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Thermal plasticity within and across generations and its relevance to contemporary evolution
No full text122 pg.Understanding and predicting how populations will react to changes in the environment is a long-standing goal in evolutionary ecology. It is also of considerable practical importance, as anthropogenic changes stress species worldwide. The relevance of phenotypic plasticity is becoming more apparent as species are forced to cope with rapid changes in the environment. This dissertation explores ways in which phenotypic plasticity will play a major role in determining the future of populations. In Chapters 1 and 2, I evaluate a modeling framework that could be used to predict plastic changes in key life history traits of ectotherms brought about by temperature. This work, based on the metabolic theory of ecology (MTE), assumes that biological rates scale exponentially with temperature. I first show the validity of the MTE for predicting lifespan gradients within species and then apply this temperature-life history relationship to predict changes in ectotherms resulting from global temperature increases over the next 50 years. In Chapter 3, I experimentally test the plastic response of sheepshead minnows, Cyprinodon variegatus, an estuarine fish common to the east coast, to combinations of temperature (24, 29, 34??C) and food availability (60, 80, or 100% of maximum consumption). The thermal response of juvenile growth rate was mediated by food availability, while the age at maturation was independently affected by temperature and food. Notably, and despite very different thermal and feeding regimes, the fish matured within a small size window. In Chapters 4 and 5, I explore transgenerational plasticity (TGP) as a means to cope with temperature changes. When the temperature experienced by the parents acts as a reliable indicator of thermal offspring environment, a parent can "pre-program" offspring traits appropriate for the predicted environment. This transfer of information from parent to offspring has been termed TGP, and is well studied in plants and invertebrates. In these chapters, I show that thermal TGP has a strong effect in larval growth of sheepshead minnows. I also explore how transgenerational and phenotypic plasticity interact to shape the size of fish throughout life, and provide evidence suggesting that the TGP effect lasts for at least 2 generations.Advisor(s): Munch, Stephan B.. Committee Member(s): Conover, David O.Futuyma, Douglas J.Lonsdale, Darcy J.Travis, Joseph ;Stony Brook University Libraries. SBU Graduate School in Department of Marine and Atmospheric Science. Charles Taber (Dean of Graduate School)
Semiparametric Bayesian modeling of density dependence
No full text110 pg.Density dependence is a foundation of population biology. Analysis of population data with parametric models has long provided estimates of the maximum reproductive rate and the form of density dependence. These in turn determine the limit of sustainable harvest and the population's stability, respectively. However, standard parametric analyses of population data generate incorrect inferences of density dependence in noisy and short series. Therefore, there is a clear need for improved statistical methods for inferring density dependence. In this thesis, I developed new semiparametric Bayesian (SB) methods for estimating reproductive rates and for identifying forms of density dependence. Using simulated data, I validated the superiority of the SB methods to parametric alternatives. Then, I conducted SB analyses of 285 fish populations' datasets to estimate reproductive rates and to identify the forms of density dependence. I compared the results of the SB analyses with those based on standard parametric analyses of the same datasets. The SB analysis indicated that the forms of density dependence in 3.4% of the datasets are Allee effects, whereas the parametric analysis indicated 1.5%, suggesting that Allee effects are more than twice as often as previously thought. However, both the SB and the parametric model (the linear model) generated essentially the same estimates of the reproductive rates, indicating that the linear model may be a reasonable approach to inferring the reproductive rates of fish populations.Advisor(s): Munch, Stephan B; Cerrato, Robert M. Committee Member(s): Ferson, Scott ; Ginzburg, Lev ; Sugihara, George.Stony Brook University Libraries. SBU Graduate School in Department of Marine and Atmospheric Science. Charles Taber (Dean of Graduate School)
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Empirical Modeling of Population Recovery Using Marine Rotifers
Get PDFThree quarters of the world’s fisheries are classified as overexploited or depleted. Management programs have mainly focused on reducing the fishing pressure on these stocks. However, some stocks fail to rebound even after fishing effort is reduced and hatchery programs may be used to facilitate population recovery. Despite substantial investment in hatchery supplementation, failed programs outnumber successful ones. It therefore seems vital to explore the abiotic and biotic factors that hinder their success. This thesis addresses the performance of several active recovery policies through the use of multispecies microcosms. Specifically, I ask 1) whether one or several supplementation efforts are needed before a sustainable stock population is established and 2) what factors influence the success or failure of recovery in these microcosms. My results show that the community within an ecosystem may strongly influence a recovery program’s likelihood of success and that multiple small additions may offer a better chance of success than one or several large additions. My results support previously made arguments that community ecology is an important framework for fisheries management. Moreover, commercial fishing alters community structure and this may happen in a way that inhibits population recovery. I suggest reconceiving population recovery as ‘facilitated invasion’ may provide useful guidance for designing future recovery programs
Extensions of empirical dynamic modeling for prediction and management in ecological systems
Get PDFHumans simultaneously depend on and affect the health of natural ecosystems on a global scale, so it is important to establish ecosystem management practices that will ensure longevity and mutualism in the relationship between humans and nature. For decades, scientists have worked in a single-species paradigm to inform most management decisions in ecology. Specifically, species have traditionally been modeled and assessed individually, with limited consideration of how they interact with other species and drivers in their ecosystems. This has led to inaccurate predictions in the past, so there has been a recent push to account for more complexity in ecological models, as this would facilitate better management decisions. While one natural extension is to incorporate multiple variables into mechanistic models, this is challenging and inefficient with our current understanding of ecosystems. Alternatively, data-driven models offer a way to predict population dynamics without requiring specific inputs for all ecosystem components.In this dissertation, we explore empirical dynamic modeling, a data-driven approach to forecasting which is derived from principles of dynamical systems theory. Empirical dynamic modeling is a promising tool that accounts for system complexity without requiring strong assumptions or full system observations. However, it cannot cope with some limitations that are common in ecological datasets, including short time series and missing samples. Thus, we develop extensions of empirical dynamic modeling to address these limitations. We then apply this approach along with optimal control methods to generate management decisions in ecological pest control scenarios. Throughout the dissertation, we demonstrate the effectiveness of our method developments on a wide range of simulated data examples in addition to empirical data from high-impact terrestrial and aquatic ecosystems
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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