While leader departures from work units frequently occur within organizations and are assumed to negatively impact unit functioning, the collective reaction to a leader departure event can vary ...across time. While a common expectation of leader departure models is that the incoming leader is permanent, it is unclear how unit-level reactions, such as collective turnover and unit performance, might change over time in response to a departure event when the departing leader is replaced with a temporary leader. We draw on context emergent turnover (CET) theory and literature on leader departures to develop and empirically test specific hypotheses exploring relationships among leader departures, collective turnover, and unit performance over time. In addition, we examine the extent to which these relationships are influenced by the temporary status of the incoming leader. Using discontinuous growth models, we examine a longitudinal data set from 324 units within a large Latin American operation of a global direct sales company (N = 3,082 performance periods). Findings indicate that, after a leader departs, there is an immediate increase in collective turnover and that unit performance decreases over time. Further, when the incoming leader is temporary, unit performance increases briefly, but the rate of performance drops over time. Overall, our research offers insights with regard to how leader departures impact unit outcomes, as well as how long such effects last.
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2.
Back to Basics with Mixed-Effects Models Bliese, Paul D.; Maltarich, Mark A.; Hendricks, Jonathan L.
Journal of business and psychology,
02/2018, Volume:
33, Issue:
1
Journal Article
Peer reviewed
Purpose
Multilevel mixed effects models are widely used in organizational behavior and organizational psychology to test and advance theory. At times, however, the complexity of the models leads ...researchers to draw erroneous inferences or otherwise use the models in less than optimal ways. We present nine take-away points intended to enhance the theoretical precision and utility of the models.
Approach
We demonstrate our points using two types of simulated data: one in which group membership is irrelevant, and the other in which relationships exist only because of group membership. We then demonstrate that the effects we observe in simulated data replicate in organizational data.
Findings
Little that we address will be new to methodology experts; nonetheless, we draw together a variety of points that we believe will help advance both theory and analytic rigor in multilevel analyses.
Implications
We make two points that run somewhat counter to conventional norms. First, we argue that mixed-effects models are appropriate even when ICC(1) values associated with the outcome data are small and non-significant. Second, we show that high ICC(2) values are not a prerequisite for detecting emergent multilevel relationships.
Originality/Value
The article is designed to be a resource for researchers who are learning about and applying mixed-effects (i.e., multilevel) models.
The biology of modern Conidae (cone snails)--which includes the hyperdiverse genus Conus--has been intensively studied, but the fossil record of the clade remains poorly understood, particularly ...within an evolutionary framework. Here, ultraviolet light is used to reveal and characterize the original shell coloration patterns of 28 species of cone snails from three Neogene coral reef-associated deposits from the Cibao Valley, northern Dominican Republic. These fossils come from the upper Miocene Cercado Fm. and lower Pliocene Gurabo Fm., and range in age from about 6.6-4.8 Ma. Comparison of the revealed coloration patterns with those of extant species allow the taxa to be assigned to three genera of cone snails (Profundiconus, Conasprella, and Conus) and at least nine subgenera. Thirteen members of these phylogenetically diverse reef faunas are described as new species. These include: Profundiconus? hennigi, Conasprella (Ximeniconus) ageri, Conus anningae, Conus lyelli, Conus (Atlanticonus?) franklinae, Conus (Stephanoconus) gouldi, Conus (Stephanoconus) bellacoensis, Conus (Ductoconus) cashi, Conus (Dauciconus) garrisoni, Conus (Dauciconus?) zambaensis, Conus (Spuriconus?) kaesleri, Conus (Spuriconus?) lombardii, and Conus (Lautoconus?) carlottae. Each of the three reef deposits contain a minimum of 14-16 cone snail species, levels of diversity that are similar to modern Indo-Pacific reef systems. Finally, most of the 28 species can be assigned to modern clades and thus have important implications for understanding the biogeographic and temporal histories of these clades in tropical America.
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For decades, scholars and managers alike have shared a sustained interest in harnessing the talents of high-performing employees primarily due to their disproportionate contributions. An emerging ...research stream has begun examining the diverse effects that high performers elicit on their peers. Prior work now spans multiple organizational fields of study and utilizes a variety of high performer conceptualizations, theoretical lenses, and methodological approaches to examine the main effects of high performers as well as the boundary conditions of these effects. However, the body of work on high performers has yet to be systematically reviewed to synthesize the current state of the high performer literature and build commonality across disciplines. In this multidisciplinary review, we first establish conceptual clarity on what a high performer is (and is not) and identify the conceptualization of high performers used in current research. We then use appraisal theories to create a framework to organize the cognitive, affective, and behavioral peer effects sparked by high performers as well as to build an integrative view of the psychological mechanisms through which peers interpret and react to high performers. Following this, we outline several boundary conditions of high performer peer effects, including the characteristics of high performers, peers, and the context in which high performers and peers interact. We further consider how the various operationalizations of high performers are associated with different peer effects. We conclude by identifying and elaborating several avenues for future research that may yield useful cross-disciplinary insights.
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The ability to detect differences between groups partially impacts how useful a group-level variable will be for subsequent analyses. Direct consensus and referent-shift consensus group-level ...constructs are often measured by aggregating group member responses to multi-item scales. We show that current measurement validation practice for these group-level constructs may not be optimized with respect to differentiating groups. More specifically, a 10-year review of multilevel articles in top journals reveals that multilevel measurement validation primarily relies on procedures designed for individual-level constructs. These procedures likely miss important information about how well each specific scale item differentiates between groups. We propose that group-level measurement validation be augmented with information about each scale item's ability to differentiate groups. Using previously published datasets, we demonstrate how ICC(1) estimates for each item of a scale provide unique information and can produce group-level scales with higher ICC(1) values that enhance predictive validity. We recommend that researchers supplement conventional measurement validation information with information about item-level ICC(1) values when developing or modifying scales to assess group-level constructs.
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AIM: Determining which species are more prone to extinction is vital for conserving Earth's biodiversity and for providing insight into macroevolutionary processes. This paper utilizes the Pliocene ...to Recent fossil record of mollusks to identify determinants of species' extinction over the past three million years of Earth history. LOCATION: Western Atlantic. METHODS: We focus on 92 bivalve and gastropod species that lived during the mid‐Pliocene Warm Period (mPWP; ∼3.264–3.025 Ma) and have either since gone extinct or are still extant. We used ecological niche modeling (ENM) to assess the vulnerability of these species to extinction as a function of both fundamental (FN) and realized (RN) niche breadth proxies, geographic range size, and amount of suitable area available to them during the Last Glacial Maximum (LGM; ∼21 Ka). RESULTS: Geographic range size emerged as a key predictor of extinction for the studied mollusk species, with RN breadth and amount of suitable area available during the LGM as secondary predictors. By contrast, FN breadth was not a significant predictor of extinction risk. MAIN CONCLUSIONS: The failure to recover FN breadth as a predictor of extinction may suggest that extinction resistance is achieved when species are more successful in filling the geographic extent of their fundamental tolerances. That is, when it comes to species' survival, being a generalist or specialist sensu stricto may be secondary to the unique historical, dispersal, and biotic constraints that dictate a species' occupation of suitable environments, and consequently of geographic space, at a particular time. Identifying the factors that promote extinction is important because of the time‐intensive nature of estimating extinction risk for individual species and populations, and because of the rising concerns about the future of marine ecosystems and biodiversity.
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Despite being the objects of numerous macroevolutionary studies, many of the best represented constituents of the fossil record—including diverse examples such as foraminifera, brachiopods, and ...mollusks—have mineralized skeletons with limited discrete characteristics, making morphological phylogenies difficult to construct. In contrast to their paucity of phylogenetic characters, the mineralized structures (tests and shells) of these fossil groups frequently have distinctive shapes that have long proved useful for their classification. The recent introduction of methodologies for including continuous data directly in a phylogenetic analysis has increased the number of available characters, making it possible to produce phylogenies based, in whole or part, on continuous character data collected from such taxa. Geometric morphometric methods provide tools for accurately characterizing shape variation and can produce quantitative data that can therefore now be included in a phylogenetic matrix in a nonarbitrary manner. Here, the marine gastropod genus Conus is used to evaluate the ability of continuous characters—generated from a geometric morphometric analysis of shell shape—to contribute to a total evidence phylogenetic hypothesis constructed using molecular and morphological data. Furthermore, the ability of continuous characters derived from geometric morphometric analyses to place fossil taxa with limited discrete characters into a phylogeny with their extant relatives was tested by simulating the inclusion of fossil taxa. This was done by removing the molecular partition of individual extant species to produce a "cladistic pseudofossil" with only the geometric morphometric derived characters coded. The phylogenetic position of each cladistic pseudofossil taxon was then compared with its placement in the total evidence tree and a symmetric resampling tree to evaluate the degree to which morphometric characters alone can correctly place simulated fossil species. In 33–45% of the test cases (depending upon the approach used for measuring success), it was possible to place the pseudofossil taxon into the correct regions of the phylogeny using only the morphometric characters. This suggests that the incorporation of extinct Conus taxa into phylogenetic hypotheses will be possible, permitting a wide range of macroevolutionary questions to be addressed within this genus. This methodology also has potential to contribute to phylogenetic reconstructions for other major components of the fossil record that lack numerous discrete characters.
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Cnidarians represent an early diverging animal group and thus insight into their origin and diversification is key to understanding metazoan evolution. Further, cnidarian jellyfish comprise an ...important component of modern marine planktonic ecosystems. Here we report on exceptionally preserved cnidarian jellyfish fossils from the Middle Cambrian (approximately 505 million years old) Marjum Formation of Utah. These are the first described Cambrian jellyfish fossils to display exquisite preservation of soft part anatomy including detailed features of structures interpreted as trailing tentacles and subumbrellar and exumbrellar surfaces. If the interpretation of these preserved characters is correct, their presence is diagnostic of modern jellyfish taxa. These new discoveries may provide insight into the scope of cnidarian diversity shortly after the Cambrian radiation, and would reinforce the notion that important taxonomic components of the modern planktonic realm were in place by the Cambrian period.
The Generification of the Fossil Record Hendricks, Jonathan R; Saupe, Erin E; Myers, Corinne E ...
Paleobiology,
09/2014, Volume:
40, Issue:
4
Journal Article
Peer reviewed
Many modern paleobiological analyses are conducted at the generic level, a practice predicated on the validity of genera as meaningful proxies for species. Uncritical application of genera in such ...analyses, however, has led—perhaps inadvertently—to the unjustified reification of genera in an evolutionary context. While the utility of genera as proxies for species in evolutionary studies should be evaluated as an empirical issue, in practice it is increasingly assumed (rather than demonstrated) that genera are suitable proxies for species. This is problematic on both ontological and epistemological grounds. Genera are arbitrarily circumscribed, non-equivalent, often paraphyletic, and sometimes polyphyletic collections of species. They are useful tools for communication but have no theoretical or biological reality of their own and, whether monophyletic or not, cannot themselves operate in the evolutionary process. Attributes considered important for understanding macroevolution—e.g., geographic ranges, niche breadths, and taxon durations—are frequently variable among species within genera and will be inflated at the generic level, especially in species-rich genera. Consequently, the meaning(s) of results attained at the generic level may not “trickle down” in any obvious way that elucidates our understanding of evolution at the species level. Ideally, then, evolutionary studies that are actually about species should be pursued using species-level data rather than proxy data tabulated using genera. Where genera are used, greater critical attention should be focused on the degree to which attributes tabulated at the generic level reflect biological properties and processes at the species level.
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Simulating Arctic sea ice conditions up to the present and predicting them several months in advance has high stakeholder value, yet remains challenging. Advanced data assimilation (DA) methods ...combine real observations with model forecasts to produce sea ice reanalyses and accurate initial conditions for sea ice prediction. This study introduces a sea ice DA framework for a sea ice model with a parameterization of the ice thickness distribution by resolving multiple thickness categories. Specifically, the Los Alamos Sea Ice Model, version 5 (CICE5), is integrated with the Data Assimilation Research Testbed (DART). A series of perfect model observing system simulation experiments (OSSEs) are designed to explore DA algorithms within the ensemble Kalman filter (EnKF) and the relative importance of different observation types. This study demonstrates that assimilating sea ice concentration (SIC) observations can effectively remove SIC errors, with the error of total Arctic sea ice area reduced by about 60% annually. When the impact of SIC observations is strongly localized in space, the error of total volume is also modestly improved. The largest simulation improvements are produced when sea ice thickness (SIT) and SIC are jointly assimilated, with the error of total volume decreased by more than 70% annually. Assimilating multiyear sea ice concentration (MYI) can reduce error in total volume by more than 50%. Assimilating MYI produces modest improvements in snow depth (errors are reduced by around 16%), while assimilating SIC and SIT has no obvious influence on snow depth. This study also suggests that different observation types may need different localization distances to optimize DA performance.
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