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1.
Heredity (Edinb) ; 122(1): 1-14, 2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-29773896

RESUMEN

Among-individual variation in behaviour is a widespread phenomenon, with several frameworks developed to explain its existence. Maternal effects, which can have significant influence over evolutionary processes, are an understudied source of behavioural variation. Maternal effects are not necessarily static, however, since their importance can change over offspring ontogeny, typically declining with age relative to additive genetic effects. Here, using a quantitative genetics approach, we test the prediction that maternal effects will influence age-specific risk-taking behaviour in Trinidadian guppies, Poecilia reticulata. Individuals were subject to a single open-field trial as juveniles and up to four repeat trials as adults, with five traits indicative of risk-taking behaviour measured in each trial. We then partitioned phenotypic variance into additive genetic (VA) and maternal identity (VM) components, in addition to testing brood size and maternal weight as specific sources of maternal effects. We found that VM had significant influence over juvenile traits, with very low VA estimates. Whereas, in adults, all traits were significantly heritable, with little support for VM. We also found a strong influence of maternal traits on juvenile behaviours as predicted, with significant, albeit smaller, effects found in adults. Maternal weight was heritable and itself subject to maternal effects. Thus, maternal weight is a likely source of maternal genetic effects that are expected to alter response to selection on personality in this system. More generally, our study highlights that while maternal effects can be an important source of personality variation, this varies over ontogeny of offspring.


Asunto(s)
Conducta Animal , Evolución Biológica , Personalidad/genética , Poecilia/genética , Animales , Peso Corporal/genética , Variación Genética/genética , Herencia Materna/genética , Personalidad/fisiología , Fenotipo , Poecilia/crecimiento & desarrollo
2.
Heredity (Edinb) ; 122(1): 15-28, 2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-29795179

RESUMEN

Sexual dimorphism in behaviour and personality has been identified in a number of species, but few studies have assessed the extent of shared genetic architecture across the sexes. Under sexually antagonistic selection, mechanisms are expected to evolve that reduce evolutionary conflict, resulting in genotype-by-sex (GxS) interactions. Here we assess the extent of sexual dimorphism in four risk-taking behaviour traits in the Trinidadian guppy, Poecilia reticulata, and apply a multivariate approach to test for GxS interactions. We also quantify the among-individual and genetic covariances between personality and size and growth, which are known a priori to differ between the sexes. We found significant sexual dimorphism in three of the four behaviours, although rmf between sex-specific homologous traits was significantly <+1 for only one behaviour. Using multivariate models, we then estimated sex-specific genetic (co)variance matrices (Gm and Gf) and tested for asymmetry of the cross-trait cross-sex genetic covariance structure (submatrix B). While Gm and Gf were not significantly different from each other overall, their respective leading eigenvectors were poorly aligned. Statistical support for asymmetry in B was found, but limited to a single trait pair for which the cross-sex covariances differed (i.e., COVA(m,f) ≠ COVA(f,m)). Thus, while single- and multi-trait perspectives evidence some GxS, the overall picture is one of similarity between the sexes in their genetic (co)variance structures. Our results suggest behavioural traits related to risk-taking may lack the sex-specific genetic architecture for further dimorphism to evolve under what is hypothesised to be antagonistic selection.


Asunto(s)
Conducta Animal , Evolución Biológica , Poecilia/genética , Conducta Sexual Animal , Animales , Peso Corporal/genética , Genotipo , Herencia Materna/genética , Personalidad/genética , Personalidad/fisiología , Poecilia/crecimiento & desarrollo , Caracteres Sexuales
3.
Evol Dev ; 20(6): 207-218, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-30191662

RESUMEN

Examining the association between trait variation and development is crucial for understanding the evolution of phenotypic differences. Male guppy ornamental caudal fin coloration is one trait that shows a striking degree of variation within and between guppy populations. Males initially have no caudal fin coloration, then gradually develop it as they reach sexual maturity. For males, there is a trade-off between female preference for caudal fin coloration and increased visibility to predators. This trade-off may reach unique endpoints in males from different predation regimes. Caudal fin coloration includes black melanin, orange/yellow pteridines or carotenoids, and shimmering iridescence. This study examined the phenotypic trajectory and genetics associated with color development. We found that black coloration always developed first, followed by orange/yellow, then iridescence. The ordering and timing of color appearance was the same regardless of predation regime. The increased expression of melanin synthesis genes correlated well with the visual appearance of black coloration, but there was no correlation between carotenoids or pteridine synthesis gene expression and the appearance of orange/yellow. The lack of orange/yellow coloration in earlier male caudal fin developmental stages may be due to reduced expression of genes underlying the development of orange/yellow xanthophores.


Asunto(s)
Pigmentación , Poecilia/crecimiento & desarrollo , Poecilia/genética , Aletas de Animales/fisiología , Animales , Femenino , Masculino , Poecilia/fisiología , Caracteres Sexuales , Transcriptoma
4.
Proc Biol Sci ; 284(1864)2017 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-29021173

RESUMEN

The size and maturity of Trinidadian guppy (Poecilia reticulata) offspring vary among populations adapted to environments of differential predation. Guppy offspring born to low-predation, high-competition environments are larger and more mature than their high-predation ancestors. Here we ask: what specific changes in developmental or birth timing occur to produce the larger, more mature neonates? We collected specimens across the perinatal window of development from five populations and quantified musculoskeletal maturation. We found that all populations undergo similar ontogenetic trajectories in skeletal and muscle acquisition; the only difference among populations is when neonates emerge along the trajectory. The smallest neonates are born with 20% of their skeleton ossified, whereas the largest neonates are born with over 70% of their skeleton ossified. The area of the major jaw-closing muscle is relatively larger in larger offspring, scaling with length as L2.5 The size range over which offspring are birthed among populations sits along the steepest part of the size-maturity relationship, which provides a large marginal increase in fitness for the high-competition female. Because of the functional effects of producing more mature offspring at birth, offspring size may be the first and most critical life-history trait selected upon in highly competitive environments.


Asunto(s)
Evolución Biológica , Tamaño Corporal , Ambiente , Poecilia/fisiología , Animales , Animales Recién Nacidos/crecimiento & desarrollo , Animales Recién Nacidos/fisiología , Desarrollo Óseo , Poecilia/crecimiento & desarrollo
5.
Gen Comp Endocrinol ; 246: 200-210, 2017 05 15.
Artículo en Inglés | MEDLINE | ID: mdl-28013033

RESUMEN

The sensory system shapes an individual's perception of the world, including social interactions with conspecifics, habitat selection, predator detection, and foraging behavior. Sensory signaling can be modulated by steroid hormones, making these processes particularly vulnerable to environmental perturbations. Here we examine the influence of exogenous estrogen manipulation on the visual physiology of female western mosquitofish (Gambusia affinis) and sailfin mollies (Poecilia latipinna), two poeciliid species that inhabit freshwater environments across the southern United States. We conducted two experiments to address this aim. First, we exposed females from both species to a one-week dose response experiment with three treatments of waterborne ß-estradiol. Next, we conducted a one-week estrogen manipulation experiment with a waterborne estrogen (ß-Estradiol), a selective estrogen receptor modulator (tamoxifen), or combination estrogen and tamoxifen treatment. We used quantitative PCR (qPCR) to examine the expression of cone opsins (SWS1, SWS2b, SWS2a, Rh2, LWS), rhodopsin (Rh1), and steroid receptor genes (ARα, ARß, ERα, ERß2, GPER) in the eyes of individual females from each species. Results from the dose response experiment revealed estradiol-sensitivity in opsin (SWS2a, Rh2, Rh1) and androgen receptor (ARα, ARß) gene expression in mosquitofish females, but not sailfins. Meanwhile, our estrogen receptor modulation experiments revealed estrogen sensitivity in LWS opsin expression in both species, along with sensitivity in SWS1, SWS2b, and Rh2 opsins in mosquitofish. Comparisons of control females across experiments reveal species-level differences in opsin expression, with mosquitofish retinas dominated by short-wavelength sensitive opsins (SWS2b) and sailfins retinas dominated by medium- and long-wavelength sensitive opsins (Rh2 and LWS). Our research suggests that variation in exogenous levels of sex hormones within freshwater environments can modify the visual physiology of fishes in a species-specific manner.


Asunto(s)
Estrógenos/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Poecilia/metabolismo , Retina/metabolismo , Opsinas de Bastones/metabolismo , Animales , Femenino , Agua Dulce , Filogenia , Poecilia/crecimiento & desarrollo , Reacción en Cadena en Tiempo Real de la Polimerasa , Retina/efectos de los fármacos , Opsinas de Bastones/genética , Especificidad de la Especie
6.
BMC Evol Biol ; 16(1): 106, 2016 May 18.
Artículo en Inglés | MEDLINE | ID: mdl-27193604

RESUMEN

BACKGROUND: The visual system is important for animals for mate choice, food acquisition, and predator avoidance. Animals possessing a visual system can sense particular wavelengths of light emanating from objects and their surroundings and perceive their environments by processing information contained in these visual perceptions of light. Visual perception in individuals varies with the absorption spectra of visual pigments and the expression levels of opsin genes, which may be altered according to the light environments. However, which light environments and the mechanism by which they change opsin expression profiles and whether these changes in opsin gene expression can affect light sensitivities are largely unknown. This study determined whether the light environment during growth induced plastic changes in opsin gene expression and behavioral sensitivity to particular wavelengths of light in guppies (Poecilia reticulata). RESULTS: Individuals grown under orange light exhibited a higher expression of long wavelength-sensitive (LWS) opsin genes and a higher sensitivity to 600-nm light than those grown under green light. In addition, we confirmed that variations in the expression levels of LWS opsin genes were related to the behavioral sensitivities to long wavelengths of light. CONCLUSIONS: The light environment during the growth stage alters the expression levels of LWS opsin genes and behavioral sensitivities to long wavelengths of light in guppies. The plastically enhanced sensitivity to background light due to changes in opsin gene expression can enhance the detection and visibility of predators and foods, thereby affecting survival. Moreover, changes in sensitivities to orange light may lead to changes in the discrimination of orange/red colors of male guppies and might alter female preferences for male color patterns.


Asunto(s)
Opsinas de los Conos/genética , Proteínas de Peces/genética , Poecilia/crecimiento & desarrollo , Poecilia/genética , Animales , Opsinas de los Conos/metabolismo , Femenino , Proteínas de Peces/metabolismo , Expresión Génica , Luz , Masculino , Preferencia en el Apareamiento Animal , Poecilia/anatomía & histología , Poecilia/fisiología , Percepción Visual
7.
Biol Lett ; 12(4)2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-27072405

RESUMEN

Recognizing and associating with specific individuals, such as conspecifics or kin, brings many benefits. One mechanism underlying such recognition is imprinting: the long-term memory of cues encountered during development. Typically, juveniles imprint on cues of nearby individuals and may later associate with phenotypes matching their 'recognition template'. However, phenotype matching could lead to maladaptive social decisions if, for instance, individuals imprint on the cues of conspecifics infected with directly transmitted diseases. To investigate the role of imprinting in the sensory ecology of disease transmission, we exposed juvenile guppies,Poecilia reticulata, to the cues of healthy conspecifics, or to those experiencing disease caused by the directly transmitted parasite Gyrodactylus turnbulli In a dichotomous choice test, adult 'disease-imprinted' guppies preferred to associate with the chemical cues of G. turnbulli-infected conspecifics, whereas 'healthy-imprinted' guppies preferred to associate with cues of uninfected conspecifics. These responses were only observed when stimulus fish were in late infection, suggesting imprinted fish responded to cues of disease, but not of infection alone. We discuss how maladaptive imprinting may promote disease transmission in natural populations of a social host.


Asunto(s)
Poecilia/fisiología , Poecilia/parasitología , Trematodos/fisiología , Animales , Señales (Psicología) , Femenino , Enfermedades de los Peces/parasitología , Enfermedades de los Peces/transmisión , Interacciones Huésped-Parásitos , Impronta Psicológica , Larva/fisiología , Masculino , Odorantes , Enfermedades Parasitarias en Animales/parasitología , Enfermedades Parasitarias en Animales/transmisión , Poecilia/crecimiento & desarrollo , Olfato
8.
J Anim Ecol ; 84(4): 955-68, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25704755

RESUMEN

Decades of theory and recent empirical results have shown that evolutionary, population, community and ecosystem properties are the result of feedbacks between ecological and evolutionary processes. The vast majority of theory and empirical research on these eco-evolutionary feedbacks has focused on interactions among population size and mean traits of populations. However, numbers and mean traits represent only a fraction of the possible feedback dimensions. Populations of many organisms consist of different size classes that differ in their impact on the environment and each other. Moreover, rarely do we know the map of ecological pathways through which changes in numbers or size structure cause evolutionary change. The goal of this study was to test the role of size structure in eco-evolutionary feedbacks of Trinidadian guppies and to begin to build an eco-evolutionary map along this unexplored dimension. We used a factorial experiment in mesocosms wherein we crossed high- and low-predation guppy phenotypes with population size structure. We tested the ability of changes in size structure to generate selection on the demographic rates of guppies using an integral projection model (IPM). To understand how fitness differences among high- and low-predation phenotypes may be generated, we measured the response of the biomass of lower trophic levels and nutrient cycling to the different phenotype and size structure treatments. We found a significant interaction between guppy phenotype and the size structure treatments for absolute fitness. Size structure had a very large effect on invertebrate biomass in the mesocosms, but there was little or no effect of the phenotype. The effect of size structure on algal biomass depended on guppy phenotype, with no difference in algal biomass in populations with more, smaller guppies, but a large decrease in algal biomass in mesocosms with phenotypes adapted to low-predation risk. These results indicate an important role for size structure partially driving eco-evolutionary feedbacks in guppies. The changes in the ecosystem suggest that the absence of a steep decline in guppy fitness of the low-predation risk populations is likely due to higher consumption of algae when invertebrates are comparatively rare. Overall, these results demonstrate size structure as a possible dimension through which eco-evolutionary feedbacks may occur in natural populations.


Asunto(s)
Ecosistema , Poecilia/fisiología , Adaptación Fisiológica , Animales , Biomasa , Invertebrados , Modelos Biológicos , Fenotipo , Poecilia/crecimiento & desarrollo , Densidad de Población , Conducta Predatoria , Trinidad y Tobago
9.
Indian J Exp Biol ; 52(3): 232-6, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24669666

RESUMEN

Norethindrone(NE) was evaluated for its efficacy on alteration of sex ratio of P. reticulata. Either the young fry or the brooders and the resultant fry were fed a commercial diet incorporated with NE at 0, 25, 50, 75 and 100 mg kg(-1) diet (ppm) for 30-40 d in rectangular glass aquaria; this was followed by 40-60 d rearing on NE-free diet in out-door concrete tanks. In general, the androgen treatment altered sex ratio, leading to the production of a dose dependent increase in the percentage of males. The oral administration of the steroid at 75 ppm for 40 d or 100 ppmfor 30 or 40 d to first feeding fry, yielded 100% males. On the other hand, NE administration to brooders before parturition and the resultant fry also produced an all-male population of guppy. The sex ratio of the untreated control was almost 1:1. The survival of fish in all the trials was high, ranging between 67 and 100%. Mating masculinized males ("XX" male) with normal female resulted in an all-female progeny, while crossing normal male (XY) from treatment groups with normal female sired normal sex ratio (1:1), elucidating XX-XY sex determination system in the guppy.


Asunto(s)
Noretindrona/farmacología , Poecilia/crecimiento & desarrollo , Procesos de Determinación del Sexo/efectos de los fármacos , Razón de Masculinidad , Animales , Femenino , Masculino , Poecilia/genética , Reproducción/genética
10.
Am Nat ; 181(2): 195-212, 2013 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-23348774

RESUMEN

Ontogenetic and static allometries describe how a character changes in size when the size of the organism changes during ontogeny and among individuals measured at the same developmental stage, respectively. Understanding the relationship between these two types of allometry is crucial to understanding the evolution of allometry and, more generally, the evolution of shape. However, the effects of ontogenetic allometry on static allometry remain largely unexplored. Here, we first show analytically how individual variation in ontogenetic allometry and body size affect static allometry. Using two longitudinal data sets on ontogenetic and static allometry, we then estimate variances and covariances for the different parameters of the ontogenetic allometry defined in our model and assess their relative contribution to the static allometric slope. The mean ontogenetic allometry is the main parameter that determines the static allometric slope, while the covariance between the ontogenetic allometric slope and body size generates most of the discrepancies between ontogenetic and static allometry. These results suggest that the apparent evolutionary stasis of the static allometric slope is not generated by internal (developmental) constraints but more likely results from external constraints imposed by selection.


Asunto(s)
Evolución Biológica , Tamaño Corporal/fisiología , Crecimiento y Desarrollo/fisiología , Modelos Biológicos , Carácter Cuantitativo Heredable , Selección Genética , Análisis de Varianza , Animales , Pesos y Medidas Corporales , Simulación por Computador , Ratones , Poecilia/crecimiento & desarrollo , Cola (estructura animal)/crecimiento & desarrollo
11.
Proc Biol Sci ; 280(1758): 20122019, 2013 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-23466982

RESUMEN

The evolution of male ornamentation often reflects compromises between sexual and natural selection, but it may also be influenced by phenotypic plasticity. We investigated the developmental plasticity of male colour ornamentation in Trinidadian guppies in response to two environmental variables that covary in nature: predation risk and food availability. We found that exposure to chemical predator cues delayed the development of pigment-based colour elements, which are conspicuous to visual-oriented predators. Predator cues also reduced the size of colour elements at the time of maturity and caused adult males to be less colourful. To the best of our knowledge, these findings provide the first example of a plastic reduction in the development of a sexually selected male ornament in response to predator cues. The influence of predator cues on ornamentation probably affects individual fitness by reducing conspicuousness to predators, but could reduce attractiveness to females. Reduced food availability during development caused males to delay the development of colour elements and mature later, probably reflecting a physiological constraint, but their coloration at maturity and later in adulthood was largely unaffected, suggesting that variation in food quantity without variation in quality does not contribute to condition dependence of the trait.


Asunto(s)
Dieta , Cadena Alimentaria , Pigmentación , Poecilia/fisiología , Animales , Evolución Biológica , Señales (Psicología) , Femenino , Masculino , Fenotipo , Poecilia/genética , Poecilia/crecimiento & desarrollo , Selección Genética , Trinidad y Tobago
12.
Proc Biol Sci ; 280(1763): 20131116, 2013 Jul 22.
Artículo en Inglés | MEDLINE | ID: mdl-23740786

RESUMEN

In semelparous populations, dormant germ banks (e.g. seeds) have been proposed as important in maintaining genotypes that are adaptive at different times in fluctuating environments. Such hidden storage of genetic diversity need not be exclusive to dormant banks. Genotype diversity may be preserved in many iteroparous animals through sperm-storage mechanisms in females. This allows males to reproduce posthumously and increase the effective sizes of seemingly female-biased populations. Although long-term sperm storage has been demonstrated in many organisms, the understanding of its importance in the wild is very poor. We here show the prevalence of male posthumous reproduction in wild Trinidadian guppies, through the combination of mark-recapture and pedigree analyses of a multigenerational individual-based dataset. A significant proportion of the reproductive population consisted of dead males, who could conceive up to 10 months after death (the maximum allowed by the length of the dataset), which is more than twice the estimated generation time. Demographic analysis shows that the fecundity of dead males can play an important role in population growth and selection.


Asunto(s)
Poecilia/fisiología , Dinámica Poblacional , Reproducción/fisiología , Selección Genética , Animales , Femenino , Masculino , Poecilia/genética , Poecilia/crecimiento & desarrollo , Reproducción/genética , Espermatozoides/fisiología , Trinidad y Tobago
13.
J Evol Biol ; 26(10): 2184-96, 2013 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-23937558

RESUMEN

Maturation is an important event in an organism's life history, with important implications on dynamics of both wild and captive populations. The probabilistic maturation reaction norm (PMRN) has emerged as an important method to describe variation in maturation in wild fish. Because most PMRNs are based on age and size only, it is important to understand limitations of these variables in explaining maturation. We experimentally assessed (i) the sensitivity of age- and size-based PMRNs to unaccounted sources of plasticity, (ii) the role of social environment on maturation and (iii) the significance of estimating PMRNs early and late in the maturation process (initiation and completion of maturation, respectively). We reared male guppies (Poecilia reticulata) under laboratory conditions, subjected to two food levels and three different social cues. We found that growth and social environment affected the maturation in a way that could not be accounted for by their effect on age and size. PMRNs estimated for the initiation stage were less plastic (growth differences and social cues influenced the PMRN shape only little) than those for completion. The initiation of maturation is probably closer to the maturation 'decision' and allows determining factors influencing maturation decision most accurately.


Asunto(s)
Ambiente , Poecilia/crecimiento & desarrollo , Animales , Tamaño Corporal , Masculino , Poecilia/anatomía & histología , Dinámica Poblacional , Maduración Sexual
14.
J Exp Biol ; 216(Pt 14): 2760-7, 2013 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-23619415

RESUMEN

Many animals, particularly reptiles, amphibians, fish and cephalopods, have the ability to change their body colour, for functions including thermoregulation, signalling and predator avoidance. Many fish plastically darken their body colouration in response to dark visual backgrounds, and this functions to reduce predation risk. Here, we tested the hypotheses that colour change in fish (1) carries with it an energetic cost and (2) affects subsequent shoal and habitat choice decisions. We demonstrate that guppies (Poecilia reticulata) change colour in response to dark and light visual backgrounds, and that doing so carries an energetic cost in terms of food consumption. By increasing food intake, however, guppies are able to maintain growth rates and meet the energetic costs of changing colour. Following colour change, fish preferentially choose habitats and shoals that match their own body colouration, and maximise crypsis, thus avoiding the need for further colour change but also potentially paying an opportunity cost associated with restriction to particular habitats and social associates. Thus, colour change to match the background is complemented by behavioural strategies, which should act to maximise fitness in variable environments.


Asunto(s)
Adaptación Fisiológica/fisiología , Color , Ecosistema , Metabolismo Energético/fisiología , Poecilia/crecimiento & desarrollo , Animales , Tamaño Corporal/fisiología , Ingestión de Alimentos/fisiología , Femenino , Masculino , Conducta Social
15.
Toxicol Ind Health ; 29(8): 716-21, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22508399

RESUMEN

Fenpyroximate (FP), an acaricide, is widely used in the prevention of acarids (mites) in fruit plant gardens. In this study, the acute toxic effects of different concentrations of FP were investigated using adult guppy (Poecilia reticulata Peters, 1859). Guppy adults were exposed to a range of FP concentrations (25, 50, 75, 100, 125, and 150 µg/L) during 48 h. Static method, which is one of the acute toxicity experiments, has been used in this study. According to probit analysis, the 48-h median lethal concentration (LC50) value of FP at 26°C was found to be 72.821 µg/L. Sublethal exposures were predetermined based on 48-h LC50 value. Guppies were exposed to low concentrations (15, 25, and 50 µg/L) of FP for 48 h. Signs of paralysis and behavior deformations were monitored every 12 h in a number of live and dead adults. Low concentrations of FP were also responsible for erratic swimming, loss of equilibrium, and being lethargic. Liver histology revealed several pathological damages including congestion, picnotic nucleus, sinusoidal dilatation, increase in melanomacrophagic centers, and endothelial degeneration. Finally, the toxicity test results provided 48-h LC50 value for FP, and low concentrations of FP can be highly detrimental to guppy adults with clear evidence of behavioral and histologic effects.


Asunto(s)
Acaricidas/toxicidad , Benzoatos/toxicidad , Monitoreo del Ambiente/métodos , Poecilia/crecimiento & desarrollo , Pirazoles/toxicidad , Pruebas de Toxicidad Aguda , Contaminantes Químicos del Agua/toxicidad , Animales , Conducta Animal/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Dosificación Letal Mediana , Natación , Contaminantes Químicos del Agua/análisis
16.
J Environ Sci Health B ; 48(7): 600-6, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23581694

RESUMEN

This study aimed to estimate the acute toxicity of teflubenzuron (1-(3,5-dichloro-2,4-difluorophenyl)-3-(2,6-difluorobenzoyl)urea) (TFB) for Daphnia magna, Lemna minor and Poecilia reticulata, in the absence and presence of sediment; evaluate the effect of sediment on the TFB bioavailability; and to classify this insecticide according to its environmental poisoning risk for agricultural and aquaculture uses. The tests of TFB acute toxicity were conducted in static system in a completely randomized design with increasing TFB concentrations, and a control group. The TFB has been classified according to the estimated values of EC50 and LC50 by its acute toxicity and environmental risk. The sediment significantly reduced toxicity and bioavailability of TFB in water column. Therefore, the insecticide can be classified as being highly toxic to Daphnia magna, which means the agricultural and aquacultural uses of TFB pose a high risk of environmental toxicity to non-target organisms. However, it was practically non-toxic to L. minor and P. reticulata.


Asunto(s)
Araceae/efectos de los fármacos , Benzamidas/toxicidad , Daphnia/efectos de los fármacos , Sedimentos Geológicos/análisis , Insecticidas/toxicidad , Poecilia/crecimiento & desarrollo , Contaminantes Químicos del Agua/toxicidad , Animales , Dosificación Letal Mediana
17.
Zoo Biol ; 32(3): 251-6, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-22610913

RESUMEN

The following work provides basic information about the life history of 10 Cuban species of the family Poeciliidae. Adult fish stocks were captured in their natural habitat, and litters obtained from them were raised and maintained in captivity for 19 weeks. For each species, we present the mean value of newborn length (TLo ), age at sexual maturity (AM), total length at sexual maturity (TLM), as well as the patterns of postnatal growth in aquarium conditions, which were described using size-age curves and nonlinear regression equations (Richards model). There are differences in growth dynamics among species. In general, growth rates differ for both sexes in all poeciliids studied, males maturing earlier than females, who reach higher values of total length at the 19th week (TLf ). Sexual size dimorphism could be explained by the specific roles of each sex (fecundity in females and early maturity in males) while differences in growth among species could be related to their distribution patterns in the wild. The data summarized in this contribution can be useful for the conservation of these fish species.


Asunto(s)
Animales de Zoológico , Tamaño Corporal/fisiología , Poecilia/crecimiento & desarrollo , Maduración Sexual/fisiología , Animales , Conservación de los Recursos Naturales/métodos , Cuba , Femenino , Gráficos de Crecimiento , Masculino , Análisis de Regresión , Especificidad de la Especie , Estadísticas no Paramétricas
18.
J Exp Biol ; 215(Pt 19): 3436-41, 2012 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-22693028

RESUMEN

Global warming poses a threat to many ectothermic organisms because of the harmful effects that elevated temperatures can have on resting metabolic rate (RMR) and body size. This study evaluated the thermal sensitivity of Trinidadian guppies (Poecilia reticulata) by describing the effects of developmental temperature on mass, burst speed and RMR, and investigated whether these tropical fish can developmentally acclimate to their thermal conditions. These traits were measured following exposure to one of three treatments: 70 days at 23, 25, 28 or 30°C (acclimated groups); 6 h at 23, 28 or 30°C following 70 days at 25°C (unacclimated groups); or 6 h at 25°C following 70 days in another 25°C tank (control group). Body mass was lower in warmer temperatures, particularly amongst females and individuals reared at 30°C. The burst speed of fish acclimated to each temperature did not differ and was marginally higher than that of unacclimated fish, indicative of complete compensation. Conversely, acclimated and unacclimated fish did not differ in their RMR at each temperature. Amongst the acclimated groups, RMR was significantly higher at 30°C, indicating that guppies may become thermally limited at this temperature as a result of less energy being available for growth, reproduction and locomotion. Like other tropical ectotherms, guppies appear to be unable to adjust their RMR through physiological acclimation and may consequently be susceptible to rising temperatures. Also, because larger females have higher fecundity, our data suggest that fecundity will be reduced in a warmer climate, potentially decreasing the viability of guppy populations.


Asunto(s)
Aclimatación/fisiología , Locomoción/fisiología , Poecilia/metabolismo , Poecilia/fisiología , Caracteres Sexuales , Temperatura , Animales , Peso Corporal/fisiología , Femenino , Masculino , Consumo de Oxígeno/fisiología , Poecilia/crecimiento & desarrollo , Descanso/fisiología , Trinidad y Tobago
19.
J Exp Biol ; 215(Pt 15): 2711-5, 2012 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-22786649

RESUMEN

Crypt cells are one of three types of olfactory sensory neuron, differing from ciliated and microvillar cells in shape, localization and number, and found only in fish. Although crypt cells are morphologically well characterized, their function remains unclear. They were hypothesized to be involved in reproductive behaviours by detecting sex pheromones, but electrophysiological investigations revealed sensitivity to only amino acids. However, the number of crypt cells in adult guppies is not the same in the two sexes. In this study, we compared the size of the crypt cell population in juvenile guppies during the first 90 days after birth. The purpose of our study was to clarify whether a correlation exists between sex and the number of these olfactory neurons. The data show that guppies reach adult crypt cell density when they become sexually mature. Despite a constant increment in volume during development of the olfactory organ, the minimum density of crypt neurons occurs at ~45 days. Moreover, in the early weeks, the density of crypt neurons is greater in males than in females because in females the total number of cells decreases significantly after just 7 days. In adults, however, crypt neurons are found in higher density in females than in males. These findings suggest that the number of crypt cells is sex specific, with independent developmental dynamics between males and females. A role in pheromone detection could explain such a difference, but the early appearance of crypt cells in the first days of life is suggestive of other, not sexually related, functions.


Asunto(s)
Bulbo Olfatorio/citología , Bulbo Olfatorio/crecimiento & desarrollo , Poecilia/crecimiento & desarrollo , Maduración Sexual/fisiología , Animales , Animales Recién Nacidos , Femenino , Proteínas de Peces/metabolismo , Gónadas/citología , Gónadas/metabolismo , Inmunohistoquímica , Masculino , Bulbo Olfatorio/metabolismo , Poecilia/metabolismo , Proteínas S100/metabolismo
20.
J Anim Ecol ; 81(4): 818-26, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22320252

RESUMEN

1. Environmental conditions in the present, more recent past and during the juvenile stage can have significant effects on adult performance and population dynamics, but their relative importance and potential interactions remain unexplored. 2. We examined the influence of food availability at the time of sampling, 2 months prior and during the juvenile stage on adult somatic growth rates in wild Trinidadian guppies (Poecilia reticulata). 3. We found that food availability during both the early and later parts of an individual's ontogeny had important consequences for adult growth strategies, but the direction of these effects differed among life stages and their magnitude, in some cases, depended on food levels experienced during other life stages. Current food levels and those 2 months prior to growth measurements had positive effects on adult growth rate; though, food levels 2 months prior had a greater effect on growth than current food levels. In contrast, the effects of food availability during the juvenile stage were higher in magnitude but opposite in direction to current food levels and those 2 months prior to growth rate measurements. Individuals recruiting under low food levels grew faster as adults than individuals recruiting during periods of high food availability. There was also a positive interaction between food levels experienced during the juvenile stage and 2 months prior such that the effects of juvenile food level diminished as the food level experienced 2 months prior increased. 4. These results suggest that the similar conditions occurring at different life stages can have different effects on short- and long-term growth strategies of individuals within a population. They also demonstrate that, while juvenile conditions can have lasting effects on adult performance, the strength of that effect can be dampened by environmental conditions experienced as an adult. 5. A simultaneous consideration of past events in both the adult and juvenile stage may therefore improve predictions for individual- and population-level responses to environmental change.


Asunto(s)
Ambiente , Poecilia/crecimiento & desarrollo , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Femenino , Modelos Biológicos , Fenotipo , Poecilia/fisiología , Estaciones del Año , Factores de Tiempo
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