The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform

Barbour, Roger W. - One of the best experts on this subject based on the ideXlab platform.

Thomas J. Near - One of the best experts on this subject based on the ideXlab platform.

  • The Geographic Distribution of the Imperiled Barrens Darter, Etheostoma forbesi, and Threats of Hybridization with the Closely Related Fringed Darter, Etheostoma crossopterum
    Bulletin of the Peabody Museum of Natural History, 2020
    Co-Authors: Richard C. Harrington, Jeffrey W. Simmons, Thomas J. Near
    Abstract:

    The Barrens Darter, Etheostoma forbesi, is one of the most geographically restricted freshwater fish species in North America, with a distribution limited to headwater portions of nine streams in the western part of the upper Caney Fork, a tributary of the Cumberland River in Tennessee. This limited geographic distribution makes Etheostoma forbesi especially vulnerable to potential threats posed by human alterations to rivers and streams, and the risk of ecological competition and introgressive hybridization with the closely related Fringed Darter, Etheostoma crossopterum. Museum collection records and targeted surveys conducted since its description suggest that present-day range of Etheostoma forbesi does not include several streams it previously inhabited—some as recently as 15 years ago. We investigate the geographic distribution and variation in meristic traits of both Etheostoma forbesi and Etheostoma crossopterum in the upper Caney Fork system through the examination of all available museum vouchers, and assess phylogeographic patterns among populations using mitochondrial DNA sequence data. We report a newly discovered population of Etheostoma forbesi from the upper Collins River, and present evidence that Etheostoma crossopterum has displaced Etheostoma forbesi in the Hickory Creek system and Mud Creek in the upper Barren Fork River system. There are no differences in scale counts between the two species, but the sum of the number of rays in the anal, pectoral, and second dorsal fins is diagnostic. Analysis of mtDNA variation indicates gene flow between Etheostoma forbesi and Etheostoma crossopterum. Our results suggest that sympatry of the two species in the western upper Caney Fork system is a potential threat to the persistence of Etheostoma forbesi.

  • Phylogenetic and Morphological Diversity of the Etheostoma zonistium Species Complex with the Description of a New Species Endemic to the Cumberland Plateau of Alabama
    Bulletin of the Peabody Museum of Natural History, 2017
    Co-Authors: Logan C. Kozal, Jeffrey W. Simmons, Jon Michael Mollish, Daniel J. Macguigan, Edgar Benavides, Benjamin P. Keck, Thomas J. Near
    Abstract:

    Abstract We provide a description of the Blueface Darter, Etheostoma cyanoprosopum, which is distributed in the upper Sipsey Fork of the Mobile Basin and the upper portion of the Bear Creek system in the Tennessee River Drainage. The distinctiveness of Etheostoma cyanoprosopum is assessed through analysis of morphological variation and molecular phylogenetic diversity within the Etheostoma zonistium species complex. In addition to analyzing disparity of morphometric and meristic traits, we present phylogenetic analyses of a mitochondrial gene and two nuclear genes and identify genetic clusters through analysis of 25 microsatellite loci. In the mitochondrial DNA (mtDNA) gene tree, Etheostoma cyanoprosopumis resolved as the sister lineage to a clade containing all other species of the Etheostoma zonistium complex. Etheostoma zonistium is paraphyletic with respect to both Etheostoma pyrrhogaster and Etheostoma cervus, which do not resolve as sister species in the mtDNA gene tree. The two nuclear gene trees a...

  • Systematics and Taxonomy of the Snubnose Darter, Etheostoma simoterum (Cope)
    Bulletin of the Peabody Museum of Natural History, 2016
    Co-Authors: Thomas J. Near, Benjamin P. Keck, Richard C. Harrington
    Abstract:

    Abstract A taxonomic revision of Etheostoma simoterum (Cope) published in 2007 resulted in the recognition of six species, with two species distributed in the Tennessee River system. A newly defined Etheostoma simoterum was restricted to populations in the Holston River above the confluence of the North and South Forks, and the Russell Fork system of the Ohio River drainage. A newly described species, Etheostoma tennesseense Powers & Mayden, included all other populations historically considered Etheostoma simoterum in the Tennessee River system from near the mouth of the Duck River upstream to the Clinch River, including the Holston River below the forks. A subsequent study utilizing molecular phylogenetics and analysis of male nuptial coloration did not support the recognition of Etheostoma tennesseense. Molecular phylogenies resolve both Etheostoma simoterum and Etheostoma tennesseense as paraphyletic. In addition, it was determined that male coloration patterns are not diagnostic for the more restrict...

  • Gene Trees Reveal Repeated Instances of Mitochondrial DNA Introgression in Orangethroat Darters (Percidae: Etheostoma)
    Systematic biology, 2009
    Co-Authors: Christen M. Bossu, Thomas J. Near
    Abstract:

    Phylogenies of closely related animal species are often inferred using mitochondrial DNA (mtDNA) gene se- quences. The accuracy of mtDNA gene trees is compromised through hybridization that leads to introgression of mito- chondrial genomes. Using DNA sequences from 6 single-copy nuclear genes and 2 regions of the mitochondrial genome, we investigated the temporal and geographic signature of mitochondrial and nuclear introgression in the Etheostoma spectabile darter clade. Phylogenetic analyses of the nuclear genes result in the monophyly of the E. spectabile clade; however, with respect to sampled specimens of 5 species (Etheostoma fragi, Etheostoma uniporum, Etheostoma pulchellum, Etheostoma burri, and E. spectabile), the mitochondrial phylogeny is inconsistent with E. spectabile clade monophyly. Etheostoma uniporum and E. fragi are both fixed for heterospecific mitochondrial genomes. Limited nuclear introgression is restricted to E. uniporum. Our analyses show that the pattern of introgression is consistently asymmetric, with movement of heterospecific mitochon- drial haplotypes and nuclear alleles into E. spectabile clade species; introgressive hybridization spans broad temporal scales; and introgression is restricted to species and populations in the Ozarks. The introgressed mitochondrial genome observed in E. fragi has an obscure phylogenetic placement among darters, an ancient age, and is possibly a mitochondrial fossil from an Etheostoma species that has subsequently gone extinct. These results indicate that introgression, both ancient and more contemporaneous, characterizes the history of diversification in the E. spectabile species clade and may be relatively common among clades comprising the species-rich North American freshwater fauna. (Gene phylogeny; hybridization; introgression; mtDNA; nuclear; molecular clock; reproductive isolation; species tree.)

Kyle R. Piller - One of the best experts on this subject based on the ideXlab platform.

  • Comparative population genetics of the federally endangered Relict Darter, and its sister taxon the Clarks Darter (Teleostei: Percidae)
    Conservation Genetics, 2020
    Co-Authors: Jerry Kattawar, Kyle R. Piller
    Abstract:

    The southeastern United States harbors one of the most diverse temperate freshwater fish faunas of the world. Unfortunately, due to improper land use practices and habitat degradation, many of the species in this region are imperiled and may become extinct without appropriate conservation efforts. This study examined the population dynamics of an endangered endemic darter of southwest Kentucky, the Relict Darter ( Etheostoma chienense ) and its sister taxon, the undescribed Clarks Darter ( Etheostoma cf. oophylax ). Mitochondrial sequence data coupled with SNP data were used to infer population structure, gene flow, genetic variation, and effective population sizes of both species. The results from this study, based on 160 individuals from nine localities, indicate that the endangered Relict Darter possesses limited genetic variation based on mitochondrial DNA haplotypes (N = 4). In addition, SNP data (6.8 k markers) further indicates limited genetic structure (K = 1), as well as a low effective population size (143–918), suggesting that the Relict Darter can be managed as a single, panmictic conservation unit. It is suggested that conservation efforts be taken to protect remaining habitats, augment the system with artificial spawning substrates, and, as a last resort (if needed), supplement the natural population with captive reared individuals. Ethesotoma cf. oophylax showed some genetic variation among distant sites, but more samples are needed throughout the range in order to fully understand the population dynamics of this species.

  • Rediagnosis of the Tuckasegee Darter, Etheostoma gutselli (Hildebrand), a Blue Ridge Endemic
    Copeia, 2017
    Co-Authors: Kyle R. Piller, Henry L.
    Abstract:

    In 1932, the Tuckasegee Darter was originally described as Poecilichthys gutselli, from the Tuckasegee River (Little Tennessee River system), North Carolina. In 1968, Miller, citing perceived areas of intergradation, relegated it to a subspecies of Etheostoma blennioides. Recent authors, however, re-elevated E. gutselli to the species level without providing any supporting data. We present morphological, meristic, and nuptial male pigmentation data that support the distinctiveness of E. gutselli. Etheostoma gutselli can be distinguished from proximal populations E. blennioides newmanii in the Tennessee River system by lower lateral-line (49–63 vs. 63–81) and caudal-peduncle (18–24 vs. 23–29) scale counts and differences in nuptial male pigmentation. Etheostoma gutselli primarily is restricted to the upper (Blue Ridge) portions of the Little Tennessee and Pigeon river drainages, generally upstream of the Tennessee-North Carolina state line.

  • Morphological Variation of the Redfin Darter, Etheostoma whipplei, with Comments on the Status of the Subspecific Populations
    Copeia, 2001
    Co-Authors: Kyle R. Piller, Henry L., Christopher A. Walser
    Abstract:

    Abstract The redfin darter, Etheostoma whipplei (Percidae: subgenus Oligocephalus) has been the subject of several taxonomic treatments over the past 50 years. At the present, two subspecies are recognized: Etheostoma whipplei whipplei in the Ozark and Ouachita Highlands and Etheostoma whipplei artesiae on the Gulf Coastal Plain. We examined variation in meristics and pigmentation to assess the distinctiveness of eastern populations of E. w. artesiae. The results indicated that E. w. artesiae differs significantly from E. w. whipplei in meristics and features of male breeding pigmentation. We conclude that all populations currently recognized as E. w. artesiae should be elevated to full species status.

Paul A. Fuerst - One of the best experts on this subject based on the ideXlab platform.

  • Molecular phylogeny of the snubnose darters, subgenus Ulocentra (genus Etheostoma, family Percidae).
    Molecular phylogenetics and evolution, 2002
    Co-Authors: B.a. Porter, T.m. Cavender, Paul A. Fuerst
    Abstract:

    Snubnose darters comprise one of the largest subgenera of the percid genus Etheostoma. Many species are described based on differences in male breeding coloration. Few morphological synapomorphies have been proposed for the subgenus and their relatives, making it difficult to delineate monophyletic clades. The phylogenetic relationships of the 20 snubnose darter species of the subgenus Ulocentra and 11 members of its proposed sister subgenus Etheostoma were investigated with partial mitochondrial DNA sequences including 1033 bp encompassing the entire mitochondrial control region, the tRNA-Phe gene, and part of the 12S rRNA gene. Two hypotheses on the relationship and monophyly of the two subgenera were evaluated. Both maximum-parsimony and neighbor-joining analyses supported monophyly of the subgenus Ulocentra and resolved some species-level relationships. The banded darter, E. zonale, and its sister taxon, E. lynceum, were not closely related to the snubnose darters and appear to be diverged from the other members of the subgenus Etheostoma, fitting their former distinction as the recognized subgenus Nanostoma. The sister group to Ulocentra appears to be a restricted species assemblage within the subgenus Etheostoma containing E. blennioides, E. rupestre, E. blennius, and the E. thalassinum species group. The placement of the harlequin darter, E. histrio, is problematic, and it may represent a basal member of Ulocentra or of the restricted subgenus Etheostoma. Despite recent estimates of divergence times between nominal Ulocentra taxa, each species exhibits its own unique set of mtDNA haplotypes, providing no direct evidence for current genetic exchange between species. The nominal taxa of snubnose darters thus appear to be evolving independently from each other and therefore constitute valid species under the Phylogenetic Species Concept.

Tim L. King - One of the best experts on this subject based on the ideXlab platform.

  • Microsatellite DNA primers for the candy darter, Etheostoma osburni and variegate darter, Etheostoma variatum, and cross-species amplification in other darters (Percidae)
    Molecular ecology resources, 2008
    Co-Authors: John F. Switzer, Stuart A. Welsh, Tim L. King
    Abstract:

    In order to investigate a potential hybrid zone between the candy darter, Etheostoma osburni, and variegate darter, Etheostoma variatum, and examine population variation within E. osburni, a suite of primers for 15 polymorphic microsatellite loci were developed. The average number of alleles per locus was 5.5 in E. osburni and 7.6 in E. variatum, and the average observed heterozygosities were 62.5% and 71.4%, respectively. There were no deviations from Hardy-Weinberg equilibrium and no observed linkage disequilibrium after Bonferroni correction. The utility of these primers was also tested in 11 species of darters representing all four genera of darters. Success of cross-species amplification was largely consistent with phylogenetic relationships of darters.