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Fulltext Compound osteoderms preserved in amber reveal the oldest known skink

Daza JD, Stanley EL, Heinicke MP, Leah C, Doucet DS, Fenner KL, et al.

Sci Rep, 2024 Jul 08;14(1):15662.
PMID: 38977836 DOI: 10.1038/s41598-024-66451-w

Scincidae is one of the most species-rich and cosmopolitan clades of squamate reptiles. Abundant disarticulated fossil material has also been attributed to this group, however, no complete pre-Cenozoic crown-scincid specimens have been found. A specimen in Burmite (99 MYA) is the first fossil that can be unambiguously referred to this clade. Our analyses place it as nested within extant skinks, supported by the presence of compound osteoderms formed by articulated small ostedermites. The specimen has a combination of dorsal and ventral compound osteoderms and overlapping cycloid scales that is limited to skinks. We propose that this type of osteoderm evolved as a response to an increased overlap of scales, and to reduced stiffness of the dermal armour. Compound osteoderms could be a key innovation that facilitated diversification in this megadiverse family.
A Multicenter Study on the Clinical Characteristics and Outcomes Among Children With Moderate to Severe Abusive Head Trauma

Yock-Corrales A, Lee JH, Domínguez-Rojas JÁ, Caporal P, Roa JD, Fernandez-Sarmiento J, et al.

J Pediatr Surg, 2024 Mar;59(3):494-499.
PMID: 37867044 DOI: 10.1016/j.jpedsurg.2023.09.038

INTRODUCTION: We aimed to identify clinical characteristics, risk factors for diagnosis, and describe outcomes among children with AHT.
METHODS: We performed an observational cohort study in tertiary care hospitals from 14 countries across Asia and Ibero-America. We included patients <5 years old who were admitted to participating pediatric intensive care units (PICUs) with moderate to severe traumatic brain injury (TBI). We performed descriptive analysis and multivariable logistic regression for risk factors of AHT.
RESULTS: 47 (12%) out of 392 patients were diagnosed with AHT. Compared to those with accidental injuries, children with AHT were more frequently < 2 years old (42, 89.4% vs 133, 38.6%, p
Fulltext Ghost admixture in eastern gorillas

Pawar H, Rymbekova A, Cuadros-Espinoza S, Huang X, de Manuel M, van der Valk T, et al.

Nat Ecol Evol, 2023 Sep;7(9):1503-1514.
PMID: 37500909 DOI: 10.1038/s41559-023-02145-2

Archaic admixture has had a substantial impact on human evolution with multiple events across different clades, including from extinct hominins such as Neanderthals and Denisovans into modern humans. In great apes, archaic admixture has been identified in chimpanzees and bonobos but the possibility of such events has not been explored in other species. Here, we address this question using high-coverage whole-genome sequences from all four extant gorilla subspecies, including six newly sequenced eastern gorillas from previously unsampled geographic regions. Using approximate Bayesian computation with neural networks to model the demographic history of gorillas, we find a signature of admixture from an archaic 'ghost' lineage into the common ancestor of eastern gorillas but not western gorillas. We infer that up to 3% of the genome of these individuals is introgressed from an archaic lineage that diverged more than 3 million years ago from the common ancestor of all extant gorillas. This introgression event took place before the split of mountain and eastern lowland gorillas, probably more than 40 thousand years ago and may have influenced perception of bitter taste in eastern gorillas. When comparing the introgression landscapes of gorillas, humans and bonobos, we find a consistent depletion of introgressed fragments on the X chromosome across these species. However, depletion in protein-coding content is not detectable in eastern gorillas, possibly as a consequence of stronger genetic drift in this species.
Fulltext The population genomic legacy of the second plague pandemic

Gopalakrishnan S, Ebenesersdóttir SS, Lundstrøm IKC, Turner-Walker G, Moore KHS, Luisi P, et al.

Curr Biol, 2022 Nov 07;32(21):4743-4751.e6.
PMID: 36182700 DOI: 10.1016/j.cub.2022.09.023

Human populations have been shaped by catastrophes that may have left long-lasting signatures in their genomes. One notable example is the second plague pandemic that entered Europe in ca. 1,347 CE and repeatedly returned for over 300 years, with typical village and town mortality estimated at 10%-40%.1 It is assumed that this high mortality affected the gene pools of these populations. First, local population crashes reduced genetic diversity. Second, a change in frequency is expected for sequence variants that may have affected survival or susceptibility to the etiologic agent (Yersinia pestis).2 Third, mass mortality might alter the local gene pools through its impact on subsequent migration patterns. We explored these factors using the Norwegian city of Trondheim as a model, by sequencing 54 genomes spanning three time periods: (1) prior to the plague striking Trondheim in 1,349 CE, (2) the 17th-19th century, and (3) the present. We find that the pandemic period shaped the gene pool by reducing long distance immigration, in particular from the British Isles, and inducing a bottleneck that reduced genetic diversity. Although we also observe an excess of large FST values at multiple loci in the genome, these are shaped by reference biases introduced by mapping our relatively low genome coverage degraded DNA to the reference genome. This implies that attempts to detect selection using ancient DNA (aDNA) datasets that vary by read length and depth of sequencing coverage may be particularly challenging until methods have been developed to account for the impact of differential reference bias on test statistics.