. l), dolastatin (4,6, ref. 2), halichondrin (15, ref. 3), halistatin (16,17, ref. 4), spongistatin (18-20, ref. 5), cephalostatin (7-14, ref. 6) and pancratistatin (34, ref. 7) series of useful anticancer drugs. The U. S. National Cancer Institute (NCI) research programs directed at discovery of new and clinically important Animal, plant, and microorganism anticancer constituents were implemented in 1957 and have amply demonstrated that 2-4% of plant species and some 10% of Marine Animal species contain a great variety of antineoplastic and/or cytotoxic (ref. 8-18) constituents. The dramatic discoveries arising from the NCI research, such as taxol, (ref. 14,15) have stimulated considerable world-wide interest and initiation of analogous programs. Because of this vitally important NCI endeavor, new antineoplastic and/or cytotoxic biosynthetic products are being discovered at an increasing rate. The potential for discovering new Animal, plant and microorganism biosynthetic products for treatment of human cancer is truly immense and offers great promise of many curative approaches to the cancer problem. Consider that the world's flora may number up to 800,000 and the more conspicuous terrestrial vegetation, the angiosperms, may number from 300,000 to some 500,000 (ref. 16). Furthermore, enormous numbers of Marine Animal (over 2,000,000) and microorganism species (ref. 17) are available for investigation. Even now, less than 10% of the higher plants and less than 0.5% of the Marine Animals (ref. 8-10) have received even a cursory effort to detect antineoplastic constituents. So the majority of important Animal and plant cancer chemotherapeutic drugs still await discovery. In 1965-66 we began the first systematic study of Marine invertebrates and vertebrates as potential sources of new and potentially useful cancer chemotherapeutic drugs (ref. 18). reproducible (confirmed active) antineoplastic activity in the NCI murine P388 in vivo lymphocytic leukemia screening system. Froill this evidence, it was abundantly clear that such natural products present an unusually good opportunity for discovering clinically useful anticancer drugs. To date we have isolated a large number of new cytotoxic and/or antineoplastic agents from Marine Animals.
