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.

scholarly journals Diversification dynamics of hypermetamorphic blister beetles (Meloidae): Are homoplastic host shifts and phoresy key factors of a rushing forward strategy to escape extinction?

2021 ◽  
Author(s):  
E.K. López-Estrada ◽  
I. Sanmartín ◽  
J.E. Uribe ◽  
S. Abalde ◽  
M. García-París
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Life History Traits ◽  
Complex Life Cycle ◽  
Life Strategies ◽  
Diversification Rates ◽  
Host Shifts ◽  
Extinction Rates ◽  
State Dependent ◽  
History Of

ABSTRACTChanges in life history traits, including reproductive strategies or host shifts, are often considered triggers of speciation, affecting diversification rates. Subsequently, these shifts can have dramatic effects on the evolutionary history of a lineage. In this study, we examine the consequences of changes in life history traits, in particular host-type and phoresy, within the hypermetamorphic clade of blister beetles (Meloidae). This clade exhibits a complex life cycle involving multiple metamorphoses and parasitoidism. Most tribes within the clade are bee-parasitoids, phoretic or non-phoretic, while two tribes feed on grasshopper eggs. Species richness differs greatly between bee and grasshopper specialist clades, and between phoretic and non-phoretic genera. We generated a mitogenomic phylogeny of the hypermetamorphic clade of Meloidae, including 21 newly generated complete mitogenomes. The phylogeny and estimated lineage divergence times were used to explore the association between diversification rates and changes in host specificity and phoresy, using State-Dependent Speciation and Extinction (SSE) models, while accounting for hidden factors and phylogenetic uncertainty within a Bayesian framework. The ancestor of the hypermetamorphic Meloidae was a non-phoretic bee-parasitoid, and independent transitions towards phoretic bee-parasitoidism or grasshopper specialization occurred multiple times. Bee-parasitoid lineages that are non-phoretic have significantly higher relative extinction rates and lower diversification rates than grasshopper specialists or phoretic bee-parasitoids, while no significant differences were found between the latter two strategies. This suggests that these two life strategies contributed independently to the evolutionary success of Nemognathinae and Meloinae, allowing them to escape from the evolutionary constraints imposed by their hypermetamorphic life-cycle, and that the “bee-by-crawling” strategy may be an evolutionary “dead end”. We show how SSE models can be used not only for testing diversification dependence in relation to the focal character but to identify hidden traits contributing to the diversification dynamics. The ability of blister beetles to explore new evolutionary scenarios including the development of homoplastic life strategies, are extraordinary outcomes along the evolution of a single lineage: the hypermetamorphic Meloidae.

scholarly journals Stochastic character mapping of state-dependent diversification reveals the tempo of evolutionary decline in self-compatible Onagraceae lineages

2017 ◽  
Author(s):  
William A. Freyman ◽  
Sebastian Höhna
Keyword(s):  
Time Lag ◽  
State Transitions ◽  
Character State ◽  
Self Incompatibility ◽  
Evolutionary Transitions ◽  
Diversification Rates ◽  
Extinction Rates ◽  
Loss Of Self ◽  
State Dependent ◽  
Character Mapping

AbstractA major goal of evolutionary biology is to identify key evolutionary transitions that correspond with shifts in speciation and extinction rates. Stochastic character mapping has become the primary method used to infer the timing, nature, and number of character state transitions along the branches of a phylogeny. The method is widely employed for standard substitution models of character evolution. However, current approaches cannot be used for models that specifically test the association of character state transitions with shifts in diversification rates such as state-dependent speciation and extinction (SSE) models. Here we introduce a new stochastic character mapping algorithm that overcomes these limitations, and apply it to study mating system evolution over a time-calibrated phylogeny of the plant family Onagraceae. Utilizing a hidden state SSE model we tested the association of the loss of self-incompatibility with shifts in diversification rates. We found that self-compatible lineages have higher extinction rates and lower net-diversification rates compared to self-incompatible lineages. Furthermore, these results provide empirical evidence for the “senescing” diversification rates predicted in highly selfing lineages: our mapped character histories show that the loss of self-incompatibility is followed by a short-term spike in speciation rates, which declines after a time lag of several million years resulting in negative net-diversification. Lineages that have long been self-compatible, such as Fuchsia and Clarkia, are in a previously unrecognized and ongoing evolutionary decline. Our results demonstrate that stochastic character mapping of SSE models is a powerful tool for examining the timing and nature of both character state transitions and shifts in diversification rates over the phylogeny.

scholarly journals Detecting hidden diversification shifts in models of trait-dependent speciation and extinction

2015 ◽  
Author(s):  
Jeremy M Beaulieu ◽  
Brian C O'Meara
Keyword(s):  
Empirical Data ◽  
Diversification Rate ◽  
Transition Rates ◽  
Diversification Rates ◽  
Extinction Rates ◽  
State Dependent ◽  
Speciation Rates ◽  
Nuanced Understanding ◽  
Hidden States ◽  
Major Criticism

The distribution of diversity can vary considerably from clade to clade. Attempts to understand these patterns often employ state-dependent speciation and extinction models to determine whether the evolution of a particular novel trait has increased speciation rates and/or decreased their extinction rates. It is still unclear, however, whether these models are uncovering important drivers of diversification, or whether they are simply pointing to more complex patterns involving many unmeasured and co-distributed factors. Here we describe an extension to the popular state-dependent speciation and extinction models that specifically accounts for the presence of unmeasured factors that could impact diversification rates estimated for the states of any observed trait, addressing at least one major criticism of BiSSE methods. Specifically, our model, which we refer to as HiSSE (Hidden-State Speciation and Extinction), assumes that related to each observed state in the model are "hidden" states that exhibit potentially distinct diversification dynamics and transition rates than the observed states in isolation. We also demonstrate how our model can be used as character-independent diversification (CID) models that allow for a complex diversification process that is independent of the evolution of a character. Under rigorous simulation tests and when applied to empirical data, we find that HiSSE performs reasonably well, and can at least detect net diversification rate differences between observed and hidden states and detect when diversification rate differences do not correlate with the observed states. We discuss the remaining issues with state-dependent speciation and extinction models in general, and the important ways in which HiSSE provides a more nuanced understanding of trait-dependent diversification.

scholarly journals Single-molecule turnover dynamics of actin and membrane coat proteins in clathrin-mediated endocytosis

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Michael M Lacy ◽  
David Baddeley ◽  
Julien Berro
Keyword(s):  
Single Molecule ◽  
Turgor Pressure ◽  
Force Production ◽  
Actin Dynamics ◽  
Coat Proteins ◽  
Turnover Rates ◽  
High Turnover ◽  
Associated Proteins ◽  
Turn Over ◽  
First Time

Actin dynamics generate forces to deform the membrane and overcome the cell’s high turgor pressure during clathrin-mediated endocytosis (CME) in yeast, but precise molecular details are still unresolved. Our previous models predicted that actin filaments of the endocytic meshwork continually polymerize and disassemble, turning over multiple times during an endocytic event, similar to other actin systems. We applied single-molecule speckle tracking in live fission yeast to directly measure molecular turnover within CME sites for the first time. In contrast with the overall ~20 s lifetimes of actin and actin-associated proteins in endocytic patches, we detected single-molecule residence times around 1 to 2 s, and similarly high turnover rates of membrane-associated proteins in CME. Furthermore, we find heterogeneous behaviors in many proteins’ motions. These results indicate that endocytic proteins turn over up to five times during the formation of an endocytic vesicle, and suggest revising quantitative models of force production.

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.

scholarly journals Elevada Rotatividade de Carteiras e o Desempenho dos Fundos de Investimento em Ações

2014 ◽  
Vol 12 (4) ◽  
pp. 469
Author(s):  
Pedro Luiz Albertin Bono Milan ◽  
William Eid Junior
Keyword(s):  
Portfolio Management ◽  
Turnover Rate ◽  
Turnover Rates ◽  
High Turnover ◽  
Investment Funds ◽  
Market Portfolio ◽  
Active Portfolio Management ◽  
The Impact ◽  
Portfolio Return ◽  
Shed Light

The active portfolio management aims to outperformance a market portfolio return, however, there is a great discussion among academics and practitioners about the real possibilities to outperformance the market portfolio return by an actively portfolio management. This paper shed light on Brazilian market, pursuing the impact of a high portfolio turnover rate in the performance of equity mutual investment funds. The study evidence high turnover rates negatively affecting the performance of the funds. Furthermore, the performance fee and the size effect are important aspects to acces better performance.

scholarly journals Rates of turnover among general practitioners: a retrospective study of all English general practices between 2007 and 2019

BMJ Open ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. e049827
Author(s):  
Rosa Parisi ◽  
Yiu-Shing Lau ◽  
Peter Bower ◽  
Kath Checkland ◽  
Jill Rubery ◽  
...  
Keyword(s):  
Retrospective Study ◽  
General Practitioners ◽  
Turnover Rate ◽  
Social Deprivation ◽  
Turnover Rates ◽  
High Turnover ◽  
Practice Characteristics ◽  
General Practices ◽  
Over Time ◽  
Deprived Areas

ObjectiveTo quantify general practitioners’ (GPs’) turnover in England between 2007 and 2019, describe trends over time, regional differences and associations with social deprivation or other practice characteristics.DesignA retrospective study of annual cross-sectional data.SettingAll general practices in England (8085 in 2007, 6598 in 2019).MethodsWe calculated turnover rates, defined as the proportion of GPs leaving a practice. Rates and their median, 25th and 75th percentiles were calculated by year and region. The proportion of practices with persistent high turnover (>10%) over consecutive years were also calculated. A negative binomial regression model assessed the association between turnover and social deprivation or other practice characteristics.ResultsTurnover rates increased over time. The 75th percentile in 2009 was 11%, but increased to 14% in 2019. The highest turnover rate was observed in 2013–2014, corresponding to the 75th percentile of 18.2%. Over time, regions experienced increases in turnover rates, although it varied across English regions. The proportion of practices with high (10% to 40%) turnover within a year almost doubled from 14% in 2009 to 27% in 2019. A rise in the number of practices with persistent high turnover (>10%) for at least three consecutive years was also observed, from 2.7% (2.3%–3.1%) in 2007 to 6.3% (5.7%–6.9%) in 2017. The statistical analyses revealed that practice-area deprivation was moderately associated with turnover rate, with practices in the most deprived area having higher turnover rates compared with practices in the least deprived areas (incidence rate ratios 1.09; 95% CI 1.06 to 1.13).ConclusionsGP turnover has increased in the last decade nationally, with regional variability. Greater attention to GP turnover is needed, in the most deprived areas in particular, where GPs often need to deal with more complex health needs. There is a large cost associated with GP turnover and practices with very high persistent turnover need to be further researched, and the causes behind this identified, to allow support strategies and policies to be developed.

scholarly journals Hidden-state-only speciation and extinction models provide accurate tip estimates of diversification rates

2021 ◽  
Author(s):  
Thais Vasconcelos ◽  
Brian C O'Meara ◽  
Jeremy M. Beaulieu
Keyword(s):  
Model Space ◽  
Comparative Methods ◽  
Character State ◽  
Large Set ◽  
Turnover Rates ◽  
Extinction Rates ◽  
State Dependent ◽  
Related Diversification ◽  
Testing Potential ◽  
Hidden States

1. State-dependent speciation and extinction (SSE) models provide a framework for testing potential correlations between the evolution of an observed trait and speciation and extinction rates. Recent expansions of these models allow for the inclusion of "hidden states" that, among other things, allow for rate heterogeneity often observed among lineages sharing a particular character state. However, in reality, multiple circumstances and interacting traits related to a focal character play a role in changing diversification dynamics of a lineage over time, restricting the use of available SSE models that require trait information to be assigned at the tips. 2. Here we introduce MiSSE, an SSE approach that infers diversification rate differences from hidden states only. It can be used similarly to other trait-free methods to estimate varying speciation, extinction, but also different functions of these parameters such as net-diversification, turnover rates, and extinction fraction. Given the size of the model space, we also describe an algorithm designed for efficiently searching through a reasonably large set of models without having to be exhaustive. 3. We compare the accuracy of rates inferred at the tips of the tree by MiSSE against popular character-free methods and demonstrate that the error associated with tip estimates is generally low. Due to certain characteristics of the SSE models, this method avoids some of the recent concerns with parameter identifiability in diversification analyses and can be used alongside regular phylogenetic comparative methods in trait-related diversification hypotheses. 4. Finally, we apply MiSSE, with a renewed focus on classic comparative methods, to understand processes happening near the present, rather than deep in the past, to examine how variation in plant height has impacted turnover rates in eucalypts, a species-rich lineage of flowering plants.

scholarly journals The Role of Competency and Succession Program to Retain Millennial Healthcare Workers (Case Study in Indonesian Small Scale Maternity Hospital)

2021 ◽  
Vol 6 (1) ◽  
pp. 198-205
Author(s):  
Mira Pratiwi ◽  
Sandra Dewi ◽  
. Hasyim
Keyword(s):  
Leadership Style ◽  
Turnover Intention ◽  
Healthcare Workers ◽  
Turnover Rate ◽  
Research Effort ◽  
Maternity Hospital ◽  
Small Scale ◽  
Leadership Traits ◽  
Turnover Rates ◽  
High Turnover

The turnover rates among millennial employees have become serious issue for many industries including healthcare industry. The negative economically outcome due to high turnover rate can vary from direct and indirect, tangible and intangible cost to the organization. The cause of high turnover rate has been explained in many literatures, which includes leadership as one of the factors. Many studies have been underlining the importance of leadership style in lowering the number of turnover. Albeit some of leadership style may be proven to be effective in certain organization, the shift of millennial characteristic pressed other scholars to analyze if current theories of leadership style may sufficient and fitting to millennial. Therefore, there has been a gap in the literature between leadership style and leadership traits. The purpose of this research is to study the relation between effective leadership traits for managing millennial and its’ impact to lower millennial healthcare workers turnover intention. Teamwork is an important aspect in millennial setting; therefore, it is used as moderator to imply if teamwork may strengthen the relation between the two previous variables. The study was held in a small-scale maternity hospital in Malang, Indonesia, with the population of 57 millennial employees. The results of this research effort may help to fill the gap in the literature about the relationship between leadership traits, teamwork, and employee’s turnover for millennial in the workplace; and will hopefully help the organization to understand better the millennial motives to stay, and to bridge understanding between employer and employees.

FAKTOR PERSONAL YANG BERHUBUNGAN DENGAN KOMITMEN ORGANISASI PERAWAT RSUD EMBUNG FATIMAH BATAM

2020 ◽  
Vol 5 (3) ◽  
pp. 875
Author(s):  
Asfri Sri Rahmadeni
Keyword(s):  
Organizational Commitment ◽  
Turnover Rate ◽  
Sampling Technique ◽  
Hospital Nurses ◽  
Test Results ◽  
Personal Factors ◽  
High Turnover ◽  
Chi Square ◽  
Cross Sectional ◽  
Chi Square Test

<p class="Normal1"><em>Commitment is the attitude or behavior of likes or dislikes shown by someone against the organization at work. Indonesia is recorded as a nurse who has a low organizational commitment (76%) so it harms services. This phenomenon in the hospital can be seen from the indicator of the high turnover rate of nurses which reaches 30.9% which exceeds the standard &lt;5%. Many factors affect organizational commitment. The purpose of this study was to analyze the Personal Factors Associated with Organizational Commitment of Hospital Nurses. This study is a cross-sectional analytic study and purposive sampling technique with a sample of 59 nurses. Chi-Square test results obtained personal factors that have a relationship with organizational commitment Nurse Hospital is age with p = 0,000 and education with p = 0,000, personal factors not related to organizational commitment are gender p = 1,053 and years of service with p = 1,147. Hospitals should conduct research/surveys on Organizational Commitment periodically as an evaluation material in the context of the organization's development and development in the future</em>.</p>

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