538 research outputs found
Spatiotemporal population genomics of marine species : invasion, expansion, and connectivity
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2017Every genome tells a story. This dissertation contains four such stories, focused on shared themes
of marine population dynamics and rapid change, with an emphasis on invasive marine species.
Biological invasions are often characterized by a range expansion, during which strong genetic
drift is hypothesized to result in decreased genetic diversity with increased distance from the center
of the historic range, or the point of invasion. In this dissertation, population genetic and genomic
tools are used to approach complex and previously intractable fundamental questions pertaining
to the non-equilibrium dynamics of species invasions and rapid range expansions in two invasive
marine species: the lionfish, Pterois volitans; and the shrimp, Palaemon macrodactylus. Using
thousands of loci sequenced with restriction enzyme associated DNA sequencing in these two
systems, this research tests theoretical predictions of the genomic signatures of range expansions.
Additionally, the first chapter elucidates patterns of population genetic connectivity for deep-sea
invertebrates in the New Zealand region demonstrating intimate relationships between genetics,
oceanographic currents, and life history traits. Invasive shrimp results extend our understanding of
marine population connectivity to suggest that human-mediated dispersal may be as important—
if not more important—than oceanographic and life history considerations in determining genetic
connectivity during specific phases of marine invasions. In invasive populations of lionfish,
measures of genomic diversity, including a difference between observed and expected
heterozygosity, were found to correlate with distance from the point of introduction, even in the
absence of spatial metapopulation genetic structure. These results indicate a signal of rapid range
expansion. The final study in this dissertation uses an innovative temporal approach to explore
observed genomic patterns in the lionfish. In all, this dissertation provides a broad perspective
through the study of multiple species undergoing superficially parallel processes that, under more
intense scrutiny, are found to be mechanistically unique. It is only through comparative approaches
that predictable patterns of population dynamics will emerge.I was privileged to receive support through a National
Science Foundation (NSF) Graduate Research Fellowship (Grant No. 1122374), a Woods Hole
Oceanographic Institution (WHOI) Fellowship administered through the Academic Program
Office, funding from NSF award OCE-1131620, and the National Oceanic and Atmospheric
Administration (NOAA OER #NA08OAR4600757). Research funding for sample collection,
laboratory materials, sequencing, and analysis was provided by the WHOI Coastal Ocean
Institute, WHOI Ocean Ventures Fund, WHOI James Education Fund for Ocean Exploration,
WHOI Biology Educational Fund, Woods Hole Sea Grant New Initiative Award, Massachusetts
Office of Coastal Zone Management, Northeast Sea Grant Consortium, and the PADI
Foundation (Grant No. 14904). Additional research support was provided by the NSF (OCE-
1131620) to Timothy M. Shank
Population genomics of rapidly invading lionfish in the Caribbean reveals signals of range expansion in the absence of spatial population structure.
© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bors, E. K., Herrera, S., Morris, J. A., Jr., & Shank, T. M. Population genomics of rapidly invading lionfish in the Caribbean reveals signals of range expansion in the absence of spatial population structure. Ecology and Evolution, 9(6), (2019):3306-3320, doi:10.1002/ece3.4952.Range expansions driven by global change and species invasions may have significant genomic, evolutionary, and ecological implications. During range expansions, strong genetic drift characterized by repeated founder events can result in decreased genetic diversity with increased distance from the center of the historic range, or the point of invasion. The invasion of the Indo‐Pacific lionfish, Pterois volitans, into waters off the US East Coast, Gulf of Mexico, and Caribbean Sea provides a natural system to study rapid range expansion in an invasive marine fish with high dispersal capabilities. We report results from 12,759 single nucleotide polymorphism loci sequenced by restriction enzyme‐associated DNA sequencing for nine P. volitans sampling areas in the invaded range, including Florida and other sites throughout the Caribbean, as well as mitochondrial control region D‐loop data. Analyses revealed low to no spatially explicit metapopulation genetic structure, which is partly consistent with previous finding of little structure within ocean basins, but partly divergent from initial reports of between‐basin structure. Genetic diversity, however, was not homogeneous across all sampled sites. Patterns of genetic diversity correlate with invasion pathway. Observed heterozygosity, averaged across all loci within a population, decreases with distance from Florida while expected heterozygosity is mostly constant in sampled populations, indicating population genetic disequilibrium correlated with distance from the point of invasion. Using an FST outlier analysis and a Bayesian environmental correlation analysis, we identified 256 and 616 loci, respectively, that could be experiencing selection or genetic drift. Of these, 24 loci were shared between the two methods.We thank the many participants of the Gulf and Caribbean Fisheries Institute for providing lionfish samples from around the Caribbean region, as well as Dr. Bernard Castillo at the University of the Virgin Islands and Kristian Rogers at the Biscayne Bay National Park. We would like to acknowledge Alex Bogdanoff at NOAA, Beaufort NC, for assistance with sample acquisition; Camrin Braun at WHOI, for assistance with the calculation of oceanic distances between sites; Dr. Tom Schultz at Duke Marine Lab and Dr. Margaret Hunter at USGS for discussions concerning ongoing population genetic projects; and Jack Cook at the WHOI Graphics department for his assistance in generating maps of the study area. We would like to extend a special thank you to Dr. John Wakeley of Harvard University for assistance in the interpretation of data. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. 1122374. Sequencing funding was provided in part by the PADI Foundation Grant No. 14904. Additional research support was provided by the Woods Hole Oceanographic Institution (WHOI) Ocean Ventures Fund, the Coastal Ocean Institute at WHOI, the National Science Foundation (OCE‐1131620 to TMS), and the James Education Fund for Ocean Exploration within the Ocean Exploration Institute at WHOI. Publication of this paper was supported, in part, by the Henry Mastin Graduate Student Fund administered by the Oregon State University Department of Fisheries and Wildlife. Finally, we sincerely thank the reviewers and editors who helped to strengthen this manuscript
Defining Image Memorability using the Visual Memory Schema
Memorability of an image is a characteristic determined by the human observers’ ability to remember images they have seen. Yet recent work on image memorability defines it as an intrinsic property that can be obtained independent of the observer. The current study aims to enhance our understanding and prediction of image memorability, improving upon existing approaches by incorporating the properties of cumulative human annotations. We propose a new concept called the Visual Memory Schema (VMS) referring to an organization of image components human observers share when encoding and recognizing images. The concept of VMS is operationalised by asking human observers to define memorable regions of images they were asked to remember during an episodic memory test. We then statistically assess the consistency of VMSs across observers for either correctly or incorrectly recognised images. The associations of the VMSs with eye fixations and saliency are analysed separately as well. Lastly, we adapt various deep learning architectures for the reconstruction and prediction of memorable regions in images and analyse the results when using transfer learning at the outputs of different convolutional network layers
Assessment for Active Living
Robert Wood Johnson Foundation’s Active Living by Design (ALbD) grant program funded 25 communities across the U.S. The ALbD National Program Office (NPO) supported grantee community partnerships with technical assistance for assessment, planning, and implementation activities intended to increase population levels of physical activity
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Structurally-related (−)-epicatechin metabolites in humans: assessment using de novo chemically synthesized authentic standards
Accumulating data suggest that diets rich in flavanols and procyanidins are beneficial for human health. In this context, there has been a great interest in elucidating the systemic levels and metabolic profiles at which these compounds occur in humans. While recent progress has been made, there still exist considerable differences and various disagreements with regard to the mammalian metabolites of these compounds, which in turn is largely a consequence of the lack of availability of authentic standards that would allow for the directed development and validation of expedient analytical methodologies. In the present study, we developed a method for the analysis of structurally-related flavanol metabolites using a wide range of authentic standards. Applying this method in the context of a human dietary intervention study using comprehensively characterized and standardized flavanol- and procyanidin-containing cocoa, we were able to identify the structurally-related (−)-epicatechin metabolites (SREM) postprandially extant in the systemic circulation of humans. Our results demonstrate that (−)-epicatechin-3′-β-D-glucuronide, (−)-epicatechin-3′-sulfate, and a 3′-O-methyl(−)-epicatechin-5/7-sulfate are the predominant SREM in humans, and further confirm the relevance of the stereochemical configuration in the context of flavanol metabolism. In addition, we also identified plausible causes for the previously reported discrepancies regarding flavanol metabolism, consisting to a significant extent of inter-laboratory differences in sample preparation (enzymatic treatment and sample conditioning for HPLC analysis) and detection systems. Thus, these findings may also aid in the establishment of consensus on this topic
Komplex molekuláris genetikai vizsgálati algoritmus myeloproliferativ neoplasiák diagnosztikájában
Introduction: Mutations in Janus kinase 2, calreticulin and thrombopoietin receptor genes have been identified in the genetic background of Philadelphia chromosome negative, "classic" myeloproliferative neoplasms. Aim: The aim of the authors was to identify driver mutations in a large myeloproliferative cohort of 949 patients. Method: A complex array of molecular techniques (qualitative and quantitative allele-specific polymerase chain reactions, fragment analyzes, high resolution melting and Sanger sequencing) was applied. Results: All 354 patients with polycythemia vera carried Janus kinase 2 mutations (V617F 98.6%, exon 12: 1.4%). In essential thrombocythemia (n = 468), the frequency of V617F was 61.3% (n = 287), that of calreticulin 25.2% (n = 118), and that of thrombopoietin receptor mutations 2.1% (n = 10), while 11.3% (n = 53) were triple-negative. Similar distribution was observed in primary myelofibrosis (n = 127): 58.3% (n = 74) V617F, 23.6% (n = 30) calreticulin, 6.3% (n = 8) thrombopoietin receptor mutation positive and 11.8% (n = 15) triple-negative. Conclusions: The recent discovery of calreticulin gene mutations led to definite molecular diagnostics in around 90% of clonal myeloproliferative cases. Orv. Hetil., 2014, 155(52), 2074-2081
Local Patch Blind Spectral Watermarking Method for 3D Graphics
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