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- Brealey, Jaelle C., et al.
(författare)
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The oral microbiota of wild bears in Sweden reflects the history of antibiotic use by humans
- 2021
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 31:20, s. 4650-4658.e6
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Tidskriftsartikel (refereegranskat)abstract
- Following the advent of industrial-scale antibiotic production in the 1940s,1 antimicrobial resistance (AMR) has been on the rise and now poses a major global health threat in terms of mortality, morbidity, and economic burden.2,3 Because AMR can be exchanged between humans, livestock, and wildlife, wild animals can be used as indicators of human-associated AMR contamination of the environment.4 However, AMR is a normal function of natural environments and is present in host-associated microbiomes, which makes it challenging to distinguish between anthropogenic and natural sources.4,5 One way to overcome this difficulty is to use historical samples that span the period from before the mass production of antibiotics to today. We used shotgun metagenomic sequencing of dental calculus, the calcified form of the oral microbial biofilm, to determine the abundance and repertoire of AMR genes in the oral microbiome of Swedish brown bears collected over the last 180 years. Our temporal metagenomics approach allowed us to establish a baseline of natural AMR in the pre-antibiotics era and to quantify a significant increase in total AMR load and diversity of AMR genes that is consistent with patterns of national human antibiotic use. We also demonstrated a significant decrease in total AMR load in bears in the last two decades, which coincides with Swedish strategies to mitigate AMR. Our study suggests that public health policies can be effective in limiting human-associated AMR contamination of the environment and wildlife.
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- Gharibi, Hassan, et al.
(författare)
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Abnormal (Hydroxy)proline Deuterium Content Redefines Hydrogen Chemical Mass
- 2022
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 144:6, s. 2484-2487
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Tidskriftsartikel (refereegranskat)abstract
- Analyzing the δ2H values in individual amino acids of proteins extracted from vertebrates, we unexpectedly found insome samples, notably bone collagen from seals, more than twice as much deuterium in proline and hydroxyproline residues than inseawater. This corresponds to at least 4 times higher δ2H than in any previously reported biogenic sample. We ruled out diet as aplausible mechanism for such anomalous enrichment. This finding puts into question the old adage that “you are what you eat”.
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- Granell-Ruiz, Maria, et al.
(författare)
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Genetic variation between and within two populations of bat-eared foxes (Otocyon megalotis Desmarest, 1822) in South Africa
- 2021
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Ingår i: African Zoology. - : Informa UK Limited. - 1562-7020 .- 2224-073X. ; 56:3, s. 165-172
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Tidskriftsartikel (refereegranskat)abstract
- Information on genetic variation within and among populations is relevant for a broad range of topics in biology. We use a combination of mitochondrial and nuclear microsatellite markers to evaluate genetic variation within and between two populations of bat-eared foxes (Otocyon megalotis Desmarest, 1822) in South Africa. The bat-eared fox is a small canid occurring in southern and eastern Africa. The species is currently not threatened with extinction, but a lack of information on genetic diversity has been identified as a deficit for its future conservation. We observed low to moderate genetic differentiation between the two geographically separated populations, but neither mitochondrial nor nuclear microsatellite markers suggested that there have been dispersal barriers between them. Similar genetic diversity within both populations was contrasted by interpopulational differences in relatedness variation among males and females. A high genetic relatedness within both populations, indicated by mitochondrial data, is likely caused by a common historical origin or a combination of species-specific social organization and environmental dispersal constraints. We call for further research on the genetic divergence of bat-eared fox populations as well as on the genetic consequences of interactions between environmental characteristics and social organization in this species.
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- Hempel, Elisabeth, et al.
(författare)
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Blue Turns to Gray : Paleogenomic Insights into the Evolutionary History and Extinction of the Blue Antelope (Hippotragus leucophaeus)
- 2022
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Ingår i: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 39:12
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Tidskriftsartikel (refereegranskat)abstract
- The blue antelope (Hippotragus leucophaeus) is the only large African mammal species to have become extinct in historical times, yet no nuclear genomic information is available for this species. A recent study showed that many alleged blue antelope museum specimens are either roan (Hippotragus equinus) or sable (Hippotragus niger) antelopes, further reducing the possibilities for obtaining genomic information for this extinct species. While the blue antelope has a rich fossil record from South Africa, climatic conditions in the region are generally unfavorable to the preservation of ancient DNA. Nevertheless, we recovered two blue antelope draft genomes, one at 3.4× mean coverage from a historical specimen (∼200 years old) and one at 2.1× mean coverage from a fossil specimen dating to 9,800–9,300 cal years BP, making it currently the oldest paleogenome from Africa. Phylogenomic analyses show that blue and sable antelope are sister species, confirming previous mitogenomic results, and demonstrate ancient gene flow from roan into blue antelope. We show that blue antelope genomic diversity was much lower than in roan and sable antelope, indicative of a low population size since at least the early Holocene. This supports observations from the fossil record documenting major decreases in the abundance of blue antelope after the Pleistocene–Holocene transition. Finally, the persistence of this species throughout the Holocene despite low population size suggests that colonial-era human impact was likely the decisive factor in the blue antelope's extinction.
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- Hempel, Elisabeth, et al.
(författare)
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Identifying the true number of specimens of the extinct blue antelope (Hippotragus leucophaeus)
- 2021
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:2100
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Tidskriftsartikel (refereegranskat)abstract
- Native to southern Africa, the blue antelope (Hippotragus leucophaeus) is the only large African mammal species known to have become extinct in historical times. However, it was poorly documented prior to its extinction ~ 1800 AD, and many of the small number of museum specimens attributed to it are taxonomically contentious. This places limitations on our understanding of its morphology, ecology, and the mechanisms responsible for its demise. We retrieved genetic information from ten of the sixteen putative blue antelope museum specimens using both shotgun sequencing and mitochondrial genome target capture in an attempt to resolve the uncertainty surrounding the identification of these specimens. We found that only four of the ten investigated specimens, and not a single skull, represent the blue antelope. This indicates that the true number of historical museum specimens of the blue antelope is even smaller than previously thought, and therefore hardly any reference material is available for morphometric, comparative and genetic studies. Our study highlights how genetics can be used to identify rare species in natural history collections where other methods may fail or when records are scarce. Additionally, we present an improved mitochondrial reference genome for the blue antelope as well as one complete and two partial mitochondrial genomes. A first analysis of these mitochondrial genomes indicates low levels of maternal genetic diversity in the ‘museum population’, possibly confirming previous results that blue antelope population size was already low at the time of the European colonization of South Africa.
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- Kalthoff, Daniela, et al.
(författare)
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A new mammal from the Turonian–Campanian (Upper Cretaceous) Galula Formation, southwestern Tanzania
- 2019
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Ingår i: Acta Palaeontologica Polonica. - : Polska Akademia Nauk Instytut Paleobiologii (Institute of Paleobiology, Polish Academy of Sciences). - 0567-7920. ; 64:1, s. 65-84
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Tidskriftsartikel (refereegranskat)abstract
- We here establish a newmammaliaform genus and species, Galulatheriumjenkinsi (Mammalia), from the UpperCretaceous Galula Formation in the Rukwa Rift Basin of southwestern Tanzania. Thisrepresents the first named taxon of a mammaliaform from the entire Late Cretaceous,an interval of 34 million years, of continental Afro-Africa. Preliminary studyof the holotype (a partial dentary) resulted in tentative assignation to the Gondwanatheria,a poorly known, enigmatic clade of Late Cretaceous–Paleogene Gondwanan mammals (Krauseet al. 2003). The application of advanced imaging (µCT) and visualizationtechniques permits a more detailed understanding of key anatomical features of thenew taxon. CT analysis reveals that the lower dentition consisted of a large,procumbent lower incisor and four cheek teeth, all which are ever growing(hypselodont). Importantly, all of the teeth appear to have been devoid ofenamel during life. Comparisons conducted with a range of Mesozoic and selectedCenozoic mammaliaform groups demonstrates that a number of features (e.g.,enamel-less and ever-growing teeth, columnar cheek teeth with relatively simpleocclusal morphology) expressed in Galulatheriumare reminiscent of disparate groups, making taxonomic assignment difficult. Hereinwe retain the provisional referral of Galulatherium(RRBP 02067) to Gondwanatheria; it is most similar to sudamericids such as Lavanify and Bharratherium from the Late Cretaceous of Madagascar and India,respectively, which exhibit relatively simple, high-crowned, columnar cheek teeth.Other features (e.g., enamel-less dentition) shared with disparate forms suchas the Late Jurassic Fruitafossor andvarious xenarthrans (e.g., sloths) are attributed to convergence. Detailed analysesof the depositional context for the type and only specimen place it as havinglived sometime between the late Turonian and latest Campanian (roughly 91–72million years ago). This enhanced geochronological context helps to refine thepalaeobiogeographical significance of Galulatheriumamong Cretaceous mammals in general and those of Gondwanan landmassesspecifically.
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| 10. |
- Kalthoff, Daniela C., et al.
(författare)
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Biomechanical adaptations for burrowing in the incisor enamel microstructure of Geomyidae and Heteromyidae (Rodentia: Geomyoidea)
- 2021
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Ingår i: Ecology and Evolution. - : Wiley-Blackwell Publishing Inc.. - 2045-7758. ; 11, s. 9447-9459
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Tidskriftsartikel (refereegranskat)abstract
- The enamel microstructure of fossil and extant Geomyoidea (Geomyidae, Heteromyidae) lower incisors incorporates three- or two-layered schmelzmusters with uniserial, transverse Hunter-Schreger bands having parallel and perpendicular or exclusively perpendicular oriented interprismatic matrix. Phylogenetically, these schmelzmusters are regarded as moderately (enamel type 2) to highly derived (enamel type 3). Our analysis detected a zone of modified radial enamel close to the enamel–dentine junction. Modified radial enamel shows a strong phylogenetic signal within the clade Geomorpha as it is restricted to fossil and extant Geomyoidea and absent in Heliscomyidae, Florentiamyidae, and Eomyidae. This character dates back to at least the early Oligocene (early Arikareean, 29 Ma), where it occurs in entoptychine gophers. We contend that this specialized incisor enamel architecture developed as a biomechanical adaptation to regular burrowing activities including chisel-tooth digging and a fiber-rich diet and was probably present in the common ancestor of the clade. We regard the occurrence of modified radial enamel in lower incisors of scratch-digging Geomyidae and Heteromyidae as the retention of a plesiomorphic character that is selectively neutral. The shared occurrence of modified radial enamel is a strong, genetically anchored argument for the close phylogenetic relationship of Geomyidae and Heteromyidae on the dental microstructure level.
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