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Insights into palaeobotany
Get PDFCopyright © 2023 Société botanique de France. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article
Microstructure and crystallographic texture data in modern giant clam shells (Tridacna squamosa and Hippopus hippopus)
No full textThis article provides novel data on the microstructure and crystallographic texture of modern giant clam shells (Tridacna squamosa and Hippopus hippopus) from the Coral Triangle region of northeast Borneo. Giant clams have two aragonitic shell layers—the inner and outer shell layer. This dataset focuses on the inner shell layer as this is well preserved and not affected by diagenetic alteration. To prepare samples for analysis, shells were cut longitudinally at the axis of maximum growth and mounted onto thin sections. Data collection involved scanning electron microscopy (SEM) to determine microstructure and SEM based electron backscatter diffraction (EBSD) for quantitative measurement of crystallographic orientation and texture. Post-acquisition reanalysis of saved EBSD patterns to optimize data quality included changing the number of reflectors and band detection mode. We provide EBSD data as band contrast images and colour-coded orientation maps (inverse pole figure maps). Crystallographic co-orientation strength obtained with multiple of uniform density (MUD) values are derived from density distributed pole figures of indexed EBSD points. Raw EBSD data files are also given to ensure repeatability of the steps provided in this article and to allow extraction of further crystallographic properties for future researchers. Overall, this dataset provides 1. a better understanding of shell growth and biomineralization in giant clams and 2. important steps for optimizing data collection with EBSD analyses in biogenic carbonates.Copyright © The Author(s) 2021. This is an open access article, available to all readers online, published under a creative commons licensing (https://creativecommons.org/licenses/by/4.0/). The attached file is the accepted version of the article.NHM Repositor
Convergent evolution of plant prickles by repeated gene co-option over deep time
Get PDFAn enduring question in evolutionary biology concerns the degree to which episodes of convergent trait evolution depend on the same genetic programs, particularly over long timescales. In this work, we genetically dissected repeated origins and losses of prickles—sharp epidermal projections—that convergently evolved in numerous plant lineages. Mutations in a cytokinin hormone biosynthetic gene caused at least 16 independent losses of prickles in eggplants and wild relatives in the genus
Solanum
. Homologs underlie prickle formation across angiosperms that collectively diverged more than 150 million years ago, including rice and roses. By developing new
Solanum
genetic systems, we leveraged this discovery to eliminate prickles in a wild species and an indigenously foraged berry. Our findings implicate a shared hormone activation genetic program underlying evolutionarily widespread and recurrent instances of plant morphological innovation.This work is licensed under a Creative Commons Attribution 4.0 International License, which allows reusers to distribute, remix,
adapt, and build upon the material in any medium or format, so long as attribution is given to the creator. The license allows for
commercial use. The attached file is the Author Manuscript - you are advised to consult the published version if you wish to cite it.NHM Repositor
A new Late Triassic sauropodomorph dinosaur from the Mid-Zambezi Basin, Zimbabwe
Get PDFAn articulated partial hind limb collected from the Pebbly Arkose Formation (Norian, Upper Triassic) of the Upper Karoo
Group of Zimbabwe is described as a new taxon of sauropodomorph dinosaur. Musankwa sanyatiensis gen. et sp. nov.
was discovered on the shoreline of Lake Kariba, on Spurwing Island in the Mid-Zambezi Basin. The holotype consists of
a right femur, tibia, and astragalus, and can be distinguished from all other Late Triassic massopodan sauropodomorphs
on the basis of numerous features, which form a unique character combination. Phylogenetic analysis recovers the new
taxon as the earliest-branching lineage within Massopoda. Musankwa is only the fourth dinosaur to be named from the
Karoo-aged basins of Zimbabwe and further demonstrates the high potential of this region for discoveries of new early
dinosaur material.Copyright © 2024 P.M. Barrett et al. This is an open-access article distributed under the terms of the Creative Commons
Attribution License (for details please see http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use,
distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article.NHM Repositor
Primum non nocere: Technologically advanced non-invasive pheromone traps for sustainable monitoring of the European threatened hermit beetles Osmoderma barnabita / eremita (Coleoptera: Scarabaeidae)
Get PDFA smart pheromone trap designed for the monitoring of Osmoderma barnabita / eremita has been successfully developed and testedin situ. The trap's design and operational principles allowa photo-recording of the capture moment and logging parameters of air temperature and humidity at the moment of capture. These dataare then seamlessly transmitted to a server via mobile network. The adaptability of environmental parameter recording allows customization to suit specific requirements of a given study. Rigorous testing of these traps within three Natura 2000 sites in Latvia in 2003has substantiated their robust performance and efficiency. Notably, the traps exhibit versatility and can be modified and tailored for monitoring various insect species, utilizing both pheromones and lures as attractants. This innovation holds promise for advancing ecological research and monitoring endeavours pertaining to diverse insect populations.Copyright © The Authors. The attached file is the published version of the article.NHM Repositor
Evaluation of genome skimming to detect and characterise human and livestock helminths
Get PDFThe identification of gastrointestinal helminth infections of humans and livestock almost exclusively relies on the detection of eggs or larvae in faeces, followed by manual counting and morphological characterisation to differentiate species using microscopy-based techniques. However, molecular approaches based on the detection and quantification of parasite DNA are becoming more prevalent, increasing the sensitivity, specificity and throughput of diagnostic assays. High-throughput sequencing, from single PCR targets through to the analysis of whole genomes, offers significant promise towards providing information-rich data that may add value beyond traditional and conventional molecular approaches; however, thus far, its utility has not been fully explored to detect helminths in faecal samples. In this study, low-depth whole genome sequencing, i.e. genome skimming, has been applied to detect and characterise helminth diversity in a set of helminth-infected human and livestock faecal material. The strengths and limitations of this approach are evaluated using three methods to characterise and differentiate metagenomic sequencing data based on (i) mapping to whole mitochondrial genomes, (ii) whole genome assemblies, and (iii) a comprehensive internal transcribed spacer 2 (ITS2) database, together with validation using quantitative PCR (qPCR). Our analyses suggest that genome skimming can successfully identify most single and multi-species infections reported by qPCR and can provide sufficient coverage within some samples to resolve consensus mitochondrial genomes, thus facilitating phylogenetic analyses of selected genera, e.g. Ascaris spp. Key to this approach is both the availability and integrity of helminth reference genomes, some of which are currently contaminated with bacterial and host sequences. The success of genome skimming of faecal DNA is dependent on the availability of vouchered sequences of helminths spanning both taxonomic and geographic diversity, together with methods to detect or amplify minute quantities of parasite nucleic acids in mixed samples.Copyright © 2023 The Author(s). Published by Elsevier Ltd on behalf of Australian Society for Parasitology. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). The attached file is the published version of the article.NHM Repositor
Microchromosome fusions underpin convergent evolution of chameleon karyotypes
No full textAbstract
Evolutionary shifts in chromosome compositions (karyotypes) are major drivers of lineage and genomic diversification. Fusion of ancestral chromosomes is one hypothesized mechanism for the evolutionary reduction of the total chromosome number, a frequently implied karyotypic shift. Empirical tests of this hypothesis require model systems with variable karyotypes, known chromosome features, and a robust phylogeny. Here we used chameleons, diverse lizards with exceptionally variable karyotypes (), to test whether chromosomal fusions explain the repeated evolution of karyotypes with fewer chromosomes than ancestral karyotypes. Using a multidisciplinary approach including cytogenetic analyses and phylogenetic comparative methods, we found that a model of constant loss through time best explained chromosome evolution across the chameleon phylogeny. Next, we tested whether fusions of microchromosomes into macrochromosomes explained these evolutionary losses using generalized linear models. Multiple comparisons supported microchromosome fusions as the predominant agent of evolutionary loss. We further compared our results to various natural history traits and found no correlations. As such, we infer that the tendency of microchromosomes to fuse was a quality of the ancestral chameleon genome and that the genomic predisposition of ancestors is a more substantive predictor of chromosome change than the ecological, physiological, and biogeographical factors involved in their diversification.Copyright ©The Author(s) 2023. Published by Oxford University Press on behalf of The Society for the Study of Evolution (SSE). This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. The linked file is the published version of the article.NHM Repositor
The operculate cyclostome bryozoans: a chronicle of convergence, controversy and classification
Get PDFThe attached file is the published version of the book chapter.NHM Repositor
Raptorial appendages of the Cambrian apex predator<i>Anomalocaris canadensis</i>are built for soft prey and speed
Get PDFThe stem-group euarthropod Anomalocaris canadensis is one of the largest Cambrian animals and is often considered the quintessential apex predator of its time. This radiodont is commonly interpreted as a demersal hunter, responsible for inflicting injuries seen in benthic trilobites. However, controversy surrounds the ability of A. canadensis to use its spinose frontal appendages to masticate or even manipulate biomineralized prey. Here, we apply a new integrative computational approach, combining three-dimensional digital modelling, kinematics, finite-element analysis (FEA) and computational fluid dynamics (CFD) to rigorously analyse an A. canadensis feeding appendage and test its morphofunctional limits. These models corroborate a raptorial function, but expose inconsistencies with a capacity for durophagy. In particular, FEA results show that certain parts of the appendage would have experienced high degrees of plastic deformation, especially at the endites, the points of impact with prey. The CFD results demonstrate that outstretched appendages produced low drag and hence represented the optimal orientation for speed, permitting acceleration bursts to capture prey. These data, when combined with evidence regarding the functional morphology of its oral cone, eyes, body flaps and tail fan, suggest that A. canadensis was an agile nektonic predator that fed on soft-bodied animals swimming in a well-lit water column above the benthos. The lifestyle of A. canadensis and that of other radiodonts, including plausible durophages, suggests that niche partitioning across this clade influenced the dynamics of Cambrian food webs, impacting on a diverse array of organisms at different sizes, tiers and trophic levels.Copyright © 2023 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. The attached file is the published version of the article.NHM Repositor
The Development and Neuronal Complexity of Bipinnaria Larvae of the Sea Star Asterias rubens
Get PDFSynopsis - Free-swimming planktonic larvae are a key stage in the development of many marine phyla, and studies of these organisms have contributed to our understanding of major genetic and evolutionary processes. Although transitory, these larvae often attain a remarkable degree of tissue complexity, with well-defined musculature and nervous systems. Among the best studied are larvae belonging to the phylum Echinodermata, but with work largely focused on the pluteus larvae of sea urchins (class Echinoidea). The greatest diversity of larval strategies among echinoderms is found in the class Asteroidea (sea stars), organisms that are rapidly emerging as experimental systems for genetic and developmental studies. However, the bipinnaria larvae of sea stars have only been studied in detail in a small number of species and although they have been relatively well described neuro-anatomically, they are poorly understood neurochemically. Here, we have analyzed embryonic development and bipinnaria larval anatomy in the common North Atlantic sea star Asterias rubens, using a variety of staining methods in combination with confocal microscopy. Importantly, the chemical complexity of the nervous system of bipinnaria larvae was revealed through use of a diverse set of antibodies, with identification of at least three centers of differing neurochemical signature within the previously described nervous system: the anterior apical organ, oral region, and ciliary bands. Furthermore, the anatomy of the musculature and sites of cell division in bipinnaria larvae was analyzed. Comparisons of developmental progression and molecular anatomy across the Echinodermata provided a basis for hypotheses on the shared evolutionary and developmental processes that have shaped this group of animals. We conclude that bipinnaria larvae appear to be remarkably conserved across ∼200 million years of evolutionary time and may represent a strong evolutionary and/or developmental constraint on species utilizing this larval strategy.Copyright © The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. The linked file is the published version of the article.NHM Repositor