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592 results for “songbirds”
Data from: Experimental amelioration of harsh weather speeds growth and development in a tropical montane songbird
<p>Organisms living at high elevations generally grow and develop slower than those at lower elevations. Slow montane ontogeny is thought to be an evolved adaptation to harsh environments that improve juvenile quality via physiological tradeoffs. However, slower montane ontogeny may also reflect proximate influences of harsh weather on parental care and offspring development. We experimentally heated and protected nests from rain to ameliorate harsh montane weather conditions for Mountain Blackeyes (<i>Chlorocharis emiliae</i>), a montane songbird living at ca. 3200 m asl in Malaysian Borneo. This experiment was designed to test if cold and wet montane conditions contribute to parental care and post-natal growth and development rates at high elevations. We found that parents increased provisioning and reduced time spent warming offspring, which grew faster and departed the nest earlier compared to unmanipulated nests. Earlier departure reduces time-dependent predation risk, benefitting parents and offspring. These plastic responses highlight the importance of proximate weather contributions to broad patterns of montane ontogeny and parental care.</p>
Data from: Genomic islands of differentiation in two songbird species reveal candidate genes for hybrid female sterility
Hybrid sterility is a common first step in the evolution of postzygotic reproductive isolation. According to Haldane's Rule it affects predominantly the heterogametic sex. While the genetic basis of hybrid male sterility in organisms with heterogametic males has been studied for decades, the genetic basis of hybrid female sterility in organisms with heterogametic females has received much less attention. We investigated the genetic basis of reproductive isolation in two closely related avian species, the Common Nightingale (Luscinia megarhynchos) and the Thrush Nightingale (L. luscinia), that hybridize in a secondary contact zone and produce viable hybrid progeny. In accordance with Haldane's Rule, hybrid females are sterile, while hybrid males are fertile, allowing gene flow to occur between the species. Using transcriptomic data from multiple individuals of both nightingale species we identified genomic islands of high differentiation (FST) and of high divergence (Dxy), and we analyzed gene content and patterns of molecular evolution within these islands. Interestingly, we found that these islands were enriched for genes related to female meiosis and metabolism. The islands of high differentiation and divergence were also characterized by higher levels of linkage disequilibrium than the rest of the genome in both species indicating that they might be situated in genomic regions of low recombination. This study provides one of the first insights into genetic basis of hybrid female sterility in organisms with heterogametic females.
Anthropogenic noise is associated with telomere length and carotenoid-based coloration in free-living nestling songbirds
<p>Growing evidence suggests that anthropogenic noise has deleterious effects on the behavior and physiology of free-living animals. These effects may be particularly pronounced early in life, when developmental trajectories are sensitive to stressors, yet studies investigating developmental effects of noise exposure in free-living populations remain scarce. To elucidate the effects of noise exposure during development, we examined whether noise exposure is associated with shorter telomeres, duller carotenoid-based coloration and reduced body mass in nestlings of a common urban bird, the great tit (Parus major). We also assessed how the noise environment is related to reproductive success. We obtained long-term measurements of the noise environment, over a ~24-h period, and characterized both the amplitude (measured by LAeq, LA90, LA10, LAmax) and variance in noise levels, since more stochastic, as well as louder, noise regimes might be more likely to induce stress. In our urban population, noise levels varied substantially, with louder, but less variable, noise characteristic of areas adjacent to a highway. Noise levels were also highly repeatable, suggesting that individuals experience consistent differences in noise exposure. The amplitude of noise near nest boxes was associated with shorter telomeres among smaller, but not larger, brood members. In addition, carotenoid chroma and hue were positively associated with variance in average and maximum noise levels, and average reflectance was negatively associated with variance in background noise. Independent of noise, hue was positively related to telomere length. Nestling mass and reproductive success were unaffected by noise exposure. Results indicate that multiple dimensions of the noise environment, or factors associated with the noise environment, could affect the phenotype of developing organisms, that noise exposure, or correlated variables, might have the strongest effects on sensitive groups of individuals, and that carotenoid hue could serve as a signal of early-life telomere length.</p>
Data from: Female ornamentation is associated with elevated aggression and testosterone in a tropical songbird
In males, testosterone plays a key role in ornament production and linking ornamentation with reproductive behaviors and other traits to produce an integrated phenotype. Less is known about whether females couple testosterone, ornamentation, and aggressive behaviors to achieve female-specific combinations of traits. Ornamentation in females may be the result of correlated expression with male ornamentation, or female traits could arise as the result of sex specific selection pressures. Resolving between these alternatives is necessary to understand the degree to which selection acts on female traits. The White-shouldered Fairywren (Malurus alboscapulatus) provides a useful context to address these questions because populations vary in degree of female ornamentation, a derived trait, whereas male ornamentation is constant across both populations. We found that ornamented females have higher levels of circulating testosterone and respond more aggressively to experimental territorial intrusions than do unornamented females. These findings are consistent with the idea that, among female White-shouldered Fairywrens, testosterone may mechanistically link plumage and behavioral traits to produce an integrated competitive phenotype, as has been reported for males of closely related species. In contrast, circulating testosterone in males did not differ significantly between populations. More broadly, our findings are consistent with ongoing selection on the mechanisms underlying female ornaments, likely via social selection.
Data from: Seasonally sympatric but allochronic: differential expression of hypothalamic genes in a songbird during gonadal development
Allochrony, the mismatch of reproductive schedules, is one mechanism that can mediate sympatric speciation and diversification. In songbirds, the transition into breeding condition and gonadal growth is regulated by the hypothalamic-pituitary-gonadal (HPG) axis at multiple levels. We investigated whether the difference in reproductive timing between two, seasonally sympatric subspecies of dark-eyed juncos (Junco hyemalis) was related to gene expression along the HPG axis. During the sympatric pre-breeding stage, we measured hypothalamic and testicular mRNA expression of candidate genes via qPCR in captive male juncos. For hypothalamic mRNA, we found our earlier breeding subspecies had increased expression of gonadotropin-releasing hormone (GnRH) and decreased expression of androgen receptor, estrogen receptor alpha, and mineralocorticoid receptor (MR). Subspecies did not differ in expression of hypothalamic gonadotropin-inhibitory hormone (GnIH) and glucocorticoid receptor (GR). While our earlier breeding subspecies had higher mRNA expression of testicular GR, subspecies did not differ in testicular luteinizing hormone receptor, follicle-stimulating hormone receptor, or MR mRNA expression levels. Our findings indicate increased GnRH production and decreased hypothalamic sensitivity to sex steroid negative feedback as factors promoting differences in the timing of gonadal recrudescence between recently diverged populations. Differential gene expression along the HPG axis may facilitate species diversification under seasonal sympatry.
Data from: Song learning and cognitive ability are not consistently related in a songbird
Learned aspects of song have been hypothesized to signal cognitive ability in songbirds. We tested this hypothesis in hand-reared song sparrows (Melospiza melodia) that were tutored with playback of adult songs during the critical period for song learning. The songs developed by the 19 male subjects were compared to the model songs to produce two measures of song learning: the proportion of notes copied from models and the average spectrogram cross-correlation between copied notes and model notes. Song repertoire size, which reflects song complexity, was also measured. At 1 year of age, subjects were given a battery of five cognitive tests that measured speed of learning in the context of a novel foraging task, color association, color reversal, detour-reaching, and spatial learning. Bivariate correlations between the three song measures and the five cognitive measures revealed no significant associations. As in other studies of avian cognition, different cognitive measures were for the most part not correlated with each other, and this result remained true when 22 hand-reared female song sparrows were added to the analysis. General linear mixed models controlling for effects of neophobia and nest of origin indicated that all three song measures were associated with better performance on color reversal and spatial learning but were associated with worse performance on novel foraging and detour-reaching. Overall, the results do not support the hypothesis that learned aspects of song signal cognitive ability.
Data from: Concealed by darkness: interactions between predatory bats and nocturnally migrating songbirds illuminated by DNA sequencing
Recently, several species of aerial-hawking bats have been found to prey on migrating songbirds, but details on this behaviour and its relevance for bird migration are still unclear. We sequenced avian DNA in feather-containing scats of the bird-feeding bat Nyctalus lasiopterus from Spain collected during bird migration seasons. We found very high prey diversity, with 31 bird species from eight families of Passeriformes, almost all of which were nocturnally flying sub-Saharan migrants. Moreover, species using tree hollows or nest boxes in the study area during migration periods were not present in the bats' diet, indicating that birds are solely captured on the wing during night-time passage. Additional to a generalist feeding strategy, we found that bats selected medium-sized bird species, thereby assumingly optimizing their energetic cost-benefit balance and injury risk. Surprisingly, bats preyed upon birds half their own body mass. This shows that the 5% prey to predator body mass ratio traditionally assumed for aerial hunting bats does not apply to this hunting strategy or even underestimates these animals' behavioural and mechanical abilities. Considering the bats' generalist feeding strategy and their large prey size range, we suggest that nocturnal bat predation may have influenced the evolution of bird migration strategies and behaviour.
Data from: Heritable variation in circulating glucocorticoids and endocrine flexibility in a free-living songbird
Phenotypic flexibility is a central way that organisms cope with challenging and changing environments. As endocrine signals mediate many phenotypic traits, heritable variation in hormone levels, or their context-dependent flexibility, could present an important target for selection. Several studies have estimated the heritability of circulating glucocorticoid levels under acute stress conditions, but little is known about the potential for either baseline hormone levels or rapid endocrine flexibility to evolve. Here we assessed the potential for selection to operate on the elevation (circulating hormone levels) and flexibility of glucocorticoid reaction norms to acute restraint stress. Multivariate animal models revealed low but significant heritability in baseline (h2=0.13-0.14) and stress-induced glucocorticoids (h2=0.18), and moderate heritability in glucocorticoid flexibility in response to acute stress (h2=0.38) in free-living juvenile tree swallows (Tachycineta bicolor; n=408). Baseline glucocorticoids were not genetically correlated with either stress-induced glucocorticoids or glucocorticoid flexibility. These findings indicate that baseline glucocorticoids and the acute stress response are distinct traits that can be independently shaped by selection. Microevolutionary changes that influence the expression or flexibility of these endocrine mediators of phenotype may be an important way that populations adapt to changing environments and novel threats.
Data from: Genomic divergence across ecological gradients in the Central African rainforest songbird (Andropadus virens)
The little greenbul, a common rainforest passerine from sub-Saharan Africa, has been the subject of long-term evolutionary studies to understand the mechanisms leading to rainforest speciation. Previous research found morphological and behavioural divergence across rainforest–savannah transition zones (ecotones), and a pattern of divergence with gene flow suggesting divergent natural selection has contributed to adaptive divergence and ecotones could be important areas for rainforests speciation. Recent advances in genomics and environmental modelling make it possible to examine patterns of genetic divergence in a more comprehensive fashion. To assess the extent to which natural selection may drive patterns of differentiation, here we investigate patterns of genomic differentiation among populations across environmental gradients and regions. We find compelling evidence that individuals form discrete genetic clusters corresponding to distinctive environmental characteristics and habitat types. Pairwise FST between populations in different habitats is significantly higher than within habitats, and this differentiation is greater than what is expected from geographic distance alone. Moreover, we identified 140 SNPs that showed extreme differentiation among populations through a genomewide selection scan. These outliers were significantly enriched in exonic and coding regions, suggesting their functional importance. Environmental association analysis of SNP variation indicates that several environmental variables, including temperature and elevation, play important roles in driving the pattern of genomic diversification. Results lend important new genomic evidence for environmental gradients being important in population differentiation.
Context-dependent effects of relative temperature extremes on bill morphology in a songbird
<p><span>Species increasingly face environmental extremes. While responses of morphological traits to changes in average environmental conditions are well-documented, responses to environmental extremes remain poorly understood. Bird bills contribute to thermoregulation, with considerable heat loss possible through the bill surface, and with bill morphology shaped by long-term thermal conditions. We used museum specimens to investigate the relationship of bill surface area (SA) in dark-eyed juncos <i>Junco hyemalis</i> to traditional measures of climate (temperature and precipitation) and to a novel measure of short-term relative temperature extremity, which quantifies the degree to which temperature maxima or minima have diverged from the recent five-year norm. We found that bill SA exhibits different patterns of association with relative extremity depending on the overall temperature regime and on precipitation. While thermoregulatory function predicts larger bill SA at higher relative temperature extremities, we found this to be the case only when the measure of temperature extremity existed in an environmental context that opposed it: relative minimum temperature in a warm climate, or relative maximum temperature in a cool climate. When, instead, environmental context amplified the relative temperature extremity, we found a negative relationship between bill SA and relative temperature extremity. We also found that the strength of associations between bill SA and relative temperature extremity increased as precipitation increased. Our results suggest that trait responses to environmental variation may qualitatively differ depending on the overall environmental context, and that environmental change that extremifies already-extreme environments should be of particular concern. Extreme-on-extreme environmental change may produce responses that cannot be predicted from observations in less extreme contexts, which should make it a priority for research on species' responses to climate change as well as trait evolution generally.Species increasingly face environmental extremes. Morphological responses to changes in average environmental conditions are well-documented, but responses to environmental extremes remain poorly understood. We used museum specimens to investigate relationships between a thermoregulatory morphological trait, bird bill surface area (SA), and a measure of short-term relative temperature extremity (RTE), which quantifies the degree that temperature maxima or minima diverge from the five-year norm. Using a widespread, generalist species, <i>Junco hyemalis</i>, we found that SA exhibited different patterns of association with RTE depending on the overall temperature regime and on precipitation. While thermoregulatory function predicts larger SA at higher RTE, we found this only when the RTE existed in an environmental context that opposed it: atypically cold minimum temperature in a warm climate, or atypically warm maximum temperature in a cool climate. When environmental context amplified the RTE, we found a negative relationship between SA and RTE. We also found that the strength of associations between SA and RTE increased with precipitation. Our results suggest that trait responses to environmental variation may qualitatively differ depending on the overall environmental context, and that environmental change that extremifies already-extreme environments may produce responses that cannot be predicted from observations in less extreme contexts.</span></p>
Data from: Apparent annual survival estimates of tropical songbirds better reflect life history variation when based on intensive field methods
Aim: Adult survival is central to theories explaining latitudinal gradients in life history strategies. Life history theory predicts higher adult survival in tropical than north temperate regions given lower fecundity and parental effort. Early studies were consistent with this prediction, but standard-effort netting studies in recent decades suggested that apparent survival rates in temperate and tropical regions strongly overlap. Such results do not fit with life history theory. Targeted marking and resighting of breeding adults yielded higher survival estimates in the tropics, but this approach is thought to overestimate survival because it does not sample social and age classes with lower survival. We compared the effect of field methods on tropical survival estimates and their relationships with life history traits. Location: Sabah, Malaysian Borneo. Time period: 2008–2016. Major taxon: Passeriformes. Methods: We used standard-effort netting and resighted individuals of all social and age classes of 18 tropical songbird species over 8 years. We compared apparent survival estimates between these two field methods with differing analytical approaches. Results: Estimated detection and apparent survival probabilities from standard-effort netting were similar to those from other tropical studies that used standard-effort netting. Resighting data verified that a high proportion of individuals that were never recaptured in standard-effort netting remained in the study area, and many were observed breeding. Across all analytical approaches, addition of resighting yielded substantially higher survival estimates than did standard-effort netting alone. These apparent survival estimates were higher than for temperate zone species, consistent with latitudinal differences in life histories. Moreover, apparent survival estimates from addition of resighting, but not from standard-effort netting alone, were correlated with parental effort as measured by egg temperature across species. Main conclusions: Inclusion of resighting showed that standard-effort netting alone can negatively bias apparent survival estimates and obscure life history relationships across latitudes and among tropical species.
Data from: Connecting the dots: Stopover strategies of an intercontinental migratory songbird in the context of the annual cycle
The phases of the annual cycle for migratory species are inextricably linked. Yet, less than five percent of ecological studies examine seasonal interactions. In this study, we utilized stable hydrogen isotopes to geographically link individual black-and-white warblers (Mniotilta varia) captured during spring migration with breeding destinations to understand a migrant's stopover strategy in the context of other phases of the annual cycle. We found that stopover strategy is not only a function of a bird's current energetic state, but also the distance remaining to breeding destination and a bird's time-schedule, which has previously been linked to habitat conditions experienced in the preceding phase of the annual cycle. Birds in close proximity to their breeding destination accumulate additional energy reserves prior to arrival on the breeding grounds, as reflected by higher migratory condition upon arrival, higher refueling rates measured via blood plasma metabolites, and longer stopover durations compared to birds migrating to breeding destinations farther from the stopover site. However, late birds near their breeding destination were more likely to depart on the day of arrival (i.e., transients), and among birds that stopped over at the site, the average duration of stopover was almost half the time of early conspecifics, suggesting late birds are trying to catch-up with the overall time-schedule of migration for optimal arrival time on the breeding grounds. In contrast, birds with long distances remaining to breeding destinations were more likely to depart on the day of arrival and primarily used stopover to rest before quickly resuming migration, adopting similar strategies regardless of a bird's time-schedule. Our study demonstrates that migrants adjust their en route strategies in relation to their time-schedule and distance remaining to their breeding destination, highlighting that strategies of migration should be examined in the context of other phases of the annual cycle.
Adaptive and non-adaptive convergent evolution in feather reflectance of Channel Islands songbirds
<p>Convergent evolution is widely regarded as a signature of adaptation. But testing the adaptive consequences of convergent phenotypes is challenging, making it difficult to exclude non-adaptive explanations for convergence. Here, we combined feather reflectance spectra and phenotypic trajectory analyses with visual and thermoregulatory modeling to test the adaptive significance of dark plumage in songbirds of the California Channel Islands. By evolving dark dorsal plumage, island birds are generally less conspicuous to visual-hunting raptors in the island environment than mainland birds. Dark dorsal plumage also reduces the energetic demands associated with maintaining homeothermy in the cool island climate. We also found an unexpected pattern of convergence, wherein the most divergent island populations evolved greater reflectance of near-infrared radiation. However, our heat flux models indicate that elevated near-infrared reflectance is not adaptive. Analysis of feather microstructure suggests that island-mainland differences are related to coloration of feather barbs and barbules rather than their structure. Our results indicate that adaptive and non-adaptive mechanisms interact to drive plumage evolution in this system. This study sheds light on the mechanisms driving the association between dark color and wet, cold environments across the tree of life, especially in island birds.</p>
Decoupling of growth, physiological state, and subsequent performance in a developmentally manipulated songbird
<p class="MsoNormal"><span>It is generally assumed that larger juveniles are more physiologically mature, hence their overall condition and subsequent performance are higher. Yet, some taxa face extreme workload transitions during development (e.g., nest departure in birds), which may select for non-linear growth profiles that decouple relationships between body size and physiological state, making associations between development<span> </span>and juvenile performance uncertain. We manipulated perceived mass in European starlings approaching fledging using 4.0 g weighted backpacks, measuring subsequent growth trajectories (mass, wing length) and physiological state (aerobic capacity, energy state, oxidative status) to test whether body size and physiology are developmentally coupled during a non-linear growth phase (pre-fledging mass recession). Nanotag radio transmitters were then used to track post-fledging performance (activity, activity-slope, dispersal). Weighted nestlings had greater pre-fledging mass recession and lower oxidative status than controls, but equal aerobic capacity and energy state. Haemoglobin and dROMs, as well as metrics of growth and body size, predicted post-fledging performance in control birds, whereas weighted birds showed no correlation between fledgling state and performance. Our data suggest mass-independent development of some physiological traits in species with non-linear growth profiles, potentially with a context-dependent oxidative cost, and that physiology (not just body size) may predict post-fledging performance.</span></p>
Reduced hybrid survival in a migratory divide between songbirds
<p>Migratory divides, hybrid zones between populations that use different seasonal migration routes, are hypothesized to contribute to speciation. Specifically, relative to parental species, hybrids at divides are predicted to exhibit intermediate migratory behavior and reduced fitness as a result. We provide the first direct test of the second prediction here with one of the largest existing avian tracking datasets, leveraging a divide between Swainson's thrushes where the first prediction is supported. Using detection rates as a proxy for survival, our results supported the migratory divide hypothesis with lower survival rates for hybrids than parental forms. This finding was juvenile-specific (vs. adults), suggesting selection against hybrids is stronger earlier in life. Reduced hybrid survival was not explained by selection against intermediate phenotypes or negative interactions among phenotypes. Additional work connecting specific features of migration is needed, but these patterns provide strong support for migration as an ecological driver of speciation.</p>
Data from: the great tit HapMap project: a continental-scale analysis of genomic variation in a songbird
<p>A major aim of evolutionary biology is to understand why patterns of genomic diversity vary within taxa and space. Large-scale genomic studies of widespread species are useful for studying how environment and demography shape patterns of genomic divergence. Here, we describe one of the most geographically comprehensive surveys of genomic variation in a wild vertebrate to date; the great tit (<em>Parus major</em>) HapMap project. We screened <em>ca</em> 500,000 SNP markers across 647 individuals from 29 populations, spanning ~30 degrees of latitude and 40 degrees of longitude - almost the entire geographic range of the European subspecies. Genome-wide variation was consistent with a recent colonisation across Europe from a South-East European refugiam, with bottlenecks and reduced genetic diversity in island populations. Differentiation across the genome was highly heterogeneous, with clear "islands of differentiation", even among populations with very low levels of genome-wide differentiation. Low local recombination rates were a strong predictor of high local genomic differentiation (F<sub>ST</sub>), especially in island and peripheral mainland populations, suggesting that the interplay between genetic drift and recombination causes highly heterogeneous differentiation landscapes. We also detected genomic outlier regions that were confined to one or more peripheral great tit populations, probably as a result of recent directional selection at the species' range edges. Haplotype-based measures of selection were related to recombination rate, albeit less strongly, and highlighted population-specific sweeps that likely resulted from positive selection. Our study highlights how comprehensive screens of genomic variation in wild organisms can provide unique insights into spatio-temporal evolutionary dynamics.</p>
Does fortune follow function? Exploring how consumer preferences drive the functional trait composition of the global songbird trade
<p>Defaunation and extinction undermine the resilience and functioning of ecological communities and ecosystems. Relative to other disturbances, overexploitation for the global wildlife trade presents a unique case of trait-based selection, as demand for specific individuals is often tied to unique morphological or aesthetic traits desired by consumers ("market traits"). Because evolutionary history leads to species that share both market and functional traits, we posit that non-random patterns of exploitation will result in non-random loss of functional diversity. <br>We applied a trait-based framework to the global songbird trade for 4616 species, 148 of which are plausibly threatened by the trade. We quantified select market traits, such as unique coloration and song quality, and ecological traits related to body size, diet, and foraging strategy to assess whether the trade disproportionately threatens particular functional groups. We additionally looked for patterns of association between market traits and functional traits to assess whether selection on certain market traits could drive selection on associated functional traits.<br>We found that overexploited birds are a distinct functional subset of the global songbird pool, with the trade disproportionately threatening large bodied, frugivorous, and seed eating birds. Across all songbirds, there were multiple non-random associations between market traits and functional traits, with the strongest associations observed among trade-threatened birds; this was consistent with our theory that consumer-driven selection on market traits could theoretically result in selection on functional traits. However, there was mixed evidence for this hypothesis at a global scale, suggesting that disproportionate threat to functional diversity may be more likely in regions where there is heavy demand for associated market traits. <br><em>Policy Implications:</em> Our results highlight the need for increased focus on the mechanistic drivers of trait-based selection on the consumer side of wildlife trade, and how patterns of overexploitation can systematically affect ecological communities and ecosystem services.</p>
Natural noise affects conspecific signal detection and territorial defense behaviors in songbirds
<p>Recent research suggests that anthropogenic noise can substantially alter animal behavior. Although there are many sources of natural background noise, the relative influence of these sounds on behavior has received much less attention. Using landscape-scale playbacks of rushing rivers and crashing ocean surf, we investigated how habitat appropriate natural noise alters territorial defense behaviors in lazuli buntings (<i>Passerina amoena</i>) occupying riparian areas and spotted towhees (<i>Pipilo maculatus</i>) in riparian and coastal areas when exposed to simulated intruder song. We also incorporated naturally occurring cicada noise as an acoustic source influencing lazuli bunting behavior. Both songbird species possess songs that share substantial spectral overlap with low-frequency, water-generated noise, and lazuli bunting song shares an additional high-frequency overlap with cicada calls. Thus, there is potential for background acoustic conditions to mask conspecific signals. We found that detection and discrimination of conspecific playback occurred more slowly for both species as background sound level increased. Lazuli buntings also exhibited complex flight behavior in noise, suggesting they respond differently depending on the amplitude and type (with versus without cicada calls) of background noise. Our results suggest natural noise can impair territorial defense behaviors in songbirds, highlighting natural soundscapes as an under-appreciated axis of the environment.</p>
Flight training and dietary antioxidants have mixed effects on the oxidative status of multiple tissues in a female migratory songbird
<p>Birds, like other vertebrates, rely on a robust antioxidant system to protect themselves against oxidative imbalance caused by energy-intensive activities such as flying. Such oxidative challenges may be especially acute for females during spring migration, since they must pay the oxidative costs of flight while preparing for reproduction; however, little previous work has examined how the antioxidant system of female spring migrants responds to dietary antioxidants and the oxidative challenges of regular flying. We fed two diets to female European starlings, one supplemented with a dietary antioxidant and one without, and then flew them daily in a windtunnel for two weeks during the fall and spring migration periods. We measured the activity of enzymatic antioxidants (GPx, SOD, CAT), non-enzymatic antioxidant capacity (ORAC), and markers of oxidative damage (protein carbonyls and lipid hydroperoxides) in four tissues: pectoralis, leg, liver, and heart. Dietary antioxidants affected enzymatic antioxidant activity and lipid damage in the heart, and non-enzymatic antioxidant capacity in the pectoralis and protein damage in leg muscle. In general, birds fed less antioxidants appear to incur increased oxidative damage while upregulating non-enzymatic and enzymatic antioxidant activity, though these effects were strongly tissue-specific. We also found a significant diet x training interaction for enzymatic antioxidant activity in the leg, and strong trends for diet x training interactions for enzymatic antioxidant activity in the heart and liver. Flight-training may condition the antioxidant system of females to dynamically respond to oxidative challenges, and females during spring migration may shift antioxidant allocation to reduce oxidative damage.</p>
Nest architecture is linked with ecological success in songbirds
<p>Nests are essential constructions that directly determine fitness, yet their structure can vary substantially across bird species. While there is evidence supporting a link between nest architecture and the habitat a species occupies, we still ignore what ecological and evolutionary processes are linked to different nest types. Using information on 3175 species of songbirds, we show that – after controlling for latitude and body size – species that build domed nests (i.e., nests with a roof) have smaller ranges, are less likely to colonise urban environments and have potentially higher extinction rates compared to species with open and cavity nests. Domed nests could be a costly specialisation, and we show these nests take more time to be built, which could restrict breeding opportunities. These diverse strands of evidence suggest that transition from domed to open nests in passerines could represent an important evolutionary innovation behind the success of the largest bird radiation.</p>
ScienceDex guides
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These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.