Congruent phylogeographic patterns in a young radiation of live‐bearing marine snakes: Pleistocene vicariance and the conservation implications of cryptic genetic diversity

Aim: To investigate phylogeographic patterns among and within co-occurring sea snake species from Australia's endemic viviparous Aipysurus lineage, which includes critically endangered species, and evaluate the conservation implications of geographically structured patterns of genetic divergence and diversity. Location: Australia's tropical shallow water marine environments spanning four regions: Great Barrier Reef (GBR), Gulf of Carpentaria (GoC), Timor Sea (TS) and coastal WA (WAC). Methods: Samples from >550 snakes representing all nine nominal Aipysurus group species were obtained from throughout their known Australian ranges. Coalescent phylogenetic analyses and Bayesian molecular dating of mitochondrial DNA, combined with Bayesian and traditional population genetic analyses of 11 microsatellite loci, were used to evaluate genetic divergence and diversity. Results: Mitochondrial DNA revealed highly congruent phylogeographic breaks among co-occurring species, largely supported by nuclear microsatellites. For each species, each region was characterized by a unique suite of haplotypes (phylogroups). Divergences between the TS, GoC and/or GBR were invariably shallow and dated as occurring 50,000-130,000 years ago, coinciding with the cyclic Pleistocene emergence of the Torres Strait land bridge. By contrast, sea snakes from coastal WA were consistently highly divergent from other regions and dated as diverging 178,000-526,000 years ago, which was not associated with any known vicariant events. Main Conclusions: Previously unappreciated highly divergent sea snake lineages in coastal WA potentially represent cryptic species, highlighting this region as a high-priority area for conservation. The cyclic emergence of the Torres Strait land bridge is consisted with observed divergences between the TS, GoC and/or GBR; however, processes involved in the earlier divergences involving the WAC remain to be determined. The observed strong population genetic structures (as surrogates for dispersal) indicate that sea snakes have limited potential to reverse population declines via replenishment from other sources over time frames relevant to conservation

Development of ten polymorphic microsatellite loci for the sea snake Hydrophis elegans (Elapidae: Hydrophiinae) and cross-species amplification for fifteen marine hydrophiine species

We developed ten microsatellite loci for the elegant sea snake, Hydrophis elegans, from partial genomic DNA libraries using a repeat enrichment protocol. Eight loci had nine or more alleles per locus (maximum 20), while the other two had three and seven. All ten loci amplified successfully in 11 of the 15 additional hydrophiine sea snake species screened. Nine loci amplified successfully for three species and eight amplified successfully for the remaining species. Based on this highly successful cross-amplification we expect these ten loci to be useful markers for investigating population genetic structure, gene flow and parentage for all sea snake species from the Hydrophis group

Molecular phylogeny of sea snakes reveals a rapidly diverged adaptive radiation

Evolutionary relationships within and between the marine hydrophiine sea snake groups have been inferred primarily using morphological characters, and two major groups traditionally are recognized. The Aipysurus group comprises nine species in two genera, and the taxonomically chaotic Hydrophis group comprises as many as 40 species, of which 27 are generally allocated to the genus Hydrophis and 13 to ten additional genera. In addition to these two major groups are three putatively 'primitive' monotypic genera, Hydrelaps darwiniensis, Ephalophis greyi and Parahydrophis mertoni. The present study investigated the evolutionary relationships of 23 representative species of marine hydrophiines, comprising 15 species from the Hydrophis group, six species from the Aipysurus group, and H. darwiniensis and P. mertoni, to address two broad aims. First, the aim was to provide a robust phylogeny for sea snakes to test previous phylogenetic hypotheses based on morphology, and thus provide some taxonomic stability to the group. Second, there was interest in evaluating the hypothesis that the Hydrophis group might represent a rapidly diverged adaptive radiation. A large mitochondrial DNA data set based on the cytochrome b gene (1080 bp, 401 parsimony informative) and the 16S rRNA gene (510 bp, 57 parsimony informative) was assembled and these data were analysed using parsimony, maximum-likelihood and Bayesian approaches. All analyses yielded virtually the same optimal tree, confirming that hydrophiine sea snakes comprise at least three lineages. The Aipysurus group formed a strongly supported and well-resolved monophyletic clade. The Hydrophis group also formed a strongly supported clade; however, resolution among the genera and species was very poor. Hydrelaps darwiniensis and P. mertoni formed a sister clade to the Hydrophis lineage. Our phylogeny was used to test the validity of previous taxonomic and phylogenetic hypotheses, and to demonstrate that the genus Hydrophis is not monophyletic. Genetic diversity relative to phenotypic diversity is four to seven times greater in the Hydrophis lineage compared with the Aipysurus lineage. The topology of our phylogenetic hypothesis, combined with the levels of genetic divergence relative to morphological diversity, demonstrate that the Hydrophis lineage represents a rapidly diverged adaptive radiation. The data are consistent with the hypothesis that this adaptive radiation may be due to historical sea level fluctuations that have isolated populations and promoted speciation

Can sea snakes slither through seascape structure? Comparative phylogeography and population genetics of Hydrophis group sea snakes in Australia and Southeast Asia

Pleistocene sea level changes substantially shaped the biogeography of northern Australia and the Indo-Malayan Archipelago (IMA). For co-distributed species, their phylogeographic and population genetic patterns are expected to be concomitant with geological transformations of the Pleistocene. However, species-specific ecologies and life history traits may also be influential in generating patterns which depart from simple expectations arising from biogeographic features. Thus, comparative population genetic studies, which use taxa that reduces variation in taxonomy and geography, may refine our understanding of how biogeographic elements shape the populations of co-occurring species. Here, we sampled two sea snake species, Hydrophis curtus and H. elegans, throughout their known ranges in the IMA and northern Australia. These sea snakes have similar life history strategies and ecologies as well as overlapping distributions across the Torres Strait, a well-known biogeographic feature. We analysed two mitochondrial DNA (mtDNA) fragments and 10 microsatellite loci using traditional population genetic approaches and used Bayesian clustering methods to examine species- specific phylogenetic relationships, genetic diversities, and population genetic structures. For both species, we found a consistent lack of significant genetic variation among sampling sites across the Gulf of Carpentaria (GOC) and the Great Barrier Reef (GBR). Similarly, Bayesian clustering showed no to weak genetic partitioning across the historical Torres Strait land bridge. Both species sampled in Australia displayed population expansion signatures in tests using mtDNA and microsatellite markers. We conclude that the phylogeographic and population genetic patterns of these sea snake species do not align with the Torres Strait land bridge. This lack of population genetic structure departs from previous findings on Aipysurus sea snakes and may be linked to the association of Hydrophis species to soft sediment habitats typically found across northern Australia. These divergent patterns between the sea snake groups present the importance of considering taxon-specific attributes in formulating conservation strategies

Alternate charging profiles for the onboard nickel cadmium batteries of the Explorer Platform/Extreme Ultraviolet Explorer

The Explorer Platform/Extreme Ultraviolet Explorer (EP/EUVE) spacecraft power is provided by the Modular Power Subsystems (MPS) which contains three 50 ampere-hour Nickel Cadmium (NiCd) batteries. The batteries were fabricated by McDonnell Douglas Electronics Systems Company, with the cells fabricated by Gates Aerospace Batteries (GAB), Gainesville, Florida. Shortly following launch, the battery performance characteristics showed similar signatures as the anomalous performance observed on both the Upper Atmosphere Research Satellite (UARS) and the Compton Gamma Ray Observatory (CGRO). This prompted the development and implementation of alternate charging profiles to optimize the spacecraft battery performance. The Flight Operations Team (FOT), under the direction of Goddard Space Flight Center's (GSFC) EP/EUVE Project and Space Power Applications Branch have monitored and managed battery performance through control of the battery Charge to Discharge (C/D) ratio and implementation of a Solar Array (SA) offset. This paper provides a brief overview of the EP/EUVE mission, the MPS, the FOT's battery management for achieving the alternate charging profile, and the observed spacecraft battery performance

Beyond the Obvious: Understanding and Integrating Producer-led and User-led Innovation Paradigms from New Perspectives

Innovation is key to ensuring sustained performance, generating economic growth, and driving progress – not only for individual organizations but also for societies as a whole. Yet, globalization, rapid technological change, and advances in information and communication technologies have turned innovation from an exclusive province of producers into a multilayered sphere that equally encompasses established manufacturing firms and entrepreneurs, as well as open collaboration communities and innovating end users. Hence, the traditional producer-led innovation paradigm is increasingly complemented and contested by a user-led counterpart. To understand the intricacies of this paradigm shift and successfully manage innovation efforts, both, from an organizational and a national level, management and policy makers are in dire need of new perspectives and differentiated insights into the two innovation paradigms, and especially their key drivers. Scientific research has greatly contributed to this quest by extensive investigations of internal and external drivers of organizational innovation, as well as person-related drivers of user innovation. But findings of central drivers are inconclusive and key areas for drivers, for example user innovators’ work environment, remain largely unexplored. Building on the conceptual distinction between producer-led and user-led innovation that frames today’s scientific and managerial discourse, this thesis is dedicated to the identification of central innovation drivers and the investigation of potentially arising interactions between the two paradigms. Specifically, to follow up on research gaps and provide new insights, organizational-level and individual-level resource-based theories are employed and two empirical studies on selected drivers of producer- and user-led innovation are conducted. Both studies extend traditional views on innovation in the two innovation paradigms and advance research by introducing new perspectives that explore beyond the obvious. First, study 1 investigates leadership as a key driver of innovation in the producer-led innovation paradigm by adopting a cross-dimensional perspective that combines innovation and efficiency performance dimensions. The study theoretically introduces and empirically analyzes newly developed scales of dual innovation leadership, a new leadership approach tailored to the unique requirements of the innovation process. Results of structural equation modeling with data from 194 executives of organizational units collected at two points in time empirically substantiate evidence that dual innovation leaders ensure sustainable organizational performance, and hence advance producer-led innovation. With regard to the user-led innovation paradigm, study 2 identifies user innovators’ work environment as a key driver of innovation and adopts a cross-domain perspective that bridges user innovators’ home and work sphere. Specifically, study 2 advances research by investigating a largely unexplored area and corroborating the notion of resource spillovers between different domains. Based on data of 147 work-inspired consumer innovators and three independent raters, results of structural equation modeling show that consumer innovators build job-related resources from their work environment that enhance the outcome of their household sector innovation efforts in terms of novelty, general use value, and technical feasibility. Second, innovation is a resource-intense undertaking and resources are increasingly in short supply. Thus, resource-protecting and mutually beneficial interactions may offer a sustainable approach to manage innovation in the new era of ‘dual paradigms’. Combining insights from study 1 and study 2, the thesis therefore illuminates the potential for interactions between the producer and user innovation sphere by elaborating how producer innovators may indirectly support user innovators. Moreover, the thesis exemplarily illustrates how (dual innovation) leadership targeted to producer-led innovation can foster cross-fertilization between the two paradigms by equally enhancing user-led innovation. To this end, an integrative perspective on the two paradigms is introduced. With these comprehensive, yet differentiated insights on key drivers and their interactions in producer- and user-led innovation, the thesis extends the scientific state of knowledge and suggests important implications for future research. Moreover, the thesis provides management and policy makers with a valuable guiding framework that may support innovation initiatives targeted to the successful realization of innovation endeavors and, hence, the fostering of economic, as well as societal progress

Nickel cadmium battery operations and performance

The Earth Radiation Budget Satellite (ERBS), Compton Gamma Ray Observatory (CGRO), Upper Atmosphere Research Satellite (UARS), and Extreme Ultraviolet Explorer (EUVE) spacecraft are operated from NASA's Goddard Space Flight Center (GSFC) in Greenbelt, Maryland. On-board power subsystems for each satellite employ NASA Standard 50 Ampere-hour (Ah) nickel-cadmium batteries in a parallel configuration. To date, these batteries have exhibited degradation over periods from several months (anomalous behavior, UARS and CGRO (MPS-1); to little if any, EUVE) to several years (old age, normal behavior, ERBS). Since the onset of degraded performance, each mission's Flight Operations Team (FOT), under the direction of their cognizant GSFC Project Personnel and Space Power Application Branch's Engineers has closely monitored the battery performance and implemented several charge control schemes in an effort to extend battery life. Various software and hardware solutions have been developed to minimize battery overcharge. Each of the four sections of this paper covers a brief overview of each mission's operational battery management and its associated spacecraft battery performance. Also included are new operational procedures developed on-orbit that may be of special interest to future mission definition and development

Tracking global population trends: population time-series data and a Living Planet Index for reptiles

Effective conservation action relies on access to the best-available species data. Reptiles have often been overlooked in conservation prioritization, especially because of a paucity of population data. Using data for 549 reptile populations representing 194 species from the Living Planet database, we provide the first detailed analysis of this database for a specific taxonomic group. We estimated an average global decline in reptile populations of 54-55% between 1970 and 2012. Disaggregated indices at taxonomic, system, and biogeographical levels showed trends of decline, often with wide confidence intervals because of a prevalence of short time series. We assessed gaps in our reptile time-series data and examined what types of publication they primarily originated from to provide an overview of the range of data sources captured in the Living Planet database. Data were biased toward crocodilians and chelonians, with only 1% and 2% of known lizard and snake species represented, respectively. Population time-series data stemmed primarily from published ecological research (squamates) and data collected for conservation management (chelonians and crocodilians). We recommend exploration of novel survey and analytical techniques to increase monitoring of reptiles, especially squamates, over time. Open access publication and sharing of data sets are vital to improve knowledge of reptile status and trends, aided by the provision of properly curated databases and data-sharing agreements. Such collaborative efforts are vital to effectively address global reptile declines