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1.
Proc Natl Acad Sci U S A ; 120(16): e2218280120, 2023 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-37036992

RESUMO

Migratory insects are key players in ecosystem functioning and services, but their spatiotemporal distributions are typically poorly known. Ecological niche modeling (ENM) may be used to predict species seasonal distributions, but the resulting hypotheses should eventually be validated by field data. The painted lady butterfly (Vanessa cardui) performs multigenerational migrations between Europe and Africa and has become a model species for insect movement ecology. While the annual migration cycle of this species is well understood for Europe and northernmost Africa, it is still unknown where most individuals spend the winter. Through ENM, we previously predicted suitable breeding grounds in the subhumid regions near the tropics between November and February. In this work, we assess the suitability of these predictions through i) extensive field surveys and ii) two-year monitoring in six countries: a large-scale monitoring scheme to study butterfly migration in Africa. We document new breeding locations, year-round phenological information, and hostplant use. Field observations were nearly always predicted with high probability by the previous ENM, and monitoring demonstrated the influence of the precipitation seasonality regime on migratory phenology. Using the updated dataset, we built a refined ENM for the Palearctic-African range of V. cardui. We confirm the relevance of the Afrotropical region and document the missing natural history pieces of the longest migratory cycle described in butterflies.


Assuntos
Borboletas , Humanos , Animais , Ecossistema , Migração Animal , Europa (Continente) , Insetos , Estações do Ano
2.
Mol Biol Evol ; 41(3)2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38401262

RESUMO

Hypolimnas misippus is a Batesian mimic of the toxic African Queen butterfly (Danaus chrysippus). Female H. misippus butterflies use two major wing patterning loci (M and A) to imitate three color morphs of D. chrysippus found in different regions of Africa. In this study, we examine the evolution of the M locus and identify it as an example of adaptive atavism. This phenomenon involves a morphological reversion to an ancestral character that results in an adaptive phenotype. We show that H. misippus has re-evolved an ancestral wing pattern present in other Hypolimnas species, repurposing it for Batesian mimicry of a D. chrysippus morph. Using haplotagging, a linked-read sequencing technology, and our new analytical tool, Wrath, we discover two large transposable element insertions located at the M locus and establish that these insertions are present in the dominant allele responsible for producing mimetic phenotype. By conducting a comparative analysis involving additional Hypolimnas species, we demonstrate that the dominant allele is derived. This suggests that, in the derived allele, the transposable elements disrupt a cis-regulatory element, leading to the reversion to an ancestral phenotype that is then utilized for Batesian mimicry of a distinct model, a different morph of D. chrysippus. Our findings present a compelling instance of convergent evolution and adaptive atavism, in which the same pattern element has independently evolved multiple times in Hypolimnas butterflies, repeatedly playing a role in Batesian mimicry of diverse model species.


Assuntos
Mimetismo Biológico , Borboletas , Animais , Borboletas/genética , Elementos de DNA Transponíveis , Mimetismo Biológico/genética , Fenótipo , África , Asas de Animais/anatomia & histologia
3.
Opt Express ; 32(10): 17152-17164, 2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38858905

RESUMO

The use of fluorescent antennas in optical wireless communications (OWC) has been demonstrated previously, and it has been shown that it is an efficient method for enhancing receiver performance, providing both signal gain and a wide field of view (FoV). To achieve a high concentration gain at the receiver output, the selected fluorophores should have a high photoluminescence quantum yield (PLQY), limited overlap between their absorption and emission spectra, and emit light that can be efficiently detected. In addition, to support a high modulation bandwidth, the photoluminescence (PL) lifetime of the fluorophore needs to be short. In this paper, we propose a new fluorescent antenna architecture based on Förster resonance energy transfer (FRET). Our results show that, due to the photophysical interactions between the energy donor and energy acceptor, the use of FRET simultaneously increases PLQY and reduces PL lifetime. Additionally, employing FRET leads to an increased Stokes shift, ensuring that the emitted light has longer wavelengths, thus reducing self-absorption. This shift can also increase the efficiency with which the fluorescence is detected by a typical silicon (Si) photodetector. Consequently, our OWC results show that a new FRET-based antenna can achieve a significantly higher concentration gain and a wider transmission bandwidth than a conventional non-FRET antenna, leading to much higher data rates.

4.
Rapid Commun Mass Spectrom ; 38(3): e9675, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38211347

RESUMO

RATIONALE: Many insect species undertake multigenerational migrations in the Afro-tropical and Palearctic ranges, and understanding their migratory connectivity remains challenging due to their small size, short life span and large population sizes. Hydrogen isotopes (δ2 H) can be used to reconstruct the movement of dispersing or migrating insects, but applying δ2 H for provenance requires a robust isotope baseline map (i.e. isoscape) for the Afro-Palearctic. METHODS: We analyzed the δ2 H in the wings (δ2 Hwing ) of 142 resident butterflies from 56 sites across the Afro-Palearctic. The δ2 Hwing values were compared to the predicted local growing-season precipitation δ2 H values (δ2 HGSP ) using a linear regression model to develop an insect wing δ2 H isoscape. We used multivariate linear mixed models and high-resolution and time-specific remote sensing climate and environmental data to explore the controls of the residual δ2 Hwing variability. RESULTS: A strong linear relationship was found between δ2 Hwing and δ2 HGSP values (r2 = 0.53). The resulting isoscape showed strong patterns across the Palearctic but limited variation and high uncertainty for the Afro-tropics. Positive residuals of this relationship were correlated with dry conditions for the month preceding sampling whereas negative residuals were correlated with more wet days for the month preceding sampling. High intra-site δ2 Hwing variance was associated with lower relative humidity for the month preceding sampling and higher elevation. CONCLUSION: The δ2 Hwing isoscape is applicable for tracing herbivorous lepidopteran insects that migrate across the Afro-Palearctic range but has limited geolocation potential in the Afro-tropics. The spatial analysis of uncertainty using high-resolution climatic data demonstrated that many African regions with highly variable evaporation rates and relative humidity have δ2 Hwing values that are less related to δ2 HGSP values. Increasing geolocation precision will require new modeling approaches using more time-specific environmental data and/or independent geolocation tools.


Assuntos
Borboletas , Animais , Hidrogênio , Isótopos/análise , Estações do Ano , Modelos Lineares
5.
Opt Express ; 31(11): 17716-17730, 2023 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-37381498

RESUMO

The use of fluorescent optical antennas in visible light communications (VLC) systems can enhance their performance by selectively absorbing light from the transmitter and concentrating the resulting fluorescence, whilst preserving a wide field of view. In this paper, we introduce a new and flexible way of creating fluorescent optical antennas. This new antenna structure is a glass capillary which is filled with a mixture of epoxy and a fluorophore before the epoxy is cured. Using this structure, an antenna can be easily and efficiently coupled to a typical photodiode. Consequently, the leakage of photons from the antenna can be significantly reduced when compared to previous antennas created using microscope slides. Moreover, the process of creating the antenna is simple enough for the performance of antennas containing different fluorophores to be compared. In particular, this flexibility has been used to compare VLC systems that incorporate optical antennas containing three different organic fluorescent materials, Coumarin 504 (Cm504), Coumarin 6 (Cm6), and 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), when a white light-emitting diode (LED) is used as the transmitter. Results show that, since it only absorbs light emitted from the gallium nitride (GaN) LED, a fluorophore that hasn't previously been used in a VLC system, Cm504, can result in a significantly higher modulation bandwidth. In addition, the bit error rate (BER) performance at different orthogonal frequency-division multiplexing (OFDM) data rates of antennas containing different fluorophores is reported. These experiments show for the first time that the best choice of fluorophore depends on the illuminance at the receiver. In particular, when the illuminance is low, the overall performance of the system is dominated by the signal-to-noise ratio (SNR). Under these conditions, the fluorophore with the highest signal gain is the best choice. In contrast, when the illuminance is high, the achievable data rate is determined by the bandwidth of the system and therefore the fluorophore that results in the highest bandwidth is the best choice.

6.
Syst Biol ; 71(3): 570-588, 2022 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-34363477

RESUMO

Compared to other regions, the drivers of diversification in Africa are poorly understood. We studied a radiation of insects with over 100 species occurring in a wide range of habitats across the Afrotropics to investigate the fundamental evolutionary processes and geological events that generate and maintain patterns of species richness on the continent. By investigating the evolutionary history of Bicyclus butterflies within a phylogenetic framework, we inferred the group's origin at the Oligo-Miocene boundary from ancestors in the Congolian rainforests of central Africa. Abrupt climatic fluctuations during the Miocene (ca. 19-17 Ma) likely fragmented ancestral populations, resulting in at least eight early-divergent lineages. Only one of these lineages appears to have diversified during the drastic climate and biome changes of the early Miocene, radiating into the largest group of extant species. The other seven lineages diversified in forest ecosystems during the late Miocene and Pleistocene when climatic conditions were more favorable-warmer and wetter. Our results suggest changing Neogene climate, uplift of eastern African orogens, and biotic interactions have had different effects on the various subclades of Bicyclus, producing one of the most spectacular butterfly radiations in Africa. [Afrotropics; biodiversity; biome; biotic interactions; Court Jester; extinction; grasslands; paleoclimates; Red Queen; refugia forests; dependent-diversification; speciation.].


Assuntos
Borboletas , Animais , Biodiversidade , Borboletas/genética , Ecossistema , Especiação Genética , Filogenia , Filogeografia
7.
PLoS Biol ; 18(2): e3000610, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32108180

RESUMO

Neo-sex chromosomes are found in many taxa, but the forces driving their emergence and spread are poorly understood. The female-specific neo-W chromosome of the African monarch (or queen) butterfly Danaus chrysippus presents an intriguing case study because it is restricted to a single 'contact zone' population, involves a putative colour patterning supergene, and co-occurs with infection by the male-killing endosymbiont Spiroplasma. We investigated the origin and evolution of this system using whole genome sequencing. We first identify the 'BC supergene', a broad region of suppressed recombination across nearly half a chromosome, which links two colour patterning loci. Association analysis suggests that the genes yellow and arrow in this region control the forewing colour pattern differences between D. chrysippus subspecies. We then show that the same chromosome has recently formed a neo-W that has spread through the contact zone within approximately 2,200 years. We also assembled the genome of the male-killing Spiroplasma, and find that it shows perfect genealogical congruence with the neo-W, suggesting that the neo-W has hitchhiked to high frequency as the male-killer has spread through the population. The complete absence of female crossing-over in the Lepidoptera causes whole-chromosome hitchhiking of a single neo-W haplotype, carrying a single allele of the BC supergene and dragging multiple non-synonymous mutations to high frequency. This has created a population of infected females that all carry the same recessive colour patterning allele, making the phenotypes of each successive generation highly dependent on uninfected male immigrants. Our findings show how hitchhiking can occur between the physically unlinked genomes of host and endosymbiont, with dramatic consequences.


Assuntos
Borboletas/genética , Cromossomos de Insetos/genética , Cromossomos Sexuais/genética , Animais , Borboletas/microbiologia , Evolução Molecular , Feminino , Ligação Genética , Genoma/genética , Haplótipos , Masculino , Fenótipo , Spiroplasma/genética
8.
Sensors (Basel) ; 23(3)2023 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-36772141

RESUMO

Silicon photomultipliers' relatively large areas and ability to detect single photons make them attractive as receivers for optical wireless communications. In this paper, the relative importance of the non-linearity and width of SiPMs' fast output in their performance in receivers is investigated using Monte Carlo simulations. Using these results, the performances of receivers containing different SiPMs are estimated. This is followed by a discussion of the potential performances of arrays of existing SiPMs. Finally, the possible dramatic improvements in performance that could be achieved by using two stacked integrated circuits are highlighted.

9.
J Synchrotron Radiat ; 29(Pt 2): 377-385, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-35254300

RESUMO

Crystal monochromators are often the primary optics in hard X-ray synchrotron beamlines. Management of power load is central to their design. Strict requirements on stability and deformation are to be met, as new-generation synchrotron sources deliver brighter beams of X-rays. This article sets out to illustrate an overall picture of the deformation caused by heat load in a cryo-cooled Si crystal monochromator using first principles. A theoretical model has been developed to predict the temperature distribution and surface deformation by applying intrinsic properties of Si material and the cooling system parameters. The model explains the universal behaviour of crystal slope error versus absorbed power; it has been benchmarked against experimental data and used to interpret finite-element analysis of cryogenically cooled crystals.

10.
Proc Biol Sci ; 287(1926): 20200443, 2020 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-32345166

RESUMO

Polymorphic Batesian mimics exhibit multiple protective morphs that each mimic a different noxious model. Here, we study the genomic transitions leading to the evolution of different mimetic wing patterns in the polymorphic Mocker Swallowtail Papilio dardanus. We generated a draft genome (231 Mb over 30 chromosomes) and re-sequenced individuals of three morphs. Genome-wide single nucleotide polymorphism (SNP) analysis revealed elevated linkage disequilibrium and divergence between morphs in the regulatory region of engrailed, a developmental gene previously implicated in the mimicry switch. The diverged region exhibits a discrete chromosomal inversion (of 40 kb) relative to the ancestral orientation that is associated with the cenea morph, but not with the bottom-recessive hippocoonides morph or with non-mimetic allopatric populations. The functional role of this inversion in the expression of the novel phenotype is currently unknown, but by preventing recombination, it allows the stable inheritance of divergent alleles enabling geographic spread and local coexistence of multiple adaptive morphs.


Assuntos
Mimetismo Biológico/fisiologia , Borboletas/parasitologia , Inversão Cromossômica , Animais , Genes de Insetos , Genômica , Desequilíbrio de Ligação , Fenótipo , Sequências Reguladoras de Ácido Nucleico , Asas de Animais
11.
J Anim Ecol ; 89(5): 1230-1241, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31955425

RESUMO

Many tropical environments experience cyclical seasonal changes, frequently with pronounced wet and dry seasons, leading to a highly uneven temporal distribution of resources. Short-lived animals inhabiting such environments often show season-specific adaptations to cope with alternating selection pressures. African Bicyclus butterflies show strong seasonal polyphenism in a suite of phenotypic and life-history traits, and their adults are thought to undergo reproductive diapause associated with the lack of available larval host plants during the dry season. Using 3 years of longitudinal field data for three species in Malawi, dissections demonstrated that one forest species reproduces continuously, whereas two savannah species undergo reproductive diapause in the dry season, either with or without pre-diapause mating. Using additional data from field-collected and museum samples, we then documented the same three mating strategies for a further 37 species. Phylogenetic analyses indicated that the ancestral state was a non-diapausing forest species, and that habitat preference and mating strategy evolved in a correlated fashion. Bicyclus butterflies underwent rapid diversification during the Late Miocene, coinciding with expansions into more open savannah habitat. We conclude that the ability to undergo reproductive diapause was a key trait that facilitated colonization and eventual radiation into savannahs in the Late Miocene.


Assuntos
Borboletas , Diapausa de Inseto , Diapausa , Radiação , Animais , Filogenia , Reprodução , Estações do Ano
12.
Public Health Nutr ; 23(17): 3114-3115, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32844737

RESUMO

Since 2009, mid-upper arm circumference (MUAC) has become an accepted measure for screening children for acute malnutrition and determining eligibility for services to manage acute malnutrition. Use of MUAC has increased the reach and enhanced the quality of community-based management of acute malnutrition services. Increasingly, MUAC is also used to assess nutritional status and eligibility for nutrition support among adolescents and adults, including pregnant and lactating women and HIV and TB clients. However, globally recognised cut-offs have not been established to classify malnutrition among adults using MUAC. Therefore, different countries and programmes use different MUAC cut-offs to determine eligibility for programme services. Patient monitoring guidelines provided by WHO for country adaptation to support the integrated management of adult illness do not include MUAC, in part because guidance does not exist about what MUAC cut-off should trigger further action.


Assuntos
Desnutrição , Magreza , Adolescente , Adulto , Braço , Criança , Feminino , Humanos , Lactação , Masculino , Desnutrição/diagnóstico , Curva ROC
13.
J Antimicrob Chemother ; 74(3): 787-790, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30462237

RESUMO

BACKGROUND: Drug-related adverse events (AEs) are reported to be common amongst patients receiving outpatient parenteral antimicrobial therapy (OPAT). However, comparative data regarding intravenous (iv) catheter-related AEs are lacking. OBJECTIVES: To compare drug- and iv catheter-related AEs from a large UK OPAT centre. PATIENTS AND METHODS: We reviewed 544 OPAT episodes [median (IQR) age: 57 (39-71) years, 60% male, 13% with diabetes] with a median (IQR) duration of 7 (2-18) days. Clinically significant drug- and iv catheter-related AEs were calculated as a percentage of OPAT episodes with an AE and also as AEs per 1000 iv drug/catheter days. RESULTS: Drug-related AEs complicated 13 (2.4%) OPAT episodes at 1.7 (95% CI 0.9-2.9) per 1000 drug days. Catheter-related AEs occurred more frequently, complicating 32 (5.9%) episodes at 5.7 (95% CI 4.2-7.9) per 1000 iv catheter days (χ2 test for difference in AE rate: P < 0.001). Non-radiologically guided midline catheters were associated with the most frequent AEs (n = 23) at 15.6 (95% CI 10.3-23.4) per 1000 iv catheter days compared with other types of iv catheters (HR 8.4, 95% CI 2.4-51.9, P < 0.004), and self-administration was associated with a higher rate of catheter-related AEs at 12.0 (95% CI 6.0-23.9) per 1000 iv catheter days (HR 4.15, 95% CI 1.7-9.1, P = 0.007). CONCLUSIONS: Clinically significant iv catheter-related AEs occurred more frequently than drug-related AEs, especially when using non-radiologically guided midline catheters. Regular review of the need for iv therapy and switching to oral antimicrobials when appropriate is likely to minimize OPAT-related AEs.


Assuntos
Anti-Infecciosos/efeitos adversos , Catéteres/efeitos adversos , Catéteres/estatística & dados numéricos , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/epidemiologia , Infusões Parenterais/efeitos adversos , Infusões Parenterais/estatística & dados numéricos , Pacientes Ambulatoriais , Administração Intravenosa/efeitos adversos , Adulto , Idoso , Anti-Infecciosos/administração & dosagem , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/etiologia , Feminino , Pesquisas sobre Atenção à Saúde , Humanos , Infusões Intravenosas/efeitos adversos , Infusões Parenterais/métodos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Dispositivos de Acesso Vascular/efeitos adversos , Dispositivos de Acesso Vascular/estatística & dados numéricos
14.
J Exp Biol ; 222(Pt 17)2019 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-31395676

RESUMO

Human running is inefficient. For every 10 calories burned, less than 1 is needed to maintain a constant forward velocity - the remaining energy is, in a sense, wasted. The majority of this wasted energy is expended to support the bodyweight and redirect the center of mass during the stance phase of gait. An order of magnitude less energy is expended to brake and accelerate the swinging leg. Accordingly, most devices designed to increase running efficiency have targeted the costlier stance phase of gait. An alternative approach is seen in nature: spring-like tissues in some animals and humans are believed to assist leg swing. While it has been assumed that such a spring simply offloads the muscles that swing the legs, thus saving energy, this mechanism has not been experimentally investigated. Here, we show that a spring, or 'exotendon', connecting the legs of a human reduces the energy required for running by 6.4±2.8%, and does so through a complex mechanism that produces savings beyond those associated with leg swing. The exotendon applies assistive forces to the swinging legs, increasing the energy optimal stride frequency. Runners then adopt this frequency, taking faster and shorter strides, and reduce the joint mechanical work to redirect their center of mass. Our study shows how a simple spring improves running economy through a complex interaction between the changing dynamics of the body and the adaptive strategies of the runner, highlighting the importance of considering each when designing systems that couple human and machine.


Assuntos
Marcha/fisiologia , Perna (Membro)/fisiologia , Corrida , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Masculino , Distribuição Aleatória , Adulto Jovem
15.
BMC Public Health ; 19(1): 806, 2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-31234806

RESUMO

BACKGROUND: The prevalence of anaemia and iron deficiency (ID) among children with severe acute malnutrition (SAM) and their correction during nutritional rehabilitation are not well documented. This study assessed anaemia and ID prevalence and their predictors at start of SAM treatment, and the efficacy of their treatment and effect on gut health of two novel Ready-To-Use Therapeutic foods (RUTF) prepared from soybean, maize and sorghum (SMS) with (MSMS-RUTF) or without added milk (FSMS-RUTF) compared to those of the standard formulation prepared from peanut and milk (PM-RUTF). METHODS: This was a 3-arms parallel groups, simple randomised, controlled non-inferiority trial in 6-59 months old Central Malawian children with SAM. Anaemia was defined using altitude- and ethnicity-adjusted haemoglobin. Iron status was defined using soluble transferrin receptor (sTfR) and body iron stores (BIS). We used Pearson's chi-square test, t-test for paired or unpaired data, Kruskal-Wallis test for between-arm differences as appropriate and logistic regression to identify independent predictors of anaemia or iron deficiency anaemia (IDA). RESULTS: The sample size was 389. At admission, the prevalence [%(95%CI)] of anaemia was 48.9(41.4-56.5)% while that of ID and IDA were 55.7(48.6-62.5)% and 34.3(28.2-41.0)% when using sTfR criterion and 29.1(24.4-34.4)% and 28.9(23.7-34.9)% when using BIS criterion, respectively. At discharge, nutrition rehabilitation with SMS-RUTF was associated with the lowest prevalence of anaemia [12.0(6.9-20.3)% for FSMS-RUTF, 18.2(11.9-26.8)% for MSMS-RUTF and 24.5(15.8-35.9)% for PM-RUTF; p = 0.023] and IDA [7.9(3.4-17.3)% for FSMS-RUTF, 10.9(4.8-22.6)% for MSMS-RUTF and 20.5(10.7-35.5)% for PM-RUTF; p = 0.028]. SMS-RUTF was also associated with the highest increase in BIS [Change in BIS (95%CI)] among the iron deplete at admission [6.2 (3.7; 8.6), 3.2 (0.8; 5.6), 2.2 (0.2; 4.3) for the same study arms; Anova p = 0.045]. Compared to P-RUTF, FSMS-RUTF had the highest adjusted recovery rate [OR (95%CI = 0.3 (0.2-0.5) with p < 0.001 for FSMS-RUTF and 0.6 (0.3-1.0) with p = 0.068 for MSMS-RUTF]. No effect of iron content on risk of iron overload or gut inflammation was observed. CONCLUSIONS: Anaemia and ID are common among children with SAM. FSMS-RUTF is more efficacious in treating anaemia and correcting BIS among this group than PM-RUTF. TRIAL REGISTRATION: This study was registered on 15 April 2015 ( PACTR201505001101224 ).


Assuntos
Anemia Ferropriva/dietoterapia , Alimentos Formulados , Glycine max , Desnutrição Aguda Grave/dietoterapia , Sorghum , Zea mays , Anemia Ferropriva/epidemiologia , Anemia Ferropriva/etiologia , Animais , Arachis , Pré-Escolar , Grão Comestível , Feminino , Humanos , Lactente , Ferro/sangue , Malaui/epidemiologia , Masculino , Leite , Prevalência , Desnutrição Aguda Grave/sangue , Desnutrição Aguda Grave/complicações , Resultado do Tratamento
16.
17.
Mol Phylogenet Evol ; 123: 50-58, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29428509

RESUMO

Hypolimnas butterflies (Nymphalidae), commonly known as eggflies, are a popular model system for studying a wide range of ecological questions including mimicry, polymorphism, wing pattern evolution, and Wolbachia-host interactions. The lack of a time-calibrated phylogeny for this group has precluded understanding its evolutionary history. We reconstruct a species-level phylogeny using a nine gene dataset and estimate species divergence times. Based on the resulting tree, we investigate the taxon's historical biogeography, examine the evolution of host plant preferences, and test the hypothesis that the endosymbiotic bacterium Wolbachia mediates gene transfer between species. Our analyses indicate that the species are grouped within three strongly supported, deeply divergent clades. However, relationships among these three clades are uncertain. In addition, many Hypolimnas species are not monophyletic or monophyletic with weak support, suggesting widespread incomplete lineage sorting and/or introgression. Biogeographic analysis strongly indicates that the genus diverged from its ancestor in Africa and subsequently dispersed to Asia; the strength of this result is not affected by topological uncertainties. While the larvae of African species feed almost exclusively on Urticaceae, larvae of species found further east often feed on several additional families. Interestingly, we found an identical mitochondrial haplotype in two Hypolimnas species, H. bolina and H. alimena, and a strong association between this mitotype and the Wolbachia strain wBol1a. Future investigations should explore the plausibility of Wolbachia-mediated introgression between species.


Assuntos
Evolução Biológica , Borboletas/genética , Borboletas/microbiologia , Wolbachia/fisiologia , África , Animais , Sequência de Bases , Teorema de Bayes , Biodiversidade , DNA Mitocondrial/genética , Haplótipos/genética , Larva/fisiologia , Funções Verossimilhança , Mitocôndrias/genética , Filogenia , Filogeografia , Análise de Sequência de DNA
18.
BMC Evol Biol ; 17(1): 174, 2017 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-28768477

RESUMO

BACKGROUND: Skippers (Family: Hesperiidae) are a large group of butterflies with ca. 4000 species under 567 genera. The lack of a time-calibrated higher-level phylogeny of the group has precluded understanding of its evolutionary past. We here use a 10-gene dataset to reconstruct the most comprehensive time-calibrated phylogeny of the group, and explore factors that affected the diversification of these butterflies. RESULTS: Ancestral state reconstructions show that the early hesperiid lineages utilized dicots as larval hostplants. The ability to feed on monocots evolved once at the K-Pg boundary (ca. 65 million years ago (Mya)), and allowed monocot-feeders to diversify much faster on average than dicot-feeders. The increased diversification rate of the monocot-feeding clade is specifically attributed to rate shifts in two of its descendant lineages. The first rate shift, a four-fold increase compared to background rates, happened ca. 50 Mya, soon after the Paleocene-Eocene thermal maximum, in a lineage of the subfamily Hesperiinae that mostly fed on forest monocots. The second rate shift happened ca. 40 Mya in a grass-feeding lineage of Hesperiinae when open-habitat grasslands appeared in the Neotropics owing to gradual cooling of the atmospheric temperature. CONCLUSIONS: The evolution of monocot feeding strongly influenced diversification of skippers. We hypothesize that although monocot feeding was an intrinsic trait that allowed exploration of novel niches, the lack of extensive availability of monocots comprised an extrinsic limitation for niche exploration. The shifts in diversification rate coincided with paleoclimatic events during which grasses and forest monocots were diversified.


Assuntos
Biodiversidade , Borboletas/classificação , Clima , Interações Hospedeiro-Parasita , Paleontologia , Animais , Ecossistema , Filogenia , Filogeografia , Poaceae/parasitologia
19.
Proc Biol Sci ; 283(1835)2016 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-27440667

RESUMO

Sexually antagonistic selection can drive both the evolution of sex chromosomes and speciation itself. The tropical butterfly the African Queen, Danaus chrysippus, shows two such sexually antagonistic phenotypes, the first being sex-linked colour pattern, the second, susceptibility to a male-killing, maternally inherited mollicute, Spiroplasma ixodeti, which causes approximately 100% mortality in male eggs and first instar larvae. Importantly, this mortality is not affected by the infection status of the male parent and the horizontal transmission of Spiroplasma is unknown. In East Africa, male-killing of the Queen is prevalent in a narrow hybrid zone centred on Nairobi. This hybrid zone separates otherwise allopatric subspecies with different colour patterns. Here we show that a neo-W chromosome, a fusion between the W (female) chromosome and an autosome that controls both colour pattern and male-killing, links the two phenotypes thereby driving speciation across the hybrid zone. Studies of the population genetics of the neo-W around Nairobi show that the interaction between colour pattern and male-killer susceptibility restricts gene flow between two subspecies of D. chrysippus Our results demonstrate how a complex interplay between sex, colour pattern, male-killing, and a neo-W chromosome, has set up a genetic 'sink' that keeps the two subspecies apart. The association between the neo-W and male-killing thus provides a 'smoking gun' for an ongoing speciation process.


Assuntos
Borboletas/genética , Especiação Genética , Pigmentação/genética , Cromossomos Sexuais/genética , Animais , Cor , Feminino , Fluxo Gênico , Genética Populacional , Quênia , Masculino , Fenótipo
20.
Syst Entomol ; 41(1): 207-228, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27076698

RESUMO

In this paper we present a thorough revision of the sciathis species group of the butterfly genus Bicyclus (Kirby). Type materials are discussed and in several cases lectotypes are assigned to specimens from original type series. Four new, and morphologically distinct, species are described (B. elishiae Brattström sp.n., B. heathi Brattström sp.n., B. sigiussidorum Brattström sp.n. and B. subtilisurae Brattström sp.n.), along with a comprehensive molecular phylogeny that includes exemplar taxa of all currently recognized species. We also investigate the types of all previously synonymized taxa and in the process invalidate the name B. ewondo Libert. This was done after finding the previously missing holotype of B. makomensis (Strand), which clearly belongs to the same species and thereby gives the older name priority. The phylogeny showed that some distinctly different species were surprisingly closely related, suggesting a high rate of morphological evolution in parts of the sciathis group. The distributional records for the group are updated after investigating over 1700 specimens kept in a range of museum collections. Many species previously thought to be broadly sympatric were found to have much more restricted ranges, with the previous overestimations probably based on misidentified specimens. The higher level of allopatry now established will make identification of many morphologically similar species easier. The fact that species often have smaller ranges than previously known, meaning that the level of endemism for African butterflies is likely to be higher than current estimates, has important implications for conservation management. An identification key for males of all 13 currently recognized species in the species group is included. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:837A9D4C-779A-4497-8176-7151D409DFA5.

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