scholarly journals The role of Quaternary environmental change in plant macroevolution: the exception or the rule?

2004 ◽  
Vol 359 (1442) ◽  
pp. 159-172 ◽  
Author(s):  
Katherine J. Willis ◽  
Karl J. Niklas
Keyword(s):  
Fossil Record ◽  
Sampling Bias ◽  
Climatic Conditions ◽  
Allopatric Speciation ◽  
Ice Age ◽  
Growth Forms ◽  
The Past ◽  
Plant Fossil ◽  
Speciation Rates ◽  
Important Time

The Quaternary has been described as an important time for genetic diversification and speciation. This is based on the premise that Quaternary climatic conditions fostered the isolation of populations and, in some instances, allopatric speciation. However, the ‘Quaternary Ice–Age speciation model’ rests on two key assumptions: (i) that biotic responses to climate change during the Quaternary were significantly different from those of other periods in Earth's history; and (ii) that the mechanisms of isolation during the Quaternary were sufficient in time and space for genetic diversification to foster speciation. These assumptions are addressed by examining the plant fossil record for the Quaternary (in detail) and for the past 410 Myr, which encompasses previous intervals of icehouse Earth. Our examination of the Quaternary record indicates that floristic responses to climate changes during the past 1.8 Myr were complex and that a distinction has to be made between those plants that were able to withstand the extremes of glacial conditions and those that could not. Generation times are also important as are different growth forms (e.g. herbaceous annuals and arborescent perennials), resulting in different responses in terms of genetic divergence rates during isolation. Because of these variations in the duration of isolation of populations and genomic diversification rates, no canonical statement about the predominant floristic response to climatic changes during the Quaternary (i.e. elevated rates of speciation or extinction, or stasis) is currently possible. This is especially true because of a sampling bias in terms of the fossil record of tree species over that of species with non–arborescent growth forms. Nevertheless, based on the available information, it appears that the dominant response of arborescent species during the Quaternary was extinction rather than speciation or stasis. By contrast, our examination of the fossil record of vascular plants for the past 410 Myr indicates that speciation rates often increased during long intervals of icehouse Earth (spanning up to 50 Myr). Therefore, longer periods of icehouse Earth than those occurring during the Quaternary may have isolated plant populations for sufficiently long periods of time to foster genomic diversification and allopatric speciation. Our results highlight the need for more detailed study of the fossil record in terms of finer temporal and spatial resolution than is currently available to examine the significance of intervals of icehouse Earth. It is equally clear that additional and detailed molecular studies of extant populations of Quaternary species are required in order to determine the extent to which these ‘relic’ species have genomically diversified across their current populations.

Did Ground Cover Change Over Geologic Time?

2000 ◽  
Vol 6 ◽  
pp. 171-182 ◽  
Author(s):  
Ben A. LePage ◽  
Hermann W. Pfefferkorn
Keyword(s):  
Fossil Record ◽  
Ground Cover ◽  
The Other ◽  
Detailed Account ◽  
Geologic Time ◽  
The Past ◽  
Other Hand ◽  
Plant Fossil

When one hears the term “ground cover,” one immediately thinks of “grasses.” This perception is so deep-seated that paleobotanists even have been overheard to proclaim that “there was no ground cover before grasses.” Today grasses are so predominant in many environments that this perception is perpetuated easily. On the other hand, it is difficult to imagine the absence or lack of ground cover prior to the mid-Tertiary. We tested the hypothesis that different forms of ground cover existed in the past against examples from the Recent and the fossil record (Table 1). The Recent data were obtained from a large number of sources including those in the ecological, horticultural, and microbiological literature. Other data were derived from our knowledge of Precambrian life, sedimentology and paleosols, and the plant fossil record, especially in situ floras and fossil “monocultures.” Some of the data are original observations, but many others are from the literature. A detailed account of these results will be presented elsewhere (Pfefferkorn and LePage, in preparation).

scholarly journals Latitudinal variations of δ<sup>30</sup>Si and δ<sup>15</sup>N signatures along the Peruvian shelf: quantifying the effects of nutrient utilization versus denitrification over the past 600 years

2018 ◽  
Author(s):  
Kristin Doering ◽  
Claudia Ehlert ◽  
Philippe Martinez ◽  
Martin Frank ◽  
Ralph Schneider
Keyword(s):  
Isotope Composition ◽  
Nitrogen Isotope ◽  
Nutrient Utilization ◽  
Climatic Conditions ◽  
Ice Age ◽  
Silicon Isotope ◽  
Short Term ◽  
The Past ◽  
Subsurface Waters ◽  
Minimum Zone

Abstract. The sedimentary stable nitrogen isotope compositions of bulk organic matter (δ15Nbulk) and silicon isotope composition of diatoms (δ30SiBSi) both mainly reflect the degree of past nutrient utilization by primary producers. However, in ocean areas where anoxic and suboxic conditions prevail, the δ15Nbulk signal ultimately recorded within the sediments is also influenced by water column denitrification causing an increase in the subsurface δ15N signature of dissolved nitrate (δ15NO3−) upwelled to the surface. Such conditions are found in the oxygen minimum zone off Peru, where at present an increase in subsurface δ15NO3− from North to South along the shelf is observed due to ongoing denitrification within the pole-ward flowing subsurface waters, while the δ30Si signature of silicic acid (δ30Si(OH)4) at the same time remains unchanged. Here, we present three new δ30SiBSi records between 11° S and 15° S and compare these to previously published δ30SiBSi and δ15Nbulk records from Peru covering the past 600 years. We present a new approach to calculate past subsurface δ15NO3− signatures based on the correlation of δ30SiBSi and δ15Nbulk signatures at a latitudinal resolution for different time periods. Our results show source water δ15NO3− compositions during the last 200 years, the Current Warm Period (CWP) and during short-term arid events prior to that, which are close to modern values increasing southward from 7 to 10 ‰ (between 11° S and 15° S). In contrast, humid conditions during the Little Ice Age (LIA) reflect consistently low δ15NO3− values between 6 and 7.5‰. Furthermore, we are able to relate the short-term variability in both isotope compositions to changes in the ratio of nutrients (NO3− : Si(OH)4) taken up by different dominating phytoplankton groups (diatoms and non-siliceous phytoplankton) under the variable climatic conditions of the past 600 years.

scholarly journals How many dinosaur species were there? Fossil bias and true richness estimated using a Poisson sampling model (TRiPS)

2015 ◽  
Author(s):  
Jostein Starrfelt ◽  
Lee Hsiang Liow
Keyword(s):  
Species Richness ◽  
Fossil Record ◽  
Biological Diversity ◽  
Temporal Dynamics ◽  
Sampling Bias ◽  
Biased Sampling ◽  
Poisson Sampling ◽  
The Past ◽  
Past Life ◽  
Source Of Information

The fossil record is a rich source of information about biological diversity in the past. However, the fossil record is not only incomplete but has inherent biases due to geological, physical, chemical and biological factors. Our knowledge of past life is also biased because of differences in academic and amateur interests and sampling efforts. As a result, not all individuals or species that lived in the past are equally likely to be discovered at any point in time or space. To reconstruct temporal dynamics of diversity using the fossil record, biased sampling must be explicitly taken into account. Here, we introduce an approach that utilizes the variation in the number of times each species is observed in the fossil record to estimate both sampling bias and true richness. We term our technique TRiPS (True Richness estimated using a Poisson Sampling model) and explore its robustness to violation of its assumptions via simulations. We then venture to estimate sampling bias and absolute species richness of dinosaurs in the geological stages of the Mesozoic. Using TRiPS, we estimate that 1936 (1543-2468) species of dinosaurs roamed the Earth during the Mesozoic. We also present improved estimates of species richness trajectories of the three major dinosaur clades; the sauropodomorphs, ornithischians and theropods, casting doubt on the Jurassic-Cretaceous extinction event and demonstrating that all dinosaur groups are subject to considerable sampling bias throughout the Mesozoic.

Evidence of plant– arthropod interaction in the fossil assemblage from Pitsidia (Messara Basin, Crete, Greece; Upper Miocene)

2020 ◽  
Vol 295 (2) ◽  
pp. 101-115
Author(s):  
Giannis Zidianakis ◽  
Johanna Kovar-Eder ◽  
Avraam Zelilidis ◽  
George Iliopoulos
Keyword(s):  
Fossil Record ◽  
Biotic Interactions ◽  
Natural Ecosystems ◽  
Ecological Functions ◽  
Abiotic Environment ◽  
The Past ◽  
Plant Fossil ◽  
Plant Assemblage ◽  
Different Types ◽  
Herbivore Community

As major components of natural ecosystems, plants interact with the biotic and abiotic environment developing a spectrum of different responses at various biological levels. Such biotic interactions are detectible in the plant fossil record and provide an outline of ecological functions during the past. The recently described Late Miocene plant assemblage from Pitsidia in the Messara Basin was examined for arthropod mediated damage. Most of the damage was detected on abundant, more than 2.500 specimens, well-preserved material of Myrica lignitum foliage, providing a broad range of traces. Eighteen different types of leaf modifications were distinguished, with hole, margin, surface feeding, lamina distortion and possibly galls as the most common while mining and exophytic oviposition were rare. Among this damage, it appears that only a few represent host-specialist feeding. These findings could serve as a database for the component herbivore community on M. lignitum. Considerations of this insect damage regarding past habitats and vegetation at Pitsidia as well as on plant–arthropod co-association are discussed. Several forms of arthropod damage on other plant taxa in this assemblage are briefly mentioned.

Calibrating the paleothermometer: climate, communities, and the evolution of size

Paleobiology ◽  
1991 ◽  
Vol 17 (2) ◽  
pp. 189-199 ◽  
Author(s):  
Tamar Dayan ◽  
Daniel Simberloff ◽  
Eitan Tchernov ◽  
Yoram Yom-Tov
Keyword(s):  
Body Size ◽  
Climatic Change ◽  
Community Composition ◽  
Fossil Record ◽  
Character Displacement ◽  
Careful Consideration ◽  
Climatic Conditions ◽  
Tooth Size ◽  
The Past ◽  
Ecological Character Displacement

Studies in the past 20 years have often interpreted size fluctuations in fossil mammal remains as a response to climatic change, in accord with Bergmann's rule. However, such paleoecological inference requires careful consideration of changes in community composition that could cause ecological character displacement or release. Recent size gradients of mammals should be screened for the possibility of character displacement if fossil size gradients are to be used as a “paleothermometer” for past climate. The use of teeth in paleontological studies as a measure of body size presents a further complication; for several carnivore guilds, it appears that competitive pressures act most strongly on tooth size. Teeth may therefore inaccurately estimate body size, even if body size accurately indicates climatic conditions. In the fossil record different species exhibit different size patterns under the same conditions of climatic change, and the same species may show diametrically opposite size fluctuations under similar conditions of climatic change, in different regions.

scholarly journals How many dinosaur species were there? Fossil bias and true richness estimated using a Poisson sampling model

2016 ◽  
Vol 371 (1691) ◽  
pp. 20150219 ◽  
Author(s):  
Jostein Starrfelt ◽  
Lee Hsiang Liow
Keyword(s):  
Species Richness ◽  
Fossil Record ◽  
Biological Diversity ◽  
Temporal Dynamics ◽  
Sampling Bias ◽  
Biased Sampling ◽  
Poisson Sampling ◽  
The Past ◽  
Past Life ◽  
Source Of Information

The fossil record is a rich source of information about biological diversity in the past. However, the fossil record is not only incomplete but has also inherent biases due to geological, physical, chemical and biological factors. Our knowledge of past life is also biased because of differences in academic and amateur interests and sampling efforts. As a result, not all individuals or species that lived in the past are equally likely to be discovered at any point in time or space. To reconstruct temporal dynamics of diversity using the fossil record, biased sampling must be explicitly taken into account. Here, we introduce an approach that uses the variation in the number of times each species is observed in the fossil record to estimate both sampling bias and true richness. We term our technique TRiPS ( T rue Ri chness estimated using a P oisson S ampling model) and explore its robustness to violation of its assumptions via simulations. We then venture to estimate sampling bias and absolute species richness of dinosaurs in the geological stages of the Mesozoic. Using TRiPS, we estimate that 1936 (1543–2468) species of dinosaurs roamed the Earth during the Mesozoic. We also present improved estimates of species richness trajectories of the three major dinosaur clades: the sauropodomorphs, ornithischians and theropods, casting doubt on the Jurassic–Cretaceous extinction event and demonstrating that all dinosaur groups are subject to considerable sampling bias throughout the Mesozoic.

scholarly journals Latitudinal variations in <i>δ</i><sup>30</sup>Si and <i>δ</i><sup>15</sup>N signatures along the Peruvian shelf: quantifying the effects of nutrient utilization versus denitrification over the past 600 years

2019 ◽  
Vol 16 (10) ◽  
pp. 2163-2180
Author(s):  
Kristin Doering ◽  
Claudia Ehlert ◽  
Philippe Martinez ◽  
Martin Frank ◽  
Ralph Schneider
Keyword(s):  
Isotope Composition ◽  
Nitrogen Isotope ◽  
Nutrient Utilization ◽  
Climatic Conditions ◽  
Ice Age ◽  
Silicon Isotope ◽  
Short Term ◽  
The Past ◽  
Subsurface Waters ◽  
Minimum Zone

Abstract. The stable sedimentary nitrogen isotope compositions of bulk organic matter (δ15Nbulk) and the silicon isotope composition of diatoms (δ30SiBSi) both mainly reflect the degree of past nutrient utilization by primary producers. However, in ocean areas where anoxic and suboxic conditions prevail, the δ15Nbulk signal ultimately recorded within the sediments is also influenced by water column denitrification, causing an increase in the subsurface δ15N signature of dissolved nitrate (δ15NO3-) upwelled to the surface. Such conditions are found in the oxygen minimum zone off the coast of Peru, where, at present, an increase in subsurface δ15NO3- from north to south along the shelf is observed due to ongoing denitrification within the poleward-flowing subsurface waters, while the δ30Si signature of silicic acid (δ30Si(OH)4) at the same time remains unchanged. Here, we present three new δ30SiBSi records between 11 and 15∘ S and compare these to previously published δ30SiBSi and δ15Nbulk records from Peru covering the past 600 years. We present a new approach to calculate past subsurface δ15NO3- signatures based on the direct comparison of δ30SiBSi and δ15Nbulk signatures at a latitudinal resolution for different time periods. Our results show that, during the Current Warm Period (CWP, since 1800 CE) and prior short-term arid events, source water δ15NO3- compositions have been close to modern values, increasing southward from 7 to 10 ‰ (between 11 and 15∘ S). In contrast, during the Little Ice Age (LIA) we calculate low δ15NO3- values between 6 ‰ and 7.5 ‰. Furthermore, the direct δ30SiBSi versus δ15Nbulk comparison also enables us to relate the short-term variability in both isotope compositions to changes in the ratio of nutrients (NO3-:Si(OH)4) taken up by different dominating phytoplankton groups (diatoms and non-siliceous phytoplankton) under the variable climatic conditions of the past 600 years. Accordingly, we estimate a shift from a 1:1 (or 1:2) ratio during the CWP and a 2:1 (up to 15:1) ratio during the LIA, associated with a shift from overall high nutrient utilization to NO3--dominated (and thus non-siliceous phytoplankton) utilization.

scholarly journals The fossil record of whip spiders: the past of Amblypygi

PalZ ◽  
2021 ◽  
Author(s):  
Carolin Haug ◽  
Joachim T. Haug
Keyword(s):  
Fossil Record ◽  
3D Imaging ◽  
Three Dimensional ◽  
Dorsal Shield ◽  
Stereo Images ◽  
Geological Time ◽  
High Quality ◽  
The Past ◽  
Over Time

AbstractWhip spiders (Amblypygi), as their name suggests, resemble spiders (Araneae) in some aspects, but differ from them by their heart-shaped (prosomal) dorsal shield, their prominent grasping pedipalps, and their subsequent elongate pair of feeler appendages. The oldest possible occurrences of whip spiders, represented by cuticle fragments, date back to the Devonian (c. 385 mya), but (almost) complete fossils are known from the Carboniferous (c. 300 mya) onwards. The fossils include specimens preserved on slabs or in nodules (Carboniferous, Cretaceous) as well as specimens preserved in amber (Cretaceous, Eocene, Miocene). We review here all fossil whip spider specimens, figure most of them as interpretative drawings or with high-quality photographs including 3D imaging (stereo images) to make the three-dimensional relief of the specimens visible. Furthermore, we amend the list by two new specimens (resulting in 37 in total). The fossil specimens as well as modern whip spiders were measured to analyse possible changes in morphology over time. In general, the shield appears to have become relatively broader and the pedipalps and walking appendages have become more elongate over geological time. The morphological details are discussed in an evolutionary framework and in comparison with results from earlier studies.

scholarly journals Pediatric Integrative Medicine: Vision for the Future

Children ◽  
2018 ◽  
Vol 5 (8) ◽  
pp. 111 ◽  
Author(s):  
Anna Esparham ◽  
Sanghamitra Misra ◽  
Erica Sibinga ◽  
Timothy Culbert ◽  
Kathi Kemper ◽  
...  
Keyword(s):  
Integrative Medicine ◽  
Professional Education ◽  
Chronic Conditions ◽  
Pediatric Population ◽  
Family Education ◽  
Pediatric Care ◽  
The Past ◽  
Significant Interest ◽  
Important Time ◽  
Ecologically Sustainable

Pediatric integrative medicine (PIM) is of significant interest to patients, with 12% of the general pediatric population and up to 80% of children with chronic conditions using PIM approaches. The field of PIM has evolved over the past 25 years, approaching child health with a number of guiding principles: preventive, context-centered, relationship-based, personalized, participatory, and ecologically sustainable. This manuscript reviews important time points for the field of PIM and reports on a series of meetings of PIM leaders, aimed at assessing the state of the field and planning for its future. Efforts in the first decade of the 2000s led to increased visibility in academic and professional pediatric organizations and through international listservs, designed to link those interested in and practicing PIM, all of which continue to flourish. The PIM leadership summits in recent years resulted in specific goals to advance PIM further in the following key areas: research, clinical practice, professional education, patient and family education, and advocacy and partnerships. Additionally, goals were developed for greater expansion of PIM professional education, broader support for pediatric PIM research, and an expanded role for PIM approaches in the provision of pediatric care.

Christianity, Plurality and Vernacular Religion in early Twentieth-Century Glastonbury: A Sign of Things to Come?

2015 ◽  
Vol 51 ◽  
pp. 302-321
Author(s):  
Marion Bowman
Keyword(s):  
Twentieth Century ◽  
Considerable Heterogeneity ◽  
Individual Level ◽  
The Past ◽  
Early Twentieth Century ◽  
Vernacular Religion ◽  
Important Time ◽  
To Come ◽  
Shed Light

This essay focuses upon a significant place, Glastonbury, at an important time during the early twentieth century, in order to shed light on a particular aspect of Christianity which is frequently overlooked: its internal plurality. This is not simply denominational diversity, but the considerable heterogeneity which exists at both institutional and individual level within denominations, and which often escapes articulation, awareness or comment. This is significant because failure to apprehend a more detailed, granular picture of religion can lead to an incomplete view of events in the past and, by extension, a partial understanding of later phenomena. This essay argues that by using the concept of vernacular religion a more nuanced picture of religion as it is – or has been – lived can be achieved.

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