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  • 1
    Publication Date: 2016-06-17
    Description: Modern cold-water coral and tropical coral environments harbor a highly diverse and ecologically important macrofauna of crustaceans that face elevated extinction risks due to reef decline. The effect of envir...
    Electronic ISSN: 1471-2148
    Topics: Biology
    Published by BioMed Central
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  • 2
    Publication Date: 2011-12-01
    Description: In the Upper Cretaceous-Danian North Sea chalk, silica composed of nano-size quartz spheres is dispersed in the chalk matrix, and quartz is present in bands and nodules of flint. In the present investigation of the North Sea Danian chalk the nano-quartz in the chalk matrix is compared with the silica in the flint. Samples of chalk and flint layers from four North Sea wells have been investigated. Atomic Force Microscopy (AFM) has been applied to image the quartz in the chalk and in the flint. X-ray diffraction (XRD), including analysis of the positions and profiles of hkl reflections in powder diffraction patterns, has been applied to characterize the lattice of the quartz in both the chalk matrix and in the flint. The quartz in the chalk matrix and in the flint is composed of nano-quartz spheres having identical cell parameters. Based on the results we propose a new model for formation of flint in North Sea chalk: (1) The nano-quartz in the flint, like the nano-quartz in the chalk matrix, has crystallized in the marine Chalk Sea environment. The colloidal quartz particles flocculated and were deposited on the sea floor mixed with calcitic bioclastic material. (2) Regional variations in the concentration of nano-quartz particles in the sediment reflect different degrees of acidification of the Chalk Sea. (3) This resulted in areas where practically all the calcite bioclasts were dissolved leaving a high concentration of nano-quartz particles to form flint layers; where there was less dissolution, indurated chalk with abundant nano-quartz particles is now preserved. (4) The acidification could have been caused by the effects of enhanced atmospheric CO2 linked to massive short-lived volcanic eruptions in the British Tertiary Igneous Province.
    Print ISSN: 0009-8558
    Electronic ISSN: 1471-8030
    Topics: Geosciences
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  • 3
    Publication Date: 2012-11-23
    Description: Most echolocating bats exhibit a strong correlation between body size and the frequency of maximum energy in their echolocation calls (peak frequency), with smaller species using signals of higher frequency than larger ones. Size-signal allometry or acoustic detection constraints imposed on wavelength by preferred prey size have been used to explain this relationship. Here we propose the hypothesis that smaller bats emit higher frequencies to achieve directional sonar beams, and that variable beam width is critical for bats. Shorter wavelengths relative to the size of the emitter translate into more directional sound beams. Therefore, bats that emit their calls through their mouths should show a relationship between mouth size and wavelength, driving smaller bats to signals of higher frequency. We found that in a flight room mimicking a closed habitat, six aerial hawking vespertilionid species (ranging in size from 4 to 21 g, ref. 5) produced sonar beams of extraordinarily similar shape and volume. Each species had a directivity index of 11 +/- 1 dB (a half-amplitude angle of approximately 37 degrees ) and an on-axis sound level of 108 +/- 4 dB sound pressure level referenced to 20 muPa root mean square at 10 cm. Thus all bats adapted their calls to achieve similar acoustic fields of view. We propose that the necessity for high directionality has been a key constraint on the evolution of echolocation, which explains the relationship between bat size and echolocation call frequency. Our results suggest that echolocation is a dynamic system that allows different species, regardless of their body size, to converge on optimal fields of view in response to habitat and task.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jakobsen, Lasse -- Ratcliffe, John M -- Surlykke, Annemarie -- England -- Nature. 2013 Jan 3;493(7430):93-6. doi: 10.1038/nature11664. Epub 2012 Nov 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Sound Communication Group, Institute of Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23172147" target="_blank"〉PubMed〈/a〉
    Keywords: *Acoustics ; Animals ; Body Size/physiology ; Chiroptera/anatomy & histology/classification/*physiology ; Echolocation/*physiology ; Ecosystem ; Flight, Animal ; Models, Biological ; Mouth/anatomy & histology/physiology ; Nose/anatomy & histology/physiology ; Predatory Behavior ; Skull/anatomy & histology/physiology ; Vocalization, Animal/physiology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2011-10-01
    Description: As an echolocating bat closes in on a flying insect, it increases call emission to rates beyond 160 calls per second. This high call rate phase, dubbed the terminal buzz, has proven enigmatic because it is unknown how bats are able to produce calls so quickly. We found that previously unknown and highly specialized superfast muscles power rapid call rates in the terminal buzz. Additionally, we show that laryngeal motor performance, not overlap between call production and the arrival of echoes at the bat's ears, limits maximum call rate. Superfast muscles are rare in vertebrates and always associated with extraordinary motor demands on acoustic communication. We propose that the advantages of rapid auditory updates on prey movement selected for superfast laryngeal muscle in echolocating bats.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Elemans, Coen P H -- Mead, Andrew F -- Jakobsen, Lasse -- Ratcliffe, John M -- New York, N.Y. -- Science. 2011 Sep 30;333(6051):1885-8. doi: 10.1126/science.1207309.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Biology, University of Southern Denmark, DK-5230 Odense M, Denmark. coen@biology.sdu.dk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21960635" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Chiroptera/*physiology ; *Echolocation ; Insects ; Laryngeal Muscles/*physiology ; Larynx/physiology ; Muscle Contraction ; Muscle Fibers, Fast-Twitch/*physiology ; Muscle Relaxation ; Sound ; Vocal Cords/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2017-01-01
    Description: Great genetic variability among teleost immunomes, with gene losses and expansions of central adaptive and innate components, has been discovered through genome sequencing over the last few years. Here, we demonstrate that the innate Myxovirus resistance gene ( Mx ) is lost from the ancestor of Gadiformes and the closely related Stylephorus chordatus , thus predating the loss of Major Histocompatibility Complex class II ( MHCII ) in Gadiformes. Although the functional implication of Mx loss is still unknown, we demonstrate that this loss is one of several ancient events appearing in successive order throughout the evolution of teleost immunity. In particular, we find that the loss of Toll-like receptor 5 predates the loss of Mx involving the entire Paracanthopterygii lineage. Using a time-calibrated phylogeny, we show that loss of MHCII and Mx overlap with major paleoclimatic and geological events indicating that these genetic changes were adaptive responses to the changing environment at the time.
    Electronic ISSN: 1759-6653
    Topics: Biology
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  • 6
    Publication Date: 2019
    Description: 〈p〉Vertebrate vision is accomplished through light-sensitive photopigments consisting of an opsin protein bound to a chromophore. In dim light, vertebrates generally rely on a single rod opsin [rhodopsin 1 (RH1)] for obtaining visual information. By inspecting 101 fish genomes, we found that three deep-sea teleost lineages have independently expanded their 〈i〉RH1〈/i〉 gene repertoires. Among these, the silver spinyfin (〈i〉Diretmus argenteus〈/i〉) stands out as having the highest number of visual opsins in vertebrates (two cone opsins and 38 rod opsins). Spinyfins express up to 14 〈i〉RH1〈/i〉s (including the most blueshifted rod photopigments known), which cover the range of the residual daylight as well as the bioluminescence spectrum present in the deep sea. Our findings present molecular and functional evidence for the recurrent evolution of multiple rod opsin–based vision in vertebrates.〈/p〉
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 132-136 (Apr. 1997), p. 185-188 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 2015-07-01
    Description: In the evolutionary arms race between prey and predator, measures and countermeasures continuously evolve to increase survival on both sides. Bats and moths are prime examples. When exposed to intense ultrasound, eared moths perform dramatic escape behaviors. Vespertilionid and rhinolophid bats broaden their echolocation beam in the final stage of...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 9
    Publication Date: 2016-03-22
    Description: Reconstructing past vegetation and species diversity from arctic lake sediments can be challenging because of low pollen and plant macrofossil concentrations. Information may be enhanced by metabarcoding of sedimentary ancient DNA ( sed aDNA). We developed a Holocene record from Lake Skartjørna, Svalbard, using sed aDNA, plant macrofossils and sediment properties, and compared it with published records. All but two genera of vascular plants identified as macrofossils in this or a previous study were identified with sed aDNA. Six additional vascular taxa were found, plus two algal and 12 bryophyte taxa, by sed aDNA analysis, which also detected more species per sample than macrofossil analysis. A shift from Salix polaris -dominated vegetation, with Koenigia islandica , Ranunculaceae and the relatively thermophilic species Arabis alpina and Betula , to Dryas octopetala -dominated vegetation ~6600–5500 cal. BP suggests a transition from moist conditions 1–2°C warmer than today to colder/drier conditions. This coincides with a decrease in runoff, inferred from core lithology, and an independent record of declining lacustrine productivity. This mid-Holocene change in terrestrial vegetation is broadly coincident with changes in records from marine sediments off the west coast of Svalbard. Over the Holocene sed aDNA records little floristic change, and it clearly shows species persisted near the lake during time intervals when they are not detected as macrofossils. The flora has shown resilience in the presence of a changing climate, and, if future warming is limited to 2°C or less, we might expect only minor floristic changes in this region. However, the Holocene record provides no analogues for greater warming.
    Print ISSN: 0959-6836
    Electronic ISSN: 1477-0911
    Topics: Geography , Geosciences
    Published by Sage
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  • 10
    Publication Date: 2010-07-19
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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