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Eric B. Taylor - One of the best experts on this subject based on the ideXlab platform.
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Molecular resolution of the systematics of a problematic group of fishes (Teleostei: Osmeridae) and evidence for morphological homoplasy.
Molecular phylogenetics and evolution, 2008Co-Authors: Katriina L. Ilves, Eric B. TaylorAbstract:Relationships among the species of Northern Hemisphere smelts (family Osmeridae) have long been debated in the fish systematics literature. Eight independent studies based on morphological characters failed to reach any consensus on osmerid interrelationships. We reconstruct the osmerid phylogeny based on DNA sequence data from three mitochondrial (cytb, 16S, 12S) and three nuclear (ITS2, S71, RAG1) gene regions from multiple individuals of the 14 species in 6 genera, using the Japanese ayu (Plecoglossus altivelis) as the outgroup. Analyses with different combinations of nuclear and mitochondrial datasets yielded a generally well-resolved phylogeny of the genera that conflicts with previous hypotheses of osmerid interrelationships, and Shimodaira-Hasegawa tests suggest our topology with the current molecular dataset is significantly better than earlier reconstructions. In addition, mapping 114 morphological characters used in previous studies onto our phylogeny shows widespread homoplasy, which is likely the source of the systematic disagreement produced in earlier works.
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Smelt
2008Co-Authors: Katriina L. Ilves, Eric B. Taylor, Nuclear DnaAbstract:Molecular resolution of the systematics of a problematic group of fishes (Teleostei: Osmeridae) and evidence for morphological homoplas
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Evolutionary and biogeographical patterns within the smelt genus Hypomesus in the North Pacific Ocean
Journal of Biogeography, 2007Co-Authors: Katriina L. Ilves, Eric B. TaylorAbstract:Aim We address questions about trans-Pacific distributions of marine organisms and the North Pacific Ocean as a centre of marine biodiversity through a phylogenetic and biogeographical study of a pan-Pacific genus of Northern Hemisphere smelts (Hypomesus, Pisces: Osmeridae). Location North Pacific Ocean. Methods Relationships of the five species of Hypomesus from throughout the North Pacific were reconstructed through maximum likelihood and Bayesian phylogenetic analyses of sequence data from two mitochondrial (cytb, 16S) and three nuclear (ITS2, S71, RAG1) gene regions of five to 25 individuals per species, totalling 3588 characters. The resulting phylogenies were used to test hypotheses of species relationships and geographical origins using both dispersal-based and maximum likelihood methods for inferring ancestral areas (lagrange). Cytb sequence divergence and a Bayesian approach (beast) were used to estimate the timeframe of Hypomesus evolution, which was compared with work on similarly distributed taxa. Results Hypothesized trans-Pacific Ocean relationships based on lateral line scale counts were not supported by the phylogeny, suggesting parallel evolution of this phenotype, although we found one such relationship between the western H. japonicus and the two eastern Pacific species (H. pretiosus and H. transpacificus). Dispersalist approaches rejected an early proposal of a double-compression vicariant mechanism as well as an eastern Pacific origin. Results from the lagrange analysis suggested a more widespread ancestor, although also supporting a role for the western Pacific. Divergence estimates suggested that most splits between species occurred in the mid-Miocene, and the most recent speciation event, between the eastern Pacific species, occurred in the Pliocene to early Pleistocene. Main conclusions Our molecular data indicate that the character historically used to define relationships within Hypomesus, lateral line scale count, does not reflect ancestry within the genus. Biogeographical reconstructions suggest an important role for the western North Pacific in the diversification of Hypomesus. While uncertainty remains over the date of origin for this genus, estimates place the divergences during periods of climatic cooling that have been important in generating diversity in a number of similarly distributed organisms. Additional comparative data will provide further insight into the relative importance of the western region in generating diversity in the North Pacific Ocean.
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Are Hypomesus chishimaensis and H. nipponensis (Osmeridae) Distinct Species? A Molecular Assessment Using Comparative Sequence Data from Five Genes
Copeia, 2007Co-Authors: Katriina L. Ilves, Eric B. TaylorAbstract:We used mitochondrial (cytb, 16S) and nuclear (ITS2, S71, RAG1) sequence data to assess the degree of genetic differentiation between the recently described lacustrine Hypomesus chishimaensis from the Kuril Islands and its anadromous congener H. nipponensis from Hokkaido, Japan. The results showed that the two species are not genetically distinct at these loci. Phylogenetic trees depicted an unstructured clade consisting of individuals of both species and sequence data showed haplotypes that are shared between putative species for all markers. We conclude that H. chishimaensis is an alternative life-history type of H. nipponensis that should not be recognized at either the species or the sub-species level.
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Species pairs of north temperate freshwater fishes: Evolution, taxonomy, and conservation
Reviews in Fish Biology and Fisheries, 1999Co-Authors: Eric B. TaylorAbstract:Many fish species contain morphologically, ecologically and geneticallydistinct populations that are sympatric during at least some portion oftheir life cycle. Such reproductively isolated populations act asdistinct biological species, but are identified by a common Latinbinomial. These ‘species pairs’ are particularly common in freshwaterfish families such as Salmonidae, Gasterosteidae and Osmeridae and aretypically associated with postglacial lakes in north temperateenvironments. The nature of the divergences between sympatric species,factors contributing to reproductive isolation, and modes of evolutionare reviewed with particular emphasis on benthic and limnetic pairs ofthreespine sticklebacks, Gasterosteus aculeatus , and anadromous(sockeye salmon) and nonanadromous (kokanee) pairs of Oncorhynchusnerka . Phylogenetic analyses typically indicate that divergencesbetween members of replicate pairs have occurred independently and,hence, particular phenotypes are not monophyletic. Consequently,taxonomic resolution of such ‘species complexes’ is a vexing problem foradherents to our traditional Linnaean classification system. Sympatricspecies pairs represent a significant component of the biodiversity oftemperate freshwater ecosystems which may be underestimated because oursystem of formal taxonomy tends to obscure diversity encompassed byspecies pairs. Conservation of such systems should be recognized as apriority without formal taxonomic designation of members of speciespairs because taxonomic resolution will likely continue to proveextremely difficult when employing traditional hierarchies andprocedures.
Bernie May - One of the best experts on this subject based on the ideXlab platform.
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hybridization between delta smelt and two other species within the family Osmeridae in the san francisco bay delta
Conservation Genetics, 2014Co-Authors: Kathleen M. Fisch, Brian Mahardja, Ronald S Burton, Bernie MayAbstract:Hybridization among closely related species may pose a threat to species persistence, especially between native and introduced species. We analyzed nine microsatellite loci, mitochondrial sequences and 16 species-specific single nucleotide polymorphisms (SNPs) in two native species (delta smelt and longfin smelt) and one introduced species (wakasagi smelt) in the family Osmeridae to describe the extent of hybridization among these species in the San Francisco Bay-Delta, CA, USA. We identified 29 putative hybrids with a microsatellite-based Bayesian assignment method, and we further screened these putative hybrids with the SNP loci and mitochondrial DNA (mtDNA) sequencing. From the Yolo Bypass, 11 % of morphologically ambiguous individuals were F1 hybrids and 0.1 % of positively identified delta smelt from throughout the San Francisco Bay-Delta were F1 hybrids according to their SNP genotypes. mtDNA sequencing revealed wakasagi smelt as the maternal parent for all five delta smelt × wakasagi smelt hybrids and longfin smelt as the maternal parent for the single longfin smelt × delta smelt hybrid. Hybridization among these three species appears to occur at relatively low frequencies and may not be an immediate threat to the persistence of the imperiled native species; however, the presence of hybrid individuals warrants continued monitoring.
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Characterization of 24 microsatellite loci in delta smelt, Hypomesus transpacificus, and their cross-species amplification in two other smelt species of the Osmeridae family.
Molecular ecology resources, 2009Co-Authors: Kathleen M. Fisch, Jessica L Petersen, Melinda R. Baerwald, John K. Pedroia, Bernie MayAbstract:We characterized 24 polymorphic tetranucleotide microsatellite loci for delta smelt (Hypomesus transpacificus) endemic to the San Francisco Bay Estuary, CA, USA. Screening of samples (n = 30) yielded two to 26 alleles per locus with observed levels of heterozygosity ranging from 0.17 to 1.0. Only one locus deviated from Hardy-Weinberg equilibrium, suggesting these individuals originate from a single panmictic population. Linkage disequilibrium was found in two pairs of loci after excluding the locus out of Hardy-Weinberg equilibrium. Twenty-two primer pairs cross-amplified in wakasagi smelt (Hypomesus nipponensis), and 15 primer pairs cross-amplified in longfin smelt (Spirinchus thaleichthys).
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© 2009 The Authors Journal compilation © 2009 Blackwell Publishing Ltd Blackwell Publishing LtdPERMANENT GENETIC RESOURCES
2008Co-Authors: Kathleen M. Fisch, Jessica L Petersen, Melinda R. Baerwald, John K. Pedroia, Bernie MayAbstract:Characterization of 24 microsatellite loci in delta smelt, Hypomesus transpacificus, and their cross-species amplification in two other smelt species of the Osmeridae famil
Craig F Purchase - One of the best experts on this subject based on the ideXlab platform.
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A novel sperm adaptation to evolutionary constraints on reproduction: Pre-ejaculatory sperm activation in the beach spawning capelin (Osmeridae).
Ecology and evolution, 2018Co-Authors: José Beirão, Jason A Lewis, Brendan F. Wringe, Craig F PurchaseAbstract:Reproduction of external fertilizing vertebrates is typically constrained to either fresh or salt water, not both. For all studied amphibians and fishes, this constraint includes immotile sperm that are activated after ejaculation only by the specific chemistry of the fertilizing medium in which the species evolved (fresh, brackish, or salt water). No amphibians can reproduce in the sea. Although diadromous fishes may migrate between salt and fresh water, they are shackled to their natal environment for spawning in part because of sperm activation. Here, we report for the first time among all documented external fertilizing vertebrates, that in the absence of any external media, sperm are motile at ejaculation in a marine spawning fish (Osmeridae, capelin, Mallotus villosus). To illuminate why, we evaluated sperm behavior at different salinities in M. villosus as well as the related freshwater spawning anadromous rainbow smelt (Osmerus mordax). Surprisingly, sperm performance was superior in fresh water for both species. M. villosus spend their entire life at sea but our results show that their sperm are deactivated by sea water, suggesting a freshwater ancestry. By circumventing constraining water chemistry, we interpret the unique pre-ejaculatory sperm activation in this species as a novel adaptation that enables fertilization in the marine environment. These findings also contribute to understanding the persistence of anadromy, despite great energetic costs to adult fishes.
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spermatozoa ultrastructure of two osmerid fishes in the context of their family teleostei osmeriformes Osmeridae
Journal of Applied Ichthyology, 2015Co-Authors: J Beirao, Jason A Lewis, Craig F PurchaseAbstract:Summary Systematics of the Osmeridae remains controversial, and may benefit from detailed examination of sperm biology. Sperm morphology and ultrastructure of two osmerids were analyzed, one from Tribe Salangini (Mallotus villosus) and another from Tribe Osmerini (Osmerus mordax) to try to clarify some of the observations previously made by other authors in the context of the Osmeridae family. In both species there is a bullet-shape head with a deep nuclear fossa where one finned flagellum is deeply inserted, and there is only one mitochondrion. A general schematic model for Osmeridae sperm is proposed that excludes the Salangini tribe but includes M. villosus. M. villosus ultrastructure is more similar to the Osmerini than the Salangini where it is currently placed.
Katriina L. Ilves - One of the best experts on this subject based on the ideXlab platform.
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Molecular resolution of the systematics of a problematic group of fishes (Teleostei: Osmeridae) and evidence for morphological homoplasy.
Molecular phylogenetics and evolution, 2008Co-Authors: Katriina L. Ilves, Eric B. TaylorAbstract:Relationships among the species of Northern Hemisphere smelts (family Osmeridae) have long been debated in the fish systematics literature. Eight independent studies based on morphological characters failed to reach any consensus on osmerid interrelationships. We reconstruct the osmerid phylogeny based on DNA sequence data from three mitochondrial (cytb, 16S, 12S) and three nuclear (ITS2, S71, RAG1) gene regions from multiple individuals of the 14 species in 6 genera, using the Japanese ayu (Plecoglossus altivelis) as the outgroup. Analyses with different combinations of nuclear and mitochondrial datasets yielded a generally well-resolved phylogeny of the genera that conflicts with previous hypotheses of osmerid interrelationships, and Shimodaira-Hasegawa tests suggest our topology with the current molecular dataset is significantly better than earlier reconstructions. In addition, mapping 114 morphological characters used in previous studies onto our phylogeny shows widespread homoplasy, which is likely the source of the systematic disagreement produced in earlier works.
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Smelt
2008Co-Authors: Katriina L. Ilves, Eric B. Taylor, Nuclear DnaAbstract:Molecular resolution of the systematics of a problematic group of fishes (Teleostei: Osmeridae) and evidence for morphological homoplas
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Evolutionary and biogeographical patterns within the smelt genus Hypomesus in the North Pacific Ocean
Journal of Biogeography, 2007Co-Authors: Katriina L. Ilves, Eric B. TaylorAbstract:Aim We address questions about trans-Pacific distributions of marine organisms and the North Pacific Ocean as a centre of marine biodiversity through a phylogenetic and biogeographical study of a pan-Pacific genus of Northern Hemisphere smelts (Hypomesus, Pisces: Osmeridae). Location North Pacific Ocean. Methods Relationships of the five species of Hypomesus from throughout the North Pacific were reconstructed through maximum likelihood and Bayesian phylogenetic analyses of sequence data from two mitochondrial (cytb, 16S) and three nuclear (ITS2, S71, RAG1) gene regions of five to 25 individuals per species, totalling 3588 characters. The resulting phylogenies were used to test hypotheses of species relationships and geographical origins using both dispersal-based and maximum likelihood methods for inferring ancestral areas (lagrange). Cytb sequence divergence and a Bayesian approach (beast) were used to estimate the timeframe of Hypomesus evolution, which was compared with work on similarly distributed taxa. Results Hypothesized trans-Pacific Ocean relationships based on lateral line scale counts were not supported by the phylogeny, suggesting parallel evolution of this phenotype, although we found one such relationship between the western H. japonicus and the two eastern Pacific species (H. pretiosus and H. transpacificus). Dispersalist approaches rejected an early proposal of a double-compression vicariant mechanism as well as an eastern Pacific origin. Results from the lagrange analysis suggested a more widespread ancestor, although also supporting a role for the western Pacific. Divergence estimates suggested that most splits between species occurred in the mid-Miocene, and the most recent speciation event, between the eastern Pacific species, occurred in the Pliocene to early Pleistocene. Main conclusions Our molecular data indicate that the character historically used to define relationships within Hypomesus, lateral line scale count, does not reflect ancestry within the genus. Biogeographical reconstructions suggest an important role for the western North Pacific in the diversification of Hypomesus. While uncertainty remains over the date of origin for this genus, estimates place the divergences during periods of climatic cooling that have been important in generating diversity in a number of similarly distributed organisms. Additional comparative data will provide further insight into the relative importance of the western region in generating diversity in the North Pacific Ocean.
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Are Hypomesus chishimaensis and H. nipponensis (Osmeridae) Distinct Species? A Molecular Assessment Using Comparative Sequence Data from Five Genes
Copeia, 2007Co-Authors: Katriina L. Ilves, Eric B. TaylorAbstract:We used mitochondrial (cytb, 16S) and nuclear (ITS2, S71, RAG1) sequence data to assess the degree of genetic differentiation between the recently described lacustrine Hypomesus chishimaensis from the Kuril Islands and its anadromous congener H. nipponensis from Hokkaido, Japan. The results showed that the two species are not genetically distinct at these loci. Phylogenetic trees depicted an unstructured clade consisting of individuals of both species and sequence data showed haplotypes that are shared between putative species for all markers. We conclude that H. chishimaensis is an alternative life-history type of H. nipponensis that should not be recognized at either the species or the sub-species level.
Inge Werner - One of the best experts on this subject based on the ideXlab platform.
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Sublethal responses to ammonia exposure in the endangered delta smelt; Hypomesus transpacificus (Fam. Osmeridae).
Aquatic toxicology (Amsterdam Netherlands), 2011Co-Authors: Richard E Connon, Linda A Deanovic, Erika B Fritsch, Leandro S D'abronzo, Inge WernerAbstract:The delta smelt (Hypomesus transpacificus) is an endangered pelagic fish species endemic to the Sacramento-San Joaquin Estuary in Northern California, which acts as an indicator of ecosystem health in its habitat range. Interrogative tools are required to successfully monitor effects of contaminants upon the delta smelt, and to research potential causes of population decline in this species. We used microarray technology to investigate genome-wide effects in fish exposed to ammonia; one of multiple contaminants arising from wastewater treatment plants and agricultural runoff. A 4-day exposure of 57-day old juveniles resulted in a total ammonium (NH(4)(+)-N) median lethal concentration (LC50) of 13 mg/L, and a corresponding un-ionized ammonia (NH(3)) LC50 of 147 μg/L. Using the previously designed delta smelt microarray we assessed altered gene transcription in juveniles exposed to 10mg/L NH(4)(+)-N from this 4-day exposure. Over half of the responding genes were associated with membrane integrity and function, however, neurological and muscular function was also affected. Amongst the notable pathways affected by ammonium exposure, directly associated with cellular membranes, are energy metabolism through oxidative phosphorylation, cellular responses to environmental stimuli, highlighted through signal transduction and molecular interactions, cellular processes encompassing transport and catabolism, along with cell motility, development, communication and cell death. To assess these impacts further, key genes were selected as potential biomarkers and investigated using quantitative PCR analysis on fish exposed to 2.5, 5, 10, 20 and 40 mg/L NH(4)(+)-N. Quantitative PCR results indicate biphasic responses, pivoting around the estimated no-observed effect concentration (NOEC; 5.0mg/L NH(4)(+)-N) and below. Genes significantly affected by ammonia exposure include claudin-10, Keratin-15, Septin-3, Transmembrane protein 4, superfamily 4 (membrane), Tropomyosin, Myosin light chain, Calmodulin (muscular), Tubulin cofactor beta (neurological), Sirtuin-6 (development), and Rhesus associated type C glycoprotein 1 (gill- and skin-specific ammonium transporter). The quantitation of the ammonium transporter may highlight the capacity of delta smelt to contend with elevated levels of ammonia, the peak response of which may be indicative of short-term thresholds of tolerance. Our study supports the notion that exposure to ammonia results in cell membrane destabilization, potentially affecting membrane permeability, enhancing uptake and thus synergistic effects of multiple-contaminant exposure.
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Linking mechanistic and behavioral responses to sublethal esfenvalerate exposure in the endangered delta smelt; Hypomesus transpacificus (Fam. Osmeridae)
BMC genomics, 2009Co-Authors: Richard E Connon, Juergen Geist, Janice Pfeiff, Henri Wintz, Leandro S D'abronzo, Alexander V Loguinov, Chris D. Vulpe, Inge WernerAbstract:The delta smelt (Hypomesus transpacificus) is a pelagic fish species listed as endangered under both the USA Federal and Californian State Endangered Species Acts and considered an indicator of ecosystem health in its habitat range, which is limited to the Sacramento-San Joaquin estuary in California, USA. Anthropogenic contaminants are one of multiple stressors affecting this system, and among them, current-use insecticides are of major concern. Interrogative tools are required to successfully monitor effects of contaminants on the delta smelt, and to research potential causes of population decline in this species. We have created a microarray to investigate genome-wide effects of potentially causative stressors, and applied this tool to assess effects of the pyrethroid insecticide esfenvalerate on larval delta smelt. Selected genes were further investigated as molecular biomarkers using quantitative PCR analyses. Exposure to esfenvalerate affected swimming behavior of larval delta smelt at concentrations as low as 0.0625 mug.L-1, and significant differences in expression were measured in genes involved in neuromuscular activity. Alterations in the expression of genes associated with immune responses, along with apoptosis, redox, osmotic stress, detoxification, and growth and development appear to have been invoked by esfenvalerate exposure. Swimming impairment correlated significantly with expression of aspartoacylase (ASPA), an enzyme involved in brain cell function and associated with numerous human diseases. Selected genes were investigated for their use as molecular biomarkers, and strong links were determined between measured downregulation in ASPA and observed behavioral responses in fish exposed to environmentally relevant pyrethroid concentrations. The results of this study show that microarray technology is a useful approach in screening for, and generation of molecular biomarkers in endangered, non-model organisms, identifying specific genes that can be directly linked with sublethal toxicological endpoints; such as changes in expression levels of neuromuscular genes resulting in measurable swimming impairments. The developed microarrays were successfully applied on larval fish exposed to esfenvalerate, a known contaminant of the Sacramento-San Joaquin estuary, and has permitted the identification of specific biomarkers which could provide insight into the factors contributing to delta smelt population decline.
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BioMed Central
2009Co-Authors: Bmc Genomics, Richard E Connon, Juergen Geist, Janice Pfeiff, Er V Loguinov, Ro S D&apos, Henri Wintz, Christopher D Vulpe, Inge WernerAbstract:Research article Linking mechanistic and behavioral responses to sublethal esfenvalerate exposure in the endangered delta smelt; Hypomesus transpacificus (Fam. Osmeridae