Browsing by Subject "Fundulidae"

Now showing 1 - 8 of 8
  • Thumbnail Image
    ItemOpen Access
    A Bayesian Approach to Inferring Rates of Selfing and Locus-Specific Mutation.
    (Genetics, 2015-11) Redelings, Benjamin D; Kumagai, Seiji; Tatarenkov, Andrey; Wang, Liuyang; Sakai, Ann K; Weller, Stephen G; Culley, Theresa M; Avise, John C; Uyenoyama, Marcy K
    We present a Bayesian method for characterizing the mating system of populations reproducing through a mixture of self-fertilization and random outcrossing. Our method uses patterns of genetic variation across the genome as a basis for inference about reproduction under pure hermaphroditism, gynodioecy, and a model developed to describe the self-fertilizing killifish Kryptolebias marmoratus. We extend the standard coalescence model to accommodate these mating systems, accounting explicitly for multilocus identity disequilibrium, inbreeding depression, and variation in fertility among mating types. We incorporate the Ewens sampling formula (ESF) under the infinite-alleles model of mutation to obtain a novel expression for the likelihood of mating system parameters. Our Markov chain Monte Carlo (MCMC) algorithm assigns locus-specific mutation rates, drawn from a common mutation rate distribution that is itself estimated from the data using a Dirichlet process prior model. Our sampler is designed to accommodate additional information, including observations pertaining to the sex ratio, the intensity of inbreeding depression, and other aspects of reproduction. It can provide joint posterior distributions for the population-wide proportion of uniparental individuals, locus-specific mutation rates, and the number of generations since the most recent outcrossing event for each sampled individual. Further, estimation of all basic parameters of a given model permits estimation of functions of those parameters, including the proportion of the gene pool contributed by each sex and relative effective numbers.
  • Thumbnail Image
    ItemOpen Access
    Bioenergetic and Fitness Costs of PAH Adapted Fundulus heteroclitus to Early Life PAH and Hypoxia Exposures
    (2019-04-26) Fuerte, Michael
    Growing evidence suggests that acute polycyclic aromatic hydrocarbon (PAH) exposures have toxic mitochondrial effects and may inhibit aerobic respiration. However, the effect of subteratogenic exposures during development is not well described in literature – especially in the presence of other deleterious environmental conditions. For example, Atlantic teleost fishes experience seasonal hypoxia that may exacerbate co-occurring PAH exposure due to molecular crosstalk with the aryl hydrocarbon receptor (AhR) pathway. This study investigated the potential link between sustained swimming performance and mitochondrial oxygen consumption in two populations of Fundulus heteroclitus months after a single initial exposure to a PAH mixture with and without hypoxia. This study used lab-reared embryos from killifish originating in the Elizabeth River (Portsmouth, VA) near a polluted wood treatment facility where the fish have become highly resistant to developmental cardiac teratogenicity (Republic Creosoting; ~113886 ng PAHs/g dry sediment). Another population of killifish were sourced from an undeveloped reference location (King’s Creek; ~526 ng PAHs/g dry sediment) outside the Elizabeth River. Subset individuals were treated with either a subteratogenic dilution of a complex PAH mixture (∑[PAHs] ≈ 25.2 μg/L) for 24 hours post-fertilization (hpf), diurnal hypoxia exposure for 14 days post-fertilization (dpf), or both. Upon reaching 6 months of age, their sustained swimming velocity (Ucrit) was measured in a recirculating swim chamber. A separate subset was processed for basal and mitochondrial oxygen consumption rate (OCR) analysis. The study found that killifish population that had historically little PAH exposure had a higher sustained swimming performance than killifish adapted to PAHs. Additionally, mitochondrial oxygen consumption, at baseline and at an induced maximal rate, increases with PAH exposure for the non-adapted fish and hypoxia exposure for PAH-adapted fish.
  • Thumbnail Image
    ItemOpen Access
    Development of the morpholino gene knockdown technique in Fundulus heteroclitus: a tool for studying molecular mechanisms in an established environmental model.
    (Aquat Toxicol, 2008-05-30) Matson, Cole W; Clark, Bryan W; Jenny, Matthew J; Fleming, Carrie R; Hahn, Mark E; Di Giulio, Richard T
    A significant challenge in environmental toxicology is that many genetic and genomic tools available in laboratory models are not developed for commonly used environmental models. The Atlantic killifish (Fundulus heteroclitus) is one of the most studied teleost environmental models, yet few genetic or genomic tools have been developed for use in this species. The advancement of genetic and evolutionary toxicology will require that many of the tools developed in laboratory models be transferred into species more applicable to environmental toxicology. Antisense morpholino oligonucleotide (MO) gene knockdown technology has been widely utilized to study development in zebrafish and has been proven to be a powerful tool in toxicological investigations through direct manipulation of molecular pathways. To expand the utility of killifish as an environmental model, MO gene knockdown technology was adapted for use in Fundulus. Morpholino microinjection methods were altered to overcome the significant differences between these two species. Morpholino efficacy and functional duration were evaluated with molecular and phenotypic methods. A cytochrome P450-1A (CYP1A) MO was used to confirm effectiveness of the methodology. For CYP1A MO-injected embryos, a 70% reduction in CYP1A activity, a 86% reduction in total CYP1A protein, a significant increase in beta-naphthoflavone-induced teratogenicity, and estimates of functional duration (50% reduction in activity 10 dpf, and 86% reduction in total protein 12 dpf) conclusively demonstrated that MO technologies can be used effectively in killifish and will likely be just as informative as they have been in zebrafish.
  • Thumbnail Image
    ItemOpen Access
    Developmental exposure to a complex PAH mixture causes persistent behavioral effects in naive Fundulus heteroclitus (killifish) but not in a population of PAH-adapted killifish.
    (Neurotoxicol Teratol, 2016-01) Brown, DR; Bailey, JM; Oliveri, AN; Levin, ED; Di Giulio, RT
    Acute exposures to some individual polycyclic aromatic hydrocarbons (PAHs) and complex PAH mixtures are known to cause cardiac malformations and edema in the developing fish embryo. However, the heart is not the only organ impacted by developmental PAH exposure. The developing brain is also affected, resulting in lasting behavioral dysfunction. While acute exposures to some PAHs are teratogenically lethal in fish, little is known about the later life consequences of early life, lower dose subteratogenic PAH exposures. We sought to determine and characterize the long-term behavioral consequences of subteratogenic developmental PAH mixture exposure in both naive killifish and PAH-adapted killifish using sediment pore water derived from the Atlantic Wood Industries Superfund Site. Killifish offspring were embryonically treated with two low-level PAH mixture dilutions of Elizabeth River sediment extract (ERSE) (TPAH 5.04 μg/L and 50.4 μg/L) at 24h post fertilization. Following exposure, killifish were raised to larval, juvenile, and adult life stages and subjected to a series of behavioral tests including: a locomotor activity test (4 days post-hatch), a sensorimotor response tap/habituation test (3 months post hatch), and a novel tank diving and exploration test (3months post hatch). Killifish were also monitored for survival at 1, 2, and 5 months over 5-month rearing period. Developmental PAH exposure caused short-term as well as persistent behavioral impairments in naive killifish. In contrast, the PAH-adapted killifish did not show behavioral alterations following PAH exposure. PAH mixture exposure caused increased mortality in reference killifish over time; yet, the PAH-adapted killifish, while demonstrating long-term rearing mortality, had no significant changes in mortality associated with ERSE exposure. This study demonstrated that early embryonic exposure to PAH-contaminated sediment pore water caused long-term locomotor and behavioral alterations in killifish, and that locomotor alterations could be observed in early larval stages. Additionally, our study highlights the resistance to behavioral alterations caused by low-level PAH mixture exposure in the adapted killifish population. Furthermore, this is the first longitudinal behavioral study to use killifish, an environmentally important estuarine teleost fish, and this testing framework can be used for future contaminant assessment.
  • Thumbnail Image
    ItemOpen Access
    Evolution of the sex ratio and effective number under gynodioecy and androdioecy.
    (Theoretical population biology, 2017-12) Uyenoyama, Marcy K; Takebayashi, Naoki
    We address the evolution of effective number of individuals under androdioecy and gynodioecy. We analyze dynamic models of autosomal modifiers of weak effect on sex expression. In our zygote control models, the sex expressed by a zygote depends on its own genotype, while in our maternal control models, it depends on the genotype of its maternal parent. Our analysis unifies full multi-dimensional local stability analysis with the Li-Price equation, which for all its heuristic appeal, describes evolutionary change over a single generation. We define a point in the neighborhood of a fixation state from which a single-generation step indicates the asymptotic behavior of the frequency of a modifier allele initiated at an arbitrary point near the fixation state. A concept of heritability appropriate for the evolutionary modification of sex emerges from the Li-Priceframework. We incorporate our theoretical analysis into our previously-developed Bayesian inference framework to develop a new method for inferring the viability of gonochores (males or females) relative to hermaphrodites. Applying this approach to microsatellite data derived from natural populations of the gynodioecious plant Schiedea salicaria and the androdioecious killifish Kryptolebias marmoratus, we find that while female and hermaphrodite S. salicaria appear to have similar viabilities, male K. marmoratus appear to survive to reproductive age at less than half the rate of hermaphrodites.
  • Thumbnail Image
    ItemOpen Access
    Experimental evaluation of evolution and coevolution as agents of ecosystem change in Trinidadian streams.
    (Philos Trans R Soc Lond B Biol Sci, 2009-06-12) Palkovacs, EP; Marshall, MC; Lamphere, BA; Lynch, BR; Weese, DJ; Fraser, DF; Reznick, DN; Pringle, CM; Kinnison, MT
    Evolution has been shown to be a critical determinant of ecological processes in some systems, but its importance relative to traditional ecological effects is not well known. In addition, almost nothing is known about the role of coevolution in shaping ecosystem function. Here, we experimentally evaluated the relative effects of species invasion (a traditional ecological effect), evolution and coevolution on ecosystem processes in Trinidadian streams. We manipulated the presence and population-of-origin of two common fish species, the guppy (Poecilia reticulata) and the killifish (Rivulus hartii). We measured epilithic algal biomass and accrual, aquatic invertebrate biomass, and detrital decomposition. Our results show that, for some ecosystem responses, the effects of evolution and coevolution were larger than the effects of species invasion. Guppy evolution in response to alternative predation regimes significantly influenced algal biomass and accrual rates. Guppies from a high-predation site caused an increase in algae relative to guppies from a low-predation site; algae effects were probably shaped by observed divergence in rates of nutrient excretion and algae consumption. Rivulus-guppy coevolution significantly influenced the biomass of aquatic invertebrates. Locally coevolved populations reduced invertebrate biomass relative to non-coevolved populations. These results challenge the general assumption that intraspecific diversity is a less critical determinant of ecosystem function than is interspecific diversity. Given existing evidence for contemporary evolution in these fish species, our findings suggest considerable potential for eco-evolutionary feedbacks to operate as populations adapt to natural or anthropogenic perturbations.
  • No Thumbnail Available
    ItemOpen Access
    Silver toxicity across salinity gradients: the role of dissolved silver chloride species (AgCl x ) in Atlantic killifish (Fundulus heteroclitus) and medaka (Oryzias latipes) early life-stage toxicity.
    (Ecotoxicology, 2016-08) Matson, Cole W; Bone, Audrey J; Auffan, Mélanie; Lindberg, T Ty; Arnold, Mariah C; Hsu-Kim, Heileen; Wiesner, Mark R; Di Giulio, Richard T
    The influence of salinity on Ag toxicity was investigated in Atlantic killifish (Fundulus heteroclitus) early life-stages. Embryo mortality was significantly reduced as salinity increased and Ag(+) was converted to AgCl(solid). However, as salinity continued to rise (>5 ‰), toxicity increased to a level at least as high as observed for Ag(+) in deionized water. Rather than correlating with Ag(+), Fundulus embryo toxicity was better explained (R(2) = 0.96) by total dissolved Ag (Ag(+), AgCl2 (-), AgCl3 (2-), AgCl4 (3-)). Complementary experiments were conducted with medaka (Oryzias latipes) embryos to determine if this pattern was consistent among evolutionarily divergent euryhaline species. Contrary to Fundulus data, medaka toxicity data were best explained by Ag(+) concentrations (R(2) = 0.94), suggesting that differing ionoregulatory physiology may drive observed differences. Fundulus larvae were also tested, and toxicity did increase at higher salinities, but did not track predicted silver speciation. Alternatively, toxicity began to increase only at salinities above the isosmotic point, suggesting that shifts in osmoregulatory strategy at higher salinities might be an important factor. Na(+) dysregulation was confirmed as the mechanism of toxicity in Ag-exposed Fundulus larvae at both low and high salinities. While Ag uptake was highest at low salinities for both Fundulus embryos and larvae, uptake was not predictive of toxicity.
  • Thumbnail Image
    ItemOpen Access
    The Elizabeth River Story: A Case Study in Evolutionary Toxicology.
    (J Toxicol Environ Health B Crit Rev, 2015) Di Giulio, Richard T; Clark, Bryan W
    The Elizabeth River system is an estuary in southeastern Virginia, surrounded by the towns of Chesapeake, Norfolk, Portsmouth, and Virginia Beach. The river has played important roles in U.S. history and has been the location of various military and industrial activities. These activities have been the source of chemical contamination in this aquatic system. Important industries, until the 1990s, included wood treatment plants that used creosote, an oil-derived product that is rich in polycyclic aromatic hydrocarbons (PAH). These plants left a legacy of PAH pollution in the river, and in particular Atlantic Wood Industries is a designated Superfund site now undergoing remediation. Numerous studies examined the distribution of PAH in the river and impacts on resident fauna. This review focuses on how a small estuarine fish with a limited home range, Fundulus heteroclitus (Atlantic killifish or mummichog), has responded to this pollution. While in certain areas of the river this species has clearly been impacted, as evidenced by elevated rates of liver cancer, some subpopulations, notably the one associated with the Atlantic Wood Industries site, displayed a remarkable ability to resist the marked effects PAH have on the embryonic development of fish. This review provides evidence of how pollutants have acted as evolutionary agents, causing changes in ecosystems potentially lasting longer than the pollutants themselves. Mechanisms underlying this evolved resistance, as well as mechanisms underlying the effects of PAH on embryonic development, are also described. The review concludes with a description of ongoing and promising efforts to restore this historic American river.