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Mitogenomics of historical type specimens of Australasian turtles: clarification of taxonomic confusion and old mitochondrial introgression.

ABSTRACT: Diagnosability is central to taxonomy as are type specimens which define taxa. New advances in technologies and the discovery of new informative traits must be matched with previous taxonomic decisions based on name-bearing type specimens. Consequently, the challenge of sequencing highly degraded DNA from historical types becomes an inevitability to resolve the very many taxonomic issues arising from, by modern standards, poor historical species descriptions leading to difficulties to assign names to genetic clusters identified from fresh material. Here we apply high-throughput parallel sequencing and sequence baiting to reconstruct the mitogenomes from 18 type specimens of Australasian side-necked turtles (Chelidae). We resolve a number of important issues that have confused the taxonomy of this family, and analyse the mitogenomes of the types and those of fresh material to improve our understanding of the phylogenetic relationships of this morphologically conservative group. Together with previously published nuclear genomic data, our study provides evidence for multiple old mitochondrial introgressions.

SUBMITTER: Kehlmaier C

PROVIDER: S-EPMC6456567 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Mitogenomics of historical type specimens of Australasian turtles

Project description:Mitogenomics of historical type specimens of Australasian turtles

| PRJEB31010 | ENA

Mitogenomics of historical type specimens clarifies the taxonomy of Ethiopian <i>Ptychadena</i> Boulenger, 1917 (Anura, Ptychadenidae).

Project description:The taxonomy of the Ptychadenaneumanni species complex, a radiation of grass frogs inhabiting the Ethiopian highlands, has puzzled scientists for decades because of the morphological resemblance among its members. Whilst molecular phylogenetic methods allowed the discovery of several species in recent years, assigning pre-existing and new names to clades was challenged by the unavailability of molecular data for century-old type specimens. We used Illumina short reads to sequence the mitochondrial DNA of type specimens in this group, as well as ddRAD-seq analyses to resolve taxonomic uncertainties surrounding the P.neumanni species complex. The phylogenetic reconstruction revealed recurrent confusion between Ptychadenaerlangeri (Ahl, 1924) and P.neumanni (Ahl, 1924) in the literature. The phylogeny also established that P.largeni Perret, 1994 represents a junior synonym of P.erlangeri (Ahl, 1924) and distinguished between two small species, P.nana Perret, 1994, restricted to the Arussi Plateau, and P.robeensis Goutte, Reyes-Velasco, Freilich, Kassie & Boissinot, 2021, which inhabits the Bale Mountains. The phylogenetic analyses of mitochondrial DNA from type specimens also corroborate the validity of seven recently described species within the group. Our study shows how modern molecular tools applied to historical type specimens can help resolve long-standing taxonomic issues in cryptic species complexes.

| S-EPMC8604866 | biostudies-literature

200 years of taxonomic confusion: Sporendonema and allies.

Project description:The genus Sporendonema (Gymnoascaceae, Onygenales) was introduced in 1827 with the type species S. casei for a red mould on cheese. Cheese is a consistent niche for this species. Sphaerosporium equinum is another species classified in Gymnoascaceae and has also been reported from cheese. Recently, other habitats have been reported for both Sporendonema casei and Sphaerosporium equinum. The present study aimed to investigate the taxonomy of Sporendonema and Sphaerosporium, as well as a close neighbour, Arachniotus. Two strains of Hormiscium aurantiacum, another related cheese-associated species were also included in the analyses. Strains were evaluated in terms of macro- and micromorphology, physiology including salt tolerance, growth rate at different temperatures, casein degradation, cellulase activity, lipolytic activity, and multi-locus phylogeny with sequences of the nuclear ribosomal internal transcribed spacer region, the D1-D2 region of the large subunit and partial β-tubulin locus sequences. The results showed that the analysed species were congeneric, and the generic names Arachniotus and Sphaerosporium should be reduced to the synonymy of Sporendonema. Therefore, four new combinations as well as one lectotype and one epitype were designated in Sporendonema. Two strains attributed to Sphaerosporium equinum from substrates other than cheese were found to be phylogenetically and morphologically deviant and were introduced as a new species named Sporendonema isthmoides.

| S-EPMC10940481 | biostudies-literature

Clarifying the confusion: old-growth savannahs and tropical ecosystem degradation.

Project description:Ancient tropical grassy biomes are often misrecognized as severely degraded forests. I trace this confusion to several factors, with roots in the nineteenth century, including misinterpretations of the nature of fire in savannahs, attempts to reconcile savannah ecology with Clementsian succession, use of physiognomic (structural) definitions of savannah and development of tropical degradation frameworks focused solely on forests. Towards clarity, I present two models that conceptualize the drivers of ecosystem degradation as operating in both savannahs and forests. These models highlight how human-induced environmental changes create ecosystems with superficially similar physiognomies but radically different conservation values. Given the limitation of physiognomy to differentiate savannahs from severely degraded forests, I present an alternative approach based on floristic composition. Data from eastern lowland Bolivia show that old-growth savannahs can be reliably distinguished by eight grass species and that species identity influences ecosystem flammability. I recommend that scientists incorporate savannahs in tropical degradation frameworks alongside forests, and that savannah be qualified as old-growth savannah in reference to ancient grassy biomes or derived savannah in reference to deforestation. These conceptual advances will require attention not only to tree cover, but also to savannah herbaceous plant species and their ecologies.This article is part of the themed issue 'Tropical grassy biomes: linking ecology, human use and conservation'.

| S-EPMC4978865 | biostudies-literature

An old confusion: Entomophthoromycosis versus mucormycosis and their main differences.

Project description:Fungal diseases were underestimated for many years. And the global burden of fungal infections is substantial and has increased in recent years. Invasive fungal infections have been linked to several risk factors in humans which basically depend on the individual homeostasis of the patients. However, many fungi can infect even apparently healthy people. Knowledge of these pathogens is critical in reducing or stopping morbidity and/or mortality statistics due to fungal pathogens. Successful therapeutic strategies rely on rapid diagnosis of the causative fungal agent and the underlying disease. However, the terminology of the diseases was updated to existing phylogenetic classifications and led to confusion in the definition of mucormycosis, conidiobolomycosis, and basidiobolomycosis, which were previously grouped under the now-uncommon term zygomycosis. Therefore, the ecological, taxonomic, clinical, and diagnostic differences are addressed to optimize the understanding and definition of these diseases. The term "coenocytic hyphomycosis" is proposed to summarize all fungal infections caused by Mucorales and species of Basidiobolus and Conidiobolus.

| S-EPMC9670544 | biostudies-literature

Sex is determined by XX/XY sex chromosomes in Australasian side-necked turtles (Testudines: Chelidae).

Project description:Turtles demonstrate variability in sex determination and, hence, constitute an excellent model for the evolution of sex chromosomes. Notably, the sex determination of the freshwater turtles from the family Chelidae, a species-rich group with wide geographical distribution in the southern hemisphere, is still poorly explored. Here we documented the presence of an XX/XY sex determination system in seven species of the Australasian chelid genera Chelodina, Emydura, and Elseya by conventional (karyogram reconstruction, C-banding) and molecular cytogenetic methods (comparative genome hybridization, in situ hybridization with probes specific for GATA microsatellite motif, the rDNA loci, and the telomeric repeats). The sex chromosomes are microchromosomes in all examined species of the genus Chelodina. In contrast, the sex chromosomes are the 4th largest pair of macrochromosomes in the genera Emydura and Elseya. Their X chromosomes are submetacentric, while their Y chromosomes are metacentric. The chelid Y chromosomes contain a substantial male-specific genomic region with an accumulation of the GATA microsatellite motif, and occasionally, of the rDNA loci and telomeric repeats. Despite morphological differences between sex chromosomes, we conclude that male heterogamety was likely already present in the common ancestor of Chelodina, Emydura and Elseya in the Mesozoic period.

| S-EPMC7062838 | biostudies-literature

Genomics Reveals the Origins of Historical Specimens.

Project description:Centuries of zoological studies have amassed billions of specimens in collections worldwide. Genomics of these specimens promises to reinvigorate biodiversity research. However, because DNA degrades with age in historical specimens, it is a challenge to obtain genomic data for them and analyze degraded genomes. We developed experimental and computational protocols to overcome these challenges and applied our methods to resolve a series of long-standing controversies involving a group of butterflies. We deduced the geographical origins of several historical specimens of uncertain provenance that are at the heart of these debates. Here, genomics tackles one of the greatest problems in zoology: countless old specimens that serve as irreplaceable embodiments of species concepts cannot be confidently assigned to extant species or population due to the lack of diagnostic morphological features and clear documentation of the collection locality. The ability to determine where they were collected will resolve many on-going disputes. More broadly, we show the utility of applying genomics to historical museum specimens to delineate the boundaries of species and populations, and to hypothesize about genotypic determinants of phenotypic traits.

| S-EPMC8097301 | biostudies-literature

Exploring historical trends using taxonomic name metadata.

Project description:BackgroundAuthority and year information have been attached to taxonomic names since Linnaean times. The systematic structure of taxonomic nomenclature facilitates the ability to develop tools that can be used to explore historical trends that may be associated with taxonomy.ResultsFrom the over 10.7 million taxonomic names that are part of the uBio system 4, approximately 3 million names were identified to have taxonomic authority information from the years 1750 to 2004. A pipe-delimited file was then generated, organized according to a Linnaean hierarchy and by years from 1750 to 2004, and imported into an Excel workbook. A series of macros were developed to create an Excel-based tool and a complementary Web site to explore the taxonomic data. A cursory and speculative analysis of the data reveals observable trends that may be attributable to significant events that are of both taxonomic (e.g., publishing of key monographs) and societal importance (e.g., world wars). The findings also help quantify the number of taxonomic descriptions that may be made available through digitization initiatives.ConclusionTemporal organization of taxonomic data can be used to identify interesting biological epochs relative to historically significant events and ongoing efforts. We have developed an Excel workbook and complementary Web site that enables one to explore taxonomic trends for Linnaean taxonomic groupings, from Kingdoms to Families.

| S-EPMC2408592 | biostudies-literature

Utilizing herbarium specimens to quantify historical mycorrhizal communities.

Project description:Premise of the studyMycorrhiza are critical to ecosystem functioning, but a lack of historical baseline data limits our understanding of the long-term belowground effects of global change. Herbarium specimens may provide this needed insight. However, it is unknown whether DNA of arbuscular mycorrhizal fungi (AMF) can be reliably extracted from vascular plant specimen roots.MethodsWe sampled roots from herbarium specimens of four herbaceous forest species collected in western Pennsylvania between 1881-2008. Using molecular methods (terminal restriction fragment length polymorphism and sequence analysis), we quantified AMF communities from specimen roots and tested for contamination.ResultsWe successfully amplified AMF DNA from 44% (21/48) of the root but not leaf samples, indicating specimen contamination was negligible. As expected, there were significant differences in AMF composition between plant species (P < 0.05). However, no differences in AMF communities were detected through time, possibly due to limited sample size and low amplification rates in recent collections.DiscussionHerbaria have potential as sources of valuable belowground microbial data to answer questions across geographic, temporal, and taxonomic scales otherwise not feasible. Ongoing methodological developments will only magnify this potential. Further tests are needed to determine curatorial practices that maximize this innovative use of herbarium specimens.

| S-EPMC6476165 | biostudies-literature

Resolving taxonomic confusion: establishing the genus Phytobacter on the list of clinically relevant Enterobacteriaceae.

Project description:Although many clinically significant strains belonging to the family Enterobacteriaceae fall into a restricted number of genera and species, there is still a substantial number of isolates that elude this classification and for which proper identification remains challenging. With the current improvements in the field of genomics, it is not only possible to generate high-quality data to accurately identify individual nosocomial isolates at the species level and understand their pathogenic potential but also to analyse retrospectively the genome sequence databases to identify past recurrences of a specific organism, particularly those originally published under an incorrect or outdated taxonomy. We propose a general use of this approach to classify further clinically relevant taxa, i.e., Phytobacter spp., that have so far gone unrecognised due to unsatisfactory identification procedures in clinical diagnostics. Here, we present a genomics and literature-based approach to establish the importance of the genus Phytobacter as a clinically relevant member of the Enterobacteriaceae family.

| S-EPMC8934334 | biostudies-literature

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