| 41. |
- Demidova, S. I., et al.
(författare)
-
A micrometeorite from a stony asteroid identified in Luna 16 soil
- 2022
-
Ingår i: Nature Astronomy. - : Springer Science and Business Media LLC. - 2397-3366. ; 6:5, s. 560-567
-
Tidskriftsartikel (refereegranskat)abstract
- Despite the intense cratering history of the Moon, very few traces of meteoritic material have been identified in the more than 380 kg of samples returned to Earth by the Apollo and Luna missions. Here we show that an ~200-µm-sized fragment collected by the Luna 16 mission has extra-lunar origins and probably originates from an LL chondrite with similar properties to near-Earth stony asteroids. The fragment has not experienced temperatures higher than 400 °C since its protolith formed early in the history of the Solar System. It arrived on the Moon, either as a micrometeorite or as the result of the break-up of a bigger impact, no earlier than 3.4 Gyr ago and possibly around 1 Gyr ago, an age that would be consistent with impact ages inferred from basaltic fragments in the Luna 16 sample and of a known dynamic upheaval in the Flora asteroid family, which is thought to be the source of L and LL chondrite meteorites. These results highlight the importance of extra-lunar fragments in constraining the impact history of the Earth–Moon system and suggest that material from LL chondrite asteroids may be an important component.
|
|
| 42. |
- Dussex, Nicolas, et al.
(författare)
-
Population genomics of the critically endangered kākāpō
- 2021
-
Ingår i: Cell Genomics. - : Elsevier BV. - 2666-979X. ; 1:1
-
Tidskriftsartikel (refereegranskat)abstract
- Summary The kākāpō is a flightless parrot endemic to New Zealand. Once common in the archipelago, only 201 individuals remain today, most of them descending from an isolated island population. We report the first genome-wide analyses of the species, including a high-quality genome assembly for kākāpō, one of the first chromosome-level reference genomes sequenced by the Vertebrate Genomes Project (VGP). We also sequenced and analyzed 35 modern genomes from the sole surviving island population and 14 genomes from the extinct mainland population. While theory suggests that such a small population is likely to have accumulated deleterious mutations through genetic drift, our analyses on the impact of the long-term small population size in kākāpō indicate that present-day island kākāpō have a reduced number of harmful mutations compared to mainland individuals. We hypothesize that this reduced mutational load is due to the island population having been subjected to a combination of genetic drift and purging of deleterious mutations, through increased inbreeding and purifying selection, since its isolation from the mainland ∼10,000 years ago. Our results provide evidence that small populations can survive even when isolated for hundreds of generations. This work provides key insights into kākāpō breeding and recovery and more generally into the application of genetic tools in conservation efforts for endangered species.
|
|
| 43. |
- Ekman, Jan, et al.
(författare)
-
Out of Gondwanaland; the evolutionary history of cooperative breeding and social behaviour among crows, magpies, jays and allies.
- 2006
-
Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 273:1590, s. 1117-25
-
Tidskriftsartikel (refereegranskat)abstract
- Cooperative breeding is comparatively rare among birds in the mainly temperate and boreal Northern Hemisphere. Here we test if the distribution of breeding systems reflects a response to latitude by means of a phylogenetic analysis using correlates with geographical range among the corvids (crows, jays, magpies and allied groups). The corvids trace their ancestry to the predominantly cooperative 'Corvida' branch of oscine passerines from the Australo-Papuan region on the ancient Gondwanaland supercontinent, but we could not confirm the ancestral state of the breeding system within the family, while family cohesion may be ancestral. Initial diversification among pair-breeding taxa that are basal in the corvid phylogeny, represented by genera such as Pyrrhocorax and Dendrocitta, indicates that the corvid family in its current form could have evolved from pair-breeding ancestors only after they had escaped the Australo-Papuan shield. Within the family, cooperative breeding (alloparental care/family cohesion) is strongly correlated to latitude and its predominance in species maintaining a southerly distribution indicates a secondary evolution of cooperative breeding in the lineage leading away from the basal corvids. Multiple transitions show plasticity in the breeding system, indicating a response to latitude rather than evolutionary inertia. The evolutionary background to the loss of cooperative breeding among species with a northerly distribution is complex and differs between species, indicating a response to a variety of selection forces. Family cohesion where the offspring provide alloparental care is a main route to cooperatively breeding groups among corvids. Some corvid species lost only alloparental care, while maintaining coherent family groups. Other species lost family cohesion and, as a corollary, they also lost the behaviour where retained offspring provide alloparental care.
|
|
| 44. |
- Ekman, Stefan, et al.
(författare)
-
Extended phylogeny and a revised generic classification of the Pannariaceae (Peltigerales, Ascomycota)
- 2014
-
Ingår i: The Lichenologist. - 0024-2829 .- 1096-1135. ; 46:5, s. 627-656
-
Tidskriftsartikel (refereegranskat)abstract
- We estimated phylogeny in the lichen-forming ascomycete family Pannariaceae. We specifically modelled spatial (across-site) heterogeneity in nucleotide frequencies, as models not incorporating this heterogeneity were found to be inadequate for our data. Model adequacy was measured here as the ability of the model to reconstruct nucleotide diversity per site in the original sequence data. A potential non-orthologue in the internal transcribed spacer region (ITS) of Degelia plumbea was observed. We propose a revised generic classification for the Pannariaceae, accepting 30 genera, based on our phylogeny, previously published phylogenies, as well as available morphological and chemical data. Four genera are established as new: Austroparmeliella (for the 'Parmeliella' lacerata group), Nebularia (for the 'Parmeliella' incrassata group), Nevesia (for 'Fuscopannaria' sampaiana), and Pectenia (for the 'Degelia' plumbea group). Two genera are reduced to synonymy, Moelleropsis (included in Fuscopannaria) and Santessoniella (non-monophyletic; type included in Psoroma). Lepidocollema, described as monotypic, is expanded to include 23 species, most of which have been treated in the 'Parmeliella' mariana group. Homothecium and Leightoniella, previously treated in the Collemataceae, are here referred to the Pannariaceae. We propose 41 new species-level combinations in the newly described and re-circumscribed genera mentioned above, as well as in Leciophysma and Psoroma.
|
|
| 45. |
|
|
| 46. |
- Fassmer, K., et al.
(författare)
-
Middle Ordovician subduction of continental crust in the Scandinavian Caledonides - an example from Tjeliken, Seve Nappe Complex, Sweden.
- 2017
-
Ingår i: Contributions to Mineralogy and Petrology. - : Springer Science and Business Media LLC. - 0010-7999 .- 1432-0967. ; 172
-
Tidskriftsartikel (refereegranskat)abstract
- The Seve Nappe Complex of the Scandinavian Caledonides is thought to be derived from the distal passive margin of Baltica which collided with Laurentia in the Scandian Phase of the Caledonian Orogeny at 430–400 Ma. Parts of the Seve Nappe Complex were affected by pre-Scandian high- and ultrahigh-pressure metamorphism, in a tectonic framework that is still unclear, partly due to uncertainties about the exact timing. Previous age determinations yielded between ~ 505 and ~ 446 Ma, with a general trend of older ages in the North (Norrbotten) than in the South (Jämtland). New age determinations were performed on eclogite and garnet–phengite gneiss at Tjeliken in northern Jämtland. Thermodynamic modelling yielded peak metamorphic conditions of 25–27 kbar/680–760 °C for the garnet–phengite gneiss, similar to published peak metamorphic conditions of the eclogite (25–26 kbar/650–700 °C). Metamorphic rims of zircons from the garnet–phengite gneiss were dated using secondary ion mass spectrometry and yielded a concordia age of 458.9 ± 2.5 Ma. Lu–Hf garnet-whole rock dating yielded 458 ± 1.0 Ma for the eclogite. Garnet in the eclogite shows prograde major-element zoning and concentration of Lu in the cores, indicating that this age is related to garnet growth during pressure increase, i.e. subduction. The identical ages from both rock types, coinciding with published Sm–Nd ages from the eclogite, confirm subduction of the Seve Nappe Complex in Northern Jämtland during the Middle Ordovician in a fast subduction–exhumation cycle.
|
|
| 47. |
- Feng, Shaohong, et al.
(författare)
-
Dense sampling of bird diversity increases power of comparative genomics
- 2020
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 587:7833
-
Tidskriftsartikel (refereegranskat)abstract
- Whole-genome sequencing projects are increasingly populating the tree of life and characterizing biodiversity(1-4). Sparse taxon sampling has previously been proposed to confound phylogenetic inference(5), and captures only a fraction of the genomic diversity. Here we report a substantial step towards the dense representation of avian phylogenetic and molecular diversity, by analysing 363 genomes from 92.4% of bird families-including 267 newly sequenced genomes produced for phase II of the Bird 10,000 Genomes (B10K) Project. We use this comparative genome dataset in combination with a pipeline that leverages a reference-free whole-genome alignment to identify orthologous regions in greater numbers than has previously been possible and to recognize genomic novelties in particular bird lineages. The densely sampled alignment provides a single-base-pair map of selection, has more than doubled the fraction of bases that are confidently predicted to be under conservation and reveals extensive patterns of weak selection in predominantly non-coding DNA. Our results demonstrate that increasing the diversity of genomes used in comparative studies can reveal more shared and lineage-specific variation, and improve the investigation of genomic characteristics. We anticipate that this genomic resource will offer new perspectives on evolutionary processes in cross-species comparative analyses and assist in efforts to conserve species. A dataset of the genomes of 363 species from the Bird 10,000 Genomes Project shows increased power to detect shared and lineage-specific variation, demonstrating the importance of phylogenetically diverse taxon sampling in whole-genome sequencing.
|
|
| 48. |
- Ferm, Julia, et al.
(författare)
-
Paracarphalea, a new genus of the coffee family segregated from the Malagasy endemic genus Carphalea (Rubiaceae, Rubioideae, Knoxieae)
- 2016
-
Ingår i: Phytotaxa. - Magnolia Press : Magnolia Press. - 1179-3155 .- 1179-3163. ; 263:2, s. 98-112
-
Tidskriftsartikel (refereegranskat)abstract
- The Malagasy genus Carphalea (Rubiaceae) consists of six species (C. angulata, C. cloiselii, C. kirondron, C. linearifolia, C. madagascariensis, C. pervilleana) of shrubs or small trees and is recognizable by a distinctly lobed calyx, 2(–4)-locular ovaries, each locule with several ovules on a rod-like stalk arising from the base of the locule, and indehiscent fruits. Carphalea linearifolia, rediscovered in 2010, has not previously been included in any Rubiaceae molecular phylogenetic studies. We re-investigated the monophyly of Carphalea using sequence data from chloroplast (rps16 and trnT-F) and nuclear (ITS and ETS) markers analysed with parsimony and Bayesian methods. Carphalea linearifolia forms a clade with C. cloiselii and the type species C. madagascariensis. This clade is sister to a clade consisting of the rest of the Carphalea species plus the genus Triainolepis. According to these results, the new genus Paracarphalea is here described to accommodate Carphalea angulata, C. kirondron, and C. pervilleana. Theconservation status of Carphalea linearifolia is assessed as critically endangered according to IUCN criteria.
|
|
| 49. |
- Feuerborn, Tatiana R., et al.
(författare)
-
Competitive mapping allows for the identification and exclusion of human DNA contamination in ancient faunal genomic datasets
- 2020
-
Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 21:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: After over a decade of developments in field collection, laboratory methods and advances in high-throughput sequencing, contamination remains a key issue in ancient DNA research. Currently, human and microbial contaminant DNA still impose challenges on cost-effective sequencing and accurate interpretation of ancient DNA data.Results: Here we investigate whether human contaminating DNA can be found in ancient faunal sequencing datasets. We identify variable levels of human contamination, which persists even after the sequence reads have been mapped to the faunal reference genomes. This contamination has the potential to affect a range of downstream analyses.Conclusions: We propose a fast and simple method, based on competitive mapping, which allows identifying and removing human contamination from ancient faunal DNA datasets with limited losses of true ancient data. This method could represent an important tool for the ancient DNA field.
|
|
| 50. |
- Finch, B. W., et al.
(författare)
-
Disjunct resident population of Melodious Lark Mirafra cheniana discovered in East Africa
- 2022
-
Ingår i: Journal of Ornithology. - : Springer Science and Business Media LLC. - 2193-7192 .- 2193-7206. ; 164, s. 55-71
-
Tidskriftsartikel (refereegranskat)abstract
- We describe the discovery of a previously unknown population of Melodious Lark Mirafra cheniana from northern Tanzania and southern Kenya, some 2000 km north of what was previously thought to be its northern limit in central Zimbabwe. The identification of this population as M. cheniana is based primarily on analyses of mitochondrial DNA and song. We also clarify relationships within this genus by sequencing material of White-tailed Lark Mirafra albicauda for the first time; although its relationships with other species in the group remain unclear, our analyses clearly show it to be different from M. cheniana in the newly discovered population. The discovery of a population of M. cheniana in East Africa conforms to a known pattern for closely related lark species to have disjunct distributions in southern and eastern Africa.
|
|
