A more precise speciation and extinction rate estimator

Paleobiology ◽  
2015 ◽  
Vol 41 (4) ◽  
pp. 633-639 ◽  
Author(s):  
John Alroy
Keyword(s):  
Turnover Rate ◽  
Marine Invertebrate ◽  
Time Interval ◽  
Extinction Rate ◽  
Turnover Rates ◽  
Sample Sizes ◽  
Extinction Rates ◽  
Highly Correlated ◽  
The One

AbstractA new turnover rate metric is introduced that combines simplicity and precision. Like the related three-timer and gap-filler equations, it involves first identifying a cohort of taxa sampled in the time interval preceding the one of interest (call the intervalsi0andi1). Taxa sampled ini0andi1are two-timers (t2); those sampled ini0andi2but noti1are part-timers (p); and taxa sampled only in eitheri1,i2, ori3are newly notated here as eithers1,s2, ors3. The gap-filler extinction proportion can be reformulated as (s1−s3)/(t2+p). The method proposed here is to substitutes3with the second-highest of the three counts when the expected orderings1≥s2≥s3is violated. In simulation, this new estimator yields values that are highly correlated with those produced by the gap-filler equation but more precise. In particular, it rarely produces highly negative values even when sample sizes are quite small. It is mildly upwards biased when sampling is extremely poor and turnover rates are extremely low, but it is otherwise highly accurate. Examples of Phanerozoic extinction rates for four major marine invertebrate groups are given to illustrate the method’s improved precision. Based on the results, the procedure is recommended for general use.

Turnover in Breeding Bird Populations on Rottnest I. Western Australia

1985 ◽  
Vol 12 (3) ◽  
pp. 467 ◽  
Author(s):  
DA Saunders ◽  
Rebeira CP de
Keyword(s):  
Turnover Rate ◽  
Marine Species ◽  
Breeding Population ◽  
Extinction Rate ◽  
Turnover Rates ◽  
Breeding Bird ◽  
Bird Populations ◽  
Breeding Populations ◽  
The Right ◽  
Do So

The avifauna of Rottnest Island, W.A., has been surveyed four times between 1904 and 1983: by Lawson in 1904, Glauert (1928), Storr between 1953 and 1962, and ourselves between 1981 and 1983. There were three recorded extinctions and 10 immigrations in the 79-year period, but none of the extinctions and only three of the immigrations could be regarded as valid for calculating natural turnover rates. The remainder had been influenced by human activity; therefore the avifauna extinction rate for Rottnest Island was 0, the immigration rate was 0.04% per year for non-marine species of bird and the relative turnover rate for the 79 years was 0.12% per year. These results for Rottnest I. support the view of Abbott (1978, 1980) that for Australian islands, immigrations and extinctions are infrequent and turnover of breeding species is also infrequent. There have been 109 sightings of vagrants recorded for the island between 1905 and 1983; only one of these had individuals present in sufficient numbers during the breeding season to establish a breeding population. The data show that for one Australian island natural extinctions of both passerines and non-passerines are rare. Water does act as a barrier and although birds do cross water and often appear as vagrants, they very rarely do so in sufficient numbers or at the right time to establish breeding populations.

scholarly journals Diatoms diversify and turn over faster in freshwater than marine environments

2018 ◽  
Author(s):  
Teofil Nakov ◽  
Jeremy Michael Beaulieu ◽  
Andrew James Alverson
Keyword(s):  
Turnover Rate ◽  
Turnover Rates ◽  
High Turnover ◽  
Diversification Rates ◽  
Extinction Rates ◽  
State Dependent ◽  
Freshwater Diatoms ◽  
Marine Realm ◽  
Turn Over ◽  
Freshwater Environments

AbstractMany clades that span the marine-freshwater boundary are disproportionately more diverse in the younger, shorter-lived, and scarcer freshwater environments than they are in the marine realm. This disparity is thought to be related to differences in diversification rates between marine and freshwater lineages. However, marine and freshwaters are not ecologically homogeneous, so the study of diversification across the salinity divide should also account for other potentially interacting variables. In diatoms, freshwater and substrate-associated (benthic) lineages are several-fold more diverse than their marine and suspended (planktonic) counterparts. These imbalances provide an excellent system to understand whether these variables interact with diversification. Using multistate hidden-state speciation and extinction models we found that freshwater lineages diversify faster than marine lineages regardless of whether they inhabit the plankton or the benthos. Freshwater lineages also had higher turnover rates (speciation + extinction), suggesting that habitat transitions impact speciation and extinction rates jointly. The plankton-benthos contrast was also consistent with state-dependent diversification, but with modest differences in diversification and turnover rates. Asymmetric, and bidirectional transitions rejected hypotheses about the plankton and freshwaters as absorbing, inescapable habitats. Our results further suggest that the high turnover rate of freshwater diatoms is related to high turnover of freshwater systems themselves.

On the declining extinction and origination rates of fossil taxa

Paleobiology ◽  
1992 ◽  
Vol 18 (1) ◽  
pp. 89-92 ◽  
Author(s):  
Craig M. Pease
Keyword(s):  
Present Model ◽  
Marine Invertebrate ◽  
Extinction Rate ◽  
Geologic Time ◽  
The Past ◽  
Extinction Rates ◽  
Rate Versus ◽  
Biological Explanation ◽  
Length Changes ◽  
Sampling Biases

The per-stage extinction rate is the product of the per-taxon extinction rate and stage length, and the per-stage origination rate is defined similarly. These rates decline from ancient to recent times because of the pull of the Recent, because there is more young than old fossiliferous rock, and because average stage length increases from the recent to the past. More specifically, the present model assumes that the graphs of ln(per-stage extinction rate) and ln(per-stage origination rate) versus geologic time have slope zero in the absence of sampling biases, and shows how sampling biases cause both these graphs to appear to have slope min(h,q) + s in the distant past, where h and q are the fossil loss and actual per-taxon extinction rates, and the stratigraphic constant, s, quantifies how stage length changes through time.Although the per-stage rates of bivalve families and marine invertebrate genera decline toward the recent, the magnitudes of these declines are entirely consistent with what the present model predicts sampling biases will produce. Hence there is no need to postulate a biological explanation for these patterns.

scholarly journals Adjusting global extinction rates to account for taxonomic susceptibility

Paleobiology ◽  
2008 ◽  
Vol 34 (4) ◽  
pp. 434-455 ◽  
Author(s):  
Steve C. Wang ◽  
Andrew M. Bush
Keyword(s):  
Inverse Correlation ◽  
Volcanic Eruptions ◽  
Time Interval ◽  
Extinction Rate ◽  
Mass Extinctions ◽  
Sea Level Changes ◽  
Marine Fauna ◽  
Extinction Rates ◽  
Global Extinction ◽  
Taxonomic Groups

Studies of extinction in the fossil record commonly involve comparisons of taxonomic extinction rates, often expressed as the percentage of taxa (e.g., families or genera) going extinct in a time interval. Such extinction rates may be influenced by factors that do not reflect the intrinsic severity of an extinction trigger. Two identical triggering events (e.g., bolide impacts, sea level changes, volcanic eruptions) could lead to different taxonomic extinction rates depending on factors specific to the time interval in which they occur, such as the susceptibility of the fauna or flora to extinction, the stability of food webs, the positions of the continents, and so on. Thus, it is possible for an extinction event with a higher taxonomic extinction rate to be caused by an intrinsically less severe trigger, compared to an event with a lower taxonomic extinction rate.Here, we isolate the effects of taxonomic susceptibility on extinction rates. Specifically, we quantify the extent to which the taxonomic extinction rate in a substage is elevated or depressed by the vulnerability to extinction of classes extant in that substage. Using a logistic regression model, we estimate that the taxonomic susceptibility of marine fauna to extinction has generally declined through the Phanerozoic, and we adjust the observed extinction rate in each substage to estimate the intrinsic extinction severity more accurately. We find that mass extinctions do not generally occur during intervals of unusually high susceptibility, although susceptibility sometimes increases in post-extinction recovery intervals. Furthermore, the susceptibility of specific animal classes to extinction is generally similar in times of background and mass extinction, providing no evidence for differing regimes of extinction selectivity. Finally, we find an inverse correlation between extinction rate within substages and the evenness of diversity of major taxonomic groups, but further analyses indicate that low evenness itself does not cause high rates of extinction.

scholarly journals Current extinction rate in European freshwater gastropods greatly exceeds that of the late Cretaceous mass extinction

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Thomas A. Neubauer ◽  
Torsten Hauffe ◽  
Daniele Silvestro ◽  
Jens Schauer ◽  
Dietrich Kadolsky ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Recovery Period ◽  
Freshwater Ecosystems ◽  
Extinction Rate ◽  
Freshwater Gastropods ◽  
Extinction Rates ◽  
Freshwater Biota ◽  
Order Of Magnitude ◽  
To Come ◽  
Mass Extinction Event

AbstractThe Cretaceous–Paleogene mass extinction event 66 million years ago eradicated three quarters of marine and terrestrial species globally. However, previous studies based on vertebrates suggest that freshwater biota were much less affected. Here we assemble a time series of European freshwater gastropod species occurrences and inferred extinction rates covering the past 200 million years. We find that extinction rates increased by more than one order of magnitude during the Cretaceous–Paleogene mass extinction, which resulted in the extinction of 92.5% of all species. The extinction phase lasted 5.4 million years and was followed by a recovery period of 6.9 million years. However, present extinction rates in European freshwater gastropods are three orders of magnitude higher than even these revised estimates for the Cretaceous–Paleogene mass extinction. Our results indicate that, unless substantial conservation effort is directed to freshwater ecosystems, the present extinction crisis will have a severe impact to freshwater biota for millions of years to come.

The determination of the specific activity of plasma glycerol

1982 ◽  
Vol 60 (6) ◽  
pp. 856-858 ◽  
Author(s):  
Clément Gauthier ◽  
Ross Layberry
Keyword(s):  
Column Chromatography ◽  
Turnover Rate ◽  
Specific Activity ◽  
Anionic Exchange ◽  
Removal Of Contaminants ◽  
The One ◽  
Exchange Resins

A method for the determination of the specific activity of plasma glycerol is described. Anionic contaminants are first removed from deproteinized plasma by anionic exchange resins (treated plasma). Glycerol in treated plasma is then quantitatively converted to glycerol-3-phosphate (G3P), which is isolated by column chromatography and counted for 14C radioactivity. The specific activity thus calculated was 100.1 ± 2.9% of a standard of known specific activity. When the specific-activity of glycerol is determined from plasma without prior removal of anionic contaminants (untreated plasma), the calculated specific activity is 1.99 ± 0.15 times higher than the one calculated after their removal. Omission of the removal of contaminants leads to a near 100% error in the calculation of the turnover rate of glycerol.not available

AN EVALUATION OF THE RELATIONSHIPS BETWEEN DIETARY PARAMETERS AND RUMEN LIQUID TURNOVER RATE

1981 ◽  
Vol 61 (1) ◽  
pp. 91-96 ◽  
Author(s):  
ESSI EVANS
Keyword(s):  
Feed Intake ◽  
Turnover Rate ◽  
Energy Content ◽  
Energy Concentration ◽  
Dietary Energy ◽  
Regression Analyses ◽  
Turnover Rates ◽  
Independent Variables ◽  
Independent Variable ◽  
Ration Composition

Data were accumulated from published sources and were combined in order to estimate the effects of level of feed intake, dietary energy concentration, energy intake level and dietary forage percentage on rumen liquid turnover rates in sheep and cattle. The effects of the dietary parameters on liquid turnover rates were estimated by regression analysis, where all possible combinations of independent variables were considered. It was found that rumen liquid turnover rates increased (P < 0.05) as feed intake increased with both sheep (r = 0.610) and cattle (r = 0.715). From multiple regression analyses it was learned that the inclusion of independent variables that were related to the physical composition of the diet along with variables for intake improved the estimation of liquid turnover rates, although the independent variable related to ration composition differed between sheep and cattle. With data from sheep experiments, elevations in the digestible energy content of the diet depressed (P < 0.05) liquid turnover rate. Based upon data from cattle, decreases in the forage portion of the diet had a similar depressing (P < 0.05) effect.

scholarly journals Paleoenvironmental and paleobiological origins of coccolithophorid genusWatznaueriaemergence during the late Aalenian–early Bajocian

Paleobiology ◽  
2015 ◽  
Vol 41 (3) ◽  
pp. 415-435 ◽  
Author(s):  
Baptiste Suchéras-Marx ◽  
Emanuela Mattioli ◽  
Fabienne Giraud ◽  
Gilles Escarguel
Keyword(s):  
Marine Invertebrate ◽  
Time Interval ◽  
Calcareous Nannofossils ◽  
Calcareous Nannoplankton ◽  
Absolute Abundance ◽  
The Pacific ◽  
Relative Abundances ◽  
The Absolute ◽  
Oceanic Plates ◽  
Central Atlantic

AbstractThe latest Aalenian–early Bajocian time interval (ca. 171-169 Ma) is marked by a global reorganization of oceanic plates with the Central Atlantic opening and the formation of the Pacific plate. This time interval is also marked by a global geochemical perturbation of δ13C with a negative excursion at the Aalenian/Bajocian boundary and a positive excursion during the early Bajocian. Evolutionary diversifications of marine invertebrate taxa, namely ammonites, radiolarians, and coccolithophorids, are recorded at that time. Concerning coccolithophorids, this interval witnesses the diversification and expansion of the most successful Mesozoic genus:Watznaueria. In this study, we explore the potential environmental, ecological, and biological forcing at the origin ofWatznaueriadiversification and its effect on the coccolith assemblages through quantification of the absolute and relative abundances of calcareous nannofossils in two Middle Jurassic key sections: Cabo Mondego (Portugal) and Chaudon-Norante (France). In both sections, we find an increase in nannofossil absolute abundance and flux at the beginning of the lower Bajocian, coeval with an increase in absolute and relative abundances ofWatznaueriaspp., followed by a plateau in the middle and upper part of the lower Bajocian. The increase ofWatznaueriaspp. is synchronous with a decrease in relative abundance of other major coccolith taxa, whereas the absolute abundance of these species did not decrease. During the climatically driven early Bajocian eutrophication event,Watznaueriaspp. integrated into the calcareous nannoplankton community in two successive evolutionary steps involving firstW. contractaandW. colaccicchii, and secondW. britannicaandW.aff.manivitiae. Step 1 was driven by an increase in niche carrying capacities linked to the early Bajocian eutrophication. Step 2 was driven by specific adaptation of the newly evolvedWatznaueriaspecies to bloom in nutrient-rich environments not exploited before. These evolutionary events have initiated the 100-Myr reign ofWatznaueriaover the calcareous nannoplankton community.

scholarly journals Bayesian probabilities for occurrence of large earthquakes in the seismogenic sources of Japan and Phillipine during the period 1998-2017

2001 ◽  
Vol 34 (4) ◽  
pp. 1619
Author(s):  
T. M. TSAPANOS ◽  
O. CH. GALANIS ◽  
S. D. MAVRIDOU ◽  
M. P. HELMl
Keyword(s):  
Seismic Hazard ◽  
Bayesian Statistics ◽  
Poisson Distribution ◽  
Bayesian Approach ◽  
Seismic Sources ◽  
Time Interval ◽  
Seismogenic Sources ◽  
The One ◽  
Large Earthquakes ◽  
The Bayesian Approach

The Bayesian statistics is adopted in 11 seismic sources of Japan and 14 of Philippine in order to estimate the probabilities of occurrence of large future earthquakes, assuming that earthquakes occurrence follows the Poisson distribution. The Bayesian approach applied represents the probability that a certain cut-off magnitude (or larger) will exceed in a given time interval of 20 years, that is 1998-2017. This cut-off magnitude is chosen the one with M=7.0 or greater. In this case we can consider these obtained probabilities as a seismic hazard presentation. More over curves are produced which present the fluctuation of the seismic hazard between these seismic sources. These graphs of varying probability are useful either for engineering or other practical purposes

scholarly journals Methods for optimal loading of the prosumer’s heat source during the heating period

2019 ◽  
Vol 102 ◽  
pp. 02006
Author(s):  
Ivan Postnikov ◽  
Andrey Penkovskii
Keyword(s):  
District Heating ◽  
Time Interval ◽  
Test Scheme ◽  
Heat Sources ◽  
Heating Period ◽  
Heating Systems ◽  
Optimal Loading ◽  
Heat Loading ◽  
New Type ◽  
The One

The paper the one of current problem of transition of district heating systems (DHS) to the new type of intelligent and integrated systems. This problem is related to the implementation the technology of prosumer, which allows regulating its own heat loading ensuring the most efficiency heating modes by using its own heat sources (HS) and/or heat storages. The statement of considered problem is formulated as the search of the optimal loading relation between the own distributed HS of prosumer and the district HS of DHS, based on the criterion of minimal cost on heating to prosumer for each calculated time interval during the heating period. The practical researches based on calculating experiment using the test scheme of DHS is provided. The results of calculations are presented as diagram of prosumer’s and district HS loading for the considered DHS scheme, as well as the economic benefit when using distributed generation of prosumers.

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