1,720,968 research outputs found
Historical shell size reduction of the dogwhelk (Nucella lapillus) across the southern UK
No full textBody size reduction is predicted to be one of the most common ecological responses to climate change, yet examples within some taxonomic groups, such as marine molluscs, are rare. Here, we document a significant reduction in shell size of the rocky shore gastropod Nucella lapillus across the southern UK using natural history collections and modern field data. These results are correlated with temporal changes in sea-surface temperature from a long-term monitoring station. The maximum height of N. lapillus shells has declined by approximately 18 mm over the past 100 years, and the median size of shells in large size classes declined by 6 mm during this time. Individuals are, on average, larger in the west than in the east, which is noted using both modern and historical samples. In some locations, there has been a local extinction of N. lapillus, potentially due to combined negative impacts of climate warming and TBT pollution. Our results further demonstrate the utility of natural history collections, paired with modern field sampling, to document biological response to climate change and other human impacts
Data from: predator-induced defences under tropicalisation: a biogeographic approach
No full textAim: The biogeography of predator-induced defences is an understudied area of predator-prey dynamics. Range overlap with predators that induce the response and local demographics (e.g., prey abundances) are likely to be important factors for determining the biogeographic distribution of induced defences within species. However, with climate warming, range expanding warm-water predators are increasingly preying upon temperate species. This is a consequence of a wider phenomenon known as tropicalisation. We aim to determine: (i) if individuals of a temperate barnacle with induced defences ("bent morphs") are primarily present where they co-occur with range-expanding warm-water predators (muricid snails) and, (ii) if bent morphs are size-structured within populations. Location: North-eastern Pacific rocky intertidal zone (~26-40ºN) Taxon: Tetraclita rubescens (Nilsson-Cantell, 1931), Balanomorpha Methods: We use photo quadrats from sites across the range of T. rubescens to determine the biogeographic distribution of populations with bent morphs and to assess size-structure. We use a combination of field surveys, literature, and museum occurrences to assess range overlap between cool and warm-water predators of T. rubescens and their association with populations with bent morphs and abundance patterns of T. rubescens. Results: Bent morphs are commonly found within the equatorward portion of the species' range (where abundances are highest), in populations overlapping with range expanding warm-water predators. Bent morphs primarily occur within the smaller size classes. Main conclusions: To be partly resilient to the effects of tropicalisation, temperate prey must acclimatize/adapt to altered predator-prey dynamics. Predator-induced defences are one way to do this. We show that bent morphs within a temperate prey species (T. rubescens) are largely restricted to populations that overlap with large-bodied and range-expanding warm-water predators. This is evidence for the partial resilience of T. rubescens to tropicalisation and provides the rationale for further exploration of the eco-evolutionary consequences of tropicalisation in this study system and others.</span
Dataset for: Disentangling the effects of ecology and life history on ectothermic temperature-size responses
No full textData used for analyses in the PhD thesis titled 'Disentangling the effects of ecology and life history on ectothermic temperature-size responses'. Species from two ectothermic taxa (Gastropoda and Lepidoptera) were included in analyses. Size measurements were taken from a combination of museum specimens and field studies, and temperature data was obtained from UK MET office.
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A comparison of epiphytic nematode diversity and assemblages in Corallina turves on British and South Korean coasts across hierarchical spatial scales
No full textCosmopolitan habitat-forming taxa of algae such as the genus Corallina provide an opportunity to compare patterns of biodiversity over wide geographic scales. Nematode assemblages inhabiting Corallina turves were compared between the south coasts of the British Isles and South Korea. A fully nested design was used with three regions in each country, two shores in each region and replicate samples taken from three patches on each shore to compare differences in the taxonomic and biological trait composition of nematode assemblages across scales. A biological traits approach, based on functional diversity of nematodes, was used to make comparisons between countries, among regions, between shores and among patches. The taxonomic and biological trait compositions of nematode assemblages were significantly different across all spatial scales (patches, shores, regions and countries). There is greater variation amongst nematode assemblages at the scale of shore than at other spatial scales. Nematode assemblage structure and functional traits are influenced by the local environmental factors on each shore including sea-surface temperature, the amount of sediment trapped in Corallina spp. and tidal range. The sea-surface temperature and the amount of sediment trapped in Corallina spp. were the predominant factors determining nematode abundance and composition of assemblages and their functional diversity
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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