Determinate growth is predominant and likely ancestral in squamate reptiles

Body growth is typically thought to be indeterminate in ectothermic vertebrates. Indeed, until recently, this growth pattern was considered to be ubiquitous in ectotherms. Our recent observations of a complete growth plate cartilage (GPC) resorption, a reliable indicator of arrested skeletal growth, in many species of lizards clearly reject the ubiquity of indeterminate growth in reptiles and raise the question about the ancestral state of the growth pattern. Using X-ray micro-computed tomography (µCT), here we examined GPCs of long bones in three basally branching clades of squamate reptiles, namely in Gekkota, Scincoidea and Lacertoidea. A complete loss of GPC, indicating skeletal growth arrest, was the predominant finding. Using a dataset of 164 species representing all major clades of lizards and the tuataras, we traced the evolution of determinate growth on the phylogenetic tree of Lepidosauria. The reconstruction of character states suggests that determinate growth is ancestral for the squamate reptiles (Squamata) and remains common in the majority of lizard lineages, while extended (potentially indeterminate) adult growth evolved several times within squamates. Although traditionally associated with endotherms, determinate growth is coupled with ectothermy in this lineage. These findings combined with existing literature suggest that determinate growth predominates in both extant and extinct amniotes.

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Growth Interruptions in Arctic Rhodoliths Correspond to Water Depth and Rhodolith Morphology

Minerals ◽

10.3390/min11050538 ◽

2021 ◽

Vol 11 (5) ◽

pp. 538

Author(s):

Moritz Schlüter ◽

Ines Pyko ◽

Max Wisshak ◽

Christian Schulbert ◽

Sebastian Teichert

Keyword(s):

Light Availability ◽

Growth Patterns ◽

Skeletal Growth ◽

Coralline Algae ◽

Ambient Light ◽

Micro Computed Tomography ◽

Svalbard Archipelago ◽

X Ray ◽

Algal Thalli ◽

Environmental Proxies

Coralline algae that form rhodoliths are widespread globally and their skeletal growth patterns have been used as (paleo-) environmental proxies in a variety of studies. However, growth interruptions (hiati) within their calcareous skeletons are regarded as problematic in this context. Here we investigated how hiati in the growth of Arctic rhodoliths from the Svalbard archipelago correspond to their environment and morphology. Using X-ray micro-computed tomography and stepwise model selections, we found that rhodoliths from deeper waters are subject to more frequent hiatus formation. In addition, rhodoliths with a higher sphericity (i.e., roundness) are less often affected by such growth interruptions. We conclude that these correlations are mainly regulated by hydrodynamics, because, in deeper waters, rhodoliths are not turned frequently enough to prevent a dieback of coralline algal thalli forming on the underside of the rhodolith. In this coherence, spheroidal rhodoliths are turned more easily, therefore shortening the amount of time between turnover events. Moreover, the incidence of light is more advantageous in shallower waters where rhodoliths exhibit a greater share of their surface to diffused ambient light, thus enabling thallus growth also on the down-facing surface of the rhodoliths. In consequence, information on the frequency of hiatus formation combined with rhodolith morphology might serve as a valuable proxy for (paleo-)environmental reconstructions in respect to light availability and the hydrodynamic regime.

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Diversification through gustatory courtship: an X-ray micro-computed tomography study on dwarf spiders

Frontiers in Zoology ◽

10.1186/s12983-021-00435-8 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Shou-Wang Lin ◽

Lara Lopardo ◽

Gabriele Uhl

Keyword(s):

Computed Tomography ◽

Sexual Selection ◽

Anterior Part ◽

Divergent Evolution ◽

Sexually Dimorphic ◽

Ancestral State ◽

Glandular Tissue ◽

Micro Computed Tomography ◽

Nuptial Gifts ◽

X Ray

Abstract Background Sexual selection has been considered to promote diversification and speciation. Sexually dimorphic species have been used to explore the supposed effect, however, with mixed results. In dwarf spiders (Erigoninae), many species are sexually dimorphic—males possess marked prosomal modifications. These male traits vary from moderate elevations to bizarre shapes in various prosomal regions. Previous studies established that male dwarf spiders produce substances in these prosomal modifications that are taken up by the females. These substances can act as nuptial gifts, which increase the mating probability of males and the oviposition rate in females. Therefore, these dimorphic traits have evolved in the context of sexual selection. Here, we explore the evolutionary lability of this gustatory trait complex with the aim of assessing the role of this trait complex in species divergence by investigating (1) if erigonine modified prosomata are inherently linked to nuptial-gift-producing glands, (2) if the evolution of the glands evolution preceded that of the modified prosomal shapes, and by assessing (3) the occurrence of convergent/divergent evolution and cryptic differentiation. Results We reconstructed the position and extent of the glandular tissue along with the muscular anatomy in the anterior part of the prosoma of 76 erigonine spiders and three outgroup species using X-ray micro-computed tomography. In all but one case, modified prosomata are associated with gustatory glands. We incorporated the location of glands and muscles into an existing matrix of somatic and genitalic morphological traits of these taxa and reanalyzed their phylogenetic relationship. Our analysis supports that the possession of glandular equipment is the ancestral state and that the manifold modifications of the prosomal shape have evolved convergently multiple times. We found differences in gland position between species with both modified and unmodified prosomata, and reported on seven cases of gland loss. Conclusions Our findings suggest that the occurrence of gustatory glands in sexually monomorphic ancestors has set the stage for the evolution of diverse dimorphic external modifications in dwarf spiders. Differences among congeners suggest that the gland position is highly susceptible to evolutionary changes. The multiple incidences might reflect costs of glandular tissue maintenance and nuptial feeding. Our results indicate divergent evolutionary patterns of gustatory-courtship-related traits, and thus a likely facilitating effect of sexual selection on speciation.

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Towards the analysis of coral skeletal density-banding using deep learning

SN Applied Sciences ◽

10.1007/s42452-021-04912-x ◽

2022 ◽

Vol 4 (2) ◽

Author(s):

Ainsley Rutterford ◽

Leonardo Bertini ◽

Erica J. Hendy ◽

Kenneth G. Johnson ◽

Rebecca Summerfield ◽

...

Keyword(s):

Neural Network ◽

Traditional Method ◽

Linear Extension ◽

Skeletal Growth ◽

Micro Computed Tomography ◽

Skeletal Density ◽

X Ray ◽

3D Space ◽

Density Banding ◽

Growth Banding

AbstractX-ray micro–computed tomography (µCT) is increasingly used to record the skeletal growth banding of corals. However, the wealth of data generated is time consuming to analyse for growth rates and colony age. Here we test an artificial intelligence (AI) approach to assist the expert identification of annual density boundaries in small colonies of massive Porites spanning decades. A convolutional neural network (CNN) was trained with µCT images combined with manually labelled ground truths to learn banding-related features. The CNN successfully predicted the position of density boundaries in independent images not used in training. Linear extension rates derived from CNN-based outputs and the traditional method were consistent. In the future, well-resolved 2D density boundaries from AI can be used to reconstruct density surfaces and enable studies focused on variations in rugosity and growth gradients across colony 3D space. We recommend the development of a community platform to share annotated images for AI.

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Diversification Through Gustatorial-Courtship: An X-ray Micro-Computed Tomography Study on Dwarf Spiders

10.21203/rs.3.rs-594155/v1 ◽

2021 ◽

Author(s):

Shou-Wang Lin ◽

Lara Lopardo ◽

Gabriele Uhl

Keyword(s):

Computed Tomography ◽

Sexual Selection ◽

Anterior Part ◽

Sexually Dimorphic ◽

Ancestral State ◽

Glandular Tissue ◽

Micro Computed Tomography ◽

Evolutionary Patterns ◽

X Ray ◽

Outgroup Species

Abstract BackgroundSexual selection has been considered to promote diversification and speciation. Sexually dimorphic species have been used to explore the supposed effect, however, with mixed results. In dwarf spiders (Erigoninae), many species are sexually dimorphic - males possess marked prosomal modifications. These male traits vary from moderate elevation to bizarre shapes in various prosomal regions. Previous studies established that male dwarf spiders produce substances in these prosomal modifications that are taken up by the female. Since the transfer of substances increases mating probability of males and oviposition rate in females, the dimorphic traits evolved in the context of sexual selection. Here, we explore the evolutionary lability of the gustatory trait complex by investigating 1) if erigonine modified prosomata are inherently linked to nuptial-gift-producing glands, 2) if gland evolution preceded that of the modified prosomal shapes and by assessing 3) the probability of convergent evolution and cryptic differentiation - with the aim of assessing the role of this trait complex in species divergence.ResultsWe reconstructed the position and extent of the glandular tissue along with the muscular anatomy in the anterior part of the prosoma of 76 erigonine spiders and three outgroup species using X-ray micro-computed tomography. We incorporated the location of glands and muscles into an existing matrix of somatic and genitalic morphological traits of these taxa and reanalyzed their phylogenetic relationship. Our analysis supports that possession of glandular equipment is the ancestral state. The manifold modifications of the prosomal shape have evolved convergently multiple times. We found differences in glandular position between species with both modified and unmodified prosomata, and reported on seven cases of gland loss. ConclusionsOur findings suggest that the occurrence of gustatory gland in sexually monomorphic ancestors has set the stage for the evolution of diverse dimorphic external modifications in dwarf spiders. Variation among congeners indicates that glandular position is highly susceptible to changes. Multiple incidences of gland loss suggest considerable maintenance costs of glandular tissue and nuptial feeding. Our results demonstrate divergent evolutionary patterns of gustatorial-courtship-related traits, and a likely facilitating effect of this type of sexual selection on speciation

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Identification of Fibrotic Thickening as Early Marker of Aortic Valve Stenosis Using X-Ray Micro Computed Tomography and Optical Coherence Tomography

The Thoracic and Cardiovascular Surgeon ◽

10.1055/s-0036-1571661 ◽

2016 ◽

Vol 64 (S 01) ◽

Author(s):

A. Jannasch ◽

C. Schnabel ◽

M. Santini ◽

S. Fest-Santini ◽

M. Lorenzi ◽

...

Keyword(s):

Computed Tomography ◽

Optical Coherence Tomography ◽

Aortic Valve ◽

Aortic Valve Stenosis ◽

Optical Coherence ◽

Micro Computed Tomography ◽

X Ray ◽

Early Marker

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Morphology and Affinities of Ampelocissites Seeds (Vitaceae: Ampelopsis clade) from the Paleogene of Texas, USA

Systematic Botany ◽

10.1600/036364420x15935294613400 ◽

2020 ◽

Vol 45 (3) ◽

pp. 478-482

Author(s):

Steven R. Manchester

Keyword(s):

Computed Tomography ◽

Cross Sections ◽

Seed Coat ◽

Ct Scanning ◽

Seed Morphology ◽

Early Eocene ◽

Micro Computed Tomography ◽

X Ray ◽

Fossil Seeds ◽

Fossil Genus

Abstract—The type material on which the fossil genus name Ampelocissites was established in 1929 has been reexamined with the aid of X-ray micro-computed tomography (μ-CT) scanning and compared with seeds of extant taxa to assess the relationships of these fossils within the grape family, Vitaceae. The specimens were collected from a sandstone of late Paleocene or early Eocene age. Although originally inferred by Berry to be intermediate in morphology between Ampelocissus and Vitis, the newly revealed details of seed morphology indicate that these seeds represent instead the Ampelopsis clade. Digital cross sections show that the seed coat maintains its thickness over the external surfaces, but diminishes quickly in the ventral infolds. This feature, along with the elliptical chalaza and lack of an apical groove, indicate that Ampelocissites lytlensis Berry probably represents Ampelopsis or Nekemias (rather than Ampelocissus or Vitis) and that the generic name Ampelocissites may be useful for fossil seeds with morphology consistent with the Ampelopsis clade that lack sufficient characters to specify placement within one of these extant genera.

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