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1.
Sci Total Environ ; 857(Pt 3): 159603, 2023 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-36272474

RESUMO

As climate change alters the global environment, it is critical to understand the relationship between shifting climate suitability and species distributions. Key questions include whether observed changes in population abundance are aligned with the velocity and direction of shifts predicted by climate suitability models and if the responses are consistent among species with similar ecological traits. We examined the direction and velocity of the observed abundance-based distribution centroids compared with the model-predicted bioclimatic distribution centroids of 250 bird species across the United States from 1969 to 2011. We hypothesized that there is a significant positive correlation in both direction and velocity between the observed and the modeled shifts. We then tested five additional hypotheses that predicted differential shifting velocity based on ecological adaptability and climate change exposure. Contrary to our hypotheses, we found large differences between the observed and modeled shifts among all studied bird species and within specific ecological guilds. However, temperate migrants and habitat generalist species tended to have higher velocity of observed shifts than other species. Neotropical migratory and wetland birds also had significantly different observed velocities than their counterparts, which may be due to their climate change exposure. The velocity based on modeled bioclimatic suitability did not exhibit significant differences among most guilds. Boreal forest birds were the only guild with significantly faster modeled-shifts than the other groups, suggesting an elevated conservation risk for high latitude and altitude species. The highly idiosyncratic species responses to climate and the mismatch between shifts in modeled and observed distribution centroids highlight the challenge of predicting species distribution change based solely on climate suitability and the importance of non-climatic factors traits in shaping species distributions.


Assuntos
Aves , Mudança Climática , Animais , Distribuição Animal , Aves/fisiologia , Ecossistema , América do Norte
2.
Artigo em Inglês | MEDLINE | ID: mdl-35051629

RESUMO

Reproduction, and parental care in particular, are among the most energy-demanding activities within the annual cycle of adult birds. Parents that cannot meet the metabolic demands and other physiological costs of raising offspring may opt to abandon chicks in favour of self-maintenance and future reproduction. Recent work examining reproductive trade-offs in birds revealed an important role of oxygen carrying capacity in mediating variation in parental effort. This study explores the aerobic factors underlying the success or failure of parental care in two closely-related petrel species during their breeding season on Bird Island, South Georgia: northern giant petrels (Macronectes halli) and southern giant petrels (M. giganteus). Failed breeders of both sexes and species had significantly lower hematocrit levels (by 5.48 ± 0.64%) than successful breeders, and reticulocyte counts also tended to be lower in failed males, consistent with the hypothesis that parental care and workload depend on aerobic capacity. We discuss these results in relation to differences in the foraging ecology of both species and sexes.


Assuntos
Aves , Reprodução , Animais , Aves/fisiologia , Feminino , Masculino , Reprodução/fisiologia , Estações do Ano
4.
Proc Natl Acad Sci U S A ; 119(47): e2205476119, 2022 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-36375073

RESUMO

Anatomy of the first flying feathered dinosaurs, modern birds and crocodylians, proposes an ancestral flight system divided between shoulder and chest muscles, before the upstroke muscles migrated beneath the body. This ancestral flight system featured the dorsally positioned deltoids and supracoracoideus controlling the upstroke and the chest-bound pectoralis controlling the downstroke. Preserved soft anatomy is needed to contextualize the origin of the modern flight system, but this has remained elusive. Here we reveal the soft anatomy of the earliest theropod flyers preserved as residual skin chemistry covering the body and delimiting its margins. These data provide preserved soft anatomy that independently validate the ancestral theropod flight system. The heavily constructed shoulder and more weakly constructed chest in the early pygostylian Confuciusornis indicated by a preserved body profile, proposes the first upstroke-enhanced flight stroke. Slender ventral body profiles in the early-diverging birds Archaeopteryx and Anchiornis suggest habitual use of the pectoralis could not maintain the sternum through bone functional adaptations. Increased wing-assisted terrestrial locomotion potentially accelerated sternum loss through higher breathing requirements. Lower expected downstroke requirements in the early thermal soarer Sapeornis could have driven sternum loss through bone functional adaption, possibly encouraged by the higher breathing demands of a Confuciusornis-like upstroke. Both factors are supported by a slender ventral body profile. These data validate the ancestral shoulder/chest flight system and provide insights into novel upstroke-enhanced flight strokes and early sternum loss, filling important gaps in our understanding of the appearance of modern flight.


Assuntos
Dinossauros , Ombro , Animais , Ombro/anatomia & histologia , Dinossauros/anatomia & histologia , Asas de Animais/fisiologia , Aves/fisiologia , Esterno/anatomia & histologia , Voo Animal/fisiologia , Fósseis , Evolução Biológica
5.
J Therm Biol ; 109: 103323, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36195398

RESUMO

With global temperatures rapidly increasing, biologists require tools to assess how wild animals are responding to heat. Thermal imaging of the eye region offers a potential non-invasive alternative to traditional techniques to study thermoregulation and stress responses in wild animals. However, we currently have a poor understanding of how the temperature of the eye region is regulated under increasing temperature and whether this regulation differs among individuals. Here, we use thermal imaging to repeatedly measure the maximum temperature of the eye region (periorbital temperature) in 42 wild pied babblers (Turdoides bicolor) under natural air temperatures ranging from 14.3 to 42.5 °C. Our aim was to determine the relationship between periorbital temperature and air temperature, whether this relationship is repeatable, and whether it differs according to individual attributes. Periorbital temperature showed a non-linear increase with air temperature, becoming independent of air temperature above 38 °C. Above 38 °C, periorbital temperature was not explained by any individual attributes. Below 38 °C, periorbital temperature increased more steeply in individuals with low body mass and it was lower in older compared to younger females. However, the effect of these individual attributes was small compared to the effect of wind speed, air temperature and head tilt. Additionally, the repeatability of individual periorbital temperature was low (R < 0.25) and non-significant both below and above 38 °C. Our findings warrant caution in the use of periorbital temperature to infer individual thermoregulatory responses to increasing temperatures, especially in the wild, where control over confounding non-physiological factors is limited.


Assuntos
Animais Selvagens , Regulação da Temperatura Corporal , Animais , Aves/fisiologia , Temperatura Corporal , Feminino , Temperatura Alta , Temperatura
6.
Curr Biol ; 32(20): R1105-R1109, 2022 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-36283374

RESUMO

Much of the awe that humans have for the flight of birds derives from our earthbound habits and our bias toward emphasizing visual cues for interpreting processes in the world. Although we move through it and breathe it, air is vastly less dense than our bodies, so it is fanciful to imagine moving our limbs in a manner that would enable us to support our weight in the air. Moreover, air is invisible to us unless we use special tools to reveal its flow patterns. As evidence of our visual bias, contemplate a strong wind. You probably form a mental image of leaves moving on tree branches, or dust swirling about in a tornado, in both cases, solids moving in response to the force of the wind rather than the essence of the wind itself.


Assuntos
Aves , Voo Animal , Animais , Humanos , Voo Animal/fisiologia , Aves/fisiologia , Vento , Sinais (Psicologia) , Poeira
7.
Curr Biol ; 32(20): R1187-R1199, 2022 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-36283388

RESUMO

Bird migrations are impressive behavioral phenomena, representing complex spatiotemporal strategies to balance costs of living while maximizing fitness. The field of bird migration research has made great strides over the past decades, yet fundamental gaps remain. Technologies have sparked a transformation in the study of bird migration research by revealing remarkable insights into the underlying behavioral, cognitive, physiological and evolutionary mechanisms of these diverse journeys. Here, we aim to encourage broad discussions and promote future studies by highlighting research fields that are characterized by major knowledge gaps or conflicting evidence, namely the fields of navigation, social learning, individual development, energetics and conservation. We approach each topic by summarizing the current state of knowledge and provide a future outlook of ideas and state-of-the-art methods to further advance the field. Integrating knowledge across these disciplines will allow us to understand the adaptive abilities of different species and to develop effective conservation strategies in a rapidly changing world.


Assuntos
Evolução Biológica , Aves , Animais , Aves/fisiologia , Migração Animal/fisiologia
8.
Proc Natl Acad Sci U S A ; 119(41): e2212925119, 2022 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-36194636

RESUMO

Cyclones can cause mass mortality of seabirds, sometimes wrecking thousands of individuals. The few studies to track pelagic seabirds during cyclones show they tend to circumnavigate the strongest winds. We tracked adult shearwaters in the Sea of Japan over 11 y and found that the response to cyclones varied according to the wind speed and direction. In strong winds, birds that were sandwiched between the storm and mainland Japan flew away from land and toward the eye of the storm, flying within ≤30 km of the eye and tracking it for up to 8 h. This exposed shearwaters to some of the highest wind speeds near the eye wall (≤21 m s-1) but enabled them to avoid strong onshore winds in the storm's wake. Extreme winds may therefore become a threat when an inability to compensate for drift could lead to forced landings and collisions. Birds may need to know where land is in order to avoid it. This provides additional selective pressure for a map sense and could explain why juvenile shearwaters, which lack a map sense, instead navigating using a compass heading, are susceptible to being wrecked. We suggest that the ability to respond to storms is influenced by both flight and navigational capacities. This may become increasingly pertinent due to changes in extreme weather patterns.


Assuntos
Aves , Tempestades Ciclônicas , Voo Animal , Animais , Aves/fisiologia , Humanos , Japão , Vento
9.
Artigo em Inglês | MEDLINE | ID: mdl-36100122

RESUMO

Physiological condition can affect survival and reproductive success in seabirds. However, seabirds rarely show outward signs of poor physiological condition, making it difficult to identify and address issues before they result in population level impacts. We investigate physiological condition of breeding northern gannets (Morus bassanus) between years and nesting stages. Blood smears were used to quantify blood cell profiles indicative of chronic stress, infection, disease, and immunocompetence. No blood parasites were observed, but elevated Heterophil to Lymphocyte (H:L) ratios, eosinophils, and monocytes suggest higher prevalence of infection in some years. Chronic stress levels, indicated by high H:L ratio, were elevated in incubation and early chick-rearing compared to late chick-rearing, which coincided with poorer body condition in breeding birds. This study highlights the value of haematology as a tool for identifying changing patterns of health that may serve as an early indicator of breeding failure, overwintering mortality, and population declines.


Assuntos
Morus , Animais , Aves/fisiologia , Melhoramento Vegetal , Reprodução
10.
Environ Monit Assess ; 194(10): 790, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-36107257

RESUMO

For decades, we have observed a major biodiversity crisis impacting all taxa. Avian species have been particularly well monitored over the long term, documenting their declines. In particular, farmland birds are decreasing worldwide, but the contribution of pesticides to their decline remains controversial. Most studies addressing the effects of agrochemicals are limited to their assessment under controlled laboratory conditions, the determination of lethal dose 50 (LD50) values and testing in a few species, most belonging to Galliformes. They often ignore the high interspecies variability in sensitivity, delayed sublethal effects on the physiology, behaviour and life-history traits of individuals and their consequences at the population and community levels. Most importantly, they have entirely neglected to test for the multiple exposure pathways to which individuals are subjected in the field (cocktail effects). The present review aims to provide a comprehensive overview for ecologists, evolutionary ecologists and conservationists. We aimed to compile the literature on the effects of pesticides on bird physiology, behaviour and life-history traits, collecting evidence from model and wild species and from field and lab experiments to highlight the gaps that remain to be filled. We show how subtle nonlethal exposure might be pernicious, with major consequences for bird populations and communities. We finally propose several prospective guidelines for future studies that may be considered to meet urgent needs.


Assuntos
Praguicidas , Animais , Aves/fisiologia , Monitoramento Ambiental , Fazendas , Humanos , Praguicidas/toxicidade , Estudos Prospectivos
11.
Glob Chang Biol ; 28(24): 7217-7233, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36166319

RESUMO

While linear infrastructures, such as roads and power lines, are vital to human development, they may also have negative impacts on wildlife populations up to several kilometres into the surrounding environment (infrastructure-effect zones, IEZs). However, species-specific IEZs are not available for the vast majority of species, hampering global assessments of infrastructure impacts on wildlife. Here, we synthesized 253 studies worldwide to quantify the magnitude and spatial extent of infrastructure impacts on the abundance of 792 vertebrate species. We also identified the extent to which species traits, infrastructure type and habitat modulate IEZs for vertebrate species. Our results reveal contrasting responses across taxa based on the local context and species traits. Carnivorous mammals were generally more abundant in the proximity of infrastructure. In turn, medium- to large-sized non-carnivorous mammals (>1 kg) were less abundant near infrastructure across habitats, while their smaller counterparts were more abundant close to infrastructure in open habitats. Bird abundance was reduced near infrastructure with larger IEZs for non-carnivorous than for carnivorous species. Furthermore, birds experienced larger IEZs in closed (carnivores: ≈130 m, non-carnivores: >1 km) compared to open habitats (carnivores: ≈70 m, non-carnivores: ≈470 m). Reptiles were more abundant near infrastructure in closed habitats but not in open habitats where abundances were reduced within an IEZ of ≈90 m. Finally, IEZs were relatively small in amphibians (<30 m). These results indicate that infrastructure impact assessments should differentiate IEZs across species and local contexts in order to capture the variety of responses to infrastructure. Our trait-based synthetic approach can be applied in large-scale assessments of the impacts of current and future infrastructure developments across multiple species, including those for which infrastructure responses are not known from empirical data.


Assuntos
Anfíbios , Répteis , Animais , Humanos , Vertebrados , Mamíferos/fisiologia , Aves/fisiologia , Ecossistema , Animais Selvagens
12.
J Anim Ecol ; 91(11): 2314-2328, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36161275

RESUMO

Anthropogenic disturbance contributes to global change by reshaping the ecological niche space available to biological communities. Quantifying the range of functional response traits required for species persistence is central towards understanding the mechanisms underlying community disassembly in disturbed landscapes. We used intensive field surveys of cloud forest bird communities across seven replicate landscapes undergoing agricultural conversion in the Peruvian Andes to examine how a suite of 16 functional response traits related to morphology, diet, foraging behaviour and environmental niche breadth predict (1) species-specific abundance changes in countryside habitats compared to forest and (2) differential changes to the ecological niche space occupied by communities. Our analyses relied on (1) hierarchical distance sampling models to examine the functional predictors of abundance change across the agricultural land use gradient while accounting for imperfect detection and (2) n-dimensional hypervolumes to quantify the expansion and contraction of ecological niche space in countryside habitats. Key traits related to increased abundance in early successional and mixed-intensity agricultural areas included (1) morphological adaptations to dense understorey habitats, (2) plant-based diets (flowers, fruit and seeds) and (3) broad elevational range limits and habitat breadth. Species occupying mixed and high-intensity agricultural land use regimes had mean elevational range limits 20%-60% wider than species found within forests. Collectively, ecological niche space expanded within agricultural habitats for traits related to diet and environmental niche breadth, while contracting for foraging and dispersal traits. Such changes were driven by species with unique functional trait combinations. Our results reveal the dynamic changes to ecological niche space that underly community structure in disturbed landscapes and highlight how increased niche breadth can ameliorate disturbance sensitivity for generalist species. We emphasize that functional traits can be used to predict changes in community structure across disturbance gradients, allowing insights into specific mechanisms underlying community disassembly beyond emergent patterns of functional diversity. By identifying key functional trait groups that align with different countryside habitats, we demonstrate how conservation practitioners can contribute to the retention of avian functional diversity in agricultural landscapes throughout the world.


La perturbación antropogénica contribuye al cambio global al remodelar el espacio de nicho ecológico disponible para las comunidades biológicas. Cuantificar la gama de rasgos de respuesta funcional requeridos para la persistencia de las especies es fundamental para comprender los mecanismos que subyacen al desensamble de la comunidad en los paisajes perturbados. Utilizamos muestreos de campo intensivos de las comunidades de aves del bosque nublado en siete paisajes replicados convertidos a uso agrícola en los Andes peruanos para examinar cómo un conjunto de 16 rasgos de respuesta funcional relacionados con la morfología, dieta, comportamiento de forrajeo, y la amplitud del nicho ambiental predicen (1) cambios en las abundancias de especies específicas en paisajes agrícolas ("countrysides") en comparación con el bosque y (2) cambios diferenciales en el espacio del nicho ecológico ocupado por las comunidades. Nuestros análisis se basaron en (1) modelos jerárquicos de muestreo por la distancia para examinar los predictores funcionales del cambio de abundancia a través del gradiente de uso de suelo para agricultura teniendo en cuenta la detección imperfecta, y (2) "n-dimensional hypervolumes" para cuantificar la expansión y contracción del espacio de nicho ecológico en los hábitats agrícolas. Los rasgos clave relacionados con el aumento de la abundancia en áreas agrícolas de sucesión temprana y de intensidad mixta incluyeron (1) adaptaciones morfológicas a hábitats de sotobosque denso, (2) dietas basadas en plantas (flores, frutas y semillas), y (3) amplios límites de rango de elevación y amplitud de hábitat. Las especies que ocupan regímenes de suelo agrícola mixto y de alta intensidad tenían límites de rango de elevación promedio 20%-60% más amplios que las especies que se encuentran en los bosques. En conjunto, el espacio del nicho ecológico se expandió dentro de los hábitats agrícolas para los rasgos relacionadas con la dieta y la amplitud del nicho ambiental, mientras que se contrajo para los rasgos de forrajeo y dispersión. Dichos cambios fueron impulsados por especies con combinaciones de rasgos funcionales únicos. Nuestros resultados revelan los cambios dinámicos en el espacio del nicho ecológico que subyacen a la estructura de la comunidad en los paisajes perturbados y destacan cómo una mayor amplitud del nicho puede mejorar la sensibilidad a las perturbaciones para las especies generalistas. Enfatizamos que los rasgos funcionales pueden utilizarse para predecir los cambios en la estructura de la comunidad a través de gradientes de perturbación, lo que permite comprender los mecanismos específicos que subyacen al desensamble de la comunidad más allá de los patrones emergentes de diversidad funcional. Al identificar grupos de rasgos funcionales claves que se alinean con diferentes hábitats agrícolas como en "countrysides" demostramos cómo los profesionales de la conservación pueden contribuir a la retención de la diversidad funcional de las aves en los paisajes agrícolas en todo el mundo.


Assuntos
Biodiversidade , Florestas , Animais , Ecossistema , Aves/fisiologia , Agricultura
13.
J Exp Zool A Ecol Integr Physiol ; 337(9-10): 985-993, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36052512

RESUMO

Detection and transduction of photic cues by nonvisual photoreceptors, located in the deep brain, is a critical component of timing seasonal reproduction in birds. However, the precise identity of the photoreceptors responsible for detection of salient photic cues remains uncertain and debated. Here I review of the existing evidence for each of the three candidate photoreceptive opsins: Vertebrate Ancient Opsin, Melanopsin, and Neuropsin, including localization, action spectrum, and data from experimental manipulation of opsin expression. These findings are compared to an updated list of key criteria established in the literature as a litmus for classifying an opsin as the "breeding photoreceptor." Integrating evidence for each of the candidate photoreceptors with respect to these criteria reveals support for all three opsins in regulation of seasonal reproduction. Taken together these findings strongly suggest that transduction of seasonal photoperiodic information involves the activity of multiple photoreceptor types and populations functioning in concert. This review also highlights the need to shift attention from simply identifying "the breeding photoreceptor" to a more integrative approach aiming to parse the contribution of specific photoreceptor populations within the brain.


Assuntos
Aves , Opsinas , Animais , Estações do Ano , Opsinas/genética , Opsinas/metabolismo , Aves/fisiologia , Reprodução , Encéfalo/metabolismo
14.
J Comp Physiol B ; 192(6): 775-787, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36100755

RESUMO

Individual body condition is frequently used to explain differences in foraging and breeding ecology in seabirds. However, little is known about the covariations of body mass with the nutritional state of animals as measured through plasma metabolites and how these different measures vary between and within individuals during breeding. Here, we assessed intra-individual variations of plasma metabolites (triglycerides, cholesterol, protein, and ß-hydroxybutyrate concentrations) and in body mass of Blue-footed boobies (Sula nebouxii) throughout their breeding season 2011-2012 in Isla El Rancho, Mexico. We found breeding-stage and sex-specific variations in individuals' plasma metabolite concentrations, but these did not mirror variations in body mass. Before egg-laying, females had higher triglycerides, cholesterol, and protein concentrations than males. In contrast, males used their nutritional reserves (higher ß-hydroxybutyrate concentrations) more than females during the breeding season (except for early chick-rearing). At the individual level, males gained weight during the breeding season, whereas females lost weight. We also found that between-individual differences in plasma metabolite concentrations and changes in body mass were not consistent throughout the breeding season, while individual body mass was significantly repeatable. This study contributes to a better understanding of seabird breeding ecology and physiology by showing that sex-specific breeding roles might highly influence the nutritional state. Similar patterns might occur in other seabird species, helping to explain why we can find stage- and sex-specific foraging behaviors even in monomorphic species.


Assuntos
Aves , Colesterol , Animais , Aves/fisiologia , Feminino , Hidroxibutiratos , Masculino , Reprodução/fisiologia , Estações do Ano , Triglicerídeos
15.
Proc Biol Sci ; 289(1983): 20221338, 2022 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-36126681

RESUMO

Plastic and selective mechanisms govern parental investment adjustments to predation threat. We investigated the relative importance of plasticity and selection in risk-taking propensity of incubating female common eiders Somateria mollissima facing unprecedented predation in SW Finland, Baltic Sea. Using a 12-year individual-based dataset, we examined within- and among-individual variation in flight initiation distance (FID), in relation to predation risk, nest detectability, individual traits and reproductive investment (NFID = 1009; Nindividual = 559). We expected females nesting in riskier environments (higher predation risk, lower nest concealment) to mitigate environmentally imposed risk by exhibiting longer FIDs, and females investing more in current reproduction (older, in better condition or laying larger clutches) to display shorter FIDs. The target of predation-adult or offspring-affected the mechanisms adapting risk-taking propensity; females plastically increased their FID under higher adult predation risk, while risk-avoiding breeders were predominant on islands with higher nest predation risk. Risk-taking females selected thicker nest cover, consistent with personality-matching habitat choice. Females plastically attenuated their anti-predator response (shorter FIDs) with advancing age, and females in better body condition were more risk-taking, a result explained by selection processes. Future research should consider predator type when investigating the fitness consequences of risk-taking strategies.


Assuntos
Aves , Comportamento de Nidação , Animais , Aves/fisiologia , Patos , Feminino , Comportamento de Nidação/fisiologia , Plásticos , Comportamento Predatório/fisiologia , Reprodução/fisiologia , Assunção de Riscos
16.
Proc Biol Sci ; 289(1983): 20212740, 2022 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-36126685

RESUMO

Human activities may impact animal habitat and resource use, potentially influencing contemporary evolution in animals. In the United Kingdom, COVID-19 lockdown restrictions resulted in sudden, drastic alterations to human activity. We hypothesized that short-term daily and long-term seasonal changes in human mobility might result in changes in bird habitat use, depending on the mobility type (home, parks and grocery) and extent of change. Using Google human mobility data and 872 850 bird observations, we determined that during lockdown, human mobility changes resulted in altered habitat use in 80% (20/25) of our focal bird species. When humans spent more time at home, over half of affected species had lower counts, perhaps resulting from the disturbance of birds in garden habitats. Bird counts of some species (e.g. rooks and gulls) increased over the short term as humans spent more time at parks, possibly due to human-sourced food resources (e.g. picnic refuse), while counts of other species (e.g. tits and sparrows) decreased. All affected species increased counts when humans spent less time at grocery services. Avian species rapidly adjusted to the novel environmental conditions and demonstrated behavioural plasticity, but with diverse responses, reflecting the different interactions and pressures caused by human activity.


Assuntos
COVID-19 , Animais , Aves/fisiologia , Controle de Doenças Transmissíveis , Ecossistema , Atividades Humanas , Humanos , Reino Unido
17.
PLoS One ; 17(8): e0271405, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35944024

RESUMO

Identifying biological processes that structure natural communities has long interested ecologists. Community structure may be determined by various processes, including differential responses of species to environmental characteristics, regional-level spatial influences such as dispersal, or stochasticity generated from ecological drift. Few studies have used the metacommunity paradigm (interacting communities linked by dispersal) to investigate avian community composition along an urban gradient, yet such a theoretical construct may provide insights into species turnover even in unnatural settings such as rural to urban gradients. We measured the influence of spatial and environmental characteristics on two aspects of avian community structure across a gradient of urbanization: 1) taxonomic composition and 2) functional richness based on diet, foraging strategies, nesting locations and morphology. We also measured the relationship between species traits and environmental variables with an RLQ-fourth corner analysis. Together, environmental and spatial processes were significantly related to taxonomic structure and functional richness, but spatial variables accounted for more variation than environmental variables. Fine spatial scales were positively correlated with insectivorous birds and negatively correlated with body and wing size. Urbanization was positively correlated with birds that forage at the canopy level, while emergent wetlands were negatively correlated with birds that nested in cliffs and frugivorous birds. Functional richness and urbanization were significantly related to fine spatial variables. Spatial and environmental factors played an important role in taxonomic and functional structure in avian metacommunity structure. This study highlights the importance of studying multiple aspects of biodiversity, such as taxonomic and functional dimensions, especially when examining effects of complementary spatial and environmental processes.


Assuntos
Biodiversidade , Aves , Animais , Aves/fisiologia , Ecossistema , Urbanização , Áreas Alagadas
18.
J R Soc Interface ; 19(193): 20220325, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35919980

RESUMO

Hundreds of studies have found that weak magnetic fields can significantly influence various biological systems. However, the underlying mechanisms behind these phenomena remain elusive. Remarkably, the magnetic energies implicated in these effects are much smaller than thermal energies. Here, we review these observations, and we suggest an explanation based on the radical pair mechanism, which involves the quantum dynamics of the electron and nuclear spins of transient radical molecules. While the radical pair mechanism has been studied in detail in the context of avian magnetoreception, the studies reviewed here show that magnetosensitivity is widespread throughout biology. We review magnetic field effects on various physiological functions, discussing static, hypomagnetic and oscillating magnetic fields, as well as isotope effects. We then review the radical pair mechanism as a potential unifying model for the described magnetic field effects, and we discuss plausible candidate molecules for the radical pairs. We review recent studies proposing that the radical pair mechanism provides explanations for isotope effects in xenon anaesthesia and lithium treatment of hyperactivity, magnetic field effects on the circadian clock, and hypomagnetic field effects on neurogenesis and microtubule assembly. We conclude by discussing future lines of investigation in this exciting new area of quantum biology.


Assuntos
Aves , Campos Magnéticos , Animais , Biologia , Aves/fisiologia
19.
J Exp Zool A Ecol Integr Physiol ; 337(9-10): 952-966, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35982509

RESUMO

The survival of offspring depends on environmental conditions. Many organisms have evolved with seasonality, characterized as initiation-termination-reinitiation of several physiological processes (i.e., body fattening, molt, plumage coloration, reproduction, etc). It is an adaptation for the survival of many species. Predominantly seasonal breeders use photoperiod as the most reliable environmental cue to adapt to seasonal changes but supplementary factors like temperature and food are synergistically involved in seasonal processes. Studies from diverse vertebrate systems have contributed to understanding the mechanism involved in seasonal reproduction at the molecular and endocrine levels. Long-day induced thyrotropin (thyroid-stimulating hormone) released from the pars tuberalis of the pituitary gland triggers local thyroid hormone activation within the mediobasal hypothalamus. This locally produced thyroid hormone, T3, regulates seasonal gonadotropin-releasing hormone secretion. Most of the bird species studied are seasonal in reproduction and linked behavior and, therefore, need to adjust reproductive decisions to environmental fluctuations. Reproductive strategies of the temperate zone breeders are well-documented, but less is known about tropical birds' reproduction and factors stimulating the annual breeding strategies. Here, we address seasonality in tropical birds with reference to seasonal reproduction and the various environmental factors influencing seasonal breeding.


Assuntos
Aves , Fotoperíodo , Animais , Estações do Ano , Aves/fisiologia , Reprodução/fisiologia , Vertebrados , Hormônios Tireóideos
20.
J Anat ; 241(4): 966-980, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35938671

RESUMO

Ibises (order: Pelecaniformes, family: Threskiornithidae) are probe-foraging birds that use 'remote-touch' to locate prey items hidden in opaque substrates. This sensory capability allows them to locate their prey using high-frequency vibrations in the substrate in the absence of other sensory cues. Remote-touch is facilitated by a specialised bill-tip organ, comprising high densities of mechanoreceptors (Herbst corpuscles) embedded in numerous foramina in the beak bones. Each foramen and its associated Herbst corpuscles make up a sensory unit, called a 'sensory pit'. These sensory pits are densely clustered in the distal portion of the beak. Previous research has indicated that interspecific differences in the extent of sensory pitting in the beak bones correlate with aquatic habitat use of ibises, and have been suggested to reflect different levels of remote-touch sensitivity. Our study investigates the interspecific differences in the bone and soft tissue histology of the bill-tip organs of three species of southern African ibises from different habitats (mainly terrestrial to mainly aquatic). We analysed the external pitting pattern on the bones, as well as internal structure of the beak using micro-CT scans and soft tissue histological sections of each species' bill-tip organs. The beaks of all three species contain remote-touch bill-tip organs and are described here in detail. Clear interspecific differences are evident between the species' bill-tip organs, both in terms of bone morphology and soft tissue histology. Glossy Ibises, which forage exclusively in wetter substrates, have a greater extent of pitting but lower numbers of Herbst corpuscles in each pit, while species foraging in drier substrates (Hadeda and Sacred Ibises) have more robust beaks, fewer pits and higher densities of Herbst corpuscles. Our data, together with previously published histological descriptions of the bill-tip organs of other remote-touch foraging bird species, indicate that species foraging in drier habitats have more sensitive bill-tip organs (based on their anatomy). The vibrations produced by prey (e.g., burrowing invertebrates) travel poorly in dry substrates compared with wetter ones (i.e., dry soil vs. mud or water), and thus we hypothesise that a more sensitive bill-tip organ may be required to successfully locate prey in dry substrates. Furthermore, our results indicate that the differences in bill-tip organ anatomy between the species reflect complex trade-offs between morphological constraints of beak shape and remote-touch sensitivity requirements, both of which are likely related to each species' foraging behaviour and substrate usage. Our study suggests that structures in the bone of the bill-tip organ could provide valuable osteological correlates for the associated soft tissues, and consequently may provide information on the sensory ecology and habitat usage of the birds in the absence of soft tissues.


Assuntos
Bico/anatomia & histologia , Aves/anatomia & histologia , Tato , África Austral , Animais , Bico/fisiologia , Aves/fisiologia , Mecanorreceptores/fisiologia , Solo , Tato/fisiologia , Vibração , Água
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