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  • 1
    Type of Medium: Book
    Pages: Seite 715 - 1273 , zahlreiche Illustrationen
    Series Statement: Marine Biodiversity Volume 48 Number 2 June 2018
    Language: English
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  • 2
    ISSN: 1432-1432
    Keywords: Key words: Leporidae — Rabbits — Cytochrome b— 12S rRNA — Lagomorph evolution — Saturation — Phylogenetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Partial sequences of two mitochondrial genes, the 12S ribosomal gene (739 bp) and the cytochrome b gene (672 bp), were analyzed in hopes of reconstructing the evolutionary relationships of 11 leporid species, representative of seven genera. However, partial cytochrome b sequences were of little phylogenetic value in this study. A suite of pairwise comparisons between taxa revealed that at the intergeneric level, the cytochrome b gene is saturated at synonymous coding positions due to multiple substitution events. Furthermore, variation at the nonsynonymous positions is limited, rendering the cytochrome b gene of little phylogenetic value for assessing the relationships between leporid genera. If the cytochrome b data are analyzed without accounting for these two classes of nucleotides (i.e., synonymous and nonsynonymous sites), one may incorrectly conclude that signal exists in the cytochrome b data. The mitochondrial 12S rRNA gene, on the other hand, has not experienced excessive saturation at either stem or loop positions. Phylogenies reconstructed from the 12S rDNA data support hypotheses based on fossil evidence that African rock rabbits (Pronolagus) are outside of the main leporid stock and that leporids experienced a rapid radiation. However, the molecular data suggest that this radiation event occurred in the mid-Miocene several millions of years earlier than the Pleistocene dates suggested by paleontological evidence.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Ecology, Evolution, and Systematics 35 (2004), S. 229-256 
    ISSN: 1543-592X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Molecular tools have profoundly rearranged our understanding of metazoan phylogeny. Initially based on the nuclear small ribosomal subunit (SSU or 18S) gene, recent hypotheses have been corroborated by several sources of data (including the nuclear large ribosomal subunit, Hox genes, mitochondrial gene order, concatenated mitochondrial genes, and the myosin II heavy chain gene). Herein, the evidence supporting our current understanding is discussed on a clade by clade basis. Bilaterian animals consist of three clades: Deuterostomia, Lophotrochozoa, and Ecdysozoa. Each clade is supported by molecular and morphological data. Deuterostomia is smaller than traditionally recognized, consisting of hemichordates, echinoderms, chordates, and Xenoturbella (an enigmatic worm-like animal). Lophotrochozoa groups animals with a lophophore feeding apparatus (Brachiopoda, Bryozoa, and Phoronida) and trochophore larvae (e.g., annelids and mollusk), as well as several other recognized phyla (e.g., platyhelmin thes, sipunculans, nemerteans). Ecdysozoa comprises molting animals (e.g., arthropods, nematodes, tardigrades, priapulids), grouping together two major model organisms (Drosophila and Caenorhabditis) in the same lineage. Platyhelminthes do not appear to be monophyletic, with Acoelomorpha holding a basal position in Bilateria. Before the emergence of bilateral animals, sponges, ctenophorans, cnidarians, and placozoans split from the main animal lineage, but order of divergence is less than certain. Many questions persist concerning relationships within Ecdysozoa and Lophotrochozoa, poriferan monophyly, and the placement of many less-studied taxa (e.g., kinorhynchs, gastrotrichs, gnathostomulids, and entoprocts).
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2020-08-15
    Description: In the Southern Ocean, that is areas south of the Polar Front, long-term oceanographic cooling, geographic separation, development of isolating current and wind systems, tectonic drift and fluctuation of ice sheets amongst others have resulted in a highly endemic benthic fauna, which is generally adapted to the long-lasting, relatively stable environmental conditions. The Southern Ocean benthic ecosystem has been subject to minimal direct anthropogenic impact (compared to elsewhere) and thus presents unique opportunities to study biodiversity and its responses to environmental change. Since the beginning of the century, research under the Census of Marine Life and International Polar Year initiatives, as well as Scientific Committee of Antarctic Research biology programmes, have considerably advanced our understanding of the Southern Ocean benthos. In this paper, we evaluate recent progress in Southern Ocean benthic research and identify priorities for future research. Intense efforts to sample and describe the benthic fauna, coupled with coordination of information in global databases, have greatly enhanced understanding of the biodiversity and biogeography of the region. Some habitats, such as chemosynthetic systems, have been sampled for the first time, while application of new technologies and methods are yielding new insights into ecosystem structure and function. These advances have also highlighted important research gaps, notably the likely consequences of climate change. In a time of potentially pivotal environmental change, one of the greatest challenges is to balance conservation with increasing demands on the Southern Ocean’s natural resources and services. In this context, the characterization of Southern Ocean biodiversity is an urgent priority requiring timely and accurate species identifications, application of standardized sampling and reporting procedures, as well as cooperation between disciplines and nations.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 5
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
    Format: application/pdf
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  • 6
    Publication Date: 2017-06-23
    Description: Assessing the enormous diversity of Southern Ocean benthic species and their evolutionary histories 2 is a central task in the era of global climate change. Based on mitochondrial markers, it was recently suggested that the circumpolar giant sea spider Colossendeis megalonyx comprises a complex of
at least six cryptic species with mostly small and non-overlapping distribution ranges. Here, we expand the sampling to include over 500 mitochondrial COI sequences of specimens from around the Antarctic. Using multiple species delimitation approaches, the number of distinct mitochondrial OTUs increased from six to 15–20 with our larger dataset. In contrast to earlier studies, many of these clades show almost circumpolar distributions. Additionally, analysis of the nuclear internal transcribed spacer region for a subset of these specimens showed incongruence between nuclear and mitochondrial results. These mito-nuclear discordances suggest that several of the divergent mitochondrial lineages can hybridize and should not be interpreted as cryptic species. Our results suggest survival of C. megalonyx during Pleistocene glaciations in multiple refugia, some of them probably located on the Antarctic shelf, and emphasize the importance of multi-gene datasets to detect the presence of cryptic species, rather than their inference based on mitochondrial data alone
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 7
    Publication Date: 2022-09-29
    Description: The calving of A-68, the 5,800 km2 iceberg that separated from the Larsen C Ice Shelf in July 2017, presents a unique and time-sensitive research opportunity. This event and other ice-shelf losses (e.g., from Larsen A and B, Wilkins, Wordie) are harbingers of warming effects along the Antarctic Peninsula in particular, and ultimately around all of Antarctica. The scientific momentum and public interest created by this most recent event led to an NSF funded workshop in November 2017. A consortium of US and international researchers with a diversity of expertise in Antarctic glaciological, geological, biological, and ecological sciences shared and reviewed the latest research, identified important research priorities and knowlegde gaps, and outlined strategic plans for the research community to advance understanding of the continent-wide changes that Antarctic ice shelves and surrounding ecosystems will experience in response to warming. The workshop has leveraged an opportunity to synergize efforts in investigating Antarctic ecosystems under the direct and indirect effects of ice-shelf collapse, and climatic warming in general. Here we present a review on the known and unknown ecosystem processes that will occur in the wake of massive, abrupt ice-shelf break-off and how they will affect ice-associated, pelagic, hard-bottom and soft-sediment substrates. We also present a view on future research approaches to address gaps in our knowledge and advance our understanding of the widespread effects of ice-shelf break-off and collapse.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 8
    Publication Date: 2023-06-21
    Description: The calving of A-68, the 5,800-km2, 1-trillion-ton iceberg shed from the Larsen C Ice Shelf in July 2017, is one of over 10 significant ice-shelf loss events in the past few decades resulting from rapid warming around the Antarctic Peninsula. The rapid thinning, retreat, and collapse of ice shelves along the Antarctic Peninsula are harbingers of warming effects around the entire continent. Ice shelves cover more than 1.5 million km2 and fringe 75% of Antarctica's coastline, delineating the primary connections between the Antarctic continent, the continental ice, and the Southern Ocean. Changes in Antarctic ice shelves bring dramatic and large-scale modifications to Southern Ocean ecosystems and continental ice movements, with global-scale implications. The thinning and rate of future ice-shelf demise is notoriously unpredictable, but models suggest increased shelf-melt and calving will become more common. To date, little is known about sub-ice-shelf ecosystems, and our understanding of ecosystem change following collapse and calving is predominantly based on responsive science once collapses have occurred. In this review, we outline what is known about (a) ice-shelf melt, volume loss, retreat, and calving, (b) ice-shelf-associated ecosystems through sub-ice, sediment-core, and pre-collapse and post-collapse studies, and (c) ecological responses in pelagic, sympagic, and benthic ecosystems. We then discuss major knowledge gaps and how science might address these gaps. This article is categorized under: Climate, Ecology, and Conservation 〉 Modeling Species and Community Interactions.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
    Format: application/pdf
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