RESUMEN
Originating in Africa, the Zika virus (ZIKV) has spread to Asia, Pacific Islands and now to the Americas and beyond. Since the first isolation in 1947, ZIKV strains have been sampled at various times in the last 69 years, but this history has not been reflected in studying the patterns of mutation accumulation in their genomes. Implementing the viral history, we show that the ZIKV ancestor appeared sometime in 1930-1945 and, at that point, its mutation rate was probably less than 0.2 × 10-3/nucleotide site/year and subsequently increased significantly in most of its descendants. Sustaining a high mutation rate of 4 × 10-3/site/year throughout its evolution, the Ancestral Asian strain, which was sampled from a mosquito in Malaysia, accumulated 13 mutations in the 3'-untranslated region of RNA stem-loops prior to 1963, seven of which generate more stable stem-loop structures and are likely to inhibit cellular antiviral activities, including immune and RNA interference (RNAi) pathways. The seven mutations have been maintained in all Asian and American strains and may be responsible for serious medical problems we are facing today and offer testable hypotheses to examine their roles in molecular interactions during brain development.
Asunto(s)
Mutación , Filogeografía/legislación & jurisprudencia , Filogeografía/métodos , Infección por el Virus Zika/virología , Virus Zika/genética , Animales , Evolución Biológica , Evolución Molecular , Genoma Viral , Humanos , Insectos Vectores , Secuencias Invertidas Repetidas , Tasa de Mutación , Filogenia , Estabilidad del ARN , ARN Viral/genética , Relación Estructura-ActividadRESUMEN
Post-copulatory sexual selection (PSS), fuelled by female promiscuity, is credited with the rapid evolution of sperm quality traits across diverse taxa. Yet, our understanding of the adaptive significance of sperm ornaments and the cryptic female preferences driving their evolution is extremely limited. Here we review the evolutionary allometry of exaggerated sexual traits (for example, antlers, horns, tail feathers, mandibles and dewlaps), show that the giant sperm of some Drosophila species are possibly the most extreme ornaments in all of nature and demonstrate how their existence challenges theories explaining the intensity of sexual selection, mating-system evolution and the fundamental nature of sex differences. We also combine quantitative genetic analyses of interacting sex-specific traits in D. melanogaster with comparative analyses of the condition dependence of male and female reproductive potential across species with varying ornament size to reveal complex dynamics that may underlie sperm-length evolution. Our results suggest that producing few gigantic sperm evolved by (1) Fisherian runaway selection mediated by genetic correlations between sperm length, the female preference for long sperm and female mating frequency, and (2) longer sperm increasing the indirect benefits to females. Our results also suggest that the developmental integration of sperm quality and quantity renders post-copulatory sexual selection on ejaculates unlikely to treat male-male competition and female choice as discrete processes.
Asunto(s)
Evolución Biológica , Tamaño de la Célula , Drosophila melanogaster/anatomía & histología , Drosophila melanogaster/fisiología , Preferencia en el Apareamiento Animal/fisiología , Espermatozoides/citología , Espermatozoides/fisiología , Animales , Conducta Competitiva/fisiología , Copulación/fisiología , Drosophila melanogaster/clasificación , Drosophila melanogaster/citología , Drosophila melanogaster/genética , Femenino , Masculino , Óvulo/citología , Óvulo/fisiología , Fenotipo , Caracteres SexualesRESUMEN
Ultraviolet (UV) reception is useful for such basic behaviors as mate choice, foraging, predator avoidance, communication, and navigation, whereas violet reception improves visual resolution and subtle contrast detection. UV and violet reception are mediated by the short wavelength-sensitive (SWS1) pigments that absorb light maximally (λmax) at ~360 nm and ~395 to 440 nm, respectively. Because of strong nonadditive (epistatic) interactions among amino acid changes in the pigments, the adaptive evolutionary mechanisms of these phenotypes are not well understood. Evolution of the violet pigment of the African clawed frog (Xenopus laevis, λmax = 423 nm) from the UV pigment in the amphibian ancestor (λmax = 359 nm) can be fully explained by eight mutations in transmembrane (TM) I-III segments. We show that epistatic interactions involving the remaining TM IV-VII segments provided evolutionary potential for the frog pigment to gradually achieve its violet-light reception by tuning its color sensitivity in small steps. Mutants in these segments also impair pigments that would cause drastic spectral shifts and thus eliminate them from viable evolutionary pathways. The overall effects of epistatic interactions involving TM IV-VII segments have disappeared at the last evolutionary step and thus are not detectable by studying present-day pigments. Therefore, characterizing the genotype-phenotype relationship during each evolutionary step is the key to uncover the true nature of epistasis.
RESUMEN
Establishing genotype-phenotype relationship is the key to understand the molecular mechanism of phenotypic adaptation. This initial step may be untangled by analyzing appropriate ancestral molecules, but it is a daunting task to recapitulate the evolution of non-additive (epistatic) interactions of amino acids and function of a protein separately. To adapt to the ultraviolet (UV)-free retinal environment, the short wavelength-sensitive (SWS1) visual pigment in human (human S1) switched from detecting UV to absorbing blue light during the last 90 million years. Mutagenesis experiments of the UV-sensitive pigment in the Boreoeutherian ancestor show that the blue-sensitivity was achieved by seven mutations. The experimental and quantum chemical analyses show that 4,008 of all 5,040 possible evolutionary trajectories are terminated prematurely by containing a dehydrated nonfunctional pigment. Phylogenetic analysis further suggests that human ancestors achieved the blue-sensitivity gradually and almost exclusively by epistasis. When the final stage of spectral tuning of human S1 was underway 45-30 million years ago, the middle and long wavelength-sensitive (MWS/LWS) pigments appeared and so-called trichromatic color vision was established by interprotein epistasis. The adaptive evolution of human S1 differs dramatically from orthologous pigments with a major mutational effect used in achieving blue-sensitivity in a fish and several mammalian species and in regaining UV vision in birds. These observations imply that the mechanisms of epistatic interactions must be understood by studying various orthologues in different species that have adapted to various ecological and physiological environments.
Asunto(s)
Visión de Colores/genética , Evolución Molecular , Adaptación Biológica/genética , Epistasis Genética , Humanos , Mutagénesis , FilogeniaRESUMEN
Aquatic organisms such as cichlids, coelacanths, seals, and cetaceans are active in UV-blue color environments, but many of them mysteriously lost their abilities to detect these colors. The loss of these functions is a consequence of the pseudogenization of their short wavelength-sensitive (SWS1) opsin genes without gene duplication. We show that the SWS1 gene (BdenS1ψ) of the deep-sea fish, pearleye (Benthalbella dentata), became a pseudogene in a similar fashion about 130 million years ago (Mya) yet it is still transcribed. The rates of nucleotide substitution (~1.4 × 10(-9)/site/year) of the pseudogenes of these aquatic species as well as some prosimian and bat species are much smaller than the previous estimates for the globin and immunoglobulin pseudogenes.
Asunto(s)
Evolución Molecular , Seudogenes , Opsinas de Bastones/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Cíclidos/genética , Proteínas de Peces/genética , Filogenia , Pigmentos Retinianos/genética , Análisis de SecuenciaRESUMEN
BACKGROUND: Identifying traits that reproductively isolate species, and the selective forces underlying their divergence, is a central goal of evolutionary biology and speciation research. There is growing recognition that postcopulatory sexual selection, which can drive rapid diversification of interacting ejaculate and female reproductive tract traits that mediate sperm competition, may be an engine of speciation. Conspecific sperm precedence (CSP) is a taxonomically widespread form of reproductive isolation, but the selective causes and divergent traits responsible for CSP are poorly understood. RESULTS: To test the hypothesis that postcopulatory sexual selection can generate reproductive isolation, we expressed GFP or RFP in sperm heads of recently diverged sister species, Drosophila simulans and D. mauritiana, to enable detailed resolution of species-specific sperm precedence mechanisms. Between-species divergence in sperm competition traits and mechanisms prompted six a priori predictions regarding mechanisms of CSP and degree of cross asymmetry in reproductive isolation. We resolved four distinct mechanisms of CSP that were highly consistent with predictions. These comprise interactions between multiple sex-specific traits, including two independent mechanisms by which females exert sophisticated control over sperm fate to favor the conspecific male. CONCLUSIONS: Our results confirm that reproductive isolation can quickly arise from diversifying (allopatric) postcopulatory sexual selection. This experimental approach to "speciation phenotypes" illustrates how knowledge of sperm precedence mechanisms can be used to predict the mechanisms and extent of reproductive isolation between populations and species.
Asunto(s)
Copulación , Drosophila/anatomía & histología , Drosophila/genética , Especiación Genética , Aislamiento Reproductivo , Animales , Drosophila/clasificación , Femenino , Fertilización/fisiología , Proteínas Fluorescentes Verdes/biosíntesis , Inseminación/fisiología , Proteínas Luminiscentes/biosíntesis , Masculino , Conducta Sexual Animal , Especificidad de la Especie , Cabeza del Espermatozoide/metabolismo , Espermatozoides/fisiología , Proteína Fluorescente RojaRESUMEN
How sperm from competing males are used to fertilize eggs is poorly understood yet has important implications for postcopulatory sexual selection. Sperm may be used in direct proportion to their numerical representation within the fertilization set or with a bias toward one male over another. Previous theoretical treatments have assumed a single sperm-storage organ, but many taxa possess multiple organs or store sperm within multiple regions of the reproductive tract. In Drosophila, females store sperm in two distinct storage organ types: the seminal receptacle (SR) and the paired spermathecae. Here, we expand previous "raffle" models to describe "fertilization bias" independently for sperm within the SR and the spermathecae and estimate the fertilization set based on the relative contribution of sperm from the different sperm-storage organ types. We apply this model to three closely related species to reveal rapid divergence in the fertilization set and the potential for female sperm choice.
Asunto(s)
Drosophila/fisiología , Fertilización , Espermatozoides/fisiología , Animales , Evolución Biológica , Drosophila melanogaster/fisiología , Femenino , Masculino , Preferencia en el Apareamiento Animal , Modelos Biológicos , Reproducción , Especificidad de la EspecieRESUMEN
We studied 95 isolates of the yeast species Kurtzmaniella cleridarum recovered from nitidulid beetles collected in flowers of cacti of the Sonoran Desert of southern Arizona and the Mojave Desert of California. They were characterized on the basis of mating type and ten polymorphic DNA markers in relation to their geographic distribution. Although all loci appeared to be free of strong linkage, the recovered haplotypes represented but a small fraction of possible combinations, indicating that abundant asexual reproduction of local genotypes accounts for much of population growth, even though the yeast is capable of sexual recombination in nature. Much of the genetic differentiation took place at the local level, indicating that gene flow across the various localities is limited. However, a relationship exists between overall genetic differentiation and geography over long distances. We estimated that populations separated by c. 1300 km would share no alleles in common and that such a separation might be enough to favor the onset of speciation.
Asunto(s)
Escarabajos/microbiología , Variación Genética , Saccharomycetales/clasificación , Saccharomycetales/aislamiento & purificación , Animales , Arizona , Cactaceae/parasitología , California , Clima Desértico , Flujo Génico , Genes del Tipo Sexual de los Hongos , Marcadores Genéticos , Genotipo , Haplotipos , Filogeografía , Saccharomycetales/genéticaRESUMEN
Phenotypic plasticity in fungi is reviewed in the context of observations on phenotypic changes in the colony morphology of the fungus Aureobasidium pullulans. The variation in colony form is shown to depend on (i) the types of single carbon substrates (sugars and sugar alcohols) used in the growth medium, (ii) colony age, (iii) incubation temperature, (iv) light cycle and (v) substrate type. Expanding colonies grow in a developmental sequence that show synchronize growth phase shifts as well as unusual transitions from homogeneous to sectored, yeast to mycelial and giant to microcolonial growth forms. Epigenetic influences on phenotypic switches are suggested to be potential causes of form changes. The desirable properties of a model organism for studying phenotypic plasticity are discussed and past work on the yeast-mycelial transition of fungi is reviewed.
Asunto(s)
Ascomicetos/fisiología , Fenotipo , Ascomicetos/efectos de los fármacos , Ascomicetos/efectos de la radiación , Medios de Cultivo/química , ADN de Hongos/análisis , ADN de Hongos/genética , Epigénesis Genética/efectos de los fármacos , Regulación Fúngica de la Expresión Génica/efectos de los fármacos , Glucosa/química , Glucosa/metabolismo , Luz , Modelos Biológicos , Niacinamida/farmacología , Análisis de Secuencia de ADN , Temperatura , Complejo Vitamínico B/farmacologíaRESUMEN
The novel species Metschnikowia shivogae is described to accommodate three isolates recovered from insects of morning glory flowers at two localities in East Africa. The isolates differ slightly in rDNA ITS and D1/D2 large-subunit sequences and one isolate featured a two-base heterogeneity that might be the result of recombination between two variant rDNAs. M. shivogae is a sister species to Metschnikowia aberdeeniae and shares the same habitat. The reproductive boundaries of M. aberdeeniae, which were not clear in the past, have now been elucidated further. The type strain of Metschnikowia shivogae sp. nov. is strain SUB 04-310.1(T) (h(+); =CBS 10292(T) =NRRL Y-27924(T)) and the allotype is strain UWOPS 07-203.2 (h(-); =CBS 10770 =NRRL Y-48447).
Asunto(s)
Insectos/microbiología , Saccharomycetales/clasificación , Saccharomycetales/aislamiento & purificación , África Oriental , Animales , ADN de Hongos/química , ADN de Hongos/genética , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Genes del Tipo Sexual de los Hongos , Datos de Secuencia Molecular , Filogenia , Polimorfismo Genético , Recombinación Genética , Análisis de Secuencia de ADN , Homología de Secuencia de Ácido NucleicoRESUMEN
Vertebrate vision is mediated by five groups of visual pigments, each absorbing a specific wavelength of light between ultraviolet and red. Despite extensive mutagenesis analyses, the mechanisms by which contemporary pigments absorb variable wavelengths of light are poorly understood. We show that the molecular basis of the spectral tuning of contemporary visual pigments can be illuminated only by mutagenesis analyses using ancestral pigments. Following this new principle, we derive the "five-sites" rule that explains the absorption spectra of red and green (M/LWS) pigments that range from 510 to 560 nm. Our findings demonstrate that the evolutionary method should be used in elucidating the mechanisms of spectral tuning of four other pigment groups and, for that matter, functional differentiations of any other proteins.
Asunto(s)
Percepción de Color/genética , Opsinas de Bastones/genética , Animales , Bovinos , ADN Complementario/metabolismo , Evolución Molecular , Humanos , Mutagénesis Sitio-Dirigida , Células Fotorreceptoras Retinianas Conos/metabolismo , Pigmentos Retinianos/genética , Opsinas de Bastones/química , Opsinas de Bastones/metabolismo , Vertebrados/genéticaRESUMEN
The teleomorph of Candida cleridarum was discovered through the detection of conjugation between isolates of a large collection from the nitidulid beetles of the genus Carpophilus found in the flowers of various cacti in Arizona, USA. The previous oversight of the sexual cycle of this yeast is attributed to the inequality (ca. 5 : 1) of the two mating types. Extensive conjugation between compatible mating types is observed after overnight incubation on 5 % malt agar, followed after 3-5 days by the formation of mature asci. The hat-shaped ascospores are reminiscent of those seen in Kodamaea species, which are members of the same guild. However, published analyses of D1/D2 large subunit rDNA sequences indicate an affinity with the genus Debaryomyces. As the latter is polyphyletic and morphologically heterogeneous, and in view of the distinct life cycle of the new teleomorph, the new genus Kurtzmaniella is described with a novel species, Kurtzmaniella cleridarum sp. nov. Given the close relatedness of Kurtzmaniella cleridarum sp. nov. to Candida quercitrusa, Candida oleophila and Candida railenensis, for which several natural isolates were available, strains of these species were mixed in pairs under the conditions found favourable for the former. Conjugation was not detected in those species. The type strain of Kurtzmaniella cleridarum sp. nov. is UWOPS 99-101.1(T) (=CBS 8793(T)=NRRL Y-48386(T), h(+)), type of Candida cleridarum. The allotype is UWOPS 07-123.1 (=CBS 10688=NRRL Y-48387, h(-)).
Asunto(s)
Candida/clasificación , Saccharomycetales/clasificación , Animales , Candida/genética , Candida/fisiología , Escarabajos/microbiología , ADN de Hongos/análisis , ADN Ribosómico/análisis , Datos de Secuencia Molecular , Técnicas de Tipificación Micológica , Saccharomycetales/genética , Saccharomycetales/fisiología , Análisis de Secuencia de ADN , Esporas Fúngicas/fisiologíaRESUMEN
Postcopulatory sexual selection favours males which are strong offensive and defensive sperm competitors. As a means of identifying component traits comprising each strategy, we used an experimental evolution approach. Separate populations of Drosophila melanogaster were selected for enhanced sperm offence and defence. Despite using a large outbred population and evidence of substantive genetic variation for each strategy, neither trait responded to selection in the two replicates of this experiment. Recent work with fixed chromosome lines of D. melanogaster suggests that complex genotypic interactions between females and competing males contribute to the maintenance of this variation. To determine whether such interactions could explain our lack of response to selection on sperm offence and defence, we quantified sperm precedence across multiple sperm competition bouts using an outbred D. melanogaster population exhibiting continuous genetic variation. Both offensive and defensive sperm competitive abilities were found to be significantly repeatable only across matings involving ejaculates of the same pair of males competing within the same female. These repeatabilities decreased when the rival male stayed the same but the female changed, and they disappeared when both the rival male and the female changed. Our results are discussed with a focus on the complex nature of sperm precedence and the maintenance of genetic variation in ejaculate characteristics.
Asunto(s)
Evolución Biológica , Drosophila melanogaster/fisiología , Variación Genética , Selección Genética , Conducta Sexual Animal/fisiología , Espermatozoides/fisiología , Análisis de Varianza , Animales , Drosophila melanogaster/genética , Femenino , Masculino , Factores SexualesRESUMEN
Contrary to early predictions of sperm competition theory, postcopulatory sexual selection favoring increased investment per sperm (e.g., sperm size, sperm quality) has been demonstrated in numerous organisms. We empirically demonstrate for Drosophila melanogaster that both sperm quality and sperm quantity independently contribute to competitive male fertilization success. In addition to these independent effects, there was a significant interaction between sperm quality and quantity that suggests an internal positive reinforcement on selection for sperm quality, with selection predicted to intensify as investment per sperm increases and the number of sperm competing declines. The mechanism underlying the sperm quality advantage is elucidated through examination of the relationship between female sperm-storage organ morphology and the differential organization of different length sperm within the organ. Our results exemplify that primary sex cells can bear secondary sexual straits.
Asunto(s)
Drosophila melanogaster/fisiología , Espermatozoides/fisiología , Animales , Tamaño de la Célula , Femenino , Fertilización , Masculino , Recuento de Espermatozoides , Cola del Espermatozoide , Espermatozoides/citologíaRESUMEN
The genetic nature of pheromone variation within species has rarely been studied, and never for male-produced long-range pheromones. Males from western North American populations of Ips pini produce predominantly (R)-(-)-ipsdienol, whereas those from eastern North American populations produce higher proportions of (S)-(+)-ipsdienol. From a population in the hybrid zone, we divergently selected lines for the opposing pheromonal types and then created F1, F2, and backcross lines. We formed additional F1, F2, and backcross lines, first by using populations with low (+)-ipsdienol enantiomeric ratios near to and distant from the hybrid zone, and then by using populations with high (+)-ipsdienol enantiomeric ratios near to and distant from the hybrid zone. Three types of analysis were employed: (1) line means analysis; (2) Mendelian analysis of assigned high and low (+)-ipsdienol enantiomeric ratio phenotypes when applicable; and (3) Castle-Wright estimation of the number of effective factors. Dominance at one autosomal locus explains much of the variation in ipsdienol blend between the divergently selected lines. Thus, as in all previously studied female long-range pheromone systems, a major genetic element is implicated. The populations with low (+)-ipsdienol enantiomeric ratios near and distant to the hybrid zone differ negligibly for this trait. We confirmed previous studies showing slightly higher ratios of (+)-ipsdienol at the hybrid zone than in a distant eastern population and reveal a genetic basis for this difference.
Asunto(s)
Escarabajos/genética , Monoterpenos/química , Octanoles/química , Feromonas/genética , Monoterpenos Acíclicos , Animales , Cruzamientos Genéticos , Ecosistema , Femenino , Variación Genética , Masculino , América del Norte , Feromonas/química , Pinus sylvestris , Transducción de Señal , EstereoisomerismoRESUMEN
The novel species Metschnikowia aberdeeniae is described to accommodate five isolates recovered from insects of morning glory flowers in the Serengeti National Park, Tanzania. On the basis of rDNA ITS and D1/D2 large-subunit sequences, these yeasts form, together with six other isolates, a novel subclade of large-spored Metschnikowia species. The exact position of the subclade within the Metschnikowiaceae cannot be determined with any confidence from these sequences or from small-subunit rDNA sequences, as the variable sites of the sequences are excessively divergent. However, in morphological and physiological terms, the novel isolates are typical of the genus Metschnikowia in general and of the large-spored group in particular. The type strain of Metschnikowia aberdeeniae sp. nov. is strain SUB 05-213.1T (=CBS 10289T=NRRL Y-27921T) (h-) and the allotype is strain SUB 05-213.2 (=CBS 10290=NRRL Y-27922) (h+).
Asunto(s)
Insectos/microbiología , Saccharomycetales/clasificación , Saccharomycetales/aislamiento & purificación , Animales , ADN de Hongos/química , ADN de Hongos/aislamiento & purificación , ADN Ribosómico/química , ADN Ribosómico/aislamiento & purificación , ADN Espaciador Ribosómico/genética , Genes de ARNr , Ipomoea , Microscopía de Contraste de Fase , Datos de Secuencia Molecular , Filogenia , ARN de Hongos/genética , Saccharomycetales/citología , Saccharomycetales/fisiología , TanzaníaRESUMEN
Many vertebrate species use ultraviolet (UV) vision for such behaviors as mating, foraging, and communication. UV vision is mediated by UV-sensitive visual pigments, which have the wavelengths of maximal absorption (lambda max) at approximately 360 nm, whereas violet (or blue) vision is mediated by orthologous pigments with lambda max values of 390-440 nm. It is widely believed that amino acids in transmembrane (TM) I-III are solely responsible for the spectral tuning of these SWS1 pigments. Recent molecular analyses of SWS1 pigments, however, show that amino acids in TM IV-VII are also involved in the spectral tuning of these pigments through synergistic interactions with those in TM I-III. Comparisons of the tertiary structures of UV and violet pigments reveal that the distance between the counterion E113 in TM III and amino acid sites 87-93 in TM II is narrower for UV pigments than for violet pigments, which may restrict the access of water molecules to the Schiff base pocket and deprotonate the Schiff base nitrogen. Both mutagenesis analyses of E113Q and quantum chemical calculations strongly suggest that unprotonated Schiff base-linked chromophore is responsible for detecting UV light.
Asunto(s)
Pigmentos Retinianos/química , Espectrofotometría Ultravioleta , Rayos Ultravioleta , Vertebrados/fisiología , Secuencia de Aminoácidos , Animales , Células COS , Chlorocebus aethiops , ADN Complementario , Evolución Molecular , Vectores Genéticos , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , Filogenia , Estructura Terciaria de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/efectos de la radiación , Pigmentos Retinianos/genética , Pigmentos Retinianos/metabolismo , Pigmentos Retinianos/efectos de la radiación , Opsinas de Bastones/química , Opsinas de Bastones/genética , Bases de Schiff/metabolismo , Bases de Schiff/efectos de la radiación , Homología de Secuencia de Aminoácido , Especificidad de la Especie , Termodinámica , Vertebrados/genéticaRESUMEN
Three heterothallic, haplontic yeast species, Metschnikowia hamakuensis, Metschnikowia kamakouana and Metschnikowia mauinuiana, are described from isolates associated with endemic nitidulid beetles living on various endemic plants on three Hawaiian islands. As morphospecies, they are similar to Metschnikowia hawaiiensis, but based on mating compatibility and ascospore formation, they can be assigned clearly to distinct biological species. Analysis of ITS/5.8S and D1/D2 large subunit rDNA sequences shows that, with M. hawaiiensis and two other isolates, these species form a distinct subclade within the large-spored Metschnikowia species, indicating that they are Hawaiian endemics. Type cultures are: M. hamakuensis, UWOPS 04-207.1(T) = CBS 10056(T) = NRRL Y-27834(T) (type, h(+)) and UWOPS 04-204.1 = CBS 10055 = NRRL Y-27833 (allotype, h(-)); M. kamakouana, UWOPS 04-112.5(T) = CBS 10058(T) = NRRL Y-27836(T) (type, h(+)) and UWOPS 04-109.1 = CBS 10057 = NRRL Y-27835 (allotype, h(-)); and M. mauinuiana, UWOPS 04-190.1(T) = CBS 10060(T) = NRRL Y-27838(T) (type, h(+)) and UWOPS 04-110.4 = CBS 10059 = NRRL Y-27837 (allotype, h(-)).
Asunto(s)
Escarabajos/microbiología , Saccharomycetales/clasificación , Saccharomycetales/aislamiento & purificación , Animales , ADN de Hongos/química , ADN de Hongos/aislamiento & purificación , ADN Ribosómico/química , ADN Ribosómico/aislamiento & purificación , ADN Espaciador Ribosómico , Genes Fúngicos , Genes de ARNr , Hawaii , Datos de Secuencia Molecular , Técnicas de Tipificación Micológica , Filogenia , ARN de Hongos/genética , Saccharomycetales/citología , Saccharomycetales/fisiología , Análisis de Secuencia de ADNRESUMEN
Identifying sources of phenotypic variability in secondary sexual traits is critical for understanding their signaling properties, role in sexual selection, and for predicting their evolutionary dynamics. The present study tests for the effects of genotype, developmental temperature, and their interaction, on size and fluctuating asymmetry of the male sex comb, a secondary sexual character, in Drosophila bipectinata Duda. Both the size and symmetry of elements of the sex comb have been shown previously to be under sexual selection in a natural population in northeastern Australia. Two independent reciprocal crosses were conducted at 25 degrees and 29 degrees C between genetic lines extracted from this population that differed in the size of the first (TC1) and third (TC3) comb segments. These temperatures are within the documented range experienced by the species in nature. Additive and dominance genetic effects were detected for TC1, whereas additive genetic, and Y-chromosomal effects were detected for TC3. TC2 and TC3 decreased sharply with increasing temperature, by 10% and 22%, respectively. In contrast, positional fluctuating asymmetry (PFA) significantly increased with temperature, by up to 38%. The results (1) document an important source of environmental variance in a sexual ornament expected to reduce trait heritability in field populations, and thus act to attenuate response to sexual selection, (2) suggest that variation in ornament size reflects differences in male condition; and (3) support the general hypothesis that asymmetry in a sexual ornament is indicative of developmental instability arising from environmental stress. The "environmental heterogeneity" (EH) hypothesis is proposed, and supportive evidence for it presented, to explain negative size-FA correlations in natural populations. Data and theory challenge the use of negative size-FA correlations observed in nature to support the FA-sexual selection hypothesis, which posits that such correlations are driven by differences in genetic quality among individuals.
Asunto(s)
Drosophila/anatomía & histología , Modelos Genéticos , Selección Genética , Caracteres Sexuales , Temperatura , Análisis de Varianza , Animales , Artocarpus , Cruzamientos Genéticos , Drosophila/crecimiento & desarrollo , Femenino , Genotipo , Masculino , QueenslandRESUMEN
Viable microorganisms (e.g. fungi, bacteria, Archaea and viruses) are distributed by wind over great distances, including globally. Microbes may settle out of the atmosphere or may be incorporated into fog, rain, sleet, hail, or snow. These organisms fall into lakes, streams, oceans, or onto the land or glaciers. When they become incorporated into environmental ice (e.g. glaciers, ice sheets, and snow), those that survive freezing and thawing may persist for years, centuries, millennia, or longer. Once they melt from the ice, they may enter contemporary populations. This mixing of ancient and modern genotypes (i.e. temporal gene flow, or what we term "genome recycling") may lead to a change of allele proportions in the population, which may have effects on mutation rates, fitness, survival, pathogenicity and other characteristics of the organisms. Pathogenic microbes that survive freezing and thawing (e.g. influenza viruses, polioviruses, caliciviruses and tobamoviruses) can remain in these icy reservoirs long enough to avoid resistance mechanisms of the hosts, thereby conveying a selective advantage to these pathogens over those that cannot survive in ice. Ice is an abiotic reservoir of microbes that has been ignored in surveillance activities for human diseases.