Understanding modern extinctions in marine ecosystems: the role of palaeoecological data

Because anthropogenic impacts on ecological systems pre-date the oldest scientific observations, historical documents and archaeological records, understanding modern extinctions requires additional data sources that extend further back in time. Palaeoecological records, which provide quantitative proxy records of ecosystems prior to human impact, are essential for understanding recent extinctions and future extinction risks. Here we critically review the value of the most recent fossil record in contributing to our understanding of modern extinctions and illustrate through case studies how naturally occurring death assemblages and Holocene sedimentary records provide context to the plight of marine ecosystems. While palaeoecological data are inherently restricted censuses of past communities (manipulative experiments are not possible), they yield quantitative records over temporal scales that are beyond the reach of ecology. Only by including palaeoecological data is it possible to fully assess the role of long-term anthropogenic processes in driving modern extinction risk.

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Adding fossil occupancy trajectories to the assessment of modern extinction risk

Biology Letters ◽

10.1098/rsbl.2015.0813 ◽

2016 ◽

Vol 12 (10) ◽

pp. 20150813 ◽

Cited By ~ 7

Author(s):

Wolfgang Kiessling ◽

Ádám T. Kocsis

Keyword(s):

Fossil Record ◽

Extinction Risk ◽

Strong Predictor ◽

Marine Species ◽

Species Traits ◽

Latent Extinction ◽

Extant Species ◽

Temporal Trajectory

Besides helping to identify species traits that are commonly linked to extinction risk, the fossil record may also be directly relevant for assessing the extinction risk of extant species. Standing geographical distribution or occupancy is a strong predictor of both recent and past extinction risk, but the role of changes in occupancy is less widely assessed. Here we demonstrate, based on the Cenozoic fossil record of marine species, that both occupancy and its temporal trajectory are significant determinants of risk. Based on extinct species we develop a model on the additive and interacting effects of occupancy and its temporal changes on extinction risk. We use this model to predict extinction risk of extant species. The predictions suggest a moderate risk for marine species on average. However, some species seem to be on a long-term decline and potentially at a latent extinction risk, which is not considered in current risk assessments.

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Assessing long-term risks of prairie seed harvest: what is the role of life-history?

Botany ◽

10.1139/cjb-2017-0069 ◽

2017 ◽

Vol 95 (11) ◽

pp. 1081-1092 ◽

Cited By ~ 2

Author(s):

Justin C. Meissen ◽

Susan M. Galatowitsch ◽

Meredith W. Cornett

Keyword(s):

Tallgrass Prairie ◽

High Intensity ◽

Reproductive Strategies ◽

Extinction Risk ◽

Native Plant ◽

Seed Harvest ◽

Prairie Restorations ◽

Clonal Species

To meet the demand for more and larger tallgrass prairie restorations, seed is frequently collected en-masse from remnant native plant populations. Overharvesting of seed may lead to population extinctions, but these risks are not well studied. Species’ reproductive strategies may provide a basis for risk assessment. We assessed extinction risks associated with seed harvest for grassland plant species with different reproductive strategies (clonal vs. non-clonal). Using stage-based matrix models, we projected the extinction risk for two clonal and four non-clonal prairie species subjected to five harvest scenarios: (i) no harvest, (ii and iii) annual harvest at low/high intensity (50% and 75% seeds removed), and (iv and v) triennial harvest at low/high intensity. We compared the magnitude of growth or decline (λ) and mean extinction risk among populations during a 25-year modeling period. Non-clonal species were robust to triennial and low-intensity harvest, but susceptible to decreases in population growth (λ) up to 0.5 and elevated extinction risks up to 95% with high intensity annual harvest. Clonal species were unaffected by seed harvest, owing to a compensatory effect of vegetative propagation on growth rates. To maintain populations of non-clonal species in remnant grasslands, high intensity annual harvest should be avoided.

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Novel insights into peptide amidation and amidating activity in the human circulation

Scientific Reports ◽

10.1038/s41598-021-95305-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Paul Kaufmann ◽

Andreas Bergmann ◽

Olle Melander

Keyword(s):

Large Population ◽

Physiological Role ◽

Population Based ◽

Naturally Occurring ◽

Long Term Follow Up ◽

Clinical Biomarker ◽

Peptide Amidation

AbstractC-terminal α-amidation is the final and essential step in the biosynthesis of several peptide hormones. Peptidylglycine α-amidating monooxygenase (PAM) is the only known enzyme to catalyse this reaction. PAM amidating activity (AMA) is known to be present in human circulation, but its physiological role and significance as a clinical biomarker remains unclear. We developed a PAM-specific amidation assay that utilizes the naturally occurring substrate Adrenomedullin-Gly (ADM-Gly, 1–53). Using our amidation assay we quantified serum amidating activities in a large population-based cohort of more than 4900 individuals. A correlation of serum amidating activity with several clinical parameters including high blood pressure was observed. Increasing PAM-AMA was an independent predictor of hard outcomes related to hemodynamic stress such as cardiovascular mortality, atrial fibrillation and heart failure during long-term follow-up (8.8 ± 2.5 years). Moreover, results from an animal study in rats utilizing recombinant human PAM provide novel insights into the physiological role of circulating PAM and show its potential significance in circulating peptide amidation.

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BDNF pro-peptide actions facilitate hippocampal LTD and are altered by the common BDNF polymorphism Val66Met

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1422336112 ◽

2015 ◽

Vol 112 (23) ◽

pp. E3067-E3074 ◽

Cited By ~ 64

Author(s):

Toshiyuki Mizui ◽

Yasuyuki Ishikawa ◽

Haruko Kumanogoh ◽

Maria Lume ◽

Tomoya Matsumoto ◽

...

Keyword(s):

Memory Function ◽

Amino Acid Position ◽

Human Memory ◽

Biological Role ◽

Neurotrophin Receptor ◽

Functional Roles ◽

Mature Form ◽

Naturally Occurring

Most growth factors are initially synthesized as precursor proteins and subsequently processed into their mature form by proteolytic cleavage, resulting in simultaneous removal of a pro-peptide. However, compared with that of mature form, the biological role of the pro-peptide is poorly understood. Here, we investigated the biological role of the pro-peptide of brain-derived neurotrophic factor (BDNF) and first showed that the pro-peptide is expressed and secreted in hippocampal tissues and cultures, respectively. Interestingly, we found that the BDNF pro-peptide directly facilitates hippocampal long-term depression (LTD), requiring the activation of GluN2B-containing NMDA receptors and the pan-neurotrophin receptor p75NTR. The BDNF pro-peptide also enhances NMDA-induced α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor endocytosis, a mechanism crucial for LTD expression. Thus, the BDNF pro-peptide is involved in synaptic plasticity that regulates a mechanism responsible for promoting LTD. The well-known BDNF polymorphism valine for methionine at amino acid position 66 (Val66Met) affects human memory function. Here, the BDNF pro-peptide with Met mutation completely inhibits hippocampal LTD. These findings demonstrate functional roles for the BDNF pro-peptide and a naturally occurring human BDNF polymorphism in hippocampal synaptic depression.

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Holocene Development of the Alaskan Boreal Forest

Alaska's Changing Boreal Forest ◽

10.1093/oso/9780195154313.003.0009 ◽

2006 ◽

Author(s):

Andrea H. Lloyd ◽

Mary E. Edwards

Keyword(s):

Boreal Forest ◽

Time Scales ◽

Regional Climate ◽

Ecological Change ◽

Bering Strait ◽

Disturbance Regimes ◽

The Past ◽

Proxy Records

Paleoecological data provide insight into patterns of change in vegetation and in the factors, such as climate and disturbance, that cause vegetation change. Disturbance by fire, insect, and mammalian herbivores and, in floodplains, flooding are the primary drivers of changes in population structure, community composition, and species distribution in the boreal forest on time scales of years to decades (Chapter 7). On longer time scales, such as centuries to millennia, the role of variation in regional climate in determining compositional changes in the boreal forest is also clearly visible. Variability in regional climate may act directly on boreal species (e.g., causing changes in species distributions) or indirectly, by altering disturbance regimes. Proxy records of environmental and ecological change (e.g., pollen and macrofossils in lake sediments, tree rings) are selective in the kind of information they record. Evidence of fires, for example, is more persistent and thus better represented in the paleoecological record than is evidence of mammalian herbivory. For this reason, our understanding of long-term patterns of compositional and structural change in the boreal forest is limited to an analysis of the effects of a few key drivers of change, primarily climate and fire. In this chapter, we offer a long-term perspective on changes in climate and disturbance regimes and their relationship to major changes in vegetation. We first consider multimillennial time scales and discuss the role of climate and disturbance in driving the two major vegetation transitions that have occurred during the Holocene (the past 12,000 years). We then explore evidence for spatial and temporal variation in disturbance regimes during the late Holocene. Much of the terrain that is currently occupied by the Alaskan boreal forest remained ice-free during the glacial episodes of the Quaternary period (Pleistocene and Holocene), which spans the past 1.8 million years. Alaska forms part of the largely unglaciated Beringian region (named after the Bering Strait that lies at its heart; see Hopkins 1967) that extends from the Kolyma River in Siberia to the MacKenzie in northwest Canada and constitutes ca. 30% of the circumboreal zone.

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Long-term archives reveal shifting extinction selectivity in China's postglacial mammal fauna

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2017.1979 ◽

2017 ◽

Vol 284 (1867) ◽

pp. 20171979 ◽

Cited By ~ 14

Author(s):

Samuel T. Turvey ◽

Jennifer J. Crees ◽

Zhipeng Li ◽

Jon Bielby ◽

Jing Yuan

Keyword(s):

Human Activities ◽

Ming Dynasty ◽

Temporal Dynamics ◽

Anthropogenic Impacts ◽

Extinction Risk ◽

Species Conservation ◽

Biodiversity Loss ◽

Mammal Species ◽

Extinction Selectivity

Ecosystems have been modified by human activities for millennia, and insights about ecology and extinction risk based only on recent data are likely to be both incomplete and biased. We synthesize multiple long-term archives (over 250 archaeological and palaeontological sites dating from the early Holocene to the Ming Dynasty and over 4400 historical records) to reconstruct the spatio-temporal dynamics of Holocene–modern range change across China, a megadiverse country experiencing extensive current-day biodiversity loss, for 34 mammal species over three successive postglacial time intervals. Our combined zooarchaeological, palaeontological, historical and current-day datasets reveal that both phylogenetic and spatial patterns of extinction selectivity have varied through time in China, probably in response both to cumulative anthropogenic impacts (an ‘extinction filter’ associated with vulnerable species and accessible landscapes being affected earlier by human activities) and also to quantitative and qualitative changes in regional pressures. China has experienced few postglacial global species-level mammal extinctions, and most species retain over 50% of their maximum estimated Holocene range despite millennia of increasing regional human pressures, suggesting that the potential still exists for successful species conservation and ecosystem restoration. Data from long-term archives also demonstrate that herbivores have experienced more historical extinctions in China, and carnivores have until recently displayed greater resilience. Accurate assessment of patterns of biodiversity loss and the likely predictive power of current-day correlates of faunal vulnerability and resilience is dependent upon novel perspectives provided by long-term archives.

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Fine structure and properties of defects in naturally occurring silicates and oxides

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100175430 ◽

1990 ◽

Vol 48 (4) ◽

pp. 460-461

Author(s):

David R. Veblen

Keyword(s):

Chemical Reactions ◽

High Resolution Electron Microscopy ◽

Extended Defects ◽

Single Chain ◽

Naturally Occurring ◽

Resolution Electron ◽

Fine Structures ◽

Image Simulations ◽

Similar Crystal Structure

Extended defects and interfaces control many processes in rock-forming minerals, from chemical reactions to rock deformation. In many cases, it is not the average structure of a defect or interface that is most important, but rather the structure of defect terminations or offsets in an interface. One of the major thrusts of high-resolution electron microscopy in the earth sciences has been to identify the role of defect fine structures in reactions and to determine the structures of such features. This paper will review studies using HREM and image simulations to determine the structures of defects in silicate and oxide minerals and present several examples of the role of defects in mineral chemical reactions. In some cases, the geological occurrence can be used to constrain the diffusional properties of defects.The simplest reactions in minerals involve exsolution (precipitation) of one mineral from another with a similar crystal structure, and pyroxenes (single-chain silicates) provide a good example. Although conventional TEM studies have led to a basic understanding of this sort of phase separation in pyroxenes via spinodal decomposition or nucleation and growth, HREM has provided a much more detailed appreciation of the processes involved.

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