Solving the woolly mammoth conundrum: amino acid 15N-enrichment suggests a distinct forage or habitat

Understanding woolly mammoth ecology is key to understanding Pleistocene community dynamics and evaluating the roles of human hunting and climate change in late Quaternary megafaunal extinctions. Previous isotopic studies of mammoths’ diet and physiology have been hampered by the ‘mammoth conundrum’: woolly mammoths have anomalously high collagen δ15N values, which are more similar to coeval carnivores than herbivores and which could imply a distinct diet and (or) habitat, or a physiological adaptation. We analyzed individual amino acids from collagen of adult woolly mammoths and coeval species and discovered greater  15N enrichment in source amino acids of woolly mammoths than in most other herbivores or carnivores. Woolly mammoths consumed an isotopically distinct food source, reflective of extreme aridity, dung fertilization and (or) plant selection. This dietary signal suggests that woolly mammoths occupied a distinct habitat or forage niche relative to other Pleistocene herbivores

Genome sequencing of the extinct Eurasian wild aurochs, Bos primigenius, illuminates the phylogeography and evolution of cattle

Background Domestication of the now-extinct wild aurochs, Bos primigenius, gave rise to the two major domestic extant cattle taxa, B. taurus and B. indicus. While previous genetic studies have shed some light on the evolutionary relationships between European aurochs and modern cattle, important questions remain unanswered, including the phylogenetic status of aurochs, whether gene flow from aurochs into early domestic populations occurred, and which genomic regions were subject to selection processes during and after domestication. Here, we address these questions using whole-genome sequencing data generated from an approximately 6,750-year-old British aurochs bone and genome sequence data from 81 additional cattle plus genome-wide single nucleotide polymorphism data from a diverse panel of 1,225 modern animals. Results Phylogenomic analyses place the aurochs as a distinct outgroup to the domestic B. taurus lineage, supporting the predominant Near Eastern origin of European cattle. Conversely, traditional British and Irish breeds share more genetic variants with this aurochs specimen than other European populations, supporting localized gene flow from aurochs into the ancestors of modern British and Irish cattle, perhaps through purposeful restocking by early herders in Britain. Finally, the functions of genes showing evidence for positive selection in B. taurus are enriched for neurobiology, growth, metabolism and immunobiology, suggesting that these biological processes have been important in the domestication of cattle. Conclusions This work provides important new information regarding the origins and functional evolution of modern cattle, revealing that the interface between early European domestic populations and wild aurochs was significantly more complex than previously thought

Early Pleistocene enamel proteome from Dmanisi resolves Stephanorhinus phylogeny

The sequencing of ancient DNA has enabled the reconstruction of speciation, migration and admixture events for extinct taxa. However, the irreversible post-mortem degradation2 of ancient DNA has so far limited its recovery—outside permafrost areas—to specimens that are not older than approximately 0.5 million years (Myr). By contrast, tandem mass spectrometry has enabled the sequencing of approximately 1.5-Myr-old collagen type I, and suggested the presence of protein residues in fossils of the Cretaceous period—although with limited phylogenetic use. In the absence of molecular evidence, the speciation of several extinct species of the Early and Middle Pleistocene epoch remains contentious. Here we address the phylogenetic relationships of the Eurasian Rhinocerotidae of the Pleistocene epoch, using the proteome of dental enamel from a Stephanorhinus tooth that is approximately 1.77-Myr old, recovered from the archaeological site of Dmanisi (South Caucasus, Georgia). Molecular phylogenetic analyses place this Stephanorhinus as a sister group to the clade formed by the woolly rhinoceros (Coelodonta antiquitatis) and Merck’s rhinoceros (Stephanorhinus kirchbergensis). We show that Coelodonta evolved from an early Stephanorhinus lineage, and that this latter genus includes at least two distinct evolutionary lines. The genus Stephanorhinus is therefore currently paraphyletic, and its systematic revision is needed. We demonstrate that sequencing the proteome of Early Pleistocene dental enamel overcomes the limitations of phylogenetic inference based on ancient collagen or DNA. Our approach also provides additional information about the sex and taxonomic assignment of other specimens from Dmanisi. Our findings reveal that proteomic investigation of ancient dental enamel—which is the hardest tissue in vertebrates, and is highly abundant in the fossil record—can push the reconstruction of molecular evolution further back into the Early Pleistocene epoch, beyond the currently known limits of ancient DNA preservation

The mammals of Angola

Scientific investigations on the mammals of Angola started over 150 years ago, but information remains scarce and scattered, with only one recent published account. Here we provide a synthesis of the mammals of Angola based on a thorough survey of primary and grey literature, as well as recent unpublished records. We present a short history of mammal research, and provide brief information on each species known to occur in the country. Particular attention is given to endemic and near endemic species. We also provide a zoogeographic outline and information on the conservation of Angolan mammals. We found confirmed records for 291 native species, most of which from the orders Rodentia (85), Chiroptera (73), Carnivora (39), and Cetartiodactyla (33). There is a large number of endemic and near endemic species, most of which are rodents or bats. The large diversity of species is favoured by the wide range of habitats with contrasting environmental conditions, while endemism tends to be associated with unique physiographic settings such as the Angolan Escarpment. The mammal fauna of Angola includes 2 Critically Endangered, 2 Endangered, 11 Vulnerable, and 14 Near-Threatened species at the global scale. There are also 12 data deficient species, most of which are endemics or near endemics to the countryinfo:eu-repo/semantics/publishedVersio

The evolutionary and phylogeographic history of woolly mammoths: a comprehensive mitogenomic analysis

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Nyquist-WDM-Based Flexible Optical Networks: Exploring Physical Layer Design Parameters

We focus on Nyquist-WDM-based flexible optical networks and examine the impact of introducing flexibility in physical layer design parameters on the network level performance. The considered physical layer parameters include the modulation format, the symbol-rate, the inter-subcarrier spacing, the inter-superchannel spacing, and the launch power. In order to examine the impact of allowing the symbol rate to be tuned on a super channel basis, three alternative launch power schemes are considered: (i) optimum launch power, (ii) constant launch power, and (iii) constant power spectral density. Case study results from a realistic reference core network highlight the identified trade-offs with respect to the utilized spectrum and the required transponders. It is shown that significant savings can be achieved by allowing the symbol rate to be dynamically tuned under different launch power options

Network Performance Evaluation for Nyquist-WDM-Based Flexible Optical Networking

We focus on the spectrally efficient Nyquist-WDM concept and quantify the effect of physical layer design parameters on the network level performance. Case studies are conducted on a realistic reference network under different traffic demand settings and trade-offs with respect to the utilized spectrum and the required transponders are identified

Spectrally and spatially flexible optical network planning and operations

The advent of spectrally flexible (a.k.a. elastic) optical networking is widely identified as the next generation optical network solution that permits varying bandwidth demands to be dynamically assigned over flexible spectral containers, targeting optimum use of the available network resources. Additionally, the adoption of the space dimension is identified as a promising solution for the capacity expansion of future networks, while novel spatial-spectral switching solutions show that the flexible networking concept can be further expanded over both the spatial and spectral dimensions. This article provides an overview of the latest developments and possible approaches with respect to flexible optical networking and the emerging benefits that spatially flexible networking approaches can offer. The focus is on the network planning and resource optimization functions, the main network operations related to fragmentation and IP/optical layer integration, and the control plane solutions