A sampling-adjusted macroevolutionary history for Ordovician-Early Silurian crinoids

Paleobiology ◽  
2008 ◽  
Vol 34 (1) ◽  
pp. 104-116 ◽  
Author(s):  
Shanan E. Peters ◽  
William I. Ausich
Keyword(s):  
Environmental Changes ◽  
Biotic Interactions ◽  
Middle Ordovician ◽  
Extinction Rates ◽  
Short Term Change ◽  
Term Change ◽  
Genus Richness ◽  
History Of ◽  
Stratigraphic Ranges ◽  
Fossil Preservation

Temporal variation in sampling intensity and geologically controlled rates of fossil preservation distort macroevolutionary patterns in the fossil record. Here, we use a comprehensive, list-based compilation of taxonomically and stratigraphically vetted global crinoid genus occurrences to evaluate and correct for the effects of variable and incomplete sampling from the Ordovician through Early Silurian. After standardizing the number of occurrences or the number of biofacies used to estimate the stratigraphic ranges of genera and after adjusting rates of turnover to account for the incomplete preservation of true extinction and origination pulses, we find support for several important revisions to the macroevolutionary history of crinoids. First, in contrast to the uncorrected data, sample-standardized genus richness does not appear to increase by more than 20% after an abrupt Middle Ordovician (Harnagian) diversification. Second, the only significant short-term change in genus richness following the Harnagian increase is a ≥24% decline from the Rawtheyan to the Hirnantian. Third, volatility in rates of genus extinction is increased after adjusting for preservation and there remain significant peaks of extinction in the Rawtheyan, which marks the end-Ordovician extinction, and in the middle of the Early Silurian. Finally, significant increases in origination rates occur in the Early Silurian. These results reaffirm the importance of the end-Ordovician extinction for crinoids, but they also highlight the comparatively poorly sampled Early Silurian as a time of turnover among crinoids.Crinoid genus extinction rates are positively correlated with area-weighted rates of sedimentary package truncation, suggesting that extinction may have been controlled by physical environmental changes, such as the contraction of unique epicontinental sea habitats. The lack of a correlation between genus origination and sedimentary package initiation reinforces this hypothesis and suggests that other factors, such as evolutionary innovations and biotic interactions during the Ordovician radiation, may have been more important in controlling the diversification of crinoids.

Household Economy, Long-Term Change, and Social Transformation: The Bronze Age Political Economy of Northwestern Europe

2007 ◽  
Vol 2 (2) ◽  
pp. 161-175 ◽  
Author(s):  
Kristian Kristiansen
Keyword(s):  
Bronze Age ◽  
Iron Age ◽  
Social Transformation ◽  
Environmental Changes ◽  
Term Change ◽  
History Of Vegetation ◽  
History Of ◽  
Triggering Factor ◽  
The Bronze Age

In this article I examine how long-term economic strategies in the Bronze Age of northern Europe between 2300 and 500 BCE transformed the environment and thus created and imposed new ecological constraints that finally led to a major social transformation and a "dark age" that became the start of the new long-term cycle of the Iron Age. During the last 30 years hundreds of well-excavated farmsteads and houses from south Scandinavia have made it possible to reconstruct the size and the structure of settlement and individual households through time. During the same period numerous pollen diagrams have established the history of vegetation and environmental changes. I will therefore use the size of individual households or farmsteads as a parameter of economic strength, and to this I add the role of metal as a triggering factor in the economy, especially after 1700 BCE when a full-scale bronze technology was adopted and after 500 BCE when it was replaced by iron as the dominant metal. A major theoretical concern is the relationships between micro- and macroeconomic changes and how they articulated in economic practices. Finally the nature of the "dark age" during the beginning of the Iron Age will be discussed, referring to Sing Chew's use of the concept (Chew 2006).

scholarly journals Crustacean biodiversity through the marine fossil record

2000 ◽  
Vol 69 (4) ◽  
pp. 213-222 ◽  
Author(s):  
J. John Sepkoski
Keyword(s):  
Fossil Record ◽  
Major Group ◽  
Mass Extinctions ◽  
Data Bases ◽  
Extinction Rates ◽  
Marine Crustaceans ◽  
History Of ◽  
Fossil Preservation ◽  
Fossil Records ◽  
High Diversity

Approximately 2,600 genera of marine crustaceans have been recognized in the fossil record, and crustaceans constitute the major component of marine arthropod diversity from the mid- Paleozoic to the Recent. Despite problems of sporadic fossil preservation and/or taxonomic ambiguity, some general statements can be made about the history of crustacean biodiversity, based on global taxonomic data bases. Ostracodes were the first major group to radiate, attaining high diversity during the Ordovician Period with other members of the Paleozoic evolutionary fauna; rates of extinction and responses to mass extinctions were also similar to those of groups within the Paleozoic fauna. Malacostracans and barnacles (cirripedes), the two other crustacean groups with important fossil records, had minor diversity throughout the Paleozoic Era. Both groups experienced diversification from the mid-Mesozoic to Recent with lower extinction rates, as characteristic members of the Modern evolutionary fauna.

Diversity and evolutionary rates of Cambro-Ordovician nautiloids

Paleobiology ◽  
1981 ◽  
Vol 7 (2) ◽  
pp. 216-229 ◽  
Author(s):  
Rex E. Crick
Keyword(s):  
North American ◽  
Fossil Record ◽  
Evolutionary Rates ◽  
Time Interval ◽  
Time Intervals ◽  
Frequency Distributions ◽  
Extinction Rates ◽  
History Of ◽  
Biological Aspects ◽  
Stratigraphic Ranges

The history of diversity, origination and extinction of Cambro-Ordovician nautiloid cephalopods is explored to determine if differences in evolutionary rates between nautiloid orders are sufficient to document significantly high or low rates of evolutionary turnover (taxotely of Raup and Marshall 1980). The stratigraphic ranges of 425 nautiloid genera are analyzed for this purpose.Evolutionary rates for five of the seven time intervals analyzed fall within frequency distributions of rates which are thought to be characteristic for a given time interval (horotelic distribution of Simpson 1944). Sufficient heterogeneity is present among extinction rates of Arenigian orders and origination rates of Caradocian orders to reject the null hypotheses of horotely in favor of taxotely. The orders Ellesmerocerida and Tarphycerida, each with a significantly high rate of extinction (P ≥ 0.99), and the Actinocerida, with a significantly low rate of extinction (P ≥ 0.99), were responsible for taxotely during the Arenigian. The Oncocerida and Discosorida, each with a significantly high rate of origination (P ≥ 0.99), were responsible for taxotely during the Caradocian. In each case, taxotely is attributable to the influence of North American endemics. This effect is believed to be more the result of real biological aspects of nautiloid evolution than an artifact of the fossil record.

scholarly journals Evolutionary drivers, morphological evolution and diversity dynamics of a surviving mammal clade: cainotherioids at the Eocene–Oligocene transition

2021 ◽  
Vol 288 (1952) ◽  
pp. 20210173
Author(s):  
R. Weppe ◽  
M. J. Orliac ◽  
G. Guinot ◽  
F. L. Condamine
Keyword(s):  
Environmental Changes ◽  
Morphological Evolution ◽  
Late Oligocene ◽  
Early Oligocene ◽  
Global Environmental ◽  
History Of ◽  
Extinction Events ◽  
Fossil Preservation ◽  
Global Environmental Changes ◽  
Diversity Dynamics

The Eocene–Oligocene transition (EOT) represents a period of global environmental changes particularly marked in Europe and coincides with a dramatic biotic turnover. Here, using an exceptional fossil preservation, we document and analyse the diversity dynamics of a mammal clade, Cainotherioidea (Artiodactyla), that survived the EOT and radiated rapidly immediately after. We infer their diversification history from Quercy Konzentrat–Lagerstätte (south-west France) at the species level using Bayesian birth–death models. We show that cainotherioid diversity fluctuated through time, with extinction events at the EOT and in the late Oligocene, and a major speciation burst in the early Oligocene. The latter is in line with our finding that cainotherioids had a high morphological adaptability following environmental changes throughout the EOT, which probably played a key role in the survival and evolutionary success of this clade in the aftermath. Speciation is positively associated with temperature and continental fragmentation in a time-continuous way, while extinction seems to synchronize with environmental change in a punctuated way. Within-clade interactions negatively affected the cainotherioid diversification, while inter-clade competition might explain their final decline during the late Oligocene. Our results provide a detailed dynamic picture of the evolutionary history of a mammal clade in a context of global change.

scholarly journals The Relationship between Body Mass Index and Mammographic Density during a Premenopausal Weight Loss Intervention Study

Cancers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 3245
Author(s):  
Emma C. Atakpa ◽  
Adam R. Brentnall ◽  
Susan Astley ◽  
Jack Cuzick ◽  
D. Gareth Evans ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Weight Loss ◽  
Body Mass ◽  
Breast Density ◽  
Small Sample ◽  
Weight Loss Intervention ◽  
Short Term ◽  
Dense Area ◽  
Short Term Change ◽  
Term Change

We evaluated the association between short-term change in body mass index (BMI) and breast density during a 1 year weight-loss intervention (Manchester, UK). We included 65 premenopausal women (35–45 years, ≥7 kg adult weight gain, family history of breast cancer). BMI and breast density (semi-automated area-based, automated volume-based) were measured at baseline, 1 year, and 2 years after study entry (1 year post intervention). Cross-sectional (between-women) and short-term change (within-women) associations between BMI and breast density were measured using repeated-measures correlation coefficients and multivariable linear mixed models. BMI was positively correlated with dense volume between-women (r = 0.41, 95%CI: 0.17, 0.61), but less so within-women (r = 0.08, 95%CI: −0.16, 0.28). There was little association with dense area (between-women r = −0.12, 95%CI: −0.38, 0.16; within-women r = 0.01, 95%CI: −0.24, 0.25). BMI and breast fat were positively correlated (volume: between r = 0.77, 95%CI: 0.69, 0.84, within r = 0.58, 95%CI: 0.36, 0.75; area: between r = 0.74, 95%CI: 0.63, 0.82, within r = 0.45, 95%CI: 0.23, 0.63). Multivariable models reported similar associations. Exploratory analysis suggested associations between BMI gain from 20 years and density measures (standard deviation change per +5 kg/m2 BMI: dense area: +0.61 (95%CI: 0.12, 1.09); fat volume: −0.31 (95%CI: −0.62, 0.00)). Short-term BMI change is likely to be positively associated with breast fat, but we found little association with dense tissue, although power was limited by small sample size.

scholarly journals Current understanding on the Cambrian Explosion: questions and answers

PalZ ◽  
2021 ◽  
Author(s):  
Xingliang Zhang ◽  
Degan Shu
Keyword(s):  
Environmental Changes ◽  
Size Variation ◽  
Progressive Increase ◽  
Cambrian Explosion ◽  
Time Interval ◽  
Early Cambrian ◽  
Ecological Processes ◽  
Questions And Answers ◽  
Evolutionary Event ◽  
History Of

AbstractThe Cambrian Explosion by nature is a three-phased explosion of animal body plans alongside episodic biomineralization, pulsed change of generic diversity, body size variation, and progressive increase of ecosystem complexity. The Cambrian was a time of crown groups nested by numbers of stem groups with a high-rank taxonomy of Linnaean system (classes and above). Some stem groups temporarily succeeded while others were ephemeral and underrepresented by few taxa. The high number of stem groups in the early history of animals is a major reason for morphological gaps across phyla that we see today. Most phylum-level clades achieved their maximal disparity (or morphological breadth) during the time interval close to their first appearance in the fossil record during the early Cambrian, whereas others, principally arthropods and chordates, exhibit a progressive exploration of morphospace in subsequent Phanerozoic. The overall envelope of metazoan morphospace occupation was already broad in the early Cambrian though it did not reach maximal disparity nor has diminished significantly as a consequence of extinction since the Cambrian. Intrinsic and extrinsic causes were extensively discussed but they are merely prerequisites for the Cambrian Explosion. Without the molecular evolution, there could be no Cambrian Explosion. However, the developmental system is alone insufficient to explain Cambrian Explosion. Time-equivalent environmental changes were often considered as extrinsic causes, but the time coincidence is also insufficient to establish causality. Like any other evolutionary event, it is the ecology that make the Cambrian Explosion possible though ecological processes failed to cause a burst of new body plans in the subsequent evolutionary radiations. The Cambrian Explosion is a polythetic event in natural history and manifested in many aspects. No simple, single cause can explain the entire phenomenon.

The Southern Ocean benthic fauna and climate change: a historical perspective

1992 ◽  
Vol 338 (1285) ◽  
pp. 299-309 ◽  
Keyword(s):  
Global Warming ◽  
Southern Ocean ◽  
Environmental Change ◽  
Benthic Communities ◽  
Benthic Fauna ◽  
Marine Fauna ◽  
Short Term Change ◽  
Term Change ◽  
Continental Ice Sheets

Environmental change is the norm and it is likely that, particularly on the geological timescale, the temperature regime experienced by marine organisms has never been stable. These temperature changes vary in timescale from daily, through seasonal variations, to long-term environmental change over tens of millions of years. Whereas physiological work can give information on how individual organisms may react phenotypically to short-term change, the way benthic communities react to long-term change can only be studied from the fossil record. The present benthic marine fauna of the Southern Ocean is rich and diverse, consisting of a mixture of taxa with differing evolutionary histories and biogeographical affinities, suggesting that at no time in the Cenozoic did continental ice sheets extend sufficiently to eradicate all shallow-water faunas around Antarctica at the same time. Nevertheless, certain features do suggest the operation of vicariant processes, and climatic cycles affecting distributional ranges and ice-sheet extension may both have enhanced speciation processes. The overall cooling of southern high-latitude seas since the mid-Eocene has been neither smooth nor steady. Intermittent periods of global warming and the influence of Milankovitch cyclicity is likely to have led to regular pulses of migration in and out of Antarctica. The resultant diversity pump may explain in part the high species richness of some marine taxa in the Southern Ocean. It is difficult to suggest how the existing fauna will react to present global warming. Although it is certain the fauna will change, as all faunas have done throughout evolutionary time, we cannot predict with confidence how it will do so.

scholarly journals Untargeted In Silico Compound Classification—A Novel Metabolomics Method to Assess the Chemodiversity in Bryophytes

2021 ◽  
Vol 22 (6) ◽  
pp. 3251
Author(s):  
Kristian Peters ◽  
Gerd Balcke ◽  
Niklas Kleinenkuhnen ◽  
Hendrik Treutler ◽  
Steffen Neumann
Keyword(s):  
In Silico ◽  
Structural Integrity ◽  
Environmental Changes ◽  
Light Availability ◽  
Biotic Interactions ◽  
Plant Ecology ◽  
Chemical Diversity ◽  
Classification Framework ◽  
Significant Difference ◽  
Compound Classification

In plant ecology, biochemical analyses of bryophytes and vascular plants are often conducted on dried herbarium specimen as species typically grow in distant and inaccessible locations. Here, we present an automated in silico compound classification framework to annotate metabolites using an untargeted data independent acquisition (DIA)–LC/MS–QToF-sequential windowed acquisition of all theoretical fragment ion mass spectra (SWATH) ecometabolomics analytical method. We perform a comparative investigation of the chemical diversity at the global level and the composition of metabolite families in ten different species of bryophytes using fresh samples collected on-site and dried specimen stored in a herbarium for half a year. Shannon and Pielou’s diversity indices, hierarchical clustering analysis (HCA), sparse partial least squares discriminant analysis (sPLS-DA), distance-based redundancy analysis (dbRDA), ANOVA with post-hoc Tukey honestly significant difference (HSD) test, and the Fisher’s exact test were used to determine differences in the richness and composition of metabolite families, with regard to herbarium conditions, ecological characteristics, and species. We functionally annotated metabolite families to biochemical processes related to the structural integrity of membranes and cell walls (proto-lignin, glycerophospholipids, carbohydrates), chemical defense (polyphenols, steroids), reactive oxygen species (ROS) protection (alkaloids, amino acids, flavonoids), nutrition (nitrogen- and phosphate-containing glycerophospholipids), and photosynthesis. Changes in the composition of metabolite families also explained variance related to ecological functioning like physiological adaptations of bryophytes to dry environments (proteins, peptides, flavonoids, terpenes), light availability (flavonoids, terpenes, carbohydrates), temperature (flavonoids), and biotic interactions (steroids, terpenes). The results from this study allow to construct chemical traits that can be attributed to biogeochemistry, habitat conditions, environmental changes and biotic interactions. Our classification framework accelerates the complex annotation process in metabolomics and can be used to simplify biochemical patterns. We show that compound classification is a powerful tool that allows to explore relationships in both molecular biology by “zooming in” and in ecology by “zooming out”. The insights revealed by our framework allow to construct new research hypotheses and to enable detailed follow-up studies.

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