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Sökning: WFRF:(Christidis P)

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11.
  • Christidis, N, et al. (författare)
  • Salivary Alpha-Amylase in Experimentally-Induced Muscle Pain
  • 2020
  • Ingår i: Diagnostics (Basel, Switzerland). - : MDPI AG. - 2075-4418. ; 10:9
  • Tidskriftsartikel (refereegranskat)abstract
    • Salivary alpha-amylase (sAA) is a marker of psychological stress and might also be a potential marker for pain-associated stress due its non-invasive, cost-effective, and stress-free collection. The current study aimed to investigate whether the levels of sAA are influenced by experimentally induced muscle pain. In this study, 26 healthy, pain-free and age-matched participants (23.8 ± 2.6 years) were included, 13 women and 13 men. Prior to the experiment, questionnaires assessing health and anxiety were completed. Muscle pain was then induced through intramuscular injection of 0.4 mL hypertonic saline (56.5 mg/mL) into the masseter muscle and unstimulated whole saliva samples were collected at baseline before injection, 2 min, and 15 min after injection. A commercially available colorimetric assay was used to analyze the sAA. Perceived pain and stress were assessed using a 0–100 Numeric Rating Scale for each sample. There were no significant differences in sAA levels prior and after injection of hypertonic saline (p > 0.05) although sAA levels showed a slight decrease during experimentally-induced muscle pain. However, a strong correlation was observed between self-reported pain and perceived level of stress during experimentally-induced muscle pain (r2 = 0.744; p < 0.0001). Furthermore, there was a moderate correlation between the levels of sAA at baseline and during experimental pain (r2 = 0.687; p < 0.0001). In conclusion, this study could not show any association between the levels of sAA and perceived pain and or/stress. However, since a significant strong correlation could be observed between perceived stress and pain intensity, this study indicates that experimentally-induced muscle pain could be used as a stress model.
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12.
  • Ericson, Per G P, 1956-, et al. (författare)
  • A Gondwanan origin of passerine birds supported by DNA sequences of the endemic New Zealand wrens.
  • 2002
  • Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 269:1488, s. 235-41
  • Tidskriftsartikel (refereegranskat)abstract
    • Zoogeographic, palaeontological and biochemical data support a Southern Hemisphere origin for passerine birds, while accumulating molecular data suggest that most extant avian orders originated in the mid-Late Cretaceous. We obtained DNA sequence data from the nuclear c-myc and RAG-1 genes of the major passerine groups and here we demonstrate that the endemic New Zealand wrens (Acanthisittidae) are the sister taxon to all other extant passerines, supporting a Gondwanan origin and early radiation of passerines. We propose that (i) the acanthisittids were isolated when New Zealand separated from Gondwana (ca. 82-85 Myr ago), (ii) suboscines, in turn, were derived from an ancestral lineage that inhabited western Gondwana, and (iii) the ancestors of the oscines (songbirds) were subsequently isolated by the separation of Australia from Antarctica. The later spread of passerines into the Northern Hemisphere reflects the northward migration of these former Gondwanan elements.
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13.
  • Ericson, Per G P, et al. (författare)
  • Parallel Evolution of Bower-Building Behavior in Two Groups of Bowerbirds Suggested by Phylogenomics
  • 2020
  • Ingår i: Systematic Biology. - 1063-5157 .- 1076-836X. ; 69:5, s. 820-829
  • Tidskriftsartikel (refereegranskat)abstract
    • The bowerbirds in New Guinea and Australia include species that build the largest and perhaps most elaborately decorated constructions outside of humans. The males use these courtship bowers, along with their displays, to attract females. In these species, the mating system is polygynous and the females alone incubate and feed the nestlings. The bowerbirds also include 10 species of the socially monogamous catbirds in which the male participates in most aspects of raising the young. How the bower-building behavior evolved has remained poorly understood, as no comprehensive phylogeny exists for the family. It has been assumed that the monogamous catbird clade is sister to all polygynous species. We here test this hypothesis using a newly developed pipeline for obtaining homologous alignments of thousands of exonic and intronic regions from genomic data to build a phylogeny. Our well-supported species tree shows that the polygynous, bower-building species are not monophyletic. The result suggests either that bower-building behavior is an ancestral condition in the family that was secondarily lost in the catbirds, or that it has arisen in parallel in two lineages of bowerbirds. We favor the latter hypothesis based on an ancestral character reconstruction showing that polygyny but not bower-building is ancestral in bowerbirds, and on the observation that Scenopoeetes dentirostris, the sister species to one of the bower-building clades, does not build a proper bower but constructs a court for male display. This species is also sexually monomorphic in plumage despite having a polygynous mating system. We argue that the relatively stable tropical and subtropical forest environment in combination with low predator pressure and rich food access (mostly fruit) facilitated the evolution of these unique life-history traits.
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14.
  • Ericson, Per G P, 1956-, et al. (författare)
  • Systematic affinities of the lyrebirds (Passeriformes : Menura), with a novel classification of the major groups of passerine birds.
  • 2002
  • Ingår i: Molecular Phylogenetics and Evolution. - 1055-7903 .- 1095-9513. ; 25:1, s. 53-62
  • Tidskriftsartikel (refereegranskat)abstract
    • Phylogenetic relationships of the lyrebirds are investigated using DNA sequence data. The aligned data matrix consists of 4027 bp obtained from three nuclear genes (c-myc, RAG-1 and myoglobin intron II) and two mitochondrial genes (cytochrome b and ND2). Both maximum-likelihood and parsimony analyses show that the lyrebirds unambiguously belong to the oscine radiation, and that they are the sister taxon to all other oscines. The results do not support the suggestion based on DNA-DNA hybridization data (Sibley and Ahlquist, 1990) that the treecreepers and bowerbirds are part of the lyrebird clade. Nevertheless, treecreepers and bowerbirds are sister taxa to all other oscines (except the lyrebirds) and may constitute a monophyletic group, although bootstrap support values for this clade are low. A major disagreement between the present analysis and that based on DNA-DNA hybridization data is that the Corvida (sensu Sibley and Ahlquist, 1990) and Passerida are not reciprocally monophyletic, as we find the latter group be nested within the Corvida. Also, the superfamilies Meliphagoidea and Corvoidea sensu, are not recovered as monophyletic in the present study. Within the oscine radiation, all taxa belonging to the earliest splits are confined to the Australo-Papuan region. This suggests strongly that the origins and early radiation of the oscines occurred in the southern supercontinent Gondwana. A new classification of the major groups of passerines is presented following from the results presented in the present study, as well as those published recently on analyses of sequence data from the nuclear c-myc and RAG-1 genes (Ericson et al., 2002; Irestedt et al., 2001).
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15.
  • Fjeldså, Jon, et al. (författare)
  • An updated classification of passerine birds
  • 2020
  • Ingår i: <em>The Largest Avian Radiation</em>. - Barcelona : Lynx Edicions. - 9788416728336 ; , s. 45-63
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)
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16.
  • Fjeldså, Jon, et al. (författare)
  • Introduction
  • 2020
  • Ingår i: <em>The Largest Avian Radiation</em>. - Barcelona : Lynx Edicions. - 9788416728336 ; , s. 11-13
  • Bokkapitel (övrigt vetenskapligt/konstnärligt)
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17.
  • Fjeldså, Jon, et al. (författare)
  • The Largest Avian Radiation: The Evolution of Perching Birds, or the Order of Passeriformes
  • 2020
  • Bok (övrigt vetenskapligt/konstnärligt)abstract
    • This book reveals the remarkable new history of how passerines diversified and dispersed across the entire world. It also presents and explains the new classification, which reflects the phylogenetic history. The new insights reveal that many of the old evolutionary lineages comprise only a few species that remained in their area of origin or underwent limited dispersal. Only a small number of groups underwent significant proliferation of new species and just five (of 145) passerine families are represented on all continents but Antarctica. Even so, the global variation in species richness generally correlates well with the variation in productivity across different environments. We see how a seemingly constant overall rate of evolution of new species is possible because of rapid proliferation in new ecological niches, including archipelagos, and an extraordinary accumulation of endemic species in certain tropical mountain ranges. In addition to describing the revised evolutionary history of passerine birds, the authors try to identify adaptational changes, including shifts in life history strategies, that underlie major evolutionary expansions.
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18.
  • Irestedt, Martin, et al. (författare)
  • An unexpectedly long history of sexual selection in birds-of-paradise.
  • 2009
  • Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 9, s. 235-
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: The birds-of-paradise (Paradisaeidae) form one of the most prominent avian examples of sexual selection and show a complex biogeographical distribution. The family has accordingly been used as a case-study in several significant evolutionary and biogeographical syntheses. As a robust phylogeny of the birds-of-paradise has been lacking, these hypotheses have been tentative and difficult to assess. Here we present a well supported species phylogeny with divergence time estimates of the birds-of-paradise. We use this to assess if the rates of the evolution of sexually selected traits and speciation have been excessively high within the birds-of-paradise, as well as to re-interpret biogeographical patterns in the group.RESULTS: The phylogenetic results confirm some traditionally recognized relationships but also suggest novel ones. Furthermore, we find that species pairs are geographically more closely linked than previously assumed. The divergence time estimates suggest that speciation within the birds-of-paradise mainly took place during the Miocene and the Pliocene, and that several polygynous and morphologically homogeneous genera are several million years old. Diversification rates further suggest that the speciation rate within birds-of-paradise is comparable to that of the enitre core Corvoidea.CONCLUSION: The estimated ages of morphologically homogeneous and polygynous genera within the birds-of-paradise suggest that there is no need to postulate a particularly rapid evolution of sexually selected morphological traits. The calculated divergence rates further suggest that the speciation rate in birds-of-paradise has not been excessively high. Thus the idea that sexual selection could generate high speciation rates and rapid changes in sexual ornamentations is not supported by our birds-of-paradise data. Potentially, hybridization and long generation times in polygynous male birds-of-paradise have constrained morphological diversification and speciation, but external ecological factors on New Guinea may also have allowed the birds-of-paradise to develop and maintain magnificent male plumages. We further propose that the restricted but geographically complex distributions of birds-of-paradise species may be a consequence of the promiscuous breeding system.
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19.
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20.
  • Irestedt, Martin, et al. (författare)
  • Phylogeny, biogeography and taxonomic consequences in a bird-of-paradise species complex, Lophorina-Ptiloris (Aves: Paradisaeidae)
  • 2017
  • Ingår i: Zoological Journal of the Linnean Society. - : OXFORD UNIV PRESS. - 0024-4082 .- 1096-3642. ; 181:2, s. 439-470
  • Tidskriftsartikel (refereegranskat)abstract
    • Biogeographical history and taxonomic delimitation in the Australo-Papuan bird-of-paradise Lophorina-Ptiloris species complex is examined with a combination of DNA and morphological markers. The results suggest that the complex started to diverge in the mid-Pliocene, driven by initial isolation and adaptation to altitudinally different habitats. As in many other New Guinean avian taxa, phylogeographic structure is more varied in montane Lophorina than foothill Ptiloris. With the exception of populations of Lophorina in the eastern New Guinean cordillera, phylogenetic patterns from molecular data and morphological discontinuities are consistently concordant, as are molecular species delimitation tests with previous morphology-based circumscription of taxa in Ptiloris. In Lophorina, however, both molecular data and significant, re-discovered morphological traits identify several taxa as more deeply differentiated than hitherto thought. Accordingly, we use these data in an integrative taxonomic approach to re-delimit taxa in the entire clade, including the recognition of three species in the previously monospecific Lophorina. In Lophorina, the identity of several type specimens is reviewed, one new subspecies is described from the Vogelkop, and the identity of the species name superba Pennant is resolved by neotypification, with correction of its author.
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  • Resultat 11-20 av 29

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