1,721,017 research outputs found
Range shifts and the population dynamics of tropical, subtropical, and rare fishes in New Zealand : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Ecology at Massey University, Auckland, New Zealand
Get PDFThe rate of species re-distribution during the Anthropocene is unprecedented. The expectation is that as global temperatures continue to rise, tropical regions will become increasingly inhospitable, and temperate regions will become more tropicalised and biodiverse as species track favourable conditions poleward. Climate change mediated range shifts are causing the distinctness of species assemblages and biogeographic regions to erode, and the most significant biodiversity changes are currently occurring in the coastal marine environment. Identifying the species currently undergoing range shifts and predicting where and when future climate-mediated range shifts will occur is critical to proactively manage changes in resource-based human livelihoods and meet conservation goals. However, identifying range shifts is often hampered by a lack of baseline distributional data. In the marine environment, large areas remain under-surveyed, and given that marine species are often cryptic, wide-ranging, and highly mobile, our knowledge of geographic distributions is far from complete. This thesis aimed to fill this knowledge gap by using a combination of novel data sources and methods to set an accurate baseline for the spatio-temporal distribution of tropical, subtropical and rare teleost fishes in a temperate marine setting and develop methods to allow us to monitor future biodiversity change. Teleost fishes are valuable indicators of current and future change; they are early responders to climate-mediated ocean warming and are charismatic and highly visible, increasing the ease of monitoring, particularly by citizen scientists. First, data sourced from published accounts, scientific surveys, commercial catches, and citizen science sources were examined to determine the spatio-temporal distribution of tropical, subtropical, and rare fish in NZ waters. I characterise their contribution to New Zealand’s marine biodiversity and set a baseline for future monitoring of climate-driven biodiversity changes. I found that the contribution of tropical, subtropical, and rare fishes to New Zealand biodiversity is significant, and their occurrences and diversity have increased over the past 50 years. Second, I present and test a novel method that combines citizen science with expert knowledge to classify out-of-range occurrences for marine fishes as potential range extensions or human-mediated dispersal events. The stepwise approach uses qualitative decision making and scoring tools to classify citizen science observations of tropical, subtropical and rare fishes and combines these classifications with expert validation to increase confidence. By applying the method to a range of focal species, I successfully identified species that had undergone range shift into or within New Zealand waters and one species whose range shift was facilitated by human-mediated dispersal. The ease of our approach and the intuitive outputs should appeal to managers and science practitioners concerned with climate-induced biodiversity changes and alien species detection. Third, I apply the classification methods and distributional baselines from Chapters 2 and 3 to citizen science occurrence data for tropical, subtropical and rare fishes in New Zealand waters to identify those species that are tohu (indicators) of change and identify the areas where biogeographic change is occurring. Labrids and Pomacentrids disproportionately contributed to out-of-range occurrences, and 87% of all out-of-range occurrences represented potential and actual range extensions. Locations with a high occurrence of potentially range shifting fishes were centred in north-eastern New Zealand, with occurrences of potentially range shifting fishes decreasing with increasing latitude. I surmise that climate-mediated biodiversity change in New Zealand fishes is occurring and present a list of species contributing to range shifts by region to facilitate effective monitoring and impact mitigation. Overall, this thesis contributes new knowledge regarding the rate of poleward climate-mediated range shifts of marine teleost fishes to New Zealand and a suite of novel tools to facilitate future monitoring and impact mitigation of climate-mediated range shifts. I successfully demonstrate the capacity of ocean-going citizen scientists to identify range shifts in the marine environment and overcome some of the common biases and sampling errors associated with citizen science data by incorporating expert validation and knowledge. My results suggest that New Zealand is currently not a hotspot for climate-mediated biodiversity shifts but biodiversity shifts are occurring and the contribution of tropical, subtropical and rare fishes to New Zealand diversity is increasing. These contributions of this thesis will provide a baseline and framework for resource managers, science practitioners and citizens, to monitor range shifts and manage the impacts of climate change on New Zealand’s marine ecosystem
Historical biogeography of marine ray-finned fishes (Actinopterygii) of the Southwest Pacific : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Marine Evolutionary Ecology at Massey University, Auckland, New Zealand
Get PDFCurrent environmental and anthropogenic pressures are driving significant biodiversity loss and range shifts in marine environments. Understanding how biodiversity is generated and how it responded to past environmental changes is fundamental to inform future management strategies for marine resources. As the largest ubiquitous taxonomic group among marine vertebrates, ray-finned fishes (Actinopterygii) represent the best model to understand the generation of biodiversity and the processes that shaped contemporary geographic patterns in the sea. In this sense, centers of marine endemism are of evolutionary value as they translate evolutionary and ecological mechanisms that drive biodiversity dynamics. In the Pacific Ocean, endemism centers for marine fishes are mainly located in remote oceanic islands at the periphery of the tropical West Pacific which harbors the highest levels of biodiversity. Biogeographic research suggests that marine fish endemism in the oceanic islands of the Central Pacific originated via multiple independent jump-dispersal colonization events, and that the islands have acted as sources of new unique biodiversity. However, as the evolutionary setting starts to be revealed for marine fish endemism in the Pacific, processes that generate and maintain biodiversity in other peripheral islands remain unknown. My thesis aims to fill this gap by studying the origin, evolution, and processes that have shaped endemism and biodiversity of marine fishes in the Southwest Pacific. I examined the historical biogeography of the region´s marine fish fauna using open-access molecular data to infer evolutionary histories, and geographic distribution information to assess spatial patterns of endemism and biodiversity. Data were analyzed across three research projects based on time-calibrated phylogenies, probabilistic biogeographic modeling, and statistical analysis of phylogenetic measures of endemism and biodiversity. My results confirm the role of the subtropical islands of the Southwest Pacific as sources of new unique biodiversity, identify mainland Australia as the major source of endemic lineages, highlight the significance of jump-dispersal and vicariance in shaping endemism patterns, and reveal that the processes shaping patterns of endemism and biodiversity differ at local scales. My thesis contributes to the understanding of unique contemporary biogeographic patterns in the marine fish fauna of the Southwest Pacific
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
Seascape genetics of Indo-Pacific reef organisms: methodologies and case studies for an emerging discipline
Get PDFMetadata Stewardship in Genetic Research: Enabling a Research Community Toward Best-practice
No full textFor over four decades, scientists have been collecting genetic DNA sequence data for thousands of the world’s species. In the biodiversity and eco-evolutionary sciences, these data are generated to describe new species, define their evolutionary relationships, determine the levels of dispersal among populations, and assess levels of genetic diversity across a species range. The rate at which we accrue these DNA sequences has increased over time as the use of genetic data has diversified, and the sequencing technologies used to decode the DNA sequences of organisms have become faster, cheaper, and much higher through-put. As this trend continues into the future, it is anticipated that we may soon have more DNA sequences in a digital form than we have existing in the natural world
Phylogeography of the New Zealand Common Skink Species Complex, Oligosoma Nigriplantare
No full textThe complex climatic and geological history of New Zealand has hindered our understanding of the processes driving the evolution of New Zealand's biota. In this thesis, I investigated the relative roles of different climatic and geological processes in the recent evolutionary history of New Zealand using phylogeographic methods and the New Zealand common skink (Oligosoma nigriplantare) as a model taxon. Oligosoma nigriplantare consists of two subspecies; O. n. nigriplantare found in the Chatham Islands, and O. n. polychroma that is distributed throughout the southern North Island, much of the South Island and Stewart Island. Both subspecies are highly variable in morphology, behaviour and ecology which has led to a number of further distinct groups being proposed. Using phylogenetic and molecular analyses of mitochondrial DNA (ND2 and ND4) I found a high level of divergence (~9%) between O. n. nigriplantare and O. n. polychroma. These data suggest that O. n. nigriplantare and O. n. polychroma should be recognised as separate species. I found no support for any other previously proposed distinct groups within the species complex. Divergence time estimates indicated O. nigriplantare colonised the Chatham Islands within the last ~6.4 million years via transoceanic dispersal. I revealed patterns of both isolation by distance and restricted gene flow using analysis of molecular variance and nested clade analysis across the Chatham Islands, consistent with the history of sea level changes in the archipelago. Across the range of O. n. polychroma, five geographically distinct clades were revealed. The phylogeographic pattern and inferred age of these clades suggests mountain building during the Pliocene along active fault lines promoted their divergence 3.98-5.45 million years ago. A short interspersed nuclear clement polymorphism in the myosin gene intron (MYH-2) confirmed a pattern of restricted gene flow between lineages on either side of the Southern Alps. The straits between the main islands of New Zealand accounted for much less of the variation found within O. n. polychroma, most likely due to the repeated emergence of inter-island landbridges during the Pleistocene that facilitated gene flow. Overall, my research has found evolutionary independence of groups within the common skink species complex, providing valuable insight for the conservation management of this species. In the future, investigating the phylogeography of co-occurring species will reveal further details on the nature of these phylogeographic patterns and the processes driving evolution in New Zealand
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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