1,721,001 research outputs found
Patterns and relationships of the distribution of arctic and boreal forest herbivores: A three-dimensional approach.
No full textBiodiversity is a complex concept that presents three primary facets: genetic, species and ecological diversity. However, biodiversity is usually viewed and valued in terms of the number of discrete species present. This approach has been demonstrated to be insufficient. Therefore, three synergetic methods that function as proxies for the three facets of biodiversity, genetic, species and ecological diversity, are used in this study to provide a better understanding of biodiversity. These methods are phylogenetic diversity, species richness and functional diversity respectively. The relationship between phylogenetic or functional diversity with species richness yields information on the evolutionary history and ecological niche representation through clustering and dispersion. The arctic and boreal biomes are under great threat from climate change and land-use change and provide important ecosystems services for both, local and global communities. In order to better understand these biomes, we’ve focused on a group of taxa that has a wide range of functions in the ecosystem and that is composed from several genetic lineages, the vertebrate herbivores. Therefore, the aim of this study is to further our understanding of the biodiversity patterns and relationships of arctic and boreal herbivores. We found that all three biodiversity measures increased towards the south, possibly correlated to plant productivity. However functional diversity did not present such a strong gradient with the values in the north not reducing drastically as in the other measures. We have identified a “doughnut” pattern of functional dispersal in the arctic and boreal biomes with functional clustering at high and low latitudes and functional dispersion at mid-latitudes. Which indicates that at high and low altitudes herbivores are functionally similar from different environmental pressures, such as predation and abiotic conditions at low and high altitudes respectively. Furthermore, we have identified areas of a possible radiation event in south eastern Russia near the Mongolian border as well as an area of a relatively recent invasion of herbivores in the Labrador Peninsula. Our study demonstrates the importance of including trophic dynamics in biodiversity assessments and calls for future studies that explore the relationship between biodiversity measures and trophic interactions
Functional traits of Epirrita autumnata (autumnal moth) across space and time: An entomological collection-based study
Get PDFNaturhistoriske samlinger representerer en enorm kilde til informasjon som knytter individer fra mange forskjellige arter til et punkt i rom og tid. Dette gjør det mulig å studere og analysere hvordan ulike artsegenskaper endres i forhold til lokale miljøforhold. Her undersøker jeg hvordan vingelengde, areal, farge og symmetri varierer med klima. Jeg fokuserer på den velkjente bjørkeavløveren Epirrita autumnata (høstmøll). Eksemplarene som er brukt her er samlet fra Norge og kuratert innenfor de naturhistoriske samlingene ved NTNU Universitetsmuseet. Jeg fotograferer individene og bruker bildeanalyser for å måle funksjonelle trekk. GLS-modeller brukes til å teste hvordan egenskapene varierer med klimaforhold, der vårtemperatur har negativ effekt på vingelengde, men likevel positiv effekt på svingende asymmetri i vingeareal. Desimalbreddegrad og sommernedbør har en positiv effekt på vingelengden. Temperaturen er ikke signifikant i endring av egenskaper som vingefarge og svingende asymmetri i vingelengden. Mønstrene som er funnet kan være nyttige for å forutsi arters respons på klimaendringer, mens metoden kan brukes på andre arter av interesse.Natural history collections represent an immense source of information relating individuals from different species to a point in space and time. This allows the study and analysis of how species traits change in relation to local environmental conditions. Here I investigate how wing length, area, color, and symmetry vary with climate. I focus on the well-known birch defoliator Epirrita autumnata (autumnal moth). The specimens used here were collected from Norway and curated within the natural history collections at the NTNU University Museum. I photograph the specimens and use image analyses to measure functional traits. GLS models are used to assess how the traits vary with climate conditions, where spring temperature has a negative effect on wing length, yet a positive effect on fluctuating asymmetry of wing area. Latitude and summer precipitation have a positive effect on wing length. Temperature is not significant in the change of traits such as wing color and fluctuating asymmetry of wing length. The patterns found may be of use to predict species response to climate change, while the method may be applied to other species of interest
Patterns and relationships of the distribution of arctic and boreal forest herbivores: A three-dimensional approach.
Get PDFBiodiversity is a complex concept that presents three primary facets: genetic, species and ecological diversity. However, biodiversity is usually viewed and valued in terms of the number of discrete species present. This approach has been demonstrated to be insufficient. Therefore, three synergetic methods that function as proxies for the three facets of biodiversity, genetic, species and ecological diversity, are used in this study to provide a better understanding of biodiversity. These methods are phylogenetic diversity, species richness and functional diversity respectively. The relationship between phylogenetic or functional diversity with species richness yields information on the evolutionary history and ecological niche representation through clustering and dispersion. The arctic and boreal biomes are under great threat from climate change and land-use change and provide important ecosystems services for both, local and global communities. In order to better understand these biomes, we’ve focused on a group of taxa that has a wide range of functions in the ecosystem and that is composed from several genetic lineages, the vertebrate herbivores. Therefore, the aim of this study is to further our understanding of the biodiversity patterns and relationships of arctic and boreal herbivores. We found that all three biodiversity measures increased towards the south, possibly correlated to plant productivity. However functional diversity did not present such a strong gradient with the values in the north not reducing drastically as in the other measures. We have identified a “doughnut” pattern of functional dispersal in the arctic and boreal biomes with functional clustering at high and low latitudes and functional dispersion at mid-latitudes. Which indicates that at high and low altitudes herbivores are functionally similar from different environmental pressures, such as predation and abiotic conditions at low and high altitudes respectively. Furthermore, we have identified areas of a possible radiation event in south eastern Russia near the Mongolian border as well as an area of a relatively recent invasion of herbivores in the Labrador Peninsula. Our study demonstrates the importance of including trophic dynamics in biodiversity assessments and calls for future studies that explore the relationship between biodiversity measures and trophic interactions
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
VARIATION IN PREVALENCE OF INVERTEBRATE HERBIVORY AMONG NATIVE AND NON-NATIVE PLANT SPECIES IN A BOTANICAL GARDEN.
No full textPlanteeting er en sentral økosystemprosess som påvirker det strukturelle mangfoldet av vegetasjon gjennom direkte forbruk av plantevevet og indirekte endrer stabiliteten til økosystemene. Invertebrate planteetere oppveier vertebrate planteetere i enkelte økosystemer, og utbrudd av virvelløse dyr kan alvorlig skade vegetasjonen og redusere forekomsten av dominerende plantearter over et stort område. Enemy Release Hypothesis (ERH) og Biotic Resistance er motstridende hypoteser som tar for seg suksessen eller fiaskoen til ikke-innfødte planter i et introdusert område. ERH og den biotiske motstanden trenger ikke å være fullstendig motstridende, en ikke-innfødt art i et introdusert område kan frigjøres fra spesialisters planteetere (ERH), men kan også møte nye generalistiske planteetere som den ikke har vært i stand til å avskrekke (Biotisk Resistent). Samspillet mellom virvelløse planteetere, med forskjellige fôringslaug, som en drivkraft for suksess for ikke-innfødte planter i en introdusert region er dårlig forstått. Planteetende prevalens og intensitet av planteetende skader ved bruk av fem forskjellige fôringslaug av planteetere i en botanisk hage i Trondheim, Norge, ble undersøkt. Invertebrate planteetende data fra 629 individuelle plantearter, hvorav 110 var hjemmehørende plantearter og 519 var ikke-hjemmehørende arter i to sesonger (tidlig sommer og sensommer) ble registrert. Planteetende prevalens så vel som intensiteten av planteetende skader blant stedegne plantearter og ikke-hjemmehørende plantearter ble sammenlignet i to sesonger. Den planteetende variasjonen mellom ikke-hjemmehørende planter med et større antall innfødte slekter eller familieplantearter og ikke-hjemmehørende planter med mindre native slekter eller kjente plantearter ble også studert i hagen. Innfødte plantearter led betydelig høyere planteetende prevalens (andelen arter med skade) enn ikke-innfødte i tre planteetende skader (tygging, saftsuging og ukjente skader), mens i to skader (bladgruvedrift og galleskader) hadde innfødte mindre planteetende prevalens enn ikke-innfødte planter. Intensiteten av planteetende skader (andelen bladskader) for alle planteetende fôringslaug var høyere hos innfødte enn hos ikke-innfødte plantearter. Ikke-innfødte plantearter med høyere antall innfødte slektninger eller native familiære arter led høyere prevalens av planteetende enn de med færre slektninger eller familiære arter og slektspar viste betydelig variasjon enn familiepar i denne studien. Vår studie støtter ERH til en viss grad som en mekanisme som forklarer at ikke-innfødte lider mindre planteetende skader enn ikke-innfødte, faktisk varierer planteetende skadene med forskjellige planteetere som fôrer laug. Dette betyr at ERH sannsynligvis gjelder for en begrenset undergruppe av planteetere
VARIATION IN PREVALENCE OF INVERTEBRATE HERBIVORY AMONG NATIVE AND NON-NATIVE PLANT SPECIES IN A BOTANICAL GARDEN.
Get PDFPlanteeting er en sentral økosystemprosess som påvirker det strukturelle mangfoldet av vegetasjon gjennom direkte forbruk av plantevevet og indirekte endrer stabiliteten til økosystemene. Invertebrate planteetere oppveier vertebrate planteetere i enkelte økosystemer, og utbrudd av virvelløse dyr kan alvorlig skade vegetasjonen og redusere forekomsten av dominerende plantearter over et stort område. Enemy Release Hypothesis (ERH) og Biotic Resistance er motstridende hypoteser som tar for seg suksessen eller fiaskoen til ikke-innfødte planter i et introdusert område. ERH og den biotiske motstanden trenger ikke å være fullstendig motstridende, en ikke-innfødt art i et introdusert område kan frigjøres fra spesialisters planteetere (ERH), men kan også møte nye generalistiske planteetere som den ikke har vært i stand til å avskrekke (Biotisk Resistent). Samspillet mellom virvelløse planteetere, med forskjellige fôringslaug, som en drivkraft for suksess for ikke-innfødte planter i en introdusert region er dårlig forstått. Planteetende prevalens og intensitet av planteetende skader ved bruk av fem forskjellige fôringslaug av planteetere i en botanisk hage i Trondheim, Norge, ble undersøkt. Invertebrate planteetende data fra 629 individuelle plantearter, hvorav 110 var hjemmehørende plantearter og 519 var ikke-hjemmehørende arter i to sesonger (tidlig sommer og sensommer) ble registrert. Planteetende prevalens så vel som intensiteten av planteetende skader blant stedegne plantearter og ikke-hjemmehørende plantearter ble sammenlignet i to sesonger. Den planteetende variasjonen mellom ikke-hjemmehørende planter med et større antall innfødte slekter eller familieplantearter og ikke-hjemmehørende planter med mindre native slekter eller kjente plantearter ble også studert i hagen. Innfødte plantearter led betydelig høyere planteetende prevalens (andelen arter med skade) enn ikke-innfødte i tre planteetende skader (tygging, saftsuging og ukjente skader), mens i to skader (bladgruvedrift og galleskader) hadde innfødte mindre planteetende prevalens enn ikke-innfødte planter. Intensiteten av planteetende skader (andelen bladskader) for alle planteetende fôringslaug var høyere hos innfødte enn hos ikke-innfødte plantearter. Ikke-innfødte plantearter med høyere antall innfødte slektninger eller native familiære arter led høyere prevalens av planteetende enn de med færre slektninger eller familiære arter og slektspar viste betydelig variasjon enn familiepar i denne studien. Vår studie støtter ERH til en viss grad som en mekanisme som forklarer at ikke-innfødte lider mindre planteetende skader enn ikke-innfødte, faktisk varierer planteetende skadene med forskjellige planteetere som fôrer laug. Dette betyr at ERH sannsynligvis gjelder for en begrenset undergruppe av planteetere.Herbivory is a key ecosystem process that affects structural diversity of vegetation through direct consumption of the plant tissues and indirectly alters the stability of ecosystems. Invertebrate herbivores outweigh vertebrate herbivores in some ecosystem and outbreaks of invertebrates can seriously damage vegetation and reduce the abundance of dominant plant species over a vast area. The Enemy Release Hypothesis (ERH) and the Biotic Resistance are conflicting hypothesis that address the success or failure of non-native plants in an introduced range. The ERH and the Biotic Resistance do not have to be completely contradictory, a non-native species in an introduced range might release from specialists’ herbivores (ERH) but may also encounter new generalist herbivores that it has not been able to deter (Biotic Resistant). The interaction between invertebrate herbivory, with different feeding guilds, as a driver of success of non-native plants in an introduced region is poorly understood. The herbivory prevalence and intensity of herbivory damages using five different feeding guilds of herbivores in a botanical garden in Trondheim, Norway was investigated. Invertebrate herbivory data from 629 individual plant species, of which 110 were native plant species and 519 were non-native species in two seasons (early summer and late summer) were recorded. Herbivory prevalence as well as intensity of herbivory damages among native plant species and non-native plant species were compared in two seasons. The herbivory variation between non-native plants with a greater number of native congeners or confamilial plant species and non-native plants with lesser native congeners or confamilial plant species was also studied in the garden. Native plant species suffered significant higher herbivory prevalence (the proportion of species with damage) than non-native in three herbivory damages (chewing, sap-sucking and unknown damages) while in two damages (leaf mining and galls damage) natives had lesser herbivory prevalence than non-native plants. Intensity of herbivory damage (the proportion of leaves damage) for all herbivore feeding guilds was higher in natives than in non-native plant species. Non-native plant species with higher number of native congeners or native confamilial species suffered higher prevalence of herbivory than those with fewer congeners or confamilial species and congeners pair showed significant variation than confamilial pair in this study. Our study supports the ERH to only a certain extent as a mechanism explaining non-native suffer less herbivory damages than non-native, in fact the herbivory damages vary with different herbivores feeding guilds. This means the ERH probably applies to a limited subset of herbivores
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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