441 research outputs found

    Testing the Metal of Late-Type Kepler Planet Hosts with Iron-Clad Methods

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    It has been shown that F, G, and early K dwarf hosts of Neptune-sized planets are not preferentially metal-rich. However, it is less clear whether the same holds for late K and M dwarf planet hosts. We report metallicities of Kepler targets and candidate transiting planet hosts with effective temperatures below 4500 K. We use new metallicity calibrations to determine [Fe/H] from visible and near-infrared spectra. We find that the metallicity distribution of late K and M dwarfs monitored by Kepler is consistent with that of the solar neighborhood. Further, we show that hosts of Earth- to Neptune-sized planets have metallicities consistent with those lacking detected planets and rule out a previously claimed 0.2 dex offset between the two distributions at 6sigma confidence. We also demonstrate that the metallicities of late K and M dwarfs hosting multiple detected planets are consistent with those lacking detected planets. Our results indicate that multiple terrestrial and Neptune-sized planets can form around late K and M dwarfs with metallicities as low as 0.25 of the solar value. The presence of Neptune-sized planets orbiting such low-metallicity M dwarfs suggests that accreting planets collect most or all of the solids from the disk and that the potential cores of giant planets can readily form around M dwarfs. The paucity of giant planets around M dwarfs compared to solar-type stars must be due to relatively rapid disk evaporation or a slower rate of core accretion, rather than insufficient solids to form a core.Comment: 9 pages, 5 figures. Accepted to Ap

    It’s All About Fishing: Robert Ellis Jenkins (1940-2023) and His Life Among Freshwater Fishes of Virginia and the Redhorse Suckers

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    Robert (Bob) Ellis Jenkins passed away in Salem, Virginia, on Wednesday, July 12, 2023. Bob was born February 9, 1940 in Brooklyn, New York. As a child, Bob took an early interest in natural history, and was a particularly avid fisherman. He attended Roanoke College (Salem, VA) as an undergraduate and entered into a Masters degree program at Virginia Tech (Blacksburg, VA), only to leave before finishing for a position at the NOAA Systematics Lab based at the Smithsonian Institution’s National Museum of Natural History. He eventually became faculty at his alma mater, Roanoke College, where he would spend virtually all of his career. It was at the Smithsonian that he began his lifelong friendship and collaboration with Ernie Lachner. He also met Edward Raney, who would become his Ph.D. advisor at Cornell University. Originally Bob was to work on the cyprinid genus Nocomis, but switched the focus of his dissertation to the catostomids of the genus Moxostoma. Bob published 38 peer-reviewed papers on a wide range of taxa (predominantly catostomids and leuciscids, but also ictalurids, percids, and centrarchids), as well as general zoogeography of fishes from the southeastern U.S. His research always emphasized taxonomy and distribution of fishes, but one of the roots of his love of this work on the diversity of fishes was his concern for the conservation of fishes and their habitats. Bob will perhaps be best remembered for his monumental book (with Noel Burkhead), The Freshwater Fishes of Virginia

    REVIEW OF THE FOSSIL RECORD OF STURGEONS, FAMILY ACIPENSERIDAE (ACTINOPTERYGII: ACIPENSERIFORMES), FROM NORTH AMERICA

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    ABSTRACT—The pre–Pleistocene fossil record of sturgeons (family Acipenseridae) from North America is reviewed based on a survey of reports in the literature and firsthand examination of specimens in museum collections. We provide a redescription of the only known specimen of †Protoscaphirhynchus squamosus (Late Cretaceous, Montana), a very poorly preserved specimen for which few morpho-logical details can be determined. Three taxa described as species of the genus Acipenser from North America (†A. albertensis, †A. eruciferus, and †A. ornatus) were described based on isolated and fragmentary remains, and are here considered to be nomina dubia. The earliest reported remains of North American sturgeons are from the Late Cretaceous (Santonian to Campanian Milk River For-mation). There is a relatively continuous record, with the exception of the Eocene and Oligocene, in which there are few (potentially in the Eocene) or no (Oligocene) known specimens available in collections. We have found that nearly all specimens are best regarded as Acipenseridae indeterminate genus and species due to their fragmentary preservation and lack of preserved diagnostic characters

    Bony-Tongue Fishes (Teleostei: Osteoglossomorpha) from the Eocene Nanjemoy Formation, Virginia

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    Bony-tongue fishes, Osteoglossomorpha, are distributed in North and South America, Africa, Asia, and Australia and are found on all continents except Antarctica in the fossil record. The group includes fishes such as the mooneyes (Hiodontidae), freshwater knifefishes (Notopteridae), elephantfishes (Mormyridae), and the arowanas and pirarucu (Osteoglossidae). Remains identified as belonging to the family Osteoglossidae are known from the Nanjemoy Formation of Maryland and northern Virginia and comprise isolated teeth and fragmentary jaw bones assigned to the now extinct †Brychaetus muelleri. The second author discovereda partial toothed parasphenoid among other isolated and frag-mentary vertebrate microfossils from the Fisher–Sullivan Site of the Nanjemoy Formation in northern Virginia. This element resembles the base of the parasphenoid of the extant osteoglossid taxa Osteoglossum and Scleropages. Although this fossil is fragmentary and not sufficient to differentially diagnose taxonomically, it provides further evidence of the substantial diversity of Osteoglossidae during the Eocene

    A taxonomic review of the family Trachipteridae (Lampridiformes), with an emphasis on taxa distributed in the Western Pacific Ocean

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    The family Trachipteridae—the Ribbonfishes, Dealfishes, and their relatives—has a circumglobal distribution, with at least 10 species in three genera (Zu Walters & Fitch 1960, Desmodema Walters & Fitch 1960, and Trachipterus Goüan 1770) that are characterized by elongate, extremely laterally compressed bodies, large eyes, absence of ribs, spines on lateral-line scales, greatly protrusible mouths, and a lack of pelvic fins in adults. They are also known for the drastic morphological changes that occur during ontogeny. Trachipterids are poorly represented in collections due to the fragile nature of their bodies. Most studies of the Trachipteridae have been limited by the numbers, developmental stages, and the completeness of the specimens that were examined. Along with the lack of available material, incomplete and conflicting character information compounds the taxonomic confusion of Trachipteridae. Despite the body of regional revisions that have examined trachipterid taxonomy, none have synthesized a suite of morphological characters across ontogeny. The goals of this paper are to (1) revise the family Trachipteridae, (2) revise the genera Trachipterus, Zu, and Desmodema, including information regarding ontogeny and biogeography, and 3) address the alpha taxonomy of Zu, Desmodema, and Trachipterus from the western Pacific Ocean. We recognize possibly five species of Trachipterus as being present in the western Pacific, as well as two species of both Zu and Desmodema. Despite additions to the specimen base that allows refinement of taxonomy and diagnoses, there are still large knowledge gaps associated with the taxonomic review of Trachipteridae. These reflect incomplete understanding of geographic distribution of taxa which may mask unrecognized taxonomic variability. The genus Trachipterus specifically remains problematic and will require greater detailed global study. Early life history stages remain unknown for several taxa which hinders full interpretation of ontogenetic transitions. Protracted transitions, some of which are clarified here, further confuse stage-based diagnoses and must be considered in future analyses of this family

    Evolutionary Characters, Phenotypes and Ontologies: Curating Data from the Systematic Biology Literature

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    Background: The wealth of phenotypic descriptions documented in the published articles, monographs, and dissertations of phylogenetic systematics is traditionally reported in a free-text format, and it is therefore largely inaccessible for linkage to biological databases for genetics, development, and phenotypes, and difficult to manage for large-scale integrative work. The Phenoscape project aims to represent these complex and detailed descriptions with rich and formal semantics that are amenable to computation and integration with phenotype data from other fields of biology. This entails reconceptualizing the traditional free-text characters into the computable Entity-Quality (EQ) formalism using ontologies. Methodology/Principal Findings: We used ontologies and the EQ formalism to curate a collection of 47 phylogenetic studies on ostariophysan fishes (including catfishes, characins, minnows, knifefishes) and their relatives with the goal of integrating these complex phenotype descriptions with information from an existing model organism database (zebrafish, http://zfin.org). We developed a curation workflow for the collection of character, taxonomic and specimen data from these publications. A total of 4,617 phenotypic characters (10,512 states) for 3,449 taxa, primarily species, were curated into EQ formalism (for a total of 12,861 EQ statements) using anatomical and taxonomic terms from teleost-specific ontologies (Teleost Anatomy Ontology and Teleost Taxonomy Ontology) in combination with terms from a quality ontology (Phenotype and Trait Ontology). Standards and guidelines for consistently and accurately representing phenotypes were developed in response to the challenges that were evident from two annotation experiments and from feedback from curators. Conclusions/Significance: The challenges we encountered and many of the curation standards and methods for improving consistency that we developed are generally applicable to any effort to represent phenotypes using ontologies. This is because an ontological representation of the detailed variations in phenotype, whether between mutant or wildtype, among individual humans, or across the diversity of species, requires a process by which a precise combination of terms from domain ontologies are selected and organized according to logical relations. The efficiencies that we have developed in this process will be useful for any attempt to annotate complex phenotypic descriptions using ontologies. We also discuss some ramifications of EQ representation for the domain of systematics

    It’s raining sturgeons: a likely occurrence of avian predation or scavenging of Atlantic Sturgeon (Acipenser oxyrinchus Mitchell, 1815)

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    Predation on the federally-endangered Atlantic Sturgeon (Acipenser oxyrinchus), and sturgeons generally is understudied. Most predation is presumed to occur on eggs and larvae, and bethe result of interactions with other aquatic organisms, primarily other fishes. Predation on larger juvenile sturgeon by terrestrial and avian predators remains largely unknown. Here we document the recovery of a juvenile Atlantic Sturgeon carcass (512 mm total length) approximately 120 m inland from the shore of the York River in Gloucester County, Virginia. This individual showed signs of predation by a bird of prey, most likely an Osprey (Pandion haliaetus), although a Bald Eagle (Haliaeetus leucocephalus) cannot be ruled out, as they are also residents in this area. The purpose of this note is to document this occurrence and suggest further study of predation on Atlantic Sturgeon in the Chesapeake Bay

    Integrative Taxonomy, a New Tool for Fisheries Conservation

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    Species delimitation is becoming increasingly objective and integrative. Sequence capture approaches allow collection of 1000s of loci for 100s of individuals. New approaches address the computational challenges of large datasets and offer potential for genome-wide sampling of variation at different evolutionary scales. These new approaches also allow integration of genetic and non-genetic data in a unified framework. Despite these advances, few studies have attempted to combine genetic and morphological data for delimiting species. Hakes (Merluccius spp.) are an ideal group for an empirical test of the power and applicability of these new methods because they are morphologically conserved and have distributional patterns ideal for studying a broad range of evolutionary questions. They also are of economic and conservation concern so the results of this phylogenetic study can be directly applied to fisheries management. Hakes are demersal fishes that inhabit the continental shelf and slope of the Atlantic, Pacific, and around New Zealand and there are 16 putative species. Hakes can be difficult to identify due to their conservative external morphology and high level of intraspecific variation, resulting in serious identification problems. Many species of hakes are sympatric and there is moderate ecological overlap. Unresolved alpha taxonomy and the lack of diagnostic characters have led to mixed-species in landings data, making management and conservation difficult. This study uses a broad taxonomic and geographic sampling combined with new morphological and genetic characters to clarify the taxonomy, systematics and the global biogeography and diversification of hake species
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