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1.
PLoS One ; 15(4): e0232282, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32352998

RESUMO

The magnitude and distribution of genetic diversity through space and time can provide useful information relating to evolutionary potential and conservation status in threatened species. In assessing genetic diversity in species that are of conservation concern, several studies have focused on the use of Toll-like receptors (TLRs). TLRs are innate immune genes related to pathogen resistance, and polymorphisms may reflect not only levels of functional diversity, but may also be used to assess genetic diversity within and among populations. Here, we combined four potentially adaptive markers (TLRs) with one mitochondrial (COI) marker to evaluate genetic variation in the endangered Sierra Madre Sparrow (Xenospiza baileyi). This species offers an ideal model to investigate population and evolutionary genetic processes that may be occurring in a habitat restricted endangered species with disjunct populations (Mexico City and Durango), the census sizes of which differ by an order of magnitude. TLRs diversity in the Sierra Madre Sparrow was relatively high, which was not expected given its two small, geographically isolated populations. Genetic diversity was different (but not significantly so) between the two populations, with less diversity seen in the smaller Durango population. Population genetic structure between populations was due to isolation and different selective forces acting on different TLRs; population structure was also evident in COI. Reduction of genetic diversity in COI was observed over 20 years in the Durango population, a result likely caused by habitat loss, a factor which may be the main cause of diversity decline generally. Our results provide information related to the ways in which adaptive variation can be altered by demographic changes due to human-mediated habitat alterations. Furthermore, our findings may help to guide conservation schemes for both populations and their restricted habitat.


Assuntos
Polimorfismo Genético/genética , Pardais/genética , Animais , Evolução Biológica , Conservação dos Recursos Naturais/métodos , Ecossistema , Espécies em Perigo de Extinção , Genética Populacional/métodos , Repetições de Microssatélites/genética , Filogenia
2.
Aust Vet J ; 98(7): 338-344, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32430906

RESUMO

CASE REPORT: An outbreak of systemic isosporosis caused mortalities in greenfinches (Carduelis chloris) and goldfinches (Carduelis carduelis) kept in an aviary in the western suburbs of Melbourne. The following year, a further outbreak in the same aviary occurred in a different flock of goldfinches. At the time of the second outbreak, dead and sick common sparrows (Passer domesticus) discovered near the aviary were also found to have systemic isosporosis. METHOD: The systemic isosporosis was investigated and described using histopathology, electron microscopy and sequence analysis of the 18s gene. RESULTS: Isospora spp. infecting the greenfinch and the goldfinch caused significant thickening of the duodenal lamina propria. Measurements in the goldfinches showed an inverse correlation coefficient between the thickening of the duodenum and the weightof the birds. Electron microscopy confirmed the presence of Isospora spp. within lymphocytes migrating into the lamina propria of the duodenum. Analysis of the 18s sequence discovered two different gene sequences across the three species of birds that didn't completely match any sequences previously deposited in GenBank. CONCLUSION: Although the sparrows were found to have died from causes other than systemic Isospora, molecular studies of samples from their liver revealed the presence of an Isospora with 18s gene sequence identical to that found in the captive greenfinches.


Assuntos
Doenças das Aves/epidemiologia , Isospora , Pardais , Animais , Surtos de Doenças
3.
Sci Total Environ ; 720: 137583, 2020 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-32325582

RESUMO

In marine species, the transcriptomic response to Deepwater Horizon (DWH) oil implicated many biochemical pathways, with corresponding adverse outcomes on organ development and physiological performance. Terrestrial organisms differ in their mechanisms of exposure to polycyclic aromatic hydrocarbons (PAHs) and their physiological challenges, and may reveal either distinct effects of oil on biochemical pathways or the generality of the responses to oil shown in marine species. Using a cross-species hybridization microarray approach, we investigated the transcriptomic response in the liver of Seaside Sparrows (Ammospiza maritima) exposed to DWH oil compared with birds from a control site. Our analysis identified 295 genes differentially expressed between birds exposed to oil and controls. Gene ontology (GO) and canonical pathway analysis suggested that the identified genes were involved in a coordinated response that promoted hepatocellular proliferation and liver regeneration while inhibiting apoptosis, necrosis, and liver steatosis. Exposure to oil also altered the expression of genes regulating energy homeostasis, including carbohydrate metabolism and gluconeogenesis, and the biosynthesis, transport and metabolism of lipids. These results provide a molecular mechanism for the long-standing observation of hepatic hypertrophy and altered lipid biosynthesis and transport in birds exposed to crude oil. Several of the activated pathways and pathological outcomes shown here overlap with the ones altered in fish species upon exposure to oil. Overall, our study shows that the path of oil contamination from the marine system into salt marshes can lead to similar responses in terrestrial birds to those described in marine organisms, suggesting similar adverse outcomes and shared machinery for detoxification.


Assuntos
Pardais , Animais , Perfilação da Expressão Gênica , Golfo do México , Petróleo , Poluição por Petróleo , Hidrocarbonetos Policíclicos Aromáticos , Poluentes Químicos da Água
4.
Int J Biometeorol ; 64(8): 1285-1293, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32328788

RESUMO

Increasing evidence suggests that the environment encountered by migrating landbirds during the nonbreeding season, including temperature and precipitation, may influence individuals and population processes in subsequent seasons. However, to date, most studies have focused on linkages between factors encountered during the wintering and breeding periods in long-distance, primarily insectivorous landbirds. Here, we take advantage of a long-term (23 breeding seasons) data set on the arrival and breeding ecology of female field sparrows (Spizella pusilla), a granivorous, short-distance species that winters in the southeastern USA, to look for time periods (windows) over the preceding winter and spring migratory periods when average daily precipitation or temperature may have influenced when a female arrived at breeding grounds in northeastern Pennsylvania and correlates of seasonal reproductive performance. We employed a sliding window analysis approach using weather data obtained from the south of our site (to evaluate effects of weather experienced during the nonbreeding period) and, separately, near our site (to evaluate effects of weather experienced during the breeding period), finding windows in which temperature and precipitation during the nonbreeding period were associated with arrival timing and clutch initiation day and a window in which temperature experienced during the breeding period was associated with clutch initiation day. We did not, however, find evidence that temperature or precipitation, either during the nonbreeding period or breeding period, was associated with clutch size nor total egg volume. Finally, early arriving females initiated clutches early, produced larger clutches, more nests, and more total eggs than later arriving females. Our findings contribute to the growing body of evidence that events experienced prior to the breeding season may influence individuals and population processes in subsequent seasons.


Assuntos
Migração Animal , Pardais , Animais , Cruzamento , Feminino , Pennsylvania , Reprodução , Estações do Ano , Tempo (Meteorologia)
5.
Ecotoxicol Environ Saf ; 197: 110622, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32311616

RESUMO

Sperm morphology and performance traits are key determinants of male fertilization success, particularly when females copulate with multiple males. Such sperm traits have been reported to be influenced by environmental pollutants in various animals; however, such studies remain rare in free-living birds exposed to heavy metal pollution. In the present study, we selected tree sparrow (Passer montanus) as the study object to explore the effect of long-term environmental heavy metal pollution on sperm morphology (assessed mainly by using the dimensions of different sperm components and the sperm abnormality rates) and sperm performance (indicated by sperm velocity), and to elucidate potential relationships between variations in sperm morphology and performance. Sperm ATP concentration was also assessed considering sperm morphology and performance could be linked via energy availability. According to our results, tree sparrows from heavy metal polluted area (1) accumulated cadmium at a higher level in their testes; (2) produced longer sperm with lower abnormality rates, in addition to sperm with longer flagella and smaller head/flagellum ratios; (3) their sperm swam faster compared to those from the relatively unpolluted area, while no differences were observed in sperm ATP concentrations. We also found that the levels of lead and cadmium in testes affected the sperm nucleus length, and the level of copper in testes was negatively related to the proportions of abnormal sperm. Furthermore, the present study showed that sperm velocity was negatively correlated with sperm head lengths, head/flagellum ratios and ATP concentrations. Our study results reveal that sperm morphology and performance in tree sparrows show positive variations to maximize male fertility ability under long-term environmental heavy metal pollution, where males increase sperm flagellum lengths to decrease head/flagellum ratios, as opposed to varying sperm energy production, to achieve higher sperm velocity.


Assuntos
Poluentes Ambientais/toxicidade , Metais Pesados/toxicidade , Pardais/crescimento & desenvolvimento , Espermatozoides/efeitos dos fármacos , Animais , Cádmio/toxicidade , Feminino , Fertilidade/efeitos dos fármacos , Masculino , Motilidade Espermática/efeitos dos fármacos , Espermatozoides/patologia
6.
Sci Total Environ ; 721: 137674, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32163734

RESUMO

Anthropogenic metal pollution is known to adversely affect bird reproduction; however, few systematic studies are available on the effects of metal pollution on breeding performance and parental investment in a common resident songbird, the tree sparrow (Passer montanus). We conducted this study in two sites, a long-term heavy metal polluted site (Baiyin [BY]) and a relatively unpolluted site at approximately 110 km distance (Liujiaxia [LJX]), to assess the potential effects of environmental metal contamination on breeding parameters (clutch size, hatching success, fledging success, and growth of nestlings) and parental investment. The results showed smaller clutch size, lower fledging success, and differences in incubation behaviors of tree sparrows in BY than in LJX. Although there was no difference in parental body condition (residual body mass) between the two study sites, the parents responded differently with respect to reproduction due to varying metal levels in their habitats and bodies. Higher Cd levels in the primary feathers of females in BY were associated with lower clutch sizes. Parental investment including incubation duration and feeding rates showed no significant difference between the two sites during the incubation and nestling periods, but the frequencies of incubation visits were higher in BY. Parental behavior during the incubation period was also negatively affected by the parental Pb and Cd levels. Although the nestling growth patterns were relatively similar between the two sites, the nestlings were smaller, had lower body weight, and fledged later and fledging rate was also lower in BY than in LJX. Metal concentrations were higher in nestling organs and feces in BY. Taken together, metal pollution might adversely affect nestling growth condition. Our results suggest a negative response in the reproduction of tree sparrows to long-term environmental metal pollution.


Assuntos
Metais Pesados/análise , Pardais , Animais , Cruzamento , Poluição Ambiental/análise , Feminino , Reprodução
7.
Environ Pollut ; 263(Pt B): 114396, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32222667

RESUMO

Genetic diversity is the bedrock of evolution. The "Genetic Erosion" hypothesis posits that environmental pollution could cause reduced genetic diversity. To explore the effects of heavy metal pollution on genetic diversity in natural populations, we selected an area with more than sixty years of heavy metal contamination (Baiyin, BY) and a relatively unpolluted one (Liujiaxia, LJX), and tree sparrow (Passer montanus) as study models. Five tree sparrow populations were sampled in BY at sites differing in heavy metal pollution level. Lower genetic diversity based on seven microsatellite loci was observed in the five tree sparrow populations from BY compared with those from LJX. Analysis of molecular variance indicated no significant genetic differentiation between BY and LJX. However, the observed heterozygosity and allelic richness were negatively correlated to the lead and cadmium concentrations in the primary feathers of tree sparrow. Our results indicated the genetic diversity might have a negative response to long-term environmental heavy metal pollution in tree sparrow, supporting the "Genetic Erosion" hypothesis. Therefore, the findings shed lights on the possible effects of heavy metal pollution on genetic diversity of wild bird populations.


Assuntos
Metais Pesados/análise , Pardais , Animais , Cádmio , Poluição Ambiental/análise , Variação Genética
8.
Proc Biol Sci ; 287(1920): 20192182, 2020 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-32019440

RESUMO

Urban sprawl increasingly affects the ecology of natural populations, including host-microbiota interactions, with observed differences in the gut microbiota between urban and rural hosts. While different mechanisms could explain this pattern, dietary uptake constitutes a likely candidate. To assess the contribution of diet in explaining urban-rural variation in gut microbiota, we performed an aviary experiment in which urban and rural house sparrows were fed with mimics of urban or rural diets. Before the experiment, rural sparrows hosted more diverse gut communities, with a higher relative abundance of Enterococcaceae and Staphylococcaceae and lower abundance of genes involved in xenobiotic degradation and lipid metabolism than their urban counterparts. The experimental diets significantly altered gut microbiota α- and ß-diversity and taxonomic composition, with the strongest shifts occurring in individuals exposed to contrasting diets. Overall, diet-induced shifts resembled initial differences between free-ranging urban and rural hosts. Furthermore, rural diet had a positive impact on urban host body mass but only in hosts with the highest initial gut diversity. Overall, our results indicate that diet constitutes an important factor contributing to differences in gut microbiota along the urbanization gradient and provide new insights on possible fitness consequences of a reduced gut diversity in urban settings.


Assuntos
Microbioma Gastrointestinal , Pardais/microbiologia , Animais , Dieta
9.
PLoS Pathog ; 16(2): e1008102, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32027727

RESUMO

Understanding the circumstances under which arboviruses emerge is critical for the development of targeted control and prevention strategies. This is highlighted by the emergence of chikungunya and Zika viruses in the New World. However, to comprehensively understand the ways in which viruses emerge and persist, factors influencing reductions in virus activity must also be understood. Western equine encephalitis virus (WEEV), which declined during the late 20th century in apparent enzootic circulation as well as equine and human disease incidence, provides a unique case study on how reductions in virus activity can be understood by studying evolutionary trends and mechanisms. Previously, we showed using phylogenetics that during this period of decline, six amino acid residues appeared to be positively selected. To assess more directly the effect of these mutations, we utilized reverse genetics and competition fitness assays in the enzootic host and vector (house sparrows and Culex tarsalis mosquitoes). We observed that the mutations contemporary with reductions in WEEV circulation and disease that were non-conserved with respect to amino acid properties had a positive effect on enzootic fitness. We also assessed the effects of these mutations on virulence in the Syrian-Golden hamster model in relation to a general trend of increased virulence in older isolates. However, no change effect on virulence was observed based on these mutations. Thus, while WEEV apparently underwent positive selection for infection of enzootic hosts, residues associated with mammalian virulence were likely eliminated from the population by genetic drift or negative selection. These findings suggest that ecologic factors rather than fitness for natural transmission likely caused decreased levels of enzootic WEEV circulation during the late 20th century.


Assuntos
Vírus da Encefalite Equina do Oeste/genética , Encefalomielite Equina/genética , Deriva Genética , Seleção Genética , Animais , Culex/imunologia , Culex/virologia , Vírus da Encefalite Equina do Oeste/imunologia , Vírus da Encefalite Equina do Oeste/patogenicidade , Encefalomielite Equina/imunologia , Encefalomielite Equina/patologia , Encefalomielite Equina/transmissão , Humanos , Mesocricetus , Mosquitos Vetores/imunologia , Mosquitos Vetores/virologia , Pardais/imunologia , Pardais/virologia
11.
Nat Plants ; 5(12): 1229-1236, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31792396

RESUMO

Among major cereals domesticated as staple food, only sorghum has a high proportion of cultivars with condensed tannins in grain, which can trigger bitter taste perception in animals by binding to type 2 taste receptors (TAS2Rs). Here, we report the completion of uncovering of a pair of duplicate recessive genes (Tannin1 and Tannin2) underlying tannin presence. Three loss-of-function alleles from each gene were identified in non-tannin sorghum desired as palatable food. Condensed tannins effectively prevented sparrows from consuming sorghum grain. Parallel geographic distributions between tannin sorghum and Quelea quelea supported the role of tannins in fighting against this major herbivore threat. Association between geographic distributions of human TAS2R variants and tannin sorghum across Africa suggested that different causes had probably driven this bidirectional selection according to varied local herbivore threats and human taste sensitivity. Our investigation uncovered coevolution among humans, plants and environments linked by allelochemicals.


Assuntos
Feromônios/metabolismo , Sorghum/metabolismo , Taninos/metabolismo , África , Alcadienos , Animais , Comportamento Alimentar , Humanos , Feromônios/análise , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Receptores Acoplados a Proteínas-G/genética , Receptores Acoplados a Proteínas-G/metabolismo , Seleção Genética , Sorghum/química , Sorghum/genética , Sorghum/parasitologia , Pardais/fisiologia , Taninos/análise , Paladar
12.
PLoS One ; 14(12): e0227092, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31887123

RESUMO

Human impacts on natural resources increasingly necessitate understanding of the demographic rates driving wildlife population trends. Breeding productivity in many avian species is the demographic parameter that primarily influences population fluctuations. Nest density is a vital component of breeding productivity despite the fact that it is most often inferred exclusively from nest success. Unfortunately, locating every nest in a given area to determine nest density is often not feasible and can be biased by measurement error. The availability of a nest to be detected and the probability it will be detected during nest searching are two prominent sources of measurement error. A time-to-event nest density estimator has been developed that, unlike standard distance sampling methods, accounts for availability and can use nest data from outside structured surveys routinely collected to assess nest success. Its application is currently limited to Anseriformes, so we evaluated the general applicability of the time-to-event estimator in the order Passeriformes. To do this, we compared estimates of nest detection rate and nest density from the time-to-event estimator to distance sampling methods for 42 Brewer's sparrow (Spizella breweri) nests monitored in 2015. The time-to-event estimator produced similar but more precise nest detection and density estimates than distance sampling methods.


Assuntos
Cruzamento , Monitorização de Parâmetros Ecológicos/métodos , Comportamento de Nidação/fisiologia , Pardais/fisiologia , Animais , Conservação dos Recursos Naturais , Estudos de Viabilidade , Montana , Dinâmica Populacional , Fatores de Tempo
13.
Parasit Vectors ; 12(1): 548, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31753041

RESUMO

BACKGROUND: Avian malaria parasites are a highly diverse group that commonly infect birds and have deleterious effects on their hosts. Some parasite lineages are geographically widespread and infect many host species in many regions. Bird migration, natural dispersal, invasive species and human-mediated introductions into areas where competent insect vectors are present, are probably the main drivers of the current distribution of avian malaria parasites. METHODS: A total of 412 and 2588 wild house sparrows (Passer domesticus) were captured in 2012 and 2013 in two areas of the Iberian Peninsula (central and southern Spain, respectively). Genomic DNA was extracted from blood samples; parasite lineages were sequenced and identified by comparing with GenBank and/or MalAvi databases. RESULTS: Thirteen Plasmodium lineages were identified in house sparrows corresponding to three major clades. Five individuals were infected by the African Plasmodium lineage PAGRI02, which has been proposed to actively circulate only in Africa. CONCLUSIONS: Despite the low prevalence of PAGRI02 in sparrows in Spain, our results suggest that the area of transmission of this parasite is more widespread than previously thought and covers both Africa and Europe. Further studies of the global distribution of Plasmodium lineages infecting wild birds are required to identify the current transmission areas of these parasites. This is vital given the current scenario of global change that is providing new opportunities for avian malaria transmission into areas where parasites were previously absent.


Assuntos
Doenças das Aves/transmissão , Transmissão de Doença Infecciosa , Genótipo , Malária/veterinária , Plasmodium/classificação , Plasmodium/genética , Pardais , África , Animais , Doenças das Aves/parasitologia , DNA de Protozoário/química , DNA de Protozoário/genética , Malária/parasitologia , Malária/transmissão , Epidemiologia Molecular , Plasmodium/isolamento & purificação , Prevalência , Análise de Sequência de DNA , Espanha
14.
Environ Pollut ; 255(Pt 2): 113278, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31574394

RESUMO

Increasing urbanisation is altering the physiology of wild animals and the mechanisms involved are largely unknown. We hypothesised that altering the physiology of urban organisms is due to the effect of extra light at night on the circadian clock by modulating the expression of pineal machinery and clock genes. Two experiments were performed. In Experiment 1, immediately after being procured from their respective sites (urban and rural sites), birds were released individually in LLdim light conditions. Circadian rhythm period, activity duration, and total activity count were calculated and did not differ between urban and rural birds. In Experiment 2, birds (from urban and rural habitats) were sampled at six time points at regular 4-h intervals, beginning 1 h after sunrise. We measured daily variations in plasma melatonin levels. We also analysed the expression levels of Aanat, Mel1A and Mel1B as an indicator of melatonin biosynthesis and action machinery. Clock and clock-controlled genes (Bmal1, Clock, Per2, Per3, Cry1 and Npas2) were studied in the hypothalamus, the pineal gland, and retina to investigate the effects of urban habitats on the circadian clock. Our results show that there is a lower expression of Aanat in the pineal gland and relatively low plasma melatonin levels in urban birds. Further, clock genes are also differentially expressed in all three central tissues of urban birds. We propose that alterations in the melatonin biosynthesis machinery and the expression of clock genes could result in miscalculations in the internal timing of the organism, with environmental timings leading to altered physiology in urban wild animals.


Assuntos
Ritmo Circadiano/genética , Glândula Pineal , Pardais/fisiologia , Animais , Relógios Circadianos/genética , Expressão Gênica , Hipotálamo/metabolismo , Melatonina/metabolismo , Fotoperíodo , Retina
15.
Biol Lett ; 15(10): 20190513, 2019 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-31662064

RESUMO

Although the effects of anthropogenic noise on animal communication have been studied widely, most research on the effect of noise in communication has focused on signals in a single modality. Consequently, how multi-modal communication is affected by anthropogenic noise is relatively poorly understood. Here, we ask whether song sparrows (Melospiza melodia) show evidence of plasticity in response to noise in two aggressive signals in acoustic and visual modalities. We test two hypotheses: (i) that song sparrows will shift signalling effort to the visual modality (the multi-modal shift hypothesis) and (ii) that they will increase redundancy of their multi-modal signalling (the back-up signal hypothesis). We presented male song sparrows with song playback and a taxidermic mount with or without a low-frequency acoustic noise from a nearby speaker. We found that males did not switch their signalling effort to visual modality (i.e. wing waves) in response to the noise. However, the correlation between warbled soft songs and wing waves increased in the noise treatment, i.e. signals became more redundant. These results suggest that when faced with anthropogenic noise, song sparrows can increase the redundancy of their multi-modal signals, which may aid in the robustness of the communication system.


Assuntos
Pardais , Acústica , Comunicação Animal , Animais , Masculino , Ruído , Vocalização Animal
16.
PLoS One ; 14(10): e0213486, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31644570

RESUMO

Theory predicts that individuals behave altruistically towards their relatives. Hence, some form of kin recognition is useful for individuals to optimize their behavior. In species that display bi-parental care and are subject to extra-pair matings, kin recognition theoretically can allow cuckolded fathers to reduce their parental investment, and thus optimize their fitness. Whether this is possible remains unclear in birds. This study investigates whether males provide differential parental care depending on relatedness, as a proxy to recognizing chicks in their nest as kin or not. We cross-fostered House sparrow (Passer domesticus) chicks after hatching, and then expected that fathers would show a decrease in their parental efforts when tending to a clutch of unrelated offspring. House sparrow males are able to adjust their parental care to the identity of their partner, making them an ideal study species. However, there was no significant effect of relatedness on provisioning rates. This suggests that sparrows may not be capable of kin recognition, or at least do not display kin discrimination despite its apparent evolutionary advantage.


Assuntos
Comportamento de Nidação/fisiologia , Reprodução/fisiologia , Comportamento Sexual Animal/fisiologia , Pardais/fisiologia , Animais , Feminino , Masculino
17.
PLoS One ; 14(10): e0223093, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31574132

RESUMO

Over the last 20 years, a new group of systemic insecticides-the neonicotinoids-has gained prominence in arable systems, and their application globally has risen year on year. Previous modelling studies using long-term data have suggested that neonicotinoid application has had a detrimental impact on bird populations, but these studies were either limited to a single species or neglected to analyse specific exposure pathways in conjunction with observed population trends. Using bird abundance data, neonicotinoid usage records and cropping data for England at a 5x5 km resolution, generalised linear mixed models were used to test for spatio-temporal associations between neonicotinoid use and changes in the populations of 22 farmland bird species between 1994 and 2014, and to determine whether any associations were explained by dietary preferences. We assigned farmland bird species to three categories of dietary exposure to neonicotinoids based on literature data for species diets and neonicotinoid residues present in dietary items. Significant estimates of neonicotinoid-related population change were obtained for 13 of the 22 species (9 positive effects, 4 negative effects). Model estimates for individual species were not collectively explained by dietary risk categories, so dietary exposure to neonicotinoids via ingestion of treated seeds and seedlings could not be confirmed as a causal factor in farmland bird declines. Although it is not possible to infer any generic effect of dietary exposure to neonicotinoids on farmland bird populations, our analysis identifies three species with significant negative estimates that may warrant further research (house sparrow Passer domesticus, skylark Alauda arvensis and red-legged partridge Alectoris rufa). We conclude that there was either no consistent effect of dietary exposure to neonicotinoids on farmland bird populations in England, or that any over-arching effect was not detectable using our study design. The potential for indirect effects of insecticide use on bird populations via reduced food availability was not considered here and should be a focus for future research.


Assuntos
Exposição Dietética/análise , Monitoramento Ambiental , Neonicotinoides/efeitos adversos , Pardais , Animais , Inglaterra , Fazendas , Humanos , Imidazóis , Inseticidas/efeitos adversos , Nitrocompostos/efeitos adversos , Controle da População
18.
Science ; 365(6458): 1177-1180, 2019 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-31515394

RESUMO

Neonicotinoids are neurotoxic insecticides widely used as seed treatments, but little is known of their effects on migrating birds that forage in agricultural areas. We tracked the migratory movements of imidacloprid-exposed songbirds at a landscape scale using a combination of experimental dosing and automated radio telemetry. Ingestion of field-realistic quantities of imidacloprid (1.2 or 3.9 milligrams per kilogram body mass) by white-crowned sparrows (Zonotrichia leucophrys) during migratory stopover caused a rapid reduction in food consumption, mass, and fat and significantly affected their probability of departure. Birds in the high-dose treatment stayed a median of 3.5 days longer at the site of capture after exposure as compared with controls, likely to regain fuel stores or recover from intoxication. Migration delays can carry over to affect survival and reproduction; thus, these results confirm a link between sublethal pesticide exposure and adverse outcomes for migratory bird populations.


Assuntos
Migração Animal , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Pardais/fisiologia , Animais , Composição Corporal , Comportamento Alimentar , Nitrocompostos/toxicidade , Ontário
19.
Genome Res ; 29(10): 1673-1684, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31548356

RESUMO

In male heterogametic systems, the X Chromosome is epigenetically differentiated between males and females, to facilitate dosage compensation. For example, the X Chromosome in female mammals is largely inactivated. Relative to well-studied male heterogametic systems, the extent of epigenetic differentiation between male and female Z Chromosomes in female heterogametic species, which often lack complete dosage compensation, is poorly understood. Here, we examined the chromosomal DNA methylation landscapes of male and female Z Chromosomes in two distantly related avian species, namely chicken and white-throated sparrow. We show that, in contrast to the pattern in mammals, male and female Z Chromosomes in these species exhibit highly similar patterns of DNA methylation, which is consistent with weak or absent dosage compensation. We further demonstrate that the epigenetic differences between male and female chicken Z Chromosomes are localized to a few regions, including a previously identified male hypermethylated region 1 (MHM1; CGNC: 80601). We discovered a novel region with elevated male-to-female methylation ratios on the chicken Z Chromosome (male hypermethylated region 2 [MHM2]; CGNC: 80602). The MHM1 and MHM2, despite little sequence similarity between them, bear similar molecular features that are likely associated with their functions. We present evidence consistent with female hypomethylation of MHMs and up-regulation of nearby genes. Therefore, despite little methylation differentiation between sexes, extremely localized DNA methylation differences between male and female chicken Z Chromosomes have evolved and affect expression of nearby regions. Our findings offer new insights into epigenetic regulation of gene expression between sexes in female heterogametic systems.


Assuntos
Galinhas/genética , Compensação de Dosagem (Genética)/genética , Pardais/genética , Inativação do Cromossomo X/genética , Animais , Epigênese Genética , Evolução Molecular , Feminino , Masculino , Mamíferos/genética , Cromossomos Sexuais/genética
20.
Dev Neurobiol ; 79(8): 794-804, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31509642

RESUMO

In adult songbirds, the telencephalic song nucleus HVC and its efferent target RA undergo pronounced seasonal changes in morphology. In breeding birds, there are increases in HVC volume and total neuron number, and RA neuronal soma area compared to nonbreeding birds. At the end of breeding, HVC neurons die through caspase-dependent apoptosis and thus, RA neuron size decreases. Changes in HVC and RA are driven by seasonal changes in circulating testosterone (T) levels. Infusing T, or its metabolites 5α-dihydrotestosterone (DHT) and 17 ß-estradiol (E2), intracerebrally into HVC (but not RA) protects HVC neurons from death, and RA neuron size, in nonbreeding birds. The phosphoinositide 3-kinase (PI3K)-Akt (a serine/threonine kinase)-mechanistic target of rapamycin (mTOR) signaling pathway is a point of convergence for neuroprotective effects of sex steroids and other trophic factors. We asked if mTOR activation is necessary for the protective effect of hormones in HVC and RA of adult male Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii). We transferred sparrows from breeding to nonbreeding hormonal and photoperiod conditions to induce regression of HVC neurons by cell death and decrease of RA neuron size. We infused either DHT + E2, DHT + E2 plus the mTOR inhibitor rapamycin, or vehicle alone in HVC. Infusion of DHT + E2 protected both HVC and RA neurons. Coinfusion of rapamycin with DHT + E2, however, blocked the protective effect of hormones on HVC volume and neuron number, and RA neuron size. These results suggest that activation of mTOR is an essential downstream step in the neuroprotective cascade initiated by sex steroid hormones in the forebrain.


Assuntos
Plasticidade Neuronal/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Sirolimo/farmacologia , Vocalização Animal/efeitos dos fármacos , Envelhecimento , Animais , Di-Hidrotestosterona/farmacologia , Estrogênios/farmacologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Pardais/fisiologia , Telencéfalo/efeitos dos fármacos , Testosterona/farmacologia , Vocalização Animal/fisiologia
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