Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 223
Filtrar
Mais filtros

Intervalo de ano de publicação
1.
Nature ; 619(7971): 788-792, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37468625

RESUMO

Ecological interactions are one of the main forces that sustain Earth's biodiversity. A major challenge for studies of ecology and evolution is to determine how these interactions affect the fitness of species when we expand from studying isolated, pairwise interactions to include networks of interacting species1-4. In networks, chains of effects caused by a range of species have an indirect effect on other species they do not interact with directly, potentially affecting the fitness outcomes of a variety of ecological interactions (such as mutualism)5-7. Here we apply analytical techniques and numerical simulations to 186 empirical mutualistic networks and show how both direct and indirect effects alter the fitness of species coevolving in these networks. Although the fitness of species usually increased with the number of mutualistic partners, most of the fitness variation across species was driven by indirect effects. We found that these indirect effects prevent coevolving species from adapting to their mutualistic partners and to other sources of selection pressure in the environment, thereby decreasing their fitness. Such decreases are distributed in a predictable way within networks: peripheral species receive more indirect effects and experience higher reductions in fitness than central species. This topological effect was also evident when we analysed an empirical study of an invasion of pollination networks by honeybees. As honeybees became integrated as a central species within networks, they increased the contribution of indirect effects on several other species, reducing their fitness. Our study shows how and why indirect effects can govern the adaptive landscape of species-rich mutualistic assemblages.


Assuntos
Biodiversidade , Evolução Biológica , Aptidão Genética , Simbiose , Animais , Polinização , Simbiose/fisiologia , Abelhas/fisiologia
2.
Ecol Lett ; 27(9): e14501, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39354909

RESUMO

In ecological networks, cohesive groups of species may shape the evolution of interactions, serving as coevolutionary units. Ranging across network scales, from motifs to isolated components, elucidating which cohesive groups are more determinant for coevolution remains a challenge in ecology. We address this challenge by integrating 376 empirical mutualistic and antagonistic networks and coevolutionary models. We identified cohesive groups at four network scales containing a significant proportion of potential direct coevolutionary effects. Cohesive groups displayed hierarchical organisation, and potential coevolutionary effects overflowing lower-scale groups were contained by higher-scale groups, underscoring the hierarchy's impact. However, indirect coevolutionary effects blurred group boundaries and hierarchy, particularly under strong selection from ecological interactions. Thus, under strong selection, indirect effects render networks themselves, and not cohesive groups, as the likely coevolutionary units of ecological systems. We hypothesise hierarchical cohesive groups to also shape how other forms of direct and indirect effects propagate in ecological systems.


Assuntos
Evolução Biológica , Ecossistema , Modelos Biológicos , Simbiose , Animais
3.
Aesthetic Plast Surg ; 2024 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-38913201

RESUMO

Background The quest to identify parameters deemed optimal for breast aesthetics holds paramount significance in both aesthetic and reconstructive surgery. The definition of ideal breast beauty, however, is subject to cultural variations and diverse standards, necessitating a detailed understanding. Objective This study delves into the perspectives of the Brazilian population regarding the aesthetics of the female breast. Methods A selection of images portraying variations in the distribution of upper and lower pole ratios across four distinct proportion models (35:65, 45:55, 50:50, and 55:45) was presented to participants. Through a meticulously crafted questionnaire administered via Google Forms, respondents were tasked with identifying the images they deemed most beautiful and attractive. Comprehensive demographic data of the study participants were gathered and subsequently correlated with their group-specific opinions. Results A total of 3744 questionnaire responses were collected 228 of which were from plastic surgeons/residents. The average age was 35 years, with 55.3% being women. Notably, breasts featuring a ratio of 45:55 emerged as the consensus choice for the epitome of beauty, garnering preference from 73% of the general population, 68% of women, 78% of men, and an equal 78% of plastic surgeons. This preference was consistent across all regions of the country. Conclusion Breasts with a ratio of 45:55 were universally deemed the most aesthetically pleasing. Similarly, breasts with a 50:50 ratio of breast tissue emerged as the next preferred choice. These insights contribute valuable perspectives on aesthetic considerations in breast surgery within the unique cultural context of Brazil.Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

4.
Med Lav ; 115(1): e2024004, 2024 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-38411978

RESUMO

BACKGROUND: Sinonasal cancers (SNC) are rare cancers with a high proportion attributable to occupational carcinogens. This study aims to describe the sociodemographic, clinical, and occupational characteristics of subjects with SNC in Brazil. METHODS: Observational study conducted with secondary data from a network of Hospital Cancer Registries. We selected epithelial/unspecified SNC records with a year of diagnosis from 2007 to 2021. We performed descriptive statistics of SNC cases and calculated crude and age-standardized rates (ASR, standard: world population) by gender and Region of residence. RESULTS: We identified 2,384 cases, 1,553 (65.1%) in men and 831 (34.9%) in women. The mean age at diagnosis was 59 years for both. Most SNC (50.7% in men and 53.2% in women) originated from the maxillary sinus. Most (65.5% in men and 54.5% in women) were squamous cell carcinomas. Information on occupation was missing in the years 2019-2021. Most male SNC patients (44.8%) were employed in group 6 (Agricultural, forestry, and fishing workers), while women had been mainly (34.6%) working in groups 8 (Workers in the production of industrial goods and services, machine operators) and in group 6 (27.6%). Crude SNC incidence rates were 1.0 per million person-years in men and 0.5 in women, while ASR were 1.0 and 0.4, respectively. In both genders, the highest ASR was in Minas Gerais (men: 1.9; women: 0.7). CONCLUSIONS: Establishing the profile of Brazilians with sinonasal cancer can stimulate epidemiologic research for monitoring this group of cancers with a high association with occupational exposures.


Assuntos
Neoplasias dos Seios Paranasais , População da América do Sul , Humanos , Feminino , Masculino , Pessoa de Meia-Idade , Brasil/epidemiologia , Sistema de Registros , Neoplasias dos Seios Paranasais/epidemiologia , Hospitais
5.
Immunology ; 170(3): 401-418, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37605469

RESUMO

The SARS-CoV-2 (COVID-19) virus has caused a devastating global pandemic of respiratory illness. To understand viral pathogenesis, methods are available for studying dissociated cells in blood, nasal samples, bronchoalveolar lavage fluid and similar, but a robust platform for deep tissue characterization of molecular and cellular responses to virus infection in the lungs is still lacking. We developed an innovative spatial multi-omics platform to investigate COVID-19-infected lung tissues. Five tissue-profiling technologies were combined by a novel computational mapping methodology to comprehensively characterize and compare the transcriptome and targeted proteome of virus infected and uninfected tissues. By integrating spatial transcriptomics data (Visium, GeoMx and RNAScope) and proteomics data (CODEX and PhenoImager HT) at different cellular resolutions across lung tissues, we found strong evidence for macrophage infiltration and defined the broader microenvironment surrounding these cells. By comparing infected and uninfected samples, we found an increase in cytokine signalling and interferon responses at different sites in the lung and showed spatial heterogeneity in the expression level of these pathways. These data demonstrate that integrative spatial multi-omics platforms can be broadly applied to gain a deeper understanding of viral effects on cellular environments at the site of infection and to increase our understanding of the impact of SARS-CoV-2 on the lungs.

6.
Proc Biol Sci ; 290(1990): 20221909, 2023 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-36629106

RESUMO

Linking local to regional ecological and evolutionary processes is key to understand the response of Earth's biodiversity to environmental changes. Here we integrate evolution and mutualistic coevolution in a model of metacommunity dynamics and use numerical simulations to understand how coevolution can shape species distribution and persistence in landscapes varying in space and time. Our simulations show that coevolution and species richness can synergistically shape distribution patterns by increasing colonization and reducing extinction of populations in metacommunities. Although conflicting selective pressures emerging from mutualisms may increase mismatches with the local environment and the rate of local extinctions, coevolution increases trait matching among mutualists at the landscape scale, counteracting local maladaptation and favouring colonization and range expansions. Our results show that by facilitating colonization, coevolution can also buffer the effects of environmental changes, preventing species extinctions and the collapse of metacommunities. Our findings reveal the mechanisms whereby coevolution can favour persistence under environmental changes and highlight that these positive effects are greater in more diverse systems that retain landscape connectivity.


Assuntos
Biodiversidade , Simbiose , Extinção Biológica , Fenótipo , Ecossistema
7.
Neurourol Urodyn ; 42(5): 921-930, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-36403286

RESUMO

INTRODUCTION: Gender dysphoria is the discrepancy between biological sex and gender identity. This can be debilitating for transgender populations, including transgender men (TM), individuals who were assigned female at birth but who identify as men, that can benefit from hormonal therapy with testosterone products to address gender dysphoria. METHODS: We aim to summarize the efficacy, safety profile, and outcomes of the different testosterone replacement treatment (TRT) in the TM population. A search of the published literature regarding the various FDA-approved TRT was performed in PubMed, Web of Science and Cochrane Library from 2007 to date. RESULTS: We complied two groups of TRT based on route of administration including the conventional testosterone therapies (intramuscular and subcutaneous injectables, and transdermal gels) and newer testosterone therapies (oral, buccal, and nasal gels). For the conventional testosterone therapies, we identified nine studies discussed conventional TRT in TM population including one randomized trial, four prospective studies, one retrospective study and three reviews. For newer testosterone therapies, we identified three studies discussed newer TRT in TM population including one prospective study and two reviews. Articles were then compiled and analyzed. Albeit majority of TRT data stemming from conventional TRT, there appear to be an overwhelmingly safety and efficacy profile in TM population translated with increased free testosterone levels comparable to male range, menses cessation, anxiety/depression decline and improved quality of life. CONCLUSION: Testosterone therapy can be impactful for TM population with improved safety, efficiency, quality of life and function. With the rise of the newer FDA-approved TRT, randomized studies are warranted to determine its safety and efficacity in this TM population.


Assuntos
Hipogonadismo , Pessoas Transgênero , Feminino , Humanos , Masculino , Géis , Identidade de Gênero , Estudos Prospectivos , Qualidade de Vida , Estudos Retrospectivos , Testosterona/efeitos adversos
8.
Nature ; 550(7677): 511-514, 2017 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-29045396

RESUMO

Ecological interactions have been acknowledged to play a key role in shaping biodiversity. Yet a major challenge for evolutionary biology is to understand the role of ecological interactions in shaping trait evolution when progressing from pairs of interacting species to multispecies interaction networks. Here we introduce an approach that integrates coevolutionary dynamics and network structure. Our results show that non-interacting species can be as important as directly interacting species in shaping coevolution within mutualistic assemblages. The contribution of indirect effects differs among types of mutualism. Indirect effects are more likely to predominate in nested, species-rich networks formed by multiple-partner mutualisms, such as pollination or seed dispersal by animals, than in small and modular networks formed by intimate mutualisms, such as those between host plants and their protective ants. Coevolutionary pathways of indirect effects favour ongoing trait evolution by promoting slow but continuous reorganization of the adaptive landscape of mutualistic partners under changing environments. Our results show that coevolution can be a major process shaping species traits throughout ecological networks. These findings expand our understanding of how evolution driven by interactions occurs through the interplay of selection pressures moving along multiple direct and indirect pathways.


Assuntos
Evolução Biológica , Ecossistema , Simbiose , Animais , Formigas/fisiologia , Plantas , Polinização
9.
Am Nat ; 199(6): 804-807, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35580229

RESUMO

AbstractA pressing issue is to understand how biological complexity impacts the persistence and adaptation of populations. Natural environments are under unprecedented pressure as a result of climate change and land use change, which makes biological populations and ecological communities vulnerable. Evolution by natural selection-that is, genetic change in response to selection-is one important way species can cope with such changes. Selection often operates on complex traits, and much of selection is due to ecological interactions that, in turn, often form complex networks of species. In this sense, ecological interactions play a dual role: ecological interactions are essential to guarantee the resilience of communities and the functioning of ecosystem services, and they are a source of selection that shapes complex traits. The development of a new integrative framework combining the complexity of selected traits with the complexity of interaction patterns is essential to address potential cascading effects and extinctions. Unfortunately, studies that focus on these two levels of complexity, whether using theoretical or empirical approaches, are still scarce. In this special feature, we bring together articles that contribute to bridging this gap in the study of species coevolution and the evolution of complex traits.


Assuntos
Ecossistema , Seleção Genética , Evolução Biológica , Biota , Mudança Climática
10.
Eur Respir J ; 59(6)2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-34675048

RESUMO

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which emerged in late 2019 has spread globally, causing a pandemic of respiratory illness designated coronavirus disease 2019 (COVID-19). A better definition of the pulmonary host response to SARS-CoV-2 infection is required to understand viral pathogenesis and to validate putative COVID-19 biomarkers that have been proposed in clinical studies. METHODS: Here, we use targeted transcriptomics of formalin-fixed paraffin-embedded tissue using the NanoString GeoMX platform to generate an in-depth picture of the pulmonary transcriptional landscape of COVID-19, pandemic H1N1 influenza and uninfected control patients. RESULTS: Host transcriptomics showed a significant upregulation of genes associated with inflammation, type I interferon production, coagulation and angiogenesis in the lungs of COVID-19 patients compared to non-infected controls. SARS-CoV-2 was non-uniformly distributed in lungs (emphasising the advantages of spatial transcriptomics) with the areas of high viral load associated with an increased type I interferon response. Once the dominant cell type present in the sample, within patient correlations and patient-patient variation, had been controlled for, only a very limited number of genes were differentially expressed between the lungs of fatal influenza and COVID-19 patients. Strikingly, the interferon-associated gene IFI27, previously identified as a useful blood biomarker to differentiate bacterial and viral lung infections, was significantly upregulated in the lungs of COVID-19 patients compared to patients with influenza. CONCLUSION: Collectively, these data demonstrate that spatial transcriptomics is a powerful tool to identify novel gene signatures within tissues, offering new insights into the pathogenesis of SARS-COV-2 to aid in patient triage and treatment.


Assuntos
COVID-19 , Influenza Humana , Interferon Tipo I , COVID-19/genética , Humanos , Vírus da Influenza A Subtipo H1N1 , Influenza Humana/genética , Interferon Tipo I/metabolismo , Pulmão/patologia , SARS-CoV-2
11.
Opt Express ; 30(2): 1976-1993, 2022 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-35209348

RESUMO

This paper presents and demonstrates the three logic processing levels based on complementary photonic crystal logic devices through photonic integrated circuit modeling. We accomplished a set of logic circuits including AND, OR, NAND, NOR, XOR, FAN-OUT, HALF ADDER, and FULL ADDER based on photonic crystal slab platforms. Furthermore, we achieved efficient all-optical logic circuits with contrast ratios as high as 5.5 dB, demonstrated in our simulation results, guaranteeing well-defined output power values for logic representations; a clock-rate up to 2 GHz; and an operating wavelength at λ ≈ 1550 nm. Thus, we can now switch up for high computing abstraction levels to build photonic integrated circuits rather than isolated gates or devices.

12.
Proc Natl Acad Sci U S A ; 116(10): 4406-4415, 2019 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-30765532

RESUMO

A major challenge in evolutionary biology is to understand how complex traits of multiple functions have diversified and codiversified across interacting lineages and geographic ranges. We evaluate intra- and interspecific variation in floral scent, which is a complex trait of documented importance for mutualistic and antagonistic interactions between plants, pollinators, and herbivores. We performed a large-scale, phylogenetically structured study of an entire plant genus (Lithophragma, Saxifragaceae), of which several species are coevolving with specialized pollinating floral parasites of the moth genus Greya (Prodoxidae). We sampled 94 Lithophragma populations distributed across all 12 recognized Lithophragma species and subspecies, and four populations of related saxifragaceous species. Our results reveal an unusually high diversity of floral volatiles among populations, species, and clades within the genus. Moreover, we found unexpectedly major changes at each of these levels in the biosynthetic pathways used by local populations in their floral scents. Finally, we detected significant, but variable, genus- and species-level patterns of ecological convergence in the floral scent signal, including an impact of the presence and absence of two pollinating Greya moth species. We propose that one potential key to understanding floral scent variation in this hypervariable genus is its geographically diverse interactions with the obligate specialized Greya moths and, in some species and sites, more generalized copollinators.


Assuntos
Flores/metabolismo , Saxifragaceae/metabolismo , Compostos Orgânicos Voláteis/metabolismo , Filogeografia , Saxifragaceae/classificação , Especificidade da Espécie
13.
Aesthetic Plast Surg ; 46(6): 2712-2722, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-35999462

RESUMO

BACKGROUND: Fat grafting is used in combination with mammoplasty to improve filling of the upper pole of the breasts. Its effectiveness remains in question due to unpredictable results. Difficulty in isolating the grafted fat and differentiating it from host tissues may hinder assessment of graft integration. The plane between the pectoral muscles is free of fat and has already been described with respect to placement of breast implants and fat grafting in breast surgeries. This study sought to evaluate via magnetic resonance imaging (MRI) the integration and retention of retropectoral fat grafts in mammoplasty. METHODS: Thirty patients with breast flaccidity who desired to undergo mammoplasty were selected. Fat collected from the abdomen was separated by sedimentation and transferred to the retropectoral region after undermining of the breast and resection of excess tissue. The patients underwent MRI preoperatively and at three and six months after surgery. Fat volumes were calculated by multiplying the values for the major vertical, horizontal, and anteroposterior axes by the constant 0.523. RESULTS: Twenty-five patients completed the study. The mean volume grafted was 116.4 ± 22.5 ml per breast. Six months after surgery, the mean fat graft volume in the retropectoral plane was 48.1 ± 25.71 ml, and the integration rate was 40.82% (range, 32.2-49.4%). The rate of complications related to fat grafting was 8%. CONCLUSIONS: In mammoplasty, retropectoral fat grafting showed good integration rates and is a safe and predictable approach that can contribute to improving the outcomes of aesthetic and reconstructive breast surgeries. LEVEL OF EVIDENCE IV, COHORT ANALYTIC STUDY: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .


Assuntos
Sobrevivência de Enxerto , Imageamento por Ressonância Magnética , Humanos
14.
Biol Lett ; 17(12): 20210478, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34847787

RESUMO

Closely related species tend to be more similar than randomly selected species from the same phylogenetic tree. This pattern, known as a phylogenetic signal, has been extensively studied for intrinsic (e.g. morphology), as well as extrinsic (e.g. climatic preferences), properties but less so for ecological interactions. Phylogenetic signals of species interactions (i.e. resource use) can vary across time and space, but the causes behind such variations across broader spatial extents remain elusive. Here, we evaluated how current and historical climates influence phylogenetic signals of bat-fruit interaction networks across the Neotropics. We performed a model selection relating the phylogenetic signals of each trophic level (bats and plants) with a set of current and historical climatic factors deemed ecologically important in shaping biotic interactions. Bat and plant phylogenetic signals in bat-fruit interaction networks varied little with climatic factors, although bat phylogenetic signals positively covaried with annual precipitation. These findings indicated that water availability could increase resource availability, favouring higher niche partitioning of trophic resources among bat species and hence bat phylogenetic signals across bat-fruit interaction networks. Overall, our study advances our understanding of the spatial dynamics of bat-fruit interactions by highlighting the association of current climatic factors with phylogenetic patterns of biotic interactions.


Assuntos
Quirópteros , Animais , Ecossistema , Frutas , Estado Nutricional , Filogenia
15.
Naturwissenschaften ; 108(4): 34, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34319436

RESUMO

Temporal constancy of pollination systems is essential for the maintenance of pollinators through time. Community-level assessment of flowering phenology allows understanding variations across seasons and years and the risks of decoupling flowering and pollinators' activity. We evaluated flowering patterns and temporal diversity of pollination systems in a tropical seasonal forest. We asked whether the temporal organization of flowering times differs among pollination systems; if there is a constancy of pollination systems through the year, since climate and phylogenies constraint flowering time; if there is a prevalent flowering pattern by pollination system, and if the temporal organization of pollination systems by modularity analyses is coherent with grouping by pre-defined seasons. We characterized 10 pollination systems, examined flowering strategies, climate cues and phylogenetic constraints. Pollination by large-to-medium bees dominated (49.2%), followed by diverse insects (22.1%) and flies (14.7%). The remaining systems represented 14% of species. Flowering occurred year-round for most pollination systems, predominating the seasonal flowering strategy. Flowering patterns ranged from aggregated to nested, and random. Climate affected the flowering of most pollination systems, but there was no phylogeny constraint. Modularity grouped pollination systems differently than rainfall seasonality. Contrasting the expectations of reduced temporal constancy, most systems were present year-round, facilitating the exploitation of floral resources by pollinators. Diversity of pollination systems remained constant despite climate seasonality, indicating that several factors influence the optimum flowering time for pollination in seasonally dry vegetations. Global warming may disrupt phenological patterns and the temporal organization of plant communities, a matter for future studies.


Assuntos
Flores , Polinização , Animais , Abelhas , Florestas , Filogenia , Estações do Ano
16.
Proc Natl Acad Sci U S A ; 115(47): 12017-12022, 2018 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-30404910

RESUMO

Ecological interactions shape adaptations through coevolution not only between pairs of species but also through entire multispecies assemblages. Local coevolution can then be further altered through spatial processes that have been formally partitioned in the geographic mosaic theory of coevolution. A major current challenge is to understand the spatial patterns of coadaptation that emerge across ecosystems through the interplay between gene flow and selection in networks of interacting species. Here, we combine a coevolutionary model, network theory, and empirical information on species interactions to investigate how gene flow and geographical variation in selection affect trait patterns in mutualistic networks. We show that gene flow has the surprising effect of favoring trait matching, especially among generalist species in species-rich networks typical of pollination and seed dispersal interactions. Using an analytical approximation of our model, we demonstrate that gene flow promotes trait matching by making the adaptive landscapes of different species more similar to each other. We use this result to show that the progressive loss of gene flow associated with habitat fragmentation may undermine coadaptation in mutualisms. Our results therefore provide predictions of how spatial processes shape the evolution of species-rich interactions and how the widespread fragmentation of natural landscapes may modify the coevolutionary process.


Assuntos
Coevolução Biológica/genética , Adaptação Fisiológica , Evolução Biológica , Ecossistema , Fluxo Gênico/genética , Geografia , Modelos Genéticos , Polinização , Simbiose
17.
Ecol Lett ; 23(12): 1789-1799, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32969577

RESUMO

Ecological interactions shape the evolution of multiple species traits in populations. These traits are often linked to each other through genetic correlations, affecting how each trait evolves through selection imposed by interacting partners. Here, we integrate quantitative genetics, coevolutionary theory and network science to explore how trait correlations affect the coevolution of mutualistic species not only in pairs of species but also in species-rich networks across space. We show that genetic correlations may determine the pace of coevolutionary change, affect species abundances and fuel divergence among populations of the same species. However, this trait divergence promoted by genetic correlations is partially buffered by the nested structure of species-rich mutualisms. Our study, therefore, highlights how coevolution and its ecological consequences may result from conflicting processes at different levels of organisation, ranging from genes to communities.


Assuntos
Evolução Biológica , Simbiose , Fenótipo
18.
Opt Lett ; 45(19): 5502-5505, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33001932

RESUMO

We theoretically propose and demonstrate through numerous simulations complementary photonic crystal integrated logic (CPCL) devices. Simulation results provide demonstration of a highly efficient clock rate, higher than 20 GHz, guaranteeing operation at both input and output with the same wavelength (around λ=1550nm). The proposed devices show well-defined output power values representing the two logic states 1 and 0, with a contrast ratio as high as 6 dB. The results presented here provide countless possibilities for future research, targeting the development of photonic crystal logic and communications systems with CPCLs acting as the core hardware devices.

19.
J Evol Biol ; 33(6): 858-868, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32198956

RESUMO

Understanding how ecological interactions have shaped the evolutionary dynamics of species traits remains a challenge in evolutionary ecology. Combining trait evolution models and phylogenies, we analysed the evolution of characters associated with seed dispersal (fruit size and colour) and herbivory (spines) in Neotropical palms to infer the role of these opposing animal-plant interactions in driving evolutionary patterns. We found that the evolution of fruit colour and fruit size was associated in Neotropical palms, supporting the adaptive interpretation of seed-dispersal syndromes and highlighting the role of frugivores in shaping plant evolution. Furthermore, we revealed a positive association between fruit size and the presence of spines on palm leaves, bracteas and stems. We hypothesize that interactions between palms and large-bodied frugivores/herbivores may explain the evolutionary relationship between fruit size and spines. Large-bodied frugivores, such as extinct megafauna, besides consuming the fruits and dispersing large seeds, may also have consumed the leaves or damaged the plants, thus simultaneously favouring the evolution of large fruits and defensive structures. Our findings show how current trait patterns can be understood as the result of the interplay between antagonistic and mutualistic interactions that have happened throughout the evolutionary history of a clade.


Assuntos
Arecaceae/genética , Evolução Biológica , Frutas/genética , Animais , Arecaceae/anatomia & histologia , Frutas/anatomia & histologia , América Latina , Pigmentação/genética , Defesa das Plantas contra Herbivoria/genética , Dispersão de Sementes/genética , Clima Tropical
20.
J Theor Biol ; 501: 110327, 2020 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-32422140

RESUMO

Many theoretical models have been formulated to better understand the coevolutionary patterns that emerge from antagonistic interactions. These models usually assume that the attacks by the exploiters are random, so the effect of victim selection by exploiters on coevolutionary patterns remains unexplored. Here we analytically studied the payoff for predators and prey under coevolution assuming that every individual predator can attack only a small number of prey any given time, considering two scenarios: (i) predation occurs at random; (ii) predators select prey according to phenotype matching. We also develop an individual based model to verify the robustness of our analytical prediction. We show that both scenarios result in well known similar coevolutionary patterns if population sizes are sufficiently high: symmetrical coevolutionary branching and symmetrical coevolutionary cycling (Red Queen dynamics). However, for small population sizes, prey selection can cause unexpected coevolutionary patterns. One is the breaking of symmetry of the coevolutionary pattern, where the phenotypes evolve towards one of two evolutionarily stable patterns. As population size increases, the phenotypes oscillate between these two values in a novel form of Red Queen dynamics, the episodic reversal between the two stable patterns. Thus, prey selection causes prey phenotypes to evolve towards more extreme values, which reduces the fitness of both predators and prey, increasing the likelihood of extinction.


Assuntos
Evolução Biológica , Comportamento Predatório , Animais , Modelos Teóricos , Fenótipo , Densidade Demográfica , Dinâmica Populacional
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA