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.

Fossil preservation and the stratigraphic ranges of taxa

Paleobiology ◽  
1996 ◽  
Vol 22 (2) ◽  
pp. 121-140 ◽  
Author(s):  
Mike Foote ◽  
David M. Raup
Keyword(s):  
Fossil Record ◽  
Mammalian Species ◽  
Evolutionary Rates ◽  
Extinction Rate ◽  
Mammal Species ◽  
Original Distribution ◽  
Lower Ordovician ◽  
Stratigraphic Ranges ◽  
Fossil Preservation ◽  
Rule Out

The incompleteness of the fossil record hinders the inference of evolutionary rates and patterns. Here, we derive relationships among true taxonomic durations, preservation probability, and observed taxonomic ranges. We use these relationships to estimate original distributions of taxonomic durations, preservation probability, and completeness (proportion of taxa preserved), given only the observed ranges. No data on occurrences within the ranges of taxa are required. When preservation is random and the original distribution of durations is exponential, the inference of durations, preservability, and completeness is exact. However, reasonable approximations are possible given non-exponential duration distributions and temporal and taxonomic variation in preservability. Thus, the approaches we describe have great potential in studies of taphonomy, evolutionary rates and patterns, and genealogy.Analyses of Upper Cambrian-Lower Ordovician trilobite species, Paleozoic crinoid genera, Jurassic bivalve species, and Cenozoic mammal species yield the following results: (1) The preservation probability inferred from stratigraphic ranges alone agrees with that inferred from the analysis of stratigraphic gaps when data on the latter are available. (2) Whereas median durations based on simple tabulations of observed ranges are biased by stratigraphic resolution, our estimates of median duration, extinction rate, and completeness are not biased. (3) The shorter geologic ranges of mammalian species relative to those of bivalves cannot be attributed to a difference in preservation potential. However, we cannot rule out the contribution of taxonomic practice to this difference. (4) In the groups studied, completeness (proportion of species [trilobites, bivalves, mammals] or genera [crinoids] preserved) ranges from 60% to 90%. The higher estimates of completeness at smaller geographic scales support previous suggestions that the incompleteness of the fossil record reflects loss of fossiliferous rock more than failure of species to enter the fossil record in the first place.

3. Extinction in the past

2019 ◽  
pp. 33-50
Author(s):  
Paul B. Wignall
Keyword(s):  
Fossil Record ◽  
The Past ◽  
Extinction Rates ◽  
History Of ◽  
Extinction Events

Despite the less-than-perfect nature of the fossil record, it still provides a unique window on the history of life, and reveals that there have been dramatic fluctuations in extinction intensities since complex life evolved around 600 million years ago. ‘Extinction in the past’ considers Jack Sepkoski’s database compiled in the 1980s, and his series of highly informative charts showing both diversity and extinction rates since the start of the Cambrian Period 541 million years ago. The calculation of extinction rates and the improved dating of extinction events are discussed, along with the extinction trends that can be observed. Fossils also provide valuable evidence on the nature of selection during extinction.

Evolution and the fossil record: patterns, rates, and processes

1987 ◽  
Vol 65 (5) ◽  
pp. 1053-1060 ◽  
Author(s):  
Philip D. Gingerich
Keyword(s):  
Fossil Record ◽  
Evolutionary Rates ◽  
Short Intervals ◽  
Evolutionary Diversification ◽  
Extinction Rates ◽  
Local Areas ◽  
Climatic Cooling ◽  
Intensive Sampling ◽  
Underlying Processes ◽  
Morphological Innovation

Mammals have an unusually good Cenozoic fossil record providing evidence of their evolutionary diversification. We view this record in hindsight, which biases our perception in many ways. Overall worldwide diversity appears to increase exponentially through time, while intensive sampling in local areas indicates that modern levels of diversity were achieved early in the Cenozoic. The evident significance of Pleistocene extinctions depends critically on how extinction rates are quantified. Our taxonomic hierarchy probably reflects the number of major faunal turnovers a group has survived rather than declining intensity of successive turnovers. Morphological innovation and taxonomic diversification appear following intervals of climatic cooling, suggesting that major features of evolution are extrinsically controlled. Favorable stratigraphic settings yield detailed records of gradual anagenesis and cladogenesis in mammals, with intermediates present as evidence of transition. The apparent dichotomy between high evolutionary rates measured by neontologists over short intervals of time and low evolutionary rates measured by paleontologists over long intervals of time disappears when rates are measured on intermediate scales of time. Microevolution and macroevolution are manifestations of common underlying processes expressed on different time scales.

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.

A kill curve for Phanerozoic marine species

Paleobiology ◽  
1991 ◽  
Vol 17 (1) ◽  
pp. 37-48 ◽  
Author(s):  
David M. Raup
Keyword(s):  
Fossil Record ◽  
Marine Species ◽  
Low Risk ◽  
Extinction Rate ◽  
Time Intervals ◽  
Typical Species ◽  
Risk Of Extinction ◽  
The Mean ◽  
Stratigraphic Ranges ◽  
Kill Curve

A kill curve for Phanerozoic species is developed from an analysis of the stratigraphic ranges of 17,621 genera, as compiled by Sepkoski. The kill curve shows that a typical species' risk of extinction varies greatly, with most time intervals being characterized by very low risk. The mean extinction rate of 0.25/m.y. is thus a mixture of long periods of negligible extinction and occasional pulses of much higher rate. Because the kill curve is merely a description of the fossil record, it does not speak directly to the causes of extinction. The kill curve may be useful, however, to limit choices of extinction mechanisms.

scholarly journals Vaccination-infection interval determines cross-neutralization potency to SARS-CoV-2 Omicron after breakthrough infection by other variants

2022 ◽  
Author(s):  
Sho Miyamoto ◽  
Takeshi Arashiro ◽  
Yu Adachi ◽  
Saya Moriyama ◽  
Hitomi Kinoshita ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Protective Immunity ◽  
Time Interval ◽  
Multiple Time ◽  
Breakthrough Infection ◽  
Time Intervals ◽  
Population Immunity ◽  
History Of ◽  
Cross Neutralization ◽  
Resistance To Infection

Background The immune profile against SARS-CoV-2 has dramatically diversified due to a complex combination of exposure to vaccines and infection by various lineages/variants, likely generating a heterogeneity in protective immunity in a given population. To further complicate this, the Omicron variant, with numerous spike mutations, has emerged. These circumstances have created the need to assess the potential of immune evasion by the Omicron in individuals with various immune histories. Methods The neutralization susceptibility of the variants including the Omicron and their ancestor was comparably assessed using a panel of plasma/serum derived from individuals with divergent immune histories. Blood samples were collected from either mRNA vaccinees or from those who suffered from breakthrough infections by the Alpha/Delta with multiple time intervals following vaccination. Findings The Omicron was highly resistant to neutralization in fully vaccinated individuals without a history of breakthrough infections. In contrast, robust cross-neutralization against the Omicron were induced in vaccinees that experienced breakthrough infections. The time interval between vaccination and infection, rather than the variant types of infection, was significantly correlated with the magnitude and potency of Omicron-neutralizing antibodies. Conclusions Immune histories with breakthrough infections can overcome the resistance to infection by the Omicron, with the vaccination-infection interval being the key determinant of the magnitude and breadth of neutralization. The diverse exposure history in each individual warrants a tailored and cautious approach to understanding population immunity against the Omicron and future variants. Funding This study was supported by grants from the Japan Agency for Medical Research and Development (AMED).

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.

Survivorship analysis of Paleozoic Crinoidea: effect of filter morphology on evolutionary rates

Paleobiology ◽  
1993 ◽  
Vol 19 (3) ◽  
pp. 304-321 ◽  
Author(s):  
Tomasz K. Baumiller
Keyword(s):  
Evolutionary Rates ◽  
Survivorship Analysis ◽  
Extinction Rates ◽  
Fine Mesh ◽  
Coarse Filter ◽  
Fine Filter ◽  
Budget Equation ◽  
Stratigraphic Ranges ◽  
Particulate Nutrients ◽  
Ecological Differences

The evolutionary rates of Paleozoic Crinoidea were obtained using dynamic survivorship analysis. The stratigraphic ranges of 838 genera were used in the analyses, revealing a mean generic duration of 12.0 m.y. and a mean species duration of 6.7 m.y., values within the range of longevities reported for other taxa.Further analyses showed differences in evolutionary rates among crinoid taxa: camerate species and genera were shorter-lived than species and genera of flexibles and inadunates. This pattern may result from ecological differences among these taxa: an energy budget equation solved for crinoids with various filter morphologies revealed that crinoids with fine-mesh filters require higher current velocities to supply them with sufficient particulate nutrients than do crinoids with coarse-mesh filters. A hypothesis stipulating that these differences control the distribution of crinoids among different environments is supported by patterns of occurrence of Mississippian crinoids: the pinnulate camerates (fine filter) dominate higher energy settings while the non-pinnulate inadunates and flexibles (coarse filter) are found in all environments. The “specialized” pinnulate crinoids may therefore be more prone to speciation and extinction than the non-pinnulate “generalists,” thus accounting for the observed differences in the evolutionary rates of the three subclasses.The above hypothesis was tested by comparing evolutionary rates of two morphological groups: fine-filtered crinoids (camerates) and coarse-filtered crinoids (non-pinnulate Paleozoic crinoids). As predicted, fine-filtered taxa had higher extinction and origination rates. A “bootstrapping” technique revealed that the differences in extinction rates were significant at the p < 0.10 level.

scholarly journals The Appropriateness of Surveillance Colonoscopy Intervals after Polypectomy

2013 ◽  
Vol 27 (1) ◽  
pp. 33-38 ◽  
Author(s):  
Eline Schreuders ◽  
Jerome Sint Nicolaas ◽  
Vincent de Jonge ◽  
Harmke van Kooten ◽  
Isaac Soo ◽  
...  
Keyword(s):  
Time Interval ◽  
Surveillance Colonoscopy ◽  
Time Intervals ◽  
Detection Rates ◽  
Median Difference ◽  
Adenoma Detection ◽  
Significant Difference ◽  
Surveillance Interval ◽  
History Of ◽  
Adenoma Detection Rates

BACKGROUND: Adherence to surveillance colonoscopy guidelines is important to prevent colorectal cancer (CRC) and unnecessary workload.OBJECTIVE: To evaluate how well Canadian gastroenterologists adhere to colonoscopy surveillance guidelines after adenoma removal or treatment for CRC.METHODS: Patients with a history of adenomas or CRC who had surveillance performed between October 2008 and October 2010 were retrospectively included. Time intervals between index colonoscopy and surveillance were compared with the 2008 guideline recommendations of the American Gastroenterological Association and regarded as appropriate when the surveillance interval was within six months of the recommended time interval.RESULTS: A total of 265 patients were included (52% men; mean age 58 years). Among patients with a normal index colonoscopy (n=110), 42% received surveillance on time, 38% too early (median difference = 1.2 years too early) and 20% too late (median difference = 1.0 year too late). Among patients with nonadvanced adenomas at index (n=96), 25% underwent surveillance on time, 61% too early (median difference = 1.85) and 14% too late (median difference = 1.1). Among patients with advanced neoplasia at index (n=59), 29% underwent surveillance on time, 34% too early (median difference = 1.86) and 37% later than recommended (median difference = 1.61). No significant difference in adenoma detection rates was observed when too early surveillance versus appropriate surveillance (34% versus 33%; P=0.92) and too late surveillance versus appropriate surveillance (21% versus 33%; P=0.11) were compared.CONCLUSION: Only a minority of surveillance colonoscopies were performed according to guideline recommendations. Deviation from the guidelines did not improve the adenoma detection rate. Interventions aimed at improving adherence to surveillance guidelines are needed.

scholarly journals Biological aspects and life table of Uroleucon ambrosiae (Thomas, 1878) as a function of temperature

2003 ◽  
Vol 60 (4) ◽  
pp. 657-662 ◽  
Author(s):  
Alexander Machado Auad ◽  
Jair Campos de Moraes
Keyword(s):  
Intrinsic Rate ◽  
Reproductive Rate ◽  
The Other ◽  
Population Increase ◽  
Time Interval ◽  
Net Reproductive Rate ◽  
Different Temperatures ◽  
History Of ◽  
Biological Aspects ◽  
Similar Development

The aphid Uroleucon ambrosiae (Thomas) is considered a pest of hidroponically-grown lettuce, but basic and applied information on its control are scarce in Brazil. The aim of this study was to determine the effect of different temperatures on biological aspects and life history of U. ambrosiae (Thomas) developing on hydroponic lettuce (Lactuca sativa L.) crop. Newly emerged nymphs were placed on 4-cm discs of hydroponic lettuce, var. Verônica, which were maintained on 5-cm Petri dishes, at temperatures of 15, 20 and 25ºC and 14 h photophase, and inside a greenhouse, within micro-cages at room temperature. The duration of development in all nymphal stages varied inversely to temperature. Nymphs maintained at 20ºC and 25ºC, had similar development period. However, at fluctuating greenhouse temperatures (daily mean = 21ºC), different results were obtained, which was also true for the pre-reproductive, reproductive and post-reproductive periods. Daily and total fertilities at 20ºC were better in comparison to the other treatments. The highest mortality rate of aphids occurred under greenhouse conditions. The production of 1.28 nymphs per female per day, the time needed for the population to double in size (TD=2.77days), and the intrinsic rate of population increase (r m=0.25), were similar for in insects maintained at 20 and 25ºC. On the other hand, time interval between generations (T) and the net reproductive rate (Ro) were higher at 20ºC. In the greenhouse, even though T was similar to laboratory conditions at 20 and 25ºC, the R0, r m and l parameters were lower and TD was higher. Based on biological aspects, fertility and life expectancy tables, constant temperature of 20ºC is the most suitable for U. ambrosiae.

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