RESUMO
Male sexual ornaments often evolve rapidly and are thought to be costly, thus contributing to sexual size dimorphism. However, little is known about their developmental costs, and even less about costs associated with structural complexity. Here, we quantified the size and complexity of three morphologically elaborate sexually dimorphic male ornaments that starkly differ across sepsid fly species (Diptera: Sepsidae): (i) male forelegs range from being unmodified, like in most females, to being adorned with spines and large cuticular protrusions; (ii) the fourth abdominal sternites are either unmodified or are converted into complex de novo appendages; and (iii) male genital claspers range from small and simple to large and complex (e.g. bifurcated). We tracked the development of 18 sepsid species from egg to adult to determine larval feeding and pupal metamorphosis times of both sexes. We then statistically explored whether pupal and adult body size, ornament size and/or ornament complexity are correlated with sex-specific development times. Larval growth and foraging periods of male and female larvae did not differ, but the time spent in the pupal stage was ca 5% longer for sepsid males despite emerging 9% smaller than females on average. Surprisingly, we found no evidence that sexual trait complexity prolongs pupal development beyond some effects of trait size. Evolving more complex traits thus does not incur developmental costs at least in this system.
Assuntos
Dípteros , Animais , Masculino , Feminino , Dípteros/anatomia & histologia , Caracteres Sexuais , Evolução Biológica , Larva , Tamanho Corporal , PupaRESUMO
Mosquitoes (Diptera: Culicidae) and biting midges (Diptera: Ceratopogonidae) are among the most important vectors of human and veterinary pathogens. For modelling the distribution of these pathogens, entomological aspects are essential, which in turn are highly dependent on environmental factors, such as temperature. In this study, mosquitoes and biting midges were sampled in multiple microclimates at two low (360, 480 meters above sea level, m.a.s.l.) and two high (1250, 1530 m.a.s.l.) altitude locations in Switzerland. Sets of various traps (CO2 -baited CDC, LED-UV, resting boxes, oviposition cups) equipped with dataloggers were placed in transects at five sites with similar vegetation at each location. Only the CDC and the LED-UV traps collected enough insects for analyses. Taxonomic diversity was greater for mosquitoes but lower for biting midges at lower altitudes. Both mosquitoes and biting midges had a thermal preference. Culicoides preferred the traps with warmer microclimate, especially at lower altitudes, whereas mosquito preferences depended on the species, but not on altitude. Relative humidity had a significant positive impact on catches of biting midges but not mosquitoes. To obtain better data on thermal preferences of resting and ovipositing vectors in addition to host seeking individuals, new and improved collecting methods are needed.
Assuntos
Ceratopogonidae , Culicidae , Feminino , Humanos , Animais , Altitude , Suíça , Mosquitos VetoresRESUMO
Climate is changing towards both higher average temperatures and more frequent and severe heat waves. Whereas numerous studies have investigated temperature effects on animal life histories, assessments of their immune function are limited. In the size- and colour-dimorphic black scavenger (or dung) fly Sepsis thoracica (Diptera: Sepsidae), we experimentally studied how developmental temperature and larval density influence phenoloxidase (PO) activity, a key enzyme in insect pigmentation, thermoregulation, and immunity. Flies from five latitudinal European populations were raised at three developmental temperatures (18, 24, 30 °C). PO activity increased with developmental temperature differently in the sexes and the two male morphs (black and orange), altering the sigmoid relationship between melanism, i.e. colouration and fly size. PO activity further positively correlated with larval rearing density, potentially because of higher risks of pathogen infection or greater developmental stress following stronger resource competition. Populations varied somewhat in PO activity, body size and colouration, however with no clear latitudinal pattern. Overall our results indicate that morph- and sex-specific PO activity, and thus likely immune function, in S. thoracica depends on temperature and larval density, modifying the underlying putative trade-off between immunity and body size. The strong dampening of the immune system of all morphs at cool temperatures suggests low-temperature stress in this warm-adapted species common in southern Europe. Our results also support the population density dependent prophylaxis hypothesis, which predicts higher investment in immunity when facing limited resource availability and increased pathogen infection probability.
Assuntos
Dípteros , Melanose , Sepse , Animais , Feminino , Masculino , Temperatura , Dípteros/fisiologia , Monofenol Mono-Oxigenase , LarvaRESUMO
Elevated temperatures are expected to rise beyond what the physiology of many organisms can tolerate. Behavioural responses facilitating microhabitat shifts may mitigate some of this increased thermal selection on physiology, but behaviours are themselves mediated by physiology, and any behavioural response may trade-off against other fitness-related activities. We investigated whether experimental evolution in different thermal regimes (Cold: 15 °C; Hot: 31 °C; Intergenerational fluctuation 15/31 °C; Control: 23 °C) resulted in genetic differentiation of standard locomotor activity in the dung fly Sepsis punctum. We assessed individual locomotor performance, an integral part of most behavioral repertoires, across eight warm temperatures from 24 °C to 45 °C using an automated device. We found no evidence for generalist-specialist trade-offs (i.e. changes in the breadth of the performance curve) for this trait. Instead, at the warmest assay temperatures hot-selected flies showed somewhat higher maximal performance than all other, especially cold-selected flies, overall more so in males than females. Yet, the flies' temperature optimum was not higher than that of the cold-selected flies, as expected under the 'hotter-is-better' hypothesis. Maximal locomotor performance merely weakly increased with body size. These results suggest that thermal performance curves are unlikely to evolve as an entity according to theory, and that locomotor activity is a trait of limited use in revealing thermal adaptation.
Assuntos
Dípteros , Sepse , Masculino , Animais , Feminino , Dípteros/fisiologia , Temperatura , Temperatura Baixa , LocomoçãoRESUMO
Mosquito-borne diseases pose a major burden on humans and animals. Temperature strongly influences the physiology and life cycle of mosquitoes and also the pathogens they transmit. Thermoregulatory behaviour of mosquitoes has been addressed in a few laboratory studies. Here, we expand such studies by investigating the thermal preference when resting of Aedes japonicus, an invasive and putative vector species of many pathogens, in a semi-field setup during summers in a temperate climate. Blood-fed or sugar-fed Ae. japonicus females were released in the late afternoon in a large outdoor cage containing three resting boxes. The next morning, temperature treatments were applied to the boxes, creating a "cool" (over all experiments around 18 °C), and a "warm" (around 35 °C) microhabitat in addition to an untreated "ambient" (around 26 °C) one. The mosquitoes resting within the three boxes were counted five times, every 2 h between 9h and 17h. The highest proportions of mosquitoes (e.g. up to 21% of blood-fed ones) were found in the cool box while both blood-fed and sugar-fed mosquitoes avoided the warm box. The mean resting temperatures of Ae. japonicus were below the ambient temperatures measured by a nearby meteorological station, and this was more pronounced at higher outdoor temperatures and in blood-fed as compared to sugar-fed mosquitoes. Thus, over all experiments with blood-fed mosquitoes, the calculated average resting temperature was 4 °C below the outdoor temperature. As mosquitoes prefer cooler resting places than temperatures measured by weather stations in summer, models to predict mosquito-borne disease outbreaks need to account for the thermoregulatory behaviour of mosquitoes, especially in the wake of climate change.
Assuntos
Aedes , Animais , Feminino , Humanos , Aedes/fisiologia , Temperatura , Açúcares , Mosquitos Vetores/fisiologia , Tempo (Meteorologia)RESUMO
Understanding how environmental variation influences even cryptic traits is important to clarify the roles of selection and developmental constraints in past evolutionary divergence and to predict future adaptation under environmental change. Female yellow dung flies (Scathophaga stercoraria) typically have three sperm storage compartments (3S), but occasionally four (4S). More spermathecae are thought to be a female adaptation facilitating sperm sorting after mating, but the phenotype is very rare in nature. We manipulated the flies' developmental environment by food restriction, pesticides, and hot temperatures to investigate the nature and extent of developmental plasticity of this trait, and whether spermatheca expression correlates with measures of performance and developmental stability, as would be expected if 4S expression is a developmental aberration. The spermathecal polymorphism of yellow dung fly females is heritable, but also highly developmentally plastic, varying strongly with rearing conditions. 4S expression is tightly linked to growth rate, and weakly positively correlated with fluctuating asymmetry of wings and legs, suggesting that the production of a fourth spermatheca could be a nonadaptive developmental aberration. However, spermathecal plasticity is opposite in the closely related and ecologically similar Scathophaga suilla, demonstrating that overexpression of spermathecae under developmental stress is not universal. At the same time, we found overall mortality costs as well as benefits of 4S pheno- and genotypes (also affecting male siblings), suggesting that a life history trade-off may potentially moderate 4S expression. We conclude that the release of cryptic genetic variation in spermatheca number in the face of strong environmental variation may expose hidden traits (here reproductive morphology) to natural selection (here under climate warming or food augmentation). Once exposed, hidden traits can potentially undergo rapid genetic assimilation, even in cases when trait changes are first triggered by random errors that destabilize developmental processes.
Assuntos
Dípteros , Animais , Evolução Biológica , Feminino , Masculino , Reprodução/genética , Seleção Genética , Asas de AnimaisRESUMO
Wolbachia bacteria are common endosymbionts of many arthropods found in gonads and various somatic tissues. They manipulate host reproduction to enhance their transmission and confer complex effects on fitness-related traits. Some of these effects can serve to increase the survival and transmission efficiency of Wolbachia in the host population. The Wolbachia-Drosophila melanogaster system represents a powerful model to study the evolutionary dynamics of host-microbe interactions and infections. Over the past decades, there has been a replacement of the ancestral wMelCS Wolbachia variant by the more recent wMel variant in worldwide D. melanogaster populations, but the reasons remain unknown. To investigate how environmental change and genetic variation of the symbiont affect host developmental and adult life-history traits, we compared effects of both Wolbachia variants and uninfected controls in wild-caught D. melanogaster strains at three developmental temperatures. While Wolbachia did not influence any developmental life-history traits, we found that both lifespan and fecundity of host females were increased without apparent fitness trade-offs. Interestingly, wMelCS-infected flies were more fecund than uninfected and wMel-infected flies. By contrast, males infected with wMel died sooner, indicating sex-specific effects of infection that are specific to the Wolbachia variant. Our study uncovered complex temperature-specific effects of Wolbachia infections, which suggests that symbiont-host interactions in nature are strongly dependent on the genotypes of both partners and the thermal environment.
Assuntos
Wolbachia , Animais , Drosophila melanogaster/genética , Feminino , Fertilidade , Longevidade , Masculino , Reprodução , Simbiose , Wolbachia/genéticaRESUMO
The male competition for fertilization that results from female multiple mating promotes the evolution of increased sperm numbers and can impact sperm morphology, with theory predicting that longer sperm can at times be advantageous during sperm competition. If so, males with longer sperm should sire more offspring than competitors with shorter sperm. Few studies have directly tested this prediction, and findings are inconsistent. Here we assessed whether longer sperm provide a competitive advantage in the yellow dung fly (Scathophaga stercoraria; Diptera: Scathophagidae). Initially, we let brothers with different temperature-mediated mean sperm lengths compete - thus minimizing confounding effects of genetic background - and found no clear advantage of longer sperm. We then used flies from lines subjected to bidirectional selection on phenoloxidase activity that had shown correlated evolutionary responses in sperm and female spermathecal duct lengths. This experiment also yielded no main effect of sperm size on siring success. Instead, there was a trend for a shorter-sperm advantage, but only when competing in females with longer spermathecal ducts. Our data corroborated many previously reported findings (last-male precedence, effects of copula duration and body size), suggesting our failure to find sperm size effects is not inherently due to our experimental protocols. We conclude that longer sperm are not competitively superior in yellow dung flies under most circumstances, and that, consistent with previous work, in this species competitive fertilization success is primarily determined by the relative numbers of sperm competing.
Assuntos
Dípteros , Animais , Dípteros/anatomia & histologia , Feminino , Masculino , Monofenol Mono-Oxigenase , Reprodução/fisiologia , Sêmen , Espermatozoides/fisiologiaRESUMO
Tissue oxygen saturation (StO2) is a crucial factor in the aetiology of pressure injury (PI), since hypoxia leads to necrotization. Pressure on the tissue occludes blood circulation and reduces the StO2, resulting in hypoxia. PI causes severe suffering, heals slowly and is expensive to treat. Hence it is important to prevent PI by detecting hypoxia, e.g., by near-infrared spectroscopy (NIRS) monitoring of StO2. For this, the NIRS device has to be wearable for a long time and it is crucial that it provokes no pressure itself. An integration of optical fibres into a textile achieves this. The aim was to investigate the feasibility of such a textile NIRS device.Knots and loops were tested as textile light emitters (LEs) or detectors (LDs) on a phantom. The light coupling efficiency of the LEs and LDs was investigated.Results show that knots perform similarly to loops. More loops per fibre increase efficiency both in LEs and in LDs. The best trade-off is at 3 loops. LEs are slightly more efficient than LDs, with an average attenuation from baseline of about -2 dB for loops of 0.5 mm diameter. Adding fibres multiplies the signal by the number of fibres. Inclusions mimicking hypoxia in phantoms were successfully identified. In-vivo arm occlusion tests showed the expected decrease in StO2. This shows feasibility of optical fibres in a textile to prevent PI.
Assuntos
Fibras Ópticas , Oxigênio , Humanos , Polímeros , Estudos de Viabilidade , Saturação de Oxigênio , Têxteis , Hipóxia , Consumo de OxigênioRESUMO
The present work aims to develop a wearable, textile-integrated NIRS-based tissue oxygen saturation (StO2) monitor for alerting mobility-restricted individuals - such as paraplegics - of critical tissue oxygen de-saturation in the regions such as the sacrum and the ischial tuberosity; these regions are proven to be extremely susceptible to the development of pressure injuries (PI).Using a combination of numerical methods including finite element analysis, image reconstruction, stochastic gradient descent with momentum (SGDm) and genetic algorithms, a methodology was developed to define the optimal combination of wavelengths and source-detector geometry needed for measuring the StO2 in tissue up to depths of 3 cm. The sensor design was optimised to account for physiologically relevant adipose tissue thicknesses (ATT) between 1 mm and 5 mm. The approach assumes only a priori knowledge of the optical properties of each of the three tissue layers used in the model (skin, fat, muscle) based on the absorption and scattering coefficients of four chromophores (O2Hb, HHb, H2O and lipid).The results show that the selected wavelengths as well as the source-detector geometries and number of sources and detectors depend on ATT and the degree and volume of the hypoxic regions. As a result of a genetic algorithm used to combine the various optimised designs into a single sensor layout, a group of four wavelengths was chosen, coinciding with the four chromophores and agreeing very well with literature. The optimised number of source points and detector points and their geometry resulted in good reconstruction of the StO2 across a wide range of layer geometries.
Assuntos
Saturação de Oxigênio , Espectroscopia de Luz Próxima ao Infravermelho , Humanos , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Oxigênio , Consumo de Oxigênio/fisiologia , HipóxiaRESUMO
BACKGROUND: The black soldier fly (Hermetia illucens) is the most promising insect candidate for nutrient-recycling through bioconversion of organic waste into biomass, thereby improving sustainability of protein supplies for animal feed and facilitating transition to a circular economy. Contrary to conventional livestock, genetic resources of farmed insects remain poorly characterised. We present the first comprehensive population genetic characterisation of H. illucens. Based on 15 novel microsatellite markers, we genotyped and analysed 2862 individuals from 150 wild and captive populations originating from 57 countries on seven subcontinents. RESULTS: We identified 16 well-distinguished genetic clusters indicating substantial global population structure. The data revealed genetic hotspots in central South America and successive northwards range expansions within the indigenous ranges of the Americas. Colonisations and naturalisations of largely unique genetic profiles occurred on all non-native continents, either preceded by demographically independent founder events from various single sources or involving admixture scenarios. A decisive primarily admixed Polynesian bridgehead population serially colonised the entire Australasian region and its secondarily admixed descendants successively mediated invasions into Africa and Europe. Conversely, captive populations from several continents traced back to a single North American origin and exhibit considerably reduced genetic diversity, although some farmed strains carry distinct genetic signatures. We highlight genetic footprints characteristic of progressing domestication due to increasing socio-economic importance of H. illucens, and ongoing introgression between domesticated strains globally traded for large-scale farming and wild populations in some regions. CONCLUSIONS: We document the dynamic population genetic history of a cosmopolitan dipteran of South American origin shaped by striking geographic patterns. These reflect both ancient dispersal routes, and stochastic and heterogeneous anthropogenic introductions during the last century leading to pronounced diversification of worldwide structure of H. illucens. Upon the recent advent of its agronomic commercialisation, however, current human-mediated translocations of the black soldier fly largely involve genetically highly uniform domesticated strains, which meanwhile threaten the genetic integrity of differentiated unique local resources through introgression. Our in-depth reconstruction of the contemporary and historical demographic trajectories of H. illucens emphasises benchmarking potential for applied future research on this emerging model of the prospering insect-livestock sector.
Assuntos
Dípteros , Ração Animal/análise , Animais , Demografia , Dípteros/genética , Genética Populacional , Humanos , LarvaRESUMO
Mosquito-borne diseases impose a high burden on human and animal health. Temperature strongly influences the physiology and life cycle of mosquitoes, but also the development and/or propagation of the pathogens they transmit. Thus, the vector capacity of mosquitoes depends strongly on temperature and their behavioural thermoregulation through microhabitat selection. Expanding on a previous study of static thermal preferences, the locomotory dynamics of temperate Aedes japonicus (reared from eggs collected in the field) and tropical Ae. aegypti (from a laboratory colony) was investigated at constant temperatures (10 °C, 25 °C, 40 °C) and in temperature gradients (10-20 °C, 20-30 °C, 30-40 °C). Blood-fed or non-blood-fed female mosquitoes were released in groups of 15 individuals into a Plexiglas box positioned on two thermoregulators connected by an aluminium plate to automatically monitor by video analysis mosquito flying, walking and resting duration, covered distances and velocity. Mosquitoes were predominantly resting, followed by walking and flying. At constant 10 °C, flights were rare and brief, and walking was slow. Most activity was observed at 25 °C for Ae. japonicus and 40 °C for Ae. aegypti. In the 30-40 °C gradient, activity of Ae. aegypti increased towards the cold end, suggesting active avoidance of very high temperatures. In the 20-30 °C gradient, edge effects were prominent, nevertheless revealing a greater proportion of mosquitoes gathered at the cooler end. Video analysis showed that this effect was not caused by a cold trap but represents true thermal preference. In the coolest gradient (10-20 °C), mosquitoes were active in all sectors without displaying a preference for either side. Overall, both the tropical and temperate mosquito species preferred cooler temperatures and actively avoided the hottest temperatures. Further studies with infected mosquitoes should provide important insights for developing models of vector-borne disease outbreaks.
Assuntos
Aedes , Aedes/fisiologia , Animais , Temperatura Baixa , Feminino , Mosquitos Vetores/fisiologia , TemperaturaRESUMO
In a study by Law and colleagues recently published in Neuroimage, the authors reported that wearing a surgical mask during an fMRI scan leads to a statistically significant subject-specific change (30%) in the baseline BOLD level in gray matter, although the response to a sensory-motor task was unaffected. An average increase in end-tidal CO2 of 7.4% was found when wearing a mask, despite little support in the literature for major effects of mask wearing on blood gas levels. We comment on these findings, point out a several relevant limitations of the study design and provide alternative interpretations of these data.
Assuntos
Substância Cinzenta , Imageamento por Ressonância Magnética , Humanos , Máscaras , Projetos de PesquisaRESUMO
Ambient temperature strongly determines the behaviour, physiology, and life history of all organisms. The technical assessment of organismal thermal niches in form of now so-called thermal performance curves (TPC) thus has a long tradition in biological research. Nevertheless, several traits do not display the idealized, intuitive dome-shaped TPC, and in practice assessments often do not cover the entire realistic or natural temperature range of an organism. We here illustrate this by presenting comprehensive sex-specific TPCs for the major (juvenile) life history traits of yellow dung flies (Scathophaga stercoraria; Diptera: Scathophagidae). This concerns estimation of prominent biogeographic rules, such as the temperature-size-rule (TSR), the common phenomenon in ectothermic organisms that body size decreases as temperature increases. S. stercoraria shows an untypical asymptotic TPC of continuous body size increase with decreasing temperature without a peak (optimum), thus following the TSR throughout their entire thermal range (unlike several other insects presented here). Egg-to-adult mortality (our best fitness estimator) also shows no intermediate maximum. Both may relate to this fly entering pupal winter diapause below 12 °C. While development time presents a negative exponential relationship with temperature, development rate and growth rate typify the classic TPC form for this fly. The hitherto largely unexplored close relative S. suilla with an even more arctic distribution showed very similar responses, demonstrating large overlap among two ecologically similar, coexisting dung fly species, thus implying limited utility of even complete TPCs for predicting species distribution and coexistence.
Assuntos
Tamanho Corporal , Temperatura Corporal , Dípteros/fisiologia , Características de História de Vida , Aclimatação , Animais , Dípteros/crescimento & desenvolvimento , Estações do AnoRESUMO
Sexual selection is generally held responsible for the exceptional diversity in secondary sexual traits in animals. Mating system evolution is therefore expected to profoundly affect the covariation between secondary sexual traits and mating success. Whereas there is such evidence at the interspecific level, data within species remain scarce. We here investigate sexual selection acting on the exaggerated male fore femur and the male wing in the common and widespread dung flies Sepsis punctum and S. neocynipsea (Diptera: Sepsidae). Both species exhibit intraspecific differences in mating systems and variation in sexual size dimorphism (SSD) across continents that correlates with the extent of male-male competition. We predicted that populations subject to increased male-male competition will experience stronger directional selection on the sexually dimorphic male foreleg. Our results suggest that fore femur size, width and shape were indeed positively associated with mating success in populations with male-biased SSD in both species, which was not evident in conspecific populations with female-biased SSD. However, this was also the case for wing size and shape, a trait often assumed to be primarily under natural selection. After correcting for selection on overall body size by accounting for allometric scaling, we found little evidence for independent selection on any of these size or shape traits in legs or wings, irrespective of the mating system. Sexual dimorphism and (foreleg) trait exaggeration is therefore unlikely to be driven by direct precopulatory sexual selection, but more so by selection on overall size or possibly selection on allometric scaling.
Assuntos
Evolução Biológica , Tamanho Corporal/fisiologia , Dípteros/anatomia & histologia , Dípteros/fisiologia , Caracteres Sexuais , Comportamento Sexual Animal/fisiologia , Seleção Sexual/fisiologia , Animais , Feminino , Masculino , Herança MultifatorialRESUMO
Temperature is an important determinant affecting the capacity of disease vectors like mosquitoes (Culicidae) to transmit disease agents. Although the impact of temperature on vector-borne disease dynamics has been studied intensively, the actual temperature encountered by the vector in a heterogeneous landscape is rarely taken into account. If disease vectors have temperature preferences and therefore select specific microhabitats, this would substantially influence key life history traits that determine transmission intensity. The thermal preferences of subtropical Aedes aegypti and temperate Ae. japonicus mosquitoes were investigated in a temperature gradient set-up consisting of a Plexiglas box on top of an aluminium plate on two thermal regulators. Blood-fed (one day after feeding) and unfed (non-blood-fed) mosquitoes were released in small (15-20 °C, 20-25 °C, 25-30 °C) and large (15-30 °C, 30-45 °C) temperature gradients to assess their thermal preferences after 15 min. Additionally, the effect of humidity was investigated in a two-choice chamber setup. Both mosquito species avoided higher temperatures, pronouncedly dangerously high temperatures in the 30-45 °C gradient. At lower temperatures, blood-fed mosquitoes preferred the cooler sides of the 20-25 °C and 25-30 °C gradient, which were all below their rearing temperature. In the lowest gradient of 15-20 °C, no preferences were found. The thermal preference of unfed mosquitoes was similar to that of the blood-fed mosquitoes. No humidity preference or effect of humidity on temperature preferences was observed within the tested range (40-90%). The set-up allows for assessing the thermal preference of mosquitoes under controlled conditions. The observed preference of mosquitoes for cooler temperatures would increase their longevity and slow down pathogen development. If similar microhabitat selection is observed in the field, vector borne disease models should be adjusted accordingly.
Assuntos
Aclimatação , Aedes/fisiologia , Temperatura Corporal , Temperatura Baixa , Ecossistema , Animais , Umidade , Locomoção , Mosquitos Vetores/fisiologia , Clima TropicalRESUMO
PURPOSE: With the ever-increasing cure rates in breast cancer, radiotherapy-induced cancers have become an important issue. This study aimed to estimate secondary cancer risks for different treatment techniques, taking into account organs throughout the body. MATERIAL AND METHODS: Organ doses were evaluated for a tangential three-dimensional conformal (3D-CRT) and a multi-field intensity-modulated radiotherapy (IMRT) plan using a validated, Monte Carlo-based treatment planning system. Effects of wedges and of forward versus inverse planning were systematically investigated on the basis of phantom measurements. Organ-specific cancer risks were estimated using risk coefficients derived from radiotherapy patients or from the atomic bomb survivors. RESULTS: In the 3D-CRT plan, mean organ doses could be kept below 1â¯Gy for more remote organs than the lung, heart, and contralateral breast, and decreased to a few cGy for organs in the lower torso. Multi-field IMRT led to considerably higher mean doses in organs at risk, the difference being higher than 50% for many organs. Likewise, the peripheral radiation burden was increased by external wedges. No difference was observed for forward versus inverse planning. Despite the lower doses, the total estimated secondary cancer risk in more remote organs was comparable to that in the lung or the contralateral breast. For multi-field IMRT it was 75% higher than for 3D-CRT without external wedges. CONCLUSION: Remote organs are important for assessment of radiation-induced cancer risk. Remote doses can be reduced effectively by application of a tangential field configuration and a linear accelerator set-up with low head scatter radiation.
Assuntos
Neoplasias da Mama/radioterapia , Leucemia Induzida por Radiação/etiologia , Neoplasias Induzidas por Radiação/etiologia , Segunda Neoplasia Primária/etiologia , Lesões por Radiação/etiologia , Radioterapia Conformacional/efeitos adversos , Radioterapia de Intensidade Modulada/efeitos adversos , Idoso , Algoritmos , Feminino , Humanos , Pessoa de Meia-Idade , Método de Monte Carlo , Órgãos em Risco/efeitos da radiação , Imagens de Fantasmas , Radiometria , Planejamento da Radioterapia Assistida por Computador , Medição de RiscoRESUMO
Although genetic and plastic responses are sometimes considered as unrelated processes, their phenotypic effects may often align because genetic adaptation is expected to mirror phenotypic plasticity if adaptive, but run counter to it when maladaptive. Because the magnitude and direction of this alignment has further consequences for both the tempo and mode of adaptation, they are relevant for predicting an organisms' reaction to environmental change. To better understand the interplay between phenotypic plasticity and genetic change in mediating adaptive phenotypic variation to climate variability, we here quantified genetic latitudinal variation and thermal plasticity in wing loading and wing shape in two closely related and widespread sepsid flies. Common garden rearing of 16 geographical populations reared across multiple temperatures revealed that wing loading decreases with latitude in both species. This pattern could be driven by selection for increased dispersal capacity in the cold. However, although allometry, sexual dimorphism, thermal plasticity and latitudinal differentiation in wing shape all show similar patterns in the two species, the relationship between the plastic and genetic responses differed between them. Although latitudinal differentiation (south to north) mirrored thermal plasticity (hot to cold) in Sepsis punctum, there was no relationship in Sepsis fulgens. While this suggests that thermal plasticity may have helped to mediate local adaptation in S. punctum, it also demonstrates that genetic wing shape differentiation and its relation to thermal plasticity may be complex and idiosyncratic, even among ecologically similar and closely related species. Hence, genetic responses can, but do not necessarily, align with phenotypic plasticity induced by changing environmental selection pressures.
Assuntos
Adaptação Fisiológica/fisiologia , Distribuição Animal , Dípteros/fisiologia , Animais , Evolução Biológica , Dípteros/anatomia & histologia , Dípteros/genética , Feminino , Masculino , Especificidade da Espécie , Temperatura , Asas de Animais/anatomia & histologiaRESUMO
Thermal performance curves (TPCs) have been estimated in multiple ectotherm species to understand their thermal plasticity and adaptation and to predict the effect of global warming. However, TPCs are typically assessed under constant temperature regimes, so their reliability for predicting thermal responses in the wild where temperature fluctuates diurnally and seasonally remains poorly documented. Here, we use distant latitudinal populations of five species of sepsid flies (Diptera: Sepsidae) from the temperate region (Europe, North Africa, North America) to compare estimates derived from constant TPCs with observed development rate under fluctuating temperatures in laboratory and field conditions. TPCs changed across gradients in that flies originating from higher latitudes showed accelerated development at higher temperatures, an adaptive response. TPCs were then used to predict development rates observed under fluctuating temperatures; these predictions were relatively accurate in the laboratory but not the field. Interestingly, the precision of TPC predictions depended not only on the resolution of temperature data, with daily and overall temperature summing performing better than hourly temperature summing, but also on the frequency of temperatures falling below the estimated critical minimum temperature. Hourly temperature resolution most strongly underestimated actual development rates, because flies apparently either did not stop growing when temperatures dropped below this threshold, or they sped up their growth when the temperature rose again, thus most severely reflecting this error. We conclude that when flies do not encounter cold temperatures, TPC predictions based on constant temperatures can accurately reflect performance under fluctuating temperatures if adequately adjusted for nonlinearities, but when encountering cold temperatures, this method is more error-prone. Our study emphasizes the importance of the resolution of temperature data and cold temperatures in shaping thermal reaction norms.
Assuntos
Mudança Climática , África do Norte , Animais , Europa (Continente) , América do Norte , Reprodutibilidade dos Testes , TemperaturaRESUMO
Seasonality is a key environmental factor that regularly promotes life history adaptation. Insects invading cold-temperate climates need to overwinter in a dormant state. We compared the role of temperature and photoperiod in dormancy induction in the laboratory, as well as winter survival and reproduction in the field and the laboratory, of 5 widespread European dung fly species (Diptera: Sepsidae) to investigate their extent of ecological differentiation and thermal adaptation. Unexpectedly, cold temperature is the primary environmental factor inducing winter dormancy, with short photoperiod playing an additional role mainly in species common at high altitudes and latitudes (Sepsis cynipsea, neocynipsea, fulgens), but not in those species also thriving in southern Europe (thoracica, punctum). All species hibernate as adults rather than juveniles. S. thoracica had very low adult winter survivorship under both (benign) laboratory and (harsh) field conditions, suggesting flexible quiescence rather than genetically fixed winter diapause, restricting their distribution towards the pole. All other species appear well suited for surviving cold, Nordic winters. Females born early in the season reproduce before winter while late-born females reproduce after winter, fulgens transitioning earliest before winter and thoracica and punctum latest; a bet-hedging strategy of reproduction during both seasons occurs rarely but is possible physiologically. Fertility patterns indicate that females can store sperm over winter. Winter dormancy induction mechanisms of European sepsids are congruent with their geographic distribution, co-defining their thermal niches. Flexible adult winter quiescence appears the easiest route for insects spreading towards the poles to evolve the necessary overwinter survival.