scholarly journals A multiscale view of the Phanerozoic fossil record reveals the three major biotic transitions

2019 ◽  
Author(s):  
Alexis Rojas ◽  
Joaquin Calatayud ◽  
Michal Kowalewski ◽  
Magnus Neuman ◽  
Martin Rosvall
Keyword(s):  
Fossil Record ◽  
Large Scale ◽  
Multilayer Network ◽  
Network Representation ◽  
Empirical Estimates ◽  
Multiscale Dynamics ◽  
Ecological Changes ◽  
Extinction Event ◽  
Fossil Data

The hypothesis of the Great Evolutionary Faunas is a foundational concept of macroevolutionary research postulating that three global mega-assemblages have dominated Phanerozoic oceans following abrupt biotic transitions. Empirical estimates of this large-scale pattern depend on several methodological decisions and are based on approaches unable to capture multiscale dynamics of the underlying Earth-Life System. Combining a multilayer network representation of fossil data with a multilevel clustering that eliminates the subjectivity inherent to distance-based approaches, we demonstrate that Phanerozoic oceans sequentially harbored four global benthic mega-assemblages. Shifts in dominance patterns among these global marine mega-assemblages are abrupt (end-Cambrian 494 Ma; end-Permian 252 Ma) or protracted (mid-Cretaceous 129 Ma), and represent the three major biotic transitions in Earth’s history. This finding suggests that the mid-Cretaceous radiation of the so-called Modern evolutionary Fauna, concurrent with gradual ecological changes associated with the Mesozoic Marine Revolution, triggered a biotic transition comparably to the transition following the largest extinction event in the Phanerozoic. Overall, our study supports the notion that both long-term ecological changes and major geological events have played crucial roles in shaping mega-assemblages that dominated Phanerozoic oceans.

scholarly journals A multiscale view of the Phanerozoic fossil record reveals the three major biotic transitions

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Alexis Rojas ◽  
Joaquin Calatayud ◽  
Michał Kowalewski ◽  
Magnus Neuman ◽  
Martin Rosvall
Keyword(s):  
Fossil Record ◽  
Large Scale ◽  
Multilayer Network ◽  
Biotic Crisis ◽  
The Past ◽  
Empirical Estimates ◽  
Multiscale Dynamics ◽  
Ecological Changes ◽  
Fossil Data

AbstractThe hypothesis of the Great Evolutionary Faunas is a foundational concept of macroevolutionary research postulating that three global mega-assemblages have dominated Phanerozoic oceans following abrupt biotic transitions. Empirical estimates of this large-scale pattern depend on several methodological decisions and are based on approaches unable to capture multiscale dynamics of the underlying Earth-Life System. Combining a multilayer network representation of fossil data with a multilevel clustering that eliminates the subjectivity inherent to distance-based approaches, we demonstrate that Phanerozoic oceans sequentially harbored four global benthic mega-assemblages. Shifts in dominance patterns among these global marine mega-assemblages were abrupt (end-Cambrian 494 Ma; end-Permian 252 Ma) or protracted (mid-Cretaceous 129 Ma), and represent the three major biotic transitions in Earth’s history. Our findings suggest that gradual ecological changes associated with the Mesozoic Marine Revolution triggered a protracted biotic transition comparable in magnitude to the end-Permian transition initiated by the most severe biotic crisis of the past 500 million years. Overall, our study supports the notion that both long-term ecological changes and major geological events have played crucial roles in shaping the mega-assemblages that dominated Phanerozoic oceans.

Preservation is predictable: quantifying the effect of taphonomic biases on ecological disparity in birds

Paleobiology ◽  
2015 ◽  
Vol 41 (2) ◽  
pp. 353-367 ◽  
Author(s):  
Jonathan S. Mitchell
Keyword(s):  
Sample Size ◽  
Environmental Conditions ◽  
Fossil Record ◽  
Large Scale ◽  
Morphological Disparity ◽  
Bird Assemblages ◽  
Lacustrine Deposits ◽  
Fossil Assemblages ◽  
Fossil Data ◽  
Relative Scarcity

AbstractEvolutionary inferences from fossil data often require accurately reconstructing differences in richness and morphological disparity between fossil sites across space and time. Biases such as sampling and rock availability are commonly accounted for in large-scale studies; however, preservation bias is usually dealt with only in smaller, more focused studies. Birds represent a diverse, but taphonomically fragile, group commonly used to infer environmental conditions in recent (Pleistocene and later) fossil assemblages, and their relative scarcity in the fossil record has led to controversy over the timing of their radiation. Here, I use simulations to show how even weak taphonomic biases can distort estimates of richness, and render variance sensitive to sample size. I then apply an ecology-based filtering model to recent bird assemblages to quantify the distortion induced by taphonomy. Certain deposit types, such as caves, show less evidence of taphonomic distortion than others, such as fluvial and lacustrine deposits. Archaeological middens unsurprisingly show some of the strongest evidence for taphonomic bias, and they should be avoided when reconstructing Pleistocene and early Holocene environments. Further, these results support previously suggested methods for detecting fossil assemblages that are relatively faithfully preserved (e.g., presence of difficult-to-preserve taxa), and I use these results to recommend that future large-scale studies include facies diversity along with metrics such as rock volume, or compare only sites with similar taphonomic histories.

scholarly journals Survey of the terrestrial habitats and vegetation of Shetland, 1974 – a framework for long-term ecological monitoring

2016 ◽  
Vol 8 (1) ◽  
pp. 89-103 ◽  
Author(s):  
Claire M. Wood ◽  
Robert G. H. Bunce
Keyword(s):  
Natural Environment ◽  
Large Scale ◽  
Oil Industry ◽  
Ecological Monitoring ◽  
Robust Methods ◽  
Ecological Changes ◽  
Terrestrial Habitats ◽  
Environmental Monitoring Programme

Abstract. A survey of the natural environment was undertaken in Shetland in 1974, after concern was expressed that large-scale development from the new oil industry could threaten the natural features of the islands. A framework was constructed by the Institute of Terrestrial Ecology on which to select samples for the survey. The vegetation and habitat data that were collected, along with the sampling framework, have recently been made public via the following doi:10.5285/06fc0b8c-cc4a-4ea8-b4be-f8bd7ee25342 (Terrestrial habitat, vegetation and soil data from Shetland, 1974) and doi:10.5285/f1b3179e-b446-473d-a5fb-4166668da146 (Land Classification of Shetland 1974). In addition to providing valuable information about the state of the natural environment of Shetland, the repeatable and statistically robust methods developed in the survey were used to underpin the Countryside Survey, Great Britain's national long-term integrated environmental monitoring programme. The demonstration of the effectiveness of the methodology indicates that a repeat of the Shetland survey would yield statistics about ecological changes in the islands, such as those arising from the impacts of the oil industry, a range of socio-economic impacts, and perhaps climate change. Currently no such figures are available, although there is much information on the sociological impacts, as well as changes in agriculture.

scholarly journals Survey of the terrestrial habitats and vegetation of Shetland, 1974 – a framework for long term ecological monitoring

2015 ◽  
Vol 8 (2) ◽  
pp. 827-857
Author(s):  
C. M. Wood ◽  
R. G. H. Bunce
Keyword(s):  
Natural Environment ◽  
Large Scale ◽  
Oil Industry ◽  
Ecological Monitoring ◽  
Robust Methods ◽  
Ecological Changes ◽  
Terrestrial Habitats ◽  
Environmental Monitoring Programme

Abstract. A survey of the natural environment was undertaken in Shetland in 1974, after concern was expressed that large scale development from the new oil industry could threaten the natural features of the islands. A framework was constructed by the Institute of Terrestrial Ecology on which to select samples for the survey. The vegetation and habitat data that were collected, along with the sampling framework, have recently been made public via the following DOIs: doi:10.5285/06fc0b8c-cc4a-4ea8-b4be-f8bd7ee25342 (Terrestrial habitat, vegetation and soil data from Shetland, 1974) and doi:10.5285/f1b3179e-b446-473d-a5fb-4166668da146 (Land Classification of Shetland 1974). In addition to providing valuable information about the state of the natural environment of Shetland, the repeatable and statistically robust methods developed in the survey were used to underpin the Countryside Survey, Great Britain's national long-term integrated environmental monitoring programme. The demonstration of the effectiveness of the methodology indicates that a repeat of the survey would yield statistics about ecological changes in the islands, such as those arising from the impacts of the oil industry. Currently no such figures are available although there is much information on the sociological impacts, as well as changes in agriculture.

scholarly journals The non-uniformity of fossil preservation

2016 ◽  
Vol 371 (1699) ◽  
pp. 20150130 ◽  
Author(s):  
Steven M. Holland
Keyword(s):  
Fossil Record ◽  
Primary Source ◽  
Sedimentary Basins ◽  
Probabilistic Methods ◽  
Depositional Facies ◽  
Empirical Estimates ◽  
Low Probability ◽  
Fossil Preservation ◽  
Long Timescales

The fossil record provides the primary source of data for calibrating the origin of clades. Although minimum ages of clades are given by the oldest preserved fossil, these underestimate the true age, which must be bracketed by probabilistic methods based on multiple fossil occurrences. Although most of these methods assume uniform preservation rates, this assumption is unsupported over geological timescales. On geologically long timescales (more than 10 Myr), the origin and cessation of sedimentary basins, and long-term variations in tectonic subsidence, eustatic sea level and sedimentation rate control the availability of depositional facies that preserve the environments in which species lived. The loss of doomed sediments, those with a low probability of preservation, imparts a secular trend to fossil preservation. As a result, the fossil record is spatially and temporally non-uniform. Models of fossil preservation should reflect this non-uniformity by using empirical estimates of fossil preservation that are spatially and temporally partitioned, or by using indirect proxies of fossil preservation. Geologically, realistic models of preservation will provide substantially more reliable estimates of the origination of clades. This article is part of the themed issue ‘Dating species divergences using rocks and clocks’.

scholarly journals Triumph of the Commons: Sustainable Community Practices on Rapa Nui (Easter Island)

2021 ◽  
Vol 13 (21) ◽  
pp. 12118
Author(s):  
Robert J. DiNapoli ◽  
Carl P. Lipo ◽  
Terry L. Hunt
Keyword(s):  
Large Scale ◽  
18Th Century ◽  
Tragedy Of The Commons ◽  
Easter Island ◽  
Rapa Nui ◽  
Ecological Changes ◽  
History Of ◽  
The Commons ◽  
Past Land Use

The history of Rapa Nui (Easter Island) has long been framed as a parable for how societies can fail catastrophically due to the selfish actions of individuals and a failure to wisely manage common-pool resources. While originating in the interpretations made by 18th-century visitors to the island, 20th-century scholars recast this narrative as a “tragedy of the commons,” assuming that past populations were unsustainable and selfishly overexploited the limited resources on the island. This narrative, however, is now at odds with a range of archaeological, ethnohistoric, and environmental evidence. Here, we argue that while Rapa Nui did experience large-scale deforestation and ecological changes, these must be contextualized given past land-use practices on the island. We provide a synthesis of this evidence, showing that Rapa Nui populations were sustainable and avoided a tragedy of the commons through a variety of community practices. We discuss this evidence in the context of Elinor Ostrom’s “core design principles” for sustainable communities and argue that Rapa Nui provides a model for long-term sustainability.

Summary

2003 ◽  
Author(s):  
M. E. J. Newman ◽  
R. G. Palmer
Keyword(s):  
Critical Point ◽  
Power Law ◽  
Fossil Record ◽  
Large Scale ◽  
Extinction Rate ◽  
Mass Extinctions ◽  
Power Law Distribution ◽  
Scale Free ◽  
Extinction Events ◽  
Fossil Data

In this book we have studied a large number of recent quantitative models aimed at explaining a variety of large-scale trends seen in the fossil record. These trends include the occurrence of mass extinctions, the distribution of the sizes of extinction events, the distribution of the lifetimes of taxa, the distribution of the numbers of species per genus, and the apparent decline in the average extinction rate. None of the models presented match all the fossil data perfectly, but all of them offer some suggestion of possible mechanisms which may be important to the processes of extinction and origination. In this chapter we conclude our review by briefly summarizing the properties and predictions of each of the models once more. Much of the interest in these models has focused on their ability (or lack of ability) to predict the observed values of exponents governing distributions of a number of quantities. In Table 7.1 we summarize the values of these exponents for each of the models. Most of the models we have described attempt to provide possible explanations for a few specific observations. (1) The fossil record appears to have a power-law (i.e., scale-free) distribution of the sizes of extinction events, with an exponent close to 2 (section 1.2.2.1). (2) The distribution of the lifetimes of genera also appears to follow a power law, with exponent about 1.7 (section 1.2.2.4). (3) The number of species per genus appears to follow a power law with exponent about 1.5 (section 1.2.3.1). One of the first models to attempt an explanation of these observations was the NK model of Kauffman and co-workers. In this model, extinction is driven by revolutionary avalanches. When tuned to the critical point between chaotic and frozen regimes, the model displays a power-law distribution of avalanche sizes with an exponent of about 1. It has been suggested that this could in turn lead to a power-law distribution of the sizes of extinction events, although the value of 1 for the exponent is not in agreement with the value 2 measured in the fossil extinction record.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

Sign in / Sign up

Export Citation Format

Share Document