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1.
Biol Lett ; 17(3): 20200620, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33726565

RESUMO

Fisher's principle states that natural selection favours an equal number of male and female births at the population level, unless there are sex differences in rearing costs or sex differences in mortality before the end of the period of parental investment. Sex differences in rearing costs should be more pronounced in low- than in high-resource settings. We, therefore, examined whether human development index and sex differences in child mortality contribute to the natural variation in human sex ratio at birth across the globe. As predicted by Fisher's principle, the proportion of male births increased with both increasing male-biased childhood mortality and level of development of each country. However, these relationships were absent after accounting for spatial autocorrelation in the residuals, which our inference is conditioned on. This work shows how the failure to account for residual spatial autocorrelation can lead to incorrect conclusions regarding support for predictions from sex allocation theory.


Assuntos
Seleção Genética , Razão de Masculinidade , Criança , Feminino , Humanos , Masculino , Caracteres Sexuais
2.
Oecologia ; 195(4): 915-925, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33786708

RESUMO

Trivers and Willard proposed that female mammals should adjust their investment in male versus female offspring relative to their ability to produce high-quality offspring. We tested whether litter size-sex ratio trade-offs predicted by Adaptive Sex Allocation (ASA) theory occur among Richardson's ground squirrel (Urocitellus richardsonii) dams over 10 distinct breeding years in a population where individuals experienced variability in food availability and habitat disruption. Litters of primiparous dams became increasingly female-biased with increasing litter size, but that trend waned among second litters born to dams, and reversed among third litters, with larger litters becoming more male-biased, suggesting that ASA is a product of interacting selection pressures. Trade-offs were not associated with habitat disruption, the availability of supplementary food, or dam age. An association between habitat disruption and male-biased sex ratios, the prevalence of litter size-sex ratio trade-offs and placental scar counts exceeding the number of juveniles at weaning in our population, but not in a geographically distinct population of conspecifics exposed to different environmental conditions reveal that the expression of ASA varies among populations and among years within populations, illustrating the conditional nature of ASA.


Assuntos
Sciuridae , Razão de Masculinidade , Animais , Feminino , Tamanho da Ninhada de Vivíparos , Masculino , Gravidez , Desmame
3.
Environ Pollut ; 277: 116864, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33714788

RESUMO

Sex determination is a complex process that can be influenced by environment in various taxa. Disturbed environments can affect population sex ratios and thus threaten their viability. Emerging evidences support a role of epigenetic mechanisms, notably DNA methylation, in environmental sex determination (ESD). In this work, using zebrafish as model and a transgenerational experiment comprising 4 successive generations, we report a strength link between the promotor methylation level of three genes in female gonads and population sex ratio. One generation of zebrafish was exposed throughout its lifetime to cadmium (Cd), a non-essential metal, at an environmentally relevant concentration. The subsequent generations were not exposed. At the first and the third generation a subset of individuals was exposed to an elevated temperature, a well-known masculinizing factor in zebrafish. While heat was associated to an increase in the methylation level of cyp19a1a gene and population masculinization, foxl2a/dmrt1 methylation levels appeared to be influenced by Cd and fish density leading to offspring feminization. Ancestral Cd exposure indeed led to a progressive feminization of the population over generations and affected the sex plastic response of zebrafish in response to heat. The effect of Cd on the methylation level of foxl2a was observed until the third generation, supporting potential transgenerational inheritance. Our results support (i) a key role of cyp19a1a methylation in SD in zebrafish in response to environmental cues and (ii) the fact that the environment experienced by parents, namely mothers in the present case, can affect their offspring sex ratio via environment-induced DNA methylation changes in gonads.


Assuntos
Razão de Masculinidade , Peixe-Zebra , Animais , Metilação de DNA , Epigênese Genética , Feminino , Gônadas/metabolismo , Humanos , Masculino , Peixe-Zebra/genética
4.
Bull Environ Contam Toxicol ; 106(5): 740-746, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33710386

RESUMO

Benzophenone-3 (BP-3) is an important ultraviolet (UV)-screening agent using in cosmetics, however, the associated environmental pollution and the toxicity to organisms, particularly aquatic organisms, cannot be neglected. In this study, the potential risks posed to zebrafish when exposed to environmental residual concentrations of BP-3 were evaluated. Zebrafish embryos (F0) were exposed to 0, 0.056, 2.3, and 38 µg/L BP-3 until 42 days' post-fertilization (dpf). The effects of BP-3 on the sex ratio and gene expression of F0 zebrafish were investigated. In the F1 embryos, cumulative hatching rate, body length, and heartbeats were observed. The result showed that F0 and F1 exposure to concentrations of 0.056 and 38 µg/L BP-3 elicited stronger toxicity at 96 hpf than single generation exposures. Overall, our results provide a new understanding on the effects of low BP-3 concentration chronic exposure on sex ratio and offspring developmental toxicity of the F0 zebrafish.


Assuntos
Poluentes Químicos da Água , Peixe-Zebra , Animais , Benzofenonas/toxicidade , Embrião não Mamífero , Razão de Masculinidade , Poluentes Químicos da Água/toxicidade
5.
J Infect Public Health ; 14(4): 437-443, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33743364

RESUMO

BACKGROUND: The aim of this study is to describe the clinical and demographic characteristics of COVID-19 patients, and the risk factors associated with death in Saudi Arabia to serve as a reference to further understand this pandemic and to help in the future decisions and control of this global crisis. METHODS: This multicenter, retrospective, observational, cross-sectional study was conducted on 240,474 patients with confirmed COVID-19 in Saudi Arabia. Data was collected retrospectively through the Health Electronic Surveillance Network at the Ministry of Health. Patients were classified based on their outcome as recovered, dead, or active with no definite outcome. We must specify the date period. RESULTS: As of 20th of June 2020, 79.7% of COVID-19 cases were young and middle-aged, ranging between 20-59 years. There was evidently a difference in the sex ratio, where males constituted 71.7% of cases. The majority were non-Saudi nationals, representing 54.7% of cases. Furthermore, the contraction of COVID-19 was travel-related in 45.1% of cases. Signs and symptoms were reported in 63% of cases, the most common of which were fever; 85.2%, and cough; 85%. Deaths occurred more frequently in patients 40-49 years, 50-59 years, and 60-69 years, representing 19.2%, 27.9%, and 21.3% of deaths, respectively. Additionally, the case fatality rate (CFR) was higher in older age-groups, reaching 10.1% in those ≥80 years. Moreover, the CFR of males was higher than that of females, with 0.95% and 0.62%, respectively. As for nationality, Saudis had a CFR of 0.46% versus 1.19% in non-Saudis. CONCLUSION: The total number of positive COVID-19 cases detected constitute 0.7% of the Saudi population to date. Older age, non-Saudi nationalities, being male, travelling outside Saudi Arabia, and the presence of symptoms, as opposed to being asymptomatic were considered risk factors and found to be significantly more associated with death in patients with COVID-19.


Assuntos
/epidemiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco , Arábia Saudita/epidemiologia , Razão de Masculinidade , Viagem , Adulto Jovem
6.
Aging (Albany NY) ; 13(3): 3190-3201, 2021 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-33550276

RESUMO

Males are at a higher risk of dying from COVID-19 than females. Older age and cardiovascular disease are also associated with COVID-19 mortality. To better understand how age and sex interact in contributing to COVID-19 mortality, we stratified the male-to-female (sex) ratios in mortality by age group. We then compared the age-stratified sex ratios with those of cardiovascular mortality and cancer mortality in the general population. Data were obtained from official government sources in the US and five European countries: Italy, Spain, France, Germany, and the Netherlands. The sex ratio of deaths from COVID-19 exceeded one throughout adult life, increasing up to a peak in midlife, and declining markedly in later life. This pattern was also observed for the sex ratio of deaths from cardiovascular disease, but not cancer, in the general populations of the US and European countries. Therefore, the sex ratios of deaths from COVID-19 and from cardiovascular disease share similar patterns across the adult life course. The underlying mechanisms are poorly understood and warrant further investigation.


Assuntos
Doenças Cardiovasculares , Mortalidade , Medição de Risco , Adulto , Fatores Etários , Idoso , /mortalidade , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/mortalidade , Europa (Continente)/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Razão de Chances , Medição de Risco/métodos , Medição de Risco/estatística & dados numéricos , Razão de Masculinidade
7.
BMC Ecol Evol ; 21(1): 16, 2021 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-33541263

RESUMO

BACKGROUND: One of the dangers of global climate change to wildlife is distorting sex ratios by temperature-induced sex reversals in populations where sex determination is not exclusively genetic, potentially leading to population collapse and/or sex-determination system transformation. Here we introduce a new concept on how these outcomes may be altered by mate choice if sex-chromosome-linked phenotypic traits allow females to choose between normal and sex-reversed (genetically female) males. RESULTS: We developed a theoretical model to investigate if an already existing autosomal allele encoding preference for sex-reversed males would spread and affect demographic and evolutionary processes under climate warming. We found that preference for sex-reversed males (1) more likely spread in ZW/ZZ than in XX/XY sex-determination systems, (2) in populations starting with ZW/ZZ system, it significantly hastened the transitions between different sex-determination systems and maintained more balanced adult sex ratio for longer compared to populations where all females preferred normal males; and (3) in ZW/ZZ systems with low but non-zero viability of WW individuals, a widespread preference for sex-reversed males saved the populations from early extinction. CONCLUSIONS: Our results suggest that climate change may affect the evolution of mate choice, which in turn may influence the evolution of sex-determination systems, sex ratios, and thereby adaptive potential and population persistence. These findings show that preferences for sex-linked traits have special implications in species with sex reversal, highlighting the need for empirical research on the role of sex reversal in mate choice.


Assuntos
Mudança Climática , Razão de Masculinidade , Feminino , Humanos , Masculino , Fenótipo , Temperatura , Virilismo
8.
Proc Biol Sci ; 288(1943): 20202819, 2021 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-33467998

RESUMO

Sex determination and differentiation in reptiles is complex. Temperature-dependent sex determination (TSD), genetic sex determination (GSD) and the interaction of both environmental and genetic cues (sex reversal) can drive the development of sexual phenotypes. The jacky dragon (Amphibolurus muricatus) is an attractive model species for the study of gene-environment interactions because it displays a form of Type II TSD, where female-biased sex ratios are observed at extreme incubation temperatures and approximately 50 : 50 sex ratios occur at intermediate temperatures. This response to temperature has been proposed to occur due to underlying sex determining loci, the influence of which is overridden at extreme temperatures. Thus, sex reversal at extreme temperatures is predicted to produce the female-biased sex ratios observed in A. muricatus. The occurrence of ovotestes during development is a cellular marker of temperature sex reversal in a closely related species Pogona vitticeps. Here, we present the first developmental data for A. muricatus, and show that ovotestes occur at frequencies consistent with a mode of sex determination that is intermediate between GSD and TSD. This is the first evidence suggestive of underlying unidentified sex determining loci in a species that has long been used as a model for TSD.


Assuntos
Lagartos , Processos de Determinação Sexual , Animais , Feminino , Lagartos/genética , Análise para Determinação do Sexo , Processos de Determinação Sexual/genética , Razão de Masculinidade , Temperatura
9.
Proc Biol Sci ; 288(1943): 20202125, 2021 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-33468006

RESUMO

According to evolutionary theory, sex ratio distortions caused by reproductive parasites such as Wolbachia and Spiroplasma are predicted to be rapidly normalized by the emergence of host nuclear suppressors. However, such processes in the evolutionary arms race are difficult to observe because sex ratio biases will be promptly hidden and become superficially unrecognizable. The evolution of genetic suppressors has been reported in just two insect species so far. In the small brown planthopper, Laodelphax striatellus, female-biases caused by Spiroplasma, which is a 'late' male-killer, have been found in some populations. During the continuous rearing of L. striatellus, we noted that a rearing strain had a 1 : 1 sex ratio even though it harboured Spiroplasma. Through introgression crossing experiments with a strain lacking suppressors, we revealed that the L. striatellus strain had the zygotic male-killing suppressor acting as a dominant trait. The male-killing phenotype was hidden by the suppressor even though Spiroplasma retained its male-killing ability. This is the first study to demonstrate the existence of a late male-killing suppressor and its mode of inheritance. Our results, together with those of previous studies, suggest that the inheritance modes of male-killing suppressors are similar regardless of insect order or early or late male killing.


Assuntos
Hemípteros , Spiroplasma , Wolbachia , Animais , Feminino , Hemípteros/genética , Homicídio , Masculino , Razão de Masculinidade
10.
Ecol Lett ; 24(4): 862-875, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33471386

RESUMO

Animals often need to invest significantly in mating behaviour in order to successfully mate. However, the expression of mating behaviour can be costly, especially in unfavourable environments, so animals are expected to adjust their behaviour in a context-dependent way to mitigate these costs. I systematically searched the literature for studies measuring animal mating behaviour (sexual signalling, response to sexual signals or the strength of mate choice) in more than one environment, and used a phylogenetically controlled meta-analysis to identify environmental factors influencing these behaviours. Across 222 studies, the strength of mate choice was significantly context-dependent, and most strongly influenced by population density, population sex ratio and predation risk. However, the average effect sizes were typically small. The amount of sexual signalling and the strength of response to sexual signals were not significantly related to the environment. Overall, this suggests that the evidence for context-dependent mating behaviour across animals is surprisingly weak.


Assuntos
Preferência de Acasalamento Animal , Comportamento Sexual Animal , Animais , Reprodução , Razão de Masculinidade
11.
PLoS One ; 16(1): e0243478, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33395404

RESUMO

This study provides regional-scale data on drivers of horseshoe crab (Limulus polyphemus) presence along the northcentral Gulf of Mexico coast and has implications for understanding habitat suitability for sparse horseshoe crab populations of conservation concern worldwide. To collect baseline data on the relationship between environmental factors and presence of horseshoe crabs, we surveyed four sites from the Fort Morgan peninsula of Mobile Bay, Alabama (AL) to Horn Island, Mississippi (MS). We documented number, size and sex of live animals, molts, and carcasses as metrics of horseshoe crab presence and demographics for two years. Data were compared to in situ and remotely sensed environmental attributes to assess environmental drivers of occurrence during the time of study. Overall, greater evidence of horseshoe crab presence was found at western sites (Petit Bois and Horn Islands) compared to eastern sites (Dauphin Island, Fort Morgan peninsula), mediated by a combination of distance from areas of high freshwater discharge and interannual variation in weather. Higher sex ratios also were found associated with higher occurrence, west of Mobile Bay. Land cover, particularly Bare Land and Estuarine Emergent Wetland classes that are common to western sites, was most predictive of live animal and to some extent carcass occurrence. Our findings suggest that small-scale variation in habitat quality can affect occurrence of horseshoe crabs in sparse populations where density is not a limiting factor. Data from molts and carcasses were informative to supplement live animal data and may be useful to enhance ecological assessment and support conservation and management in regions with sparse populations.


Assuntos
Meio Ambiente , Caranguejos Ferradura/fisiologia , Animais , Baías , Tamanho Corporal , Clima , Geografia , Golfo do México , Caranguejos Ferradura/anatomia & histologia , Modelos Lineares , Rios , Razão de Masculinidade , Inquéritos e Questionários , Fatores de Tempo
12.
Pest Manag Sci ; 77(5): 2530-2538, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33470514

RESUMO

BACKGROUND: Resistant populations of Ae. aegypti have been a major problem in arboviruses epidemic areas, generating a strong demand for novel methods of vector control. In this regard, our group has demonstrated the use of curcumin as an efficient photoactive larvicide to eliminate Ae. aegypti larvae. This work was aimed to evaluate the Ae. aegypti (Rockefeller) development under sublethal conditions, using a curcumin/d-mannitol (DMC) formulation. The photolarvicidal efficacy under semi-field and field conditions (wild populations) was also analyzed, as well as the photobleaching and residual activity of DMC. RESULTS: A delay in development time when larvae were exposed to sublethal concentrations of DMC was observed, followed by significant changes in sex ratio and reduction in longevity. DMC also presented a low residual activity when compared to usual larvicides, and had a substantial photolarvicidal activity against wild populations in field trials, achieving 71.3% mortality after 48 h. CONCLUSIONS: Overall, these findings are of great biological importance for the process of enabling the implementation of DMC as a new product in the control of Ae. aegypti larvae, and contributes to the improvement of new plant-based larvicides. © 2021 Society of Chemical Industry.


Assuntos
Aedes , Curcumina , Inseticidas , Animais , Inseticidas/farmacologia , Larva , Manitol , Mosquitos Vetores , Razão de Masculinidade
13.
Oecologia ; 195(1): 65-75, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33392790

RESUMO

Although ecological disturbances can have a strong influence on pollinators through changes in habitat, virtually no studies have quantified how characteristics of wildfire influence the demography of essential pollinators. Nevertheless, evaluating this topic is critical for understanding how wildfire is linked to pollinator population dynamics, particularly given recent changes in wildfire frequency and severity in many regions of the world. In this study, we measured the demographic response of the blue orchard bee (Osmia lignaria) across a natural gradient of wildfire severity to assess how variation in wildfire characteristics influenced reproductive output, offspring sex ratio, and offspring mass. We placed nest blocks with a standardized number and sex ratio of pre-emergent adult bees across the wildfire gradient, finding some evidence for a positive but highly variable relationship between reproductive output and fire severity surrounding the nest site at both local (100 m) and landscape (750 m) scales. In addition, the production of female offspring was > 10% greater at nest sites experiencing the greatest landscape-scale fire severity relative to the lowest-severity areas. The finding that blue orchard bees biased offspring production towards the more expensive offspring sex with increasing fire severity shows a functional response to changes in habitat quality through increased density of flowering plants. Our findings indicate that burned mixed-conifer forest provides forage for the blue orchard bee across a severity gradient, and that the increase in floral resources that follows high-severity fire leads females to shift resource allocation to the more costly sex when nesting.


Assuntos
Fogo , Incêndios Florestais , Animais , Abelhas , Ecossistema , Feminino , Reprodução , Razão de Masculinidade
14.
Bull Entomol Res ; 111(3): 348-356, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33345769

RESUMO

Parasitoids can be used as biological agents of pest control. Anagyrus saccharicola Timberlake (Hymenoptera: Encyrtidae) is a parasitoid of the pink sugarcane mealybug Saccharicoccus sacchari (Cockerell) (Hemiptera: Pseudococcidae). Although this mealybug is present in all sugarcane-producing countries, there is limited information regarding this pest and its parasitoid. Aiming to elucidate information on bioecological parameters of A. saccharicola, were evaluated the survival of parasitoid females and males at three temperatures, the host preference of the parasitoid, and the fecundity and longevity of the host. In addition, the parasitism rate of A. saccharicola was estimated based on three factors, feeding, mating, and time. Survival was evaluated at 20, 25, and 30°C. Host preference was conducted on 15-, 20-, and 30-day-old mealybugs. And the parasitism rate was evaluated in fed and unfed, mated and unmated parasitoids and with 24 h and newly emerged. The temperature of 20°C was the most favorable for parasitoid survival. Parasitism occurred at all evaluated ages of the mealybug; however, the preference was for those that were 30-days-old. The parasitized mealybugs longevity was approximately 8 additional days after parasitization, and non-parasitized mealybugs lived for an additional 20 days for mealybugs aged 30 and 20 days at the outset of the tests, and a further 13 days for the 15 days. Feeding and mating after 24 h of emergence resulted in a higher parasitism rate. These findings can contribute to more efficient rearing of A. saccharicola and in the planning of the biological control of S. sacchari in the integrated pest management programs.


Assuntos
Hemípteros/parasitologia , Controle Biológico de Vetores/métodos , Vespas/fisiologia , Animais , Produtos Agrícolas , Fertilidade/fisiologia , Interações Hospedeiro-Parasita , Longevidade/fisiologia , Parasitos/fisiologia , Saccharum , Razão de Masculinidade , Especificidade da Espécie , Temperatura
15.
Biochem Biophys Res Commun ; 535: 6-11, 2021 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-33340766

RESUMO

No effective cryopreservation technique exists for fish eggs and embryos; thus, the cryopreservation of germ cells (spermatogonia or oogonia) and subsequent generation of eggs and sperm would be an alternative solution for the long-term preservation of piscine genetic resources. Nevertheless, in our previous study using rainbow trout, we showed that recipients transplanted with XY spermatogonia or XX oogonia produced unnatural sex-biased F1 offspring. To overcome these obstacles, we transplanted immature germ cells (XX oogonia or XY spermatogonia; frozen for 33 days) into the body cavities of triploid hatchlings, and the transplanted germ cells possessed a high capacity for differentiating into eggs and sperm in the ovaries and testes of recipients. Approximately 30% of triploid recipients receiving frozen germ cells generated normal salmon that displayed the donor-derived black body color phenotype, although all triploid salmon not receiving transplants were functionally sterile. Furthermore, F1 offspring obtained from insemination of the oogonia-derived eggs and spermatogonia-derived sperm show a normal sex ratio of 1:1 (female:male). Thus, this method presented a critical technique for practical conservation projects for other teleost fish species and masu salmon.


Assuntos
Criopreservação/métodos , Oncorhynchus/crescimento & desenvolvimento , Oogônios/citologia , Oogônios/transplante , Óvulo/citologia , Espermatogônias/citologia , Espermatogônias/transplante , Espermatozoides/citologia , Envelhecimento , Animais , Diferenciação Celular , Conservação dos Recursos Naturais/métodos , Feminino , Células Germinativas , Masculino , Oncorhynchus/embriologia , Oogônios/metabolismo , Óvulo/metabolismo , Razão de Masculinidade , Espermatogônias/metabolismo , Espermatozoides/metabolismo , Triploidia
16.
Aquat Toxicol ; 231: 105722, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33360311

RESUMO

The current study investigated the effect of environmentally relevant mixtures of estrogens at levels representative of receiving waters on the metabolome of the Sydney rock oyster, Saccostrea glomerata. Oysters were exposed to a "low" and a "high" mixture of (xeno) estrogens (representative of Australian and global receiving waters respectively) for 7 days and digestive gland, gill, and gonad tissue were sampled for quantification of polar metabolites by 1H NMR spectroscopy. Exposure to both mixtures lowered body mass and altered the metabolite profile in the digestive glands. Comparatively, gills, and ovaries demonstrated lesser sensitivity to the mixtures, with significant metabolomic alterations observed only for the high mixture. The male gonad did not respond to either estrogenic exposure. In the responsive tissues, major metabolites including amino acids, carbohydrates, intermediates of the tricarboxylic acid cycle and ATP were all down-regulated and exhibited tissue-specific patterns of down-regulation with the greatest proportion of metabolites down-regulated due to estrogenic exposure in the digestive gland. Exposure to (xeno) estrogen mixtures representative of concentrations reported in receiving waters in Australia and globally can impact the metabolome and associated energy metabolism, especially in the digestive gland, translating to lower pools of available ATP energy for potential cellular homeostasis, somatic maintenance and growth, reproduction and fitness.


Assuntos
Exposição Ambiental , Estrogênios/toxicidade , Metaboloma/efeitos dos fármacos , Especificidade de Órgãos , Ostreidae/metabolismo , Animais , Austrália , Peso Corporal/efeitos dos fármacos , Ciclo do Ácido Cítrico/efeitos dos fármacos , Feminino , Glicólise/efeitos dos fármacos , Masculino , Metabolômica , Ostreidae/efeitos dos fármacos , Ovário/efeitos dos fármacos , Ovário/metabolismo , Razão de Masculinidade , Testículo/efeitos dos fármacos , Testículo/metabolismo , Poluentes Químicos da Água/toxicidade
17.
Proc Biol Sci ; 287(1934): 20201377, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32900311

RESUMO

Ever since Darwin's discovery of natural selection, we expect traits to evolve to increase organisms' fitness. As a result, we can use optimization models to make a priori predictions of phenotypic variation, even when selection is frequency-dependent. A notable example is the prediction of female-biased sex ratios resulting from local mate competition (LMC) and inbreeding. LMC models incorporate the effects of LMC and inbreeding. Fig wasp sex ratio adjustments fit LMC predictions well. However, the appropriateness of LMC models to fig wasps has been questioned, and the role that a coincidental by-product plays in creating the apparent fit has been clearly illustrated. Here, we show that the sex ratio adjustments of a fig wasp are the result of a dual mechanism. It consists of a standard facultative LMC response favoured by natural selection, as well as a mechanism that may be the result of selection, but that could also be a coincidental by-product. If it is a by-product, the fitness increase is coincidental and natural selection's role was limited to fine-tuning it for higher fitness returns. We further document a case of an apparent fitness-reducing sex ratio adjustment. We conclude that the use of the adaptationist approach demands that our understanding of traits must be remodelled continually to rectify spurious assumptions.


Assuntos
Seleção Genética , Comportamento Sexual Animal/fisiologia , Vespas/fisiologia , Animais , Feminino , Masculino , Razão de Masculinidade
19.
PLoS One ; 15(8): e0236249, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32804964

RESUMO

BACKGROUND: The insect predator Coccinella septempunctata can effectively control many types of pests, such as aphids, whiteflies, and small lepidopteran larvae. We previously found that C. septempunctata fed an artificial diet showed diminished biological properties(e.g. fecundity, egg hatching rate, survival rate, etc.) compared with those fed natural prey (Aphis craccivora), likely due to different nutritional characteristics of the diet. In this study, we used transcriptome sequencing analysis to identify nutrition- and metabolism-related genes of C. septempunctata that were differentially expressed depending on diet. METHODOLOGY/PRINCIPAL FINDINGS: The Illumina HiSeq2000 was used to sequence 691,942,058 total clean reads from artificial diet-fed and A. craccivora-fed C. septempunctata libraries, and the clean reads were assembled using Trinity de novo software (Tabel 2). Comparison of transcriptome sequences revealed that expression of 38,315 genes was affected by the artificial diet, and 1,182 of these genes showed a significant change in expression levels (FDR ≤ 0.05,|log2FC|≥1, "FC" stands for "fold change"). These differentially expressed genes (DEGs) were likely associated with the decreased egg laying capacity, hatching rate, longevity, and increased sex ratio (♀:♂) of adult C. septempunctata observed in the group fed the artificial diet. Furthermore, in the most DEGs metabolic pathways for C. septempunctata feeding on the artificial diet accumulated amino acid metabolic pathways, lipid metabolic pathways, and starch and glucose metabolism were down-regulated. CONCLUSIONS/SIGNIFICANCE: We found some differentially expressed genes and metabolic pathways are related to nutrition, from which a more informative feedback for diet formulation was obtained and the artificial diet could be more efficiently optimized.


Assuntos
Fenômenos Fisiológicos da Nutrição Animal/genética , Afídeos , Besouros/fisiologia , Genes de Insetos , Comportamento Predatório/fisiologia , Aminoácidos/metabolismo , Animais , Regulação para Baixo , Fertilidade/fisiologia , Perfilação da Expressão Gênica , Glucose/metabolismo , Metabolismo dos Lipídeos/genética , Longevidade/fisiologia , Redes e Vias Metabólicas/genética , Controle Biológico de Vetores/métodos , Razão de Masculinidade , Amido/metabolismo , Sequenciamento Completo do Exoma
20.
BMC Evol Biol ; 20(1): 103, 2020 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-32807071

RESUMO

BACKGROUND: Vertebrates exhibit diverse sex determination systems and reptiles stand out by having highly variable sex determinations that include temperature-dependent and genotypic sex determination (TSD and GSD, respectively). Theory predicts that populations living in either highly variable or cold climatic conditions should evolve genotypic sex determination to buffer the populations from extreme sex ratios, yet these fundamental predictions have not been tested across a wide range of taxa. RESULTS: Here, we use phylogenetic analyses of 213 reptile species representing 38 families (TSD = 101 species, GSD = 112 species) and climatic data to compare breeding environments between reptiles with GSD versus TSD. We show that GSD and TSD are confronted with the same level of climatic fluctuation during breeding seasons. However, TSD reptiles are significantly associated with warmer climates. We found a strong selection on the breeding season length that minimises exposure to cold and fluctuating climate. Phylogenetic path analyses comparing competing evolutionary hypotheses support that transitions in sex determination systems influenced the ambient temperature at which the species reproduces and nests. In turn, this interaction affects other variables such as the duration of the breeding season and life-history traits. CONCLUSIONS: Taken together, our results challenge long-standing hypotheses about the association between sex determination and climate variability. We also show that ambient temperature is important during breeding seasons and it helps explain the effects of sex determination systems on the geographic distribution of extant reptile species.


Assuntos
Clima , Répteis/fisiologia , Processos de Determinação Sexual , Temperatura , Animais , Cruzamento , Filogenia , Répteis/genética , Processos de Determinação Sexual/genética , Razão de Masculinidade
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