Publications by authors named "Sarah Lemer"

Article Synopsis
  • A genome assembly was completed for the heart cockle, a type of bivalve mollusk, with a total sequence length of 1,206.1 megabases.
  • The assembly is organized into 19 chromosomal pseudomolecules, and the mitochondrial genome measures 92.77 kilobases.
  • Gene annotation revealed 70,309 protein-coding genes in the assembled genome, as documented in Ensembl.
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Corals in marginal reef habitats generally exhibit less bleaching and associated mortality compared to nearby corals in more pristine reef environments. It is unclear, however, if these differences are due to environmental differences, including turbidity, or genomic differences between the coral hosts in these different environments. One particularly interesting case is in the coral genus Porites, which contains numerous morphologically similar massive Porites species inhabiting a wide range of reef habitats, from turbid river deltas and stagnant back reefs to high-energy fore reefs.

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Article Synopsis
  • A genome assembly has been created from a single individual of a heart cockle (part of the mollusk family).
  • The genome spans 1,153.1 megabases and has been organized into 19 chromosomal pseudomolecules, along with a 22.36 kilobase mitochondrial genome.
  • Gene annotation revealed a total of 17,262 protein-coding genes in this assembly, as identified on Ensembl.
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As in most colonial and sessile marine invertebrates, bryozoan life history is characterized by asexual propagation of zooids for colonial growth and by sexual production of larvae for dispersal. However, comprehensive life histories, particularly in cryptic species such as endolithic (boring) bryozoans, remain poorly understood. The ctenostome family Penetrantiidae is widespread from temperate to tropical waters and often found in molluscan shells, offering an opportunity to study the boring lifestyle and its potential impact on bioerosion through growth and settlement experiments.

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Article Synopsis
  • - Ctenostomes are difficult to classify due to their uncalcified structure and endolithic lifestyle, with four recent families identified that reside in hard substrates like mollusk shells.
  • - The family Penetrantiidae has been the subject of debate regarding its classification and exhibits significant variation, making species identification challenging.
  • - Through sequencing mitochondrial genomes and nuclear markers from various ctenostome species, the study reveals the Penetrantiidae as a distinct group closely related to other families, providing new insights into bryozoan classification and evolutionary relationships.
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Unlabelled: An endolithic lifestyle in mineralized substrates has evolved multiple times in various phyla including Bryozoa. The family Penetrantiidae includes one genus with ten extant and two fossil species. They predominantly colonize the shells of molluscs and establish colonies by chemical dissolution of calcium carbonate.

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Ocean acidification, caused by anthropogenic CO emissions, is predicted to have major consequences for reef-building corals, jeopardizing the scaffolding of the most biodiverse marine habitats. However, whether corals can adapt to ocean acidification and how remains unclear. We addressed these questions by re-examining transcriptome and genome data of Acropora millepora coral holobionts from volcanic CO seeps with end-of-century pH levels.

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Nautiloids are a charismatic group of marine molluscs best known for their rich fossil record, but today they are restricted to a handful of species in the family Nautilidae from around the Coral Triangle. Recent genetic work has shown a disconnect between traditional species, originally defined on shell characters, but now with new findings from genetic structure of various populations. Here, three new species of from the Coral Sea and South Pacific region are formally named using observations of shell and soft anatomical data augmented by genetic information: (from American Samoa), (from Fiji), and (from Vanuatu).

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Unlabelled: As global ocean temperatures continue to rise, severe declines in coral reef health and diversity are reported on a global scale. Recovery of coral reefs relies on reproduction and increased rates of successful recruitment, which can vary tremendously across coral species. We investigated the effects of increased temperatures in the environment of parental colonies on larval production, size, settlement and survival, in the heat-resistant coral in Guam Thanks to two tank experiments (eleven and four weeks, respectively) conducted over two consecutive years we found that larvae released by heat-treated parents (30 °C) were significantly smaller in size but greater in number, had normal settlement behavior and increased post-settlement survival rates compared to those released by control parent colonies (28 °C).

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Coolia Meunier 1919 from benthic assemblages of Hawai'i and Guam were isolated and clonal cultures were established from single cells. Cultures were identified to species-level based on 28S rRNA and ITS-5.8S rRNA genes and tested for toxicity.

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Harvesting models are based upon the ideology that removing large, old individuals provides space for young, fast-growing counterparts that can maximize (fisheries) yields while maintaining population stability and ecosystem function. Yet, this compensatory density dependent response has rarely been examined in multispecies systems. We combined extensive data sets from coral-reef fisheries across a suite of Pacific islands and provided unique context to the universal assumptions of compensatory density dependence.

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Island communities that rely on reef fish are currently faced with declining marine resources due to unsustainable fishing and climate change. Identification of genetic stocks through phylogenetic analyses has become a growing field of study with conservation implications, but genetic information on reef fish in Micronesia is limited. In this study we focus on Lethrinidae, one of the most commonly fished reef fish families in Micronesia.

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Article Synopsis
  • - Coral reefs are deteriorating globally due to rising sea temperatures, with individual coral colonies displaying different reactions to heat stress based on their local environments, particularly water flow conditions.
  • - Research on Acropora cf. pulchra examined how varying water flow influences gene expression during a natural bleaching event and in controlled experiments, revealing distinct genetic responses related to energy use and coral health.
  • - Corals in high-flow areas showed "frontloading" of heat-stress-related genes, suggesting that increased water movement enhances metabolism and resilience, leading to better survival and recovery during bleaching events.
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Background: Photosymbiotic associations between metazoan hosts and photosynthetic dinoflagellates are crucial to the trophic and structural integrity of many marine ecosystems, including coral reefs. Although extensive efforts have been devoted to study the short-term ecological interactions between coral hosts and their symbionts, long-term evolutionary dynamics of photosymbiosis in many marine animals are not well understood. Within Bivalvia, the second largest class of mollusks, obligate photosymbiosis is found in two marine lineages: the giant clams (subfamily Tridacninae) and the heart cockles (subfamily Fraginae), both in the family Cardiidae.

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Proper biological interpretation of a phylogeny can sometimes hinge on the placement of key taxa-or fail when such key taxa are not sampled. In this light, we here present the first attempt to investigate (though not conclusively resolve) animal relationships using genome-scale data from all phyla. Results from the site-heterogeneous CAT + GTR model recapitulate many established major clades, and strongly confirm some recent discoveries, such as a monophyletic Lophophorata, and a sister group relationship between Gnathifera and Chaetognatha, raising continued questions on the nature of the spiralian ancestor.

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Bivalvia has been the subject of extensive recent phylogenetic work to attempt resolving either the backbone of the bivalve tree using transcriptomic data, or the tips using morpho-anatomical data and up to five genetic markers. Yet the first approach lacked decisive taxon sampling and the second failed to resolve many interfamilial relationships, especially within the diverse clade Imparidentia. Here we combine dense taxon sampling with 108 deep-sequenced Illumina-based transcriptomes to provide resolution in nodes that required additional study.

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Article Synopsis
  • - Fissurellidae are a diverse group of marine snails, and this research uses molecular, geographical, and fossil evidence to clarify their evolutionary relationships and dispersal patterns.
  • - The study finds that many current genera classifications are incorrect and suggests a need for systematic revisions, particularly in the Emarginulinae group, while also estimating that these snails originated around 175 million years ago.
  • - Biogeographic analysis indicates that fissurellids likely originated in the Indo-West Pacific region and spread westward after Pangea's breakup, with established new synonyms and a new subfamily designation for Rimula in the process.
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Living fossils are survivors of previously more diverse lineages that originated millions of years ago and persisted with little morphological change. Therefore, living fossils are model organisms to study both long-term and ongoing adaptation and speciation processes. However, many aspects of living fossil evolution and their persistence in the modern world remain unclear.

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Article Synopsis
  • The study investigates the evolutionary relationships within the class Bivalvia using a comprehensive sampling of 219 species, aiming to clarify the bivalve Tree of Life at the family level and identify areas needing further taxonomic research.
  • While it does not recover monophyly for Bivalvia or its subgroups, it provides better resolution for some clades and confirms the monophyly of several higher-level clades such as Autobranchia and Pteriomorphia.
  • The findings challenge the classification and validity of numerous bivalve families, suggesting significant taxonomic revisions may be necessary, particularly for families like Psammobiidae and Cleidothaeridae, based on new phylogenetic insights.
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Mussels (Mytilida) are a group of bivalves with ancient origins and some of the most important commercial shellfish worldwide. Mytilida consists of approximately 400 species found in various littoral and deep-sea environments, and are part of the higher clade Pteriomorphia, but their exact position within the group has been unstable. The multiple adaptive radiations that occurred within Pteriomorphia have rendered phylogenetic classifications difficult and uncertainty remains regarding the relationships among most families.

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Background: Color polymorphism in the nacre of pteriomorphian bivalves is of great interest for the pearl culture industry. The nacreous layer of the Polynesian black-lipped pearl oyster Pinctada margaritifera exhibits a large array of color variation among individuals including reflections of blue, green, yellow and pink in all possible gradients. Although the heritability of nacre color variation patterns has been demonstrated by experimental crossing, little is known about the genes involved in these patterns.

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Sipunculans (also known as peanut worms) are an ancient group of exclusively marine worms with a global distribution and a fossil record that dates back to the Early Cambrian. The systematics of sipunculans, now considered a distinct subclade of Annelida, has been studied for decades using morphological and molecular characters, and has reached the limits of Sanger-based approaches. Here, we reevaluate their family-level phylogeny by comparative transcriptomic analysis of eight species representing all known families within Sipuncula.

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The family Pinnidae Leach, 1819, includes approximately 50 species of large subtidal and coastal marine bivalves. These commercially important species occur in tropical and temperate waters around the world and are most frequently found in seagrass meadows. The taxonomy of the family has been revised a number of times since the early 20th Century, the most recent revision recognizing 55 species distributed in three genera: Pinna, Atrina and Streptopinna, the latter being monotypic.

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Translocation has been widely studied as a tool for conservation management to restore or enhance degraded populations. On the contrary, few studies have been conducted on translocation for commercial purposes. In this study, we evaluate the genetic consequences of translocation of wild individuals of Pinctada margaritifera on farmed and adjacent wild populations.

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