Understanding why some groups of organisms are more diverse than others is a central goal in macroevolution. Evolvability, or the intrinsic capacity of lineages for evolutionary change, is thought to ...influence disparities in species diversity across taxa. Over macroevolutionary time scales, clades that exhibit high evolvability are expected to have higher speciation rates. Cone snails (family: Conidae, >900 spp.) provide a unique opportunity to test this prediction because their toxin genes can be used to characterize differences in evolvability between clades. Cone snails are carnivorous, use prey-specific venom (conotoxins) to capture prey, and the genes that encode venom are known and diversify through gene duplication. Theory predicts that higher gene diversity confers a greater potential to generate novel phenotypes for specialization and adaptation. Therefore, if conotoxin gene diversity gives rise to varying levels of evolvability, conotoxin gene diversity should be coupled with macroevolutionary speciation rates. We applied exon capture techniques to recover phylogenetic markers and conotoxin loci across 314 species, the largest venom discovery effort in a single study. We paired a reconstructed timetree using 12 fossil calibrations with species-specific estimates of conotoxin gene diversity and used trait-dependent diversification methods to test the impact of evolvability on diversification patterns. Surprisingly, we did not detect any signal for the relationship between conotoxin gene diversity and speciation rates, suggesting that venom evolution may not be the rate-limiting factor controlling diversification dynamics in Conidae. Comparative analyses showed some signal for the impact of diet and larval dispersal strategy on diversification patterns, though detection of a signal depended on the dataset and the method. If our results remain true with increased taxonomic sampling in future studies, they suggest that the rapid evolution of conid venom may cause other factors to become more critical to diversification, such as ecological opportunity or traits that promote isolation among lineages. Macroevolution; phylogenetics; venom evolution.
Full text
Available for:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
AIM: Numerous studies have examined potential responses of terrestrial biotas to future climate change, but fewer have considered marine realms. We forecast how marine molluscan faunas might respond ...to environmental change over the remainder of this century. We test the hypotheses that suitable areas will shift northwards for studied species, and that species will show varied responses to future climate change. LOCATION: North and South America and the Caribbean. METHODS: We generated ecological niche models (in GARP and Maxent) for 14 ecologically, economically and potentially medically important mollusc species, using present‐day summaries and future forecasts of climate from the Hadley Centre and known species occurrence data from natural history collections. Niche models were used to forecast potential distributions according to three scenarios of future change for three time slices. RESULTS: Northern extremes of suitability are predicted to shift northwards for only three (GARP) or four (Maxent) of the 14 species, whereas the southern edge of suitability is predicted to shift southwards for seven (GARP) and one (Maxent) of the 14 species. When changes in the geographical centroids of suitability are considered, no significant poleward shifts are anticipated for individual species. Instead, half of the study species (many economically important) experience substantial (> 20%) loss of suitable environmental area, even under the lowest‐emission future climate scenario. Furthermore, the direction and magnitude of the response to predicted climate change is species‐specific. MAIN CONCLUSIONS: We do not find a coherent pattern of areas with suitable environments expanding at high‐latitude range boundaries, with simultaneous contraction at their low‐latitude boundaries. Tropical marine molluscs may thus show varied responses as average temperatures warm. These results contrast with trends among terrestrial and other marine species, which are rapidly shifting their ranges to higher latitudes. Conversely, the differing responses of these species to future warming are consistent with responses of species to past episodes of change, as observed in the fossil record.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
An ensemble optimal interpolation (EnOI) data assimilation system for a high‐resolution (0.1° horizontal) version of the Community Earth System Model Version 2 (CESM2) ocean component is presented. ...For this purpose, a new version of the Data Assimilation Research Testbed (DART Manhattan) that enables large‐state data assimilation by distributing state vector information across multiple processors at high resolution is used. The EnOI scheme uses a static (but seasonally varying) 84‐member ensemble of precomputed perturbations to approximate samples from the forecast error covariance and utilizes a single model integration to estimate the forecast mean. Satellite altimetry and sea surface temperature observations along with in situ temperature and salinity observations are assimilated. This new data assimilation framework is then used to produce a global high‐resolution retrospective analysis for the 2005–2016 period. Not surprisingly, the assimilation is shown to generally improve the time‐mean ocean state estimate relative to an identically forced ocean model simulation where no observations are ingested. However, diminished improvements are found in undersampled regions. Lack of adequate salinity observations in the upper ocean actually results in deterioration of salinity there. The EnOI scheme is found to provide a practical and cost‐effective alternative to the use of an ensemble of forecasts.
Plain Language Summary
Decadal climate prediction focuses on climate changes on time scales from a year to a decade or more and is a combination of forced boundary condition and initial value problems. A well‐established source of predictability on decadal time scales comes from the initialization of the ocean state. To exploit the capabilities of the next generation of high‐resolution climate prediction systems, proper initialization of their ocean components is required. This work represents our first attempt at data assimilation in a high‐resolution version of the Community Earth System Model (CESM2). We use a new version of the Data Assimilation Research Testbed (DART) that enables large‐state data assimilation. However, the integration of an ensemble of high‐resolution models remains computationally prohibitive. For this reason, we introduce an ensemble optimal interpolation (EnOI) scheme to assimilate observations much more efficiently. The EnOI scheme uses a static, but seasonally varying, ensemble of precomputed perturbations to approximate samples from the forecast error covariance and eliminates the need for running an ensemble. While our prototype retrospective analysis for the 2005–2016 period shows some limitations, the EnOI scheme is found to provide a practical and cost‐effective alternative to the use of an ensemble of forecasts.
Key Points
An EnOI data assimilation system for a high‐resolution version of the Community Earth System Model Version 2 ocean component is presented
A new DART version that enables large‐state data assimilation by distributing the state vector across multiple processors is introduced
The EnOI scheme is found to provide a practical and cost‐effective alternative to the use of an ensemble of forecasts
Full text
Available for:
DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Middle Cambrian Arthropods from Utah Briggs, Derek E. G; Lieberman, Bruce S; Hendricks, Jonathan R ...
Journal of paleontology,
03/2008, Volume:
82, Issue:
2
Journal Article
Peer reviewed
The Middle Cambrian Spence Shale Member (Langston Formation) and Wheeler and Marjum Formations of Utah are known to contain a diverse soft-bodied fauna, but important new paleontological material ...continues to be uncovered from these strata. New specimens of anomalocaridids include the largest and smallest near complete examples yet reported from Utah. New material of stem group arthropods includes two new genera and species of arachnomorphs: Nettapezoura basilika and Dicranocaris guntherorum. Other new arachnomorph material includes a new species of Leanchoilia comparable to L. protogonia Simonetta, 1970; Leanchoilia superlata? Walcott, 1912; Sidneyia Walcott, 1911a; and Mollisonia symmetrica Walcott, 1912. L. protogonia from the Burgess Shale is confirmed as a separate species and is not a composite fossil. The first example of the trilobite Elrathia kingii preserving traces of the appendages is described. In addition, new material of the bivalved arthropods Canadaspis Novozhilov in Orlov, 1960; Branchiocaris Briggs, 1976; Waptia Walcott, 1912; and Isoxys Walcott, 1890 is described.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Biological asymmetries are important elements of the structure and function of many living organisms. Using the Plio-Pleistocene fossil record of crab predation on morphologically similar pairs of ...right- and left-handed snail species, we show here for the first time, contrary to traditional wisdom, that rare left-handed coiling promotes survival from attacks by right-handed crabs. This frequency-dependent result influences the balance of selection processes that maintain left-handedness at the species level and parallels some social interactions in human cultures, such as sports that involve dual contests between opponents of opposite handedness.
Extant research on stars has demonstrated stars’ immense direct and indirect contributions to value creation, yet it lags behind strategy scholarship, which has emphasized the dynamic nature of value ...creation associated with firms’ core resources. In particular, we lack knowledge regarding how stars’ knowledge creation varies across a star’s career. Drawing on insights from the stars and careers literatures, we develop theoretical arguments that suggest that over their careers, stars shift focus from emphasizing personal attainment and status to prioritizing legacy building—shifts that we predict will correspond to decreases in stars’ relative individual productivity and conveyance of explicit knowledge spillovers to collaborators (which reinforce stars’ status) and increases in stars’ relative conveyance of tacit knowledge spillovers (that aid in colleagues’ development) as stars advance in career tenure. We test our hypotheses through the analysis of patenting activities spanning the years 2000-2022, 291 firms, and 214,398 inventors, cumulating to more than 1,210,989 inventor-year observations. Through the integration of temporal and psychological perspectives in our consideration of stars’ multiple contributions to knowledge creation over their careers, we bring our understanding of stars into alignment with insights related to the dynamic value creation associated with firms’ resources and advance knowledge on stars’ roles in the micro-foundations of human capital-based competitive advantage.
Full text
Available for:
IJS, NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
While some marine animals are capable of traveling great distances, many have limited mobility as adults and spend the majority of their lifetimes in a small geographical area or may even be cemented ...to a single place. While it might be expected that species with limited mobility would have small geographic distributions, some nevertheless occur over very large areas. This is the case for some marine snails (gastropods). A key factor that impacts the geographic distribution of marine snails is the type of larvae they have during the phase of their life history that follows hatching from an egg. Because adult snails do not typically travel vast distances, the mobility of the larval stage determines the species’ ability to reach new territories. Some larvae are capable of long-distance travel, while others are not. An important component of the process of speciation involves geographic isolation, so the type of larvae a snail species possesses impacts the likelihood that it will become geographically isolated and give rise to a new species. Larval form also affects how long snail species will persist on geological timescales before going extinct, as well as rates of speciation. This paper briefly reviews the evolutionary consequences of different types of larval development in marine gastropods (especially cone snails, which are one of the most diverse groups of marine animals), particularly in determining the dispersal ability and geographic ranges of individual species, the amount of genetic exchange among populations within species, and the duration of species through time. The goal of this short review is to provide context and examples for classroom discussions of the connections between biogeography and macroevolution. Furthermore, a classroom activity is presented that involves students’ using information about snail life history and biogeography to develop research plans (and predicted results) that could be utilized to test (i.e., support or reject) several macroevolutionary hypotheses.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The paucity of sinistral (left‐coiling) relative to dextral (right‐coiling) species of gastropods in the marine realm is an enigma. In Conus, one of the most diverse marine animal genera, sinistral ...shell coiling has evolved as a species‐wide character only once. Fossils of this species, Conus adversarius, are found in Upper Pliocene and lowermost Pleistocene deposits in the southeastern USA. Conus adversarius had nonplanktonic larval development; this may have been a critical factor for the early establishment of the species, as well as sinistral marine species in other clades. Notably, most specimens of aberrantly sinistral modern Conus are derived from typically dextral species that have nonplanktonic development. If C. adversarius was reproductively isolated from dextral conspecifics, then this species may provide an example of nearly instantaneous sympatric speciation in the fossil record. Furthermore, the common and widespread – while geologically short‐lived – fossil shells of C. adversarius show large amounts of variability in form and this variation may be related, at least in part, to a pleiotropic effect associated with the reversed coiling direction of this species.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Research on impression management within organizations is extensive and provides valuable insights regarding both impression management motivation and the ways in which impression management is ...enacted. However, inconsistent findings in the literature limit our ability to confidently glean clear research and practice conclusions. Further, current impression management perspectives are primarily based on face-to-face communication, but technology and world events have changed how we interact within organizations. Our integrative literature review examines the impression management literature, and integrates research from related literatures (organizational citizenship behavior, faking behavior, and computer-human interaction), to identify how context influences impression motivation and construction. Based on this review, we propose that impression motivation is shaped, in part, by the situation's evaluative potential (e.g., public behavior, high stakes), and the nature of the workplace interaction (e.g., anonymity, permanence, verifiability, and synchronicity) moderates the impression motivation-impression construction relationship. We then use the contextual framework to provide a better understanding of past research, stimulate new research, and provide practical recommendations for HR professionals.
•Context influences on impression management (IM) motivation and construction were identified.•Research on IM, citizenship behavior, faking, and computer-human interaction was reviewed.•Based on this review, we propose a contextual framework of impression management.•The framework offers research directions and advice for HR professionals to address IM behavior.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Cambrian fossil record of the Arachnomorpha is rich and diverse and includes trilobites, chelicerates, and many taxa known from various soft-bodied faunas including the Burgess Shale and the ...Chengjiang. Exceptionally well-preserved arthropod fossils are also known from Middle Cambrian strata in Utah. Recently, two new arachnomorphs (Dicranocaris Briggs, Lieberman, Hendricks, Halgedahl, and Jarrard, 2008 and Nettapezoura Briggs, Lieberman, Hendricks, Halgedahl, and Jarrard, 2008) were described from the Wheeler and Marjum formations of Utah. Cladistic analysis is undertaken to investigate arachnomorph relationships in light of these two new genera. The character matrix of Edgecombe and Ramsköld (1999) serves as the foundation for this study, augmented by new characters and taxa. The results of our cladistic analysis suggest that at least three distinct arachnomorph clades had diverged by the Middle Cambrian, and perhaps much earlier; the Utah genera can be referred to groups within one of these clades.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
PDF
