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inside the supergene of the bird with four sexes.the white-throated sparrow (zonotrichia albicollis) offers unique opportunities to understand the adaptive value of supergenes, particularly their role in alternative phenotypes. in this species, alternative plumage morphs segregate with a nonrecombining segment of chromosome 2, which has been called a 'supergene'. the species mates disassortatively with respect to the supergene; that is, each breeding pair consists of one individual with it and one without it. this species has therefore been ca ...202032937166
a supergene-linked estrogen receptor drives alternative phenotypes in a polymorphic songbird.behavioral evolution relies on genetic changes, yet few behaviors can be traced to specific genetic sequences in vertebrates. here we provide experimental evidence showing that differentiation of a single gene has contributed to the evolution of divergent behavioral phenotypes in the white-throated sparrow, a common backyard songbird. in this species, a series of chromosomal inversions has formed a supergene that segregates with an aggressive phenotype. the supergene has captured esr1, the gene ...202032817554
animal culture: how a new birdsong went viral.a new white-throated sparrow song has overtaken most of canada in less than 20 years. the explanation for this remarkably fast spread may lie in the southern migratory grounds, where populations from across canada converge each winter.202032810461
stopover refuelling, movement and departure decisions in the white-throated sparrow: the influence of intrinsic and extrinsic factors during spring migration.differential migration timing between sex or age classes is an example of how migratory movement strategies can differ among subgroups within a population. however, in songbirds, evidence for intrinsic differences in en route migratory behaviour is often mixed, suggesting that the local environmental context may play a role in accentuating or diminishing patterns. we evaluated how multiple intrinsic and extrinsic variables influenced refuelling rates, local movement behaviour and departure decis ...202032770676
continent-wide shifts in song dialects of white-throated sparrows.hypotheses on regional song variation ("dialects") assume that dialects remain stable within regions, are distinct between regions, and persist within populations over extensive periods [1-3]. theories to explain dialects focus on mechanisms that promote persistence of regional song variants despite gene flow between regions [4-6], such as juveniles settling in non-natal populations retaining only those songs from their repertoires that match neighbors [7, 8]. it would be considered atypical for ...202032619475
time course of photo-induced egr-1 expression in the hypothalamus of a seasonally breeding songbird.many seasonally-breeding species use daylength to time reproduction. light-induced release of progonadal hormones involves a complex cascade of responses both inside and outside the brain. in this study, we used induction of early growth response 1 (egr-1), the protein product of an immediate early gene, to evaluate the time course of such responses in male white-throated sparrows (zonotrichia albicollis) exposed to a single long day. induction of egr-1 in the pars tuberalis began ∼11 h after da ...202032422399
vasoactive intestinal peptide as a mediator of the effects of a supergene on social behaviour.supergenes, or linked groups of alleles that are inherited together, present excellent opportunities to understand gene-behaviour relationships. in white-throated sparrows (zonotrichia albicollis), a supergene on the second chromosome associates with a more aggressive and less parental phenotype. this supergene includes the gene for vasoactive intestinal peptide (vip), a neuropeptide known to play a causal role in both aggression and parental behaviour. here, using a free-living population, we c ...202032259472
experimental malaria infection affects songbirds' nocturnal migratory activity.migratory animals encounter multiple parasite communities, raising concerns that migration may aid transport of infectious disease. how migration affects disease spread depends fundamentally on how disease affects migration, specifically whether infection alters individuals' migratory physiology and behavior. we inoculated white-throated sparrows (zonotrichia albicollis) with avian malaria parasites (plasmodium sp.), monitored parasite loads for 5 wk as the birds reached spring migratory conditi ...202032013740
chromosomal polymorphism and comparative chromosome painting in the rufous-collared sparrow (zonotrichia capensis).zonotrichia capensis is widely distributed in the neotropics. previous cytogenetic studies demonstrated the presence of polymorphisms in two chromosome pairs (zca2 and zca4). here, we report results based on comparative chromosome painting, using probes derived from gallus gallus and leucopternis albicollis, focused on characterizing the chromosome organization of z. capensis. our results demonstrate the conservation of ancestral syntenies as observed previously in other species of passerine. sy ...202030534855
extrapair mating and the strength of sexual selection: insights from a polymorphic species.extrapair mating could drive sexual selection in socially monogamous species, but support for this hypothesis remains equivocal. we used lifetime fitness data and a unique model species, the dimorphic white-throated sparrow (zonotrichia albicollis), to examine how extrapair mating affects the potential for sexual selection. in this species, the morphs employ distinct reproductive strategies, with white males pursuing extrapair mating at higher rates than tan counterparts. social and extrapair ma ...202030971857
influence of the agricultural conservation easement program wetland practices on winter occupancy of passerellidae sparrows and avian species richness.wetlands enrolled in the agricultural conservation easement program (acep) are established as a means of restoring wetland ecosystems and wildlife habitat on private, agricultural land. in west virginia, usa, acep wetlands have never been evaluated to determine how they function as wildlife habitat in comparison to other available wetland habitat in the state. we measured the wintering occupancy of passerellidae species and apparent avian species richness on acep wetlands and a set of reference ...201930677050
regional epigenetic differentiation of the z chromosome between sexes in a female heterogametic system.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 l ...201931548356
parent and offspring genotypes influence gene expression in early life.parents can have profound effects on offspring fitness. little, however, is known about the mechanisms through which parental genetic variation influences offspring physiology in natural systems. white-throated sparrows (zonotrichia albicollis, wtsp) exist in two genetic morphs, tan and white, controlled by a large polymorphic supergene. morphs mate disassortatively, resulting in two pair types: tan male × white female (t × w) pairs, which provide biparental care and white male × tan female (w × ...201931421010
a chromosomal inversion predicts the expression of sex steroid-related genes in a species with alternative behavioral phenotypes.in white-throated sparrows, a chromosomal rearrangement has led to alternative phenotypes that differ in sex steroid-dependent behaviors. the rearrangement has captured the genes estrogen receptor alpha and 5-alpha reductase, making these genes strong candidates for mediating the behavioral phenotypes. we report here that of the two genes, expression of estrogen receptor alpha mrna differs between the morphs and predicts behavior to a much greater extent than does expression of 5-alpha reductase ...201931348983
developmental stress and telomere dynamics in a genetically polymorphic species.a central objective of evolutionary biology is understanding variation in life-history trajectories and the rate of aging, or senescence. senescence can be affected by trade-offs and behavioural strategies in adults but may also be affected by developmental stress. developmental stress can accelerate telomere degradation, with long-term longevity and fitness consequences. little is known regarding whether variation in developmental stress and telomere dynamics contributes to patterns of senescen ...201930417475
alternative reproductive strategies in white-throated sparrows are associated with differences in parasite load following experimental infection.immune defences often trade off with other life-history components. within species, optimal allocation to immunity may differ between the sexes or between alternative life-history strategies. white-throated sparrows (zonotrichia albicollis) are unusual in having two discrete plumage morphs, white-striped and tan-striped. within each sex, white-striped individuals are more aggressive and provide less parental care than tan-striped individuals. we extended immunocompetence handicap models, which p ...201829973391
comparative genomics reveals a burst of homoplasy-free numt insertions.mitochondrial dna sequences are frequently transferred into the nuclear genome, giving rise to numts (nuclear mitochondrial dna segments). in the absence of whole genomes, avian numts have been suggested to be rare and relatively short. we examined 64 bird genomes to test hypotheses regarding numt frequency, distribution among taxa, and likelihood of homoplasy. we discovered 100-fold variation in numt number across species. two songbirds, geospiza fortis (darwin's finch) and zonotrichia albicoll ...201829860531
morph-specific patterns of reproductive senescence: connections to discrete reproductive strategies.how reproductive strategies contribute to patterns of senescence in natural populations remains contentious. we studied reproductive senescence in the dimorphic white-throated sparrow, an excellent species for exploring this issue. within both sexes the morphs use distinct reproductive strategies, and disassortative pairing by morph results in pair types with distinct parental systems. white morph birds are more colorful and aggressive than tan counterparts, and white males compete for extrapair ...201829750559
sound-induced monoaminergic turnover in the auditory forebrain depends on endocrine state in a seasonally-breeding songbird.sensory responses to courtship signals can be altered by reproductive hormones. in seasonally-breeding female songbirds, for example, sound-induced immediate early gene expression in the auditory pathway is selective for male song over behaviourally irrelevant sounds only when plasma estradiol reaches breeding-like levels. this selectivity has been hypothesized to be mediated by release of monoaminergic neuromodulators in the auditory pathway. we previously showed that in oestrogen-primed female ...201829738608
rapid effects of 17β-estradiol on aggressive behavior in songbirds: environmental and genetic influences.contribution to special issue on fast effects of steroids. 17β-estradiol (e2) has numerous rapid effects on the brain and behavior. this review focuses on the rapid effects of e2 on aggression, an important social behavior, in songbirds. first, we highlight the contributions of studies on song sparrows, which reveal that seasonal changes in the environment profoundly influence the capacity of e2 to rapidly alter aggressive behavior. e2 administration to male song sparrows increases aggression wi ...201829605636
rapid regulatory evolution of a nonrecombining autosome linked to divergent behavioral phenotypes.in the white-throated sparrow (zonotrichia albicollis), the second chromosome bears a striking resemblance to sex chromosomes. first, within each breeding pair of birds, one bird is homozygous for the standard arrangement of the chromosome (zal2/zal2) and its mate is heterozygous for a different version (zal2/zal2m). second, recombination is profoundly suppressed between the two versions, leading to genetic differentiation between them. third, the zal2m version is linked with phenotypic traits, ...201829483264
multiple signaling functions of song in a polymorphic species with alternative reproductive strategies.vocal traits can be sexually selected to reflect male quality, but may also evolve to serve additional signaling functions. we used a long-term dataset to examine the signaling potential of song in dimorphic white-throated sparrows (zonotrichia albicollis). we investigated whether song conveys multifaceted information about the vocalizing individual, including fitness, species identity, individual identity, and morph. we also evaluated whether song traits correlate differently with fitness in th ...201829375804
rapid effects of estradiol on aggression depend on genotype in a species with an estrogen receptor polymorphism.the white-throated sparrow (zonotrichia albicollis) represents a powerful model in behavioral neuroendocrinology because it occurs in two plumage morphs that differ with respect to steroid-dependent social behaviors. birds of the white-striped (ws) morph engage in more territorial aggression than do birds of the tan-striped (ts) morph, and the ts birds engage in more parenting behavior. this behavioral polymorphism is caused by a chromosomal inversion that has captured many genes, including estr ...201829277700
negative-assortative mating in the white-throated sparrow.nonrandom mating based on phenotype has been observed in a number of organisms, but a very high proportion of these examples are of assortative mating. the strongest example of negative-assortative mating is for white-striped versus tan-striped crown in the white-throated sparrow, where about 98% of the observed pairings (mated pairs or social pairs) are between mates with different phenotypes and the correlation between mating types is -0.964. although nonrandom mating has been explored theoret ...201829040605
stress-induced hyperglycemia in white-throated and white-crowned sparrows: a new technique for rapid glucose measurement in the field.organisms experience stressors, and the physiological response to these stressors is highly conserved. acute stress activates both the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis, increasing epinephrine, norepinephrine, and glucocorticoids, collectively promoting glucose mobilization. while this is well characterized in mammals, the hyperglycemic response to stress in avian and nonavian reptiles has received less attention. a number of factors, ranging from time of day ...201829847208
actuarial senescence in a dimorphic bird: different rates of ageing in morphs with discrete reproductive strategies.it is often hypothesized that intra-sexual competition accelerates actuarial senescence, or the increase in mortality rates with age. however, an alternative hypothesis is that parental investment is more important to determining senescence rates. we used a unique model system, the white-throated sparrow (zonotrichia albicollis), to study variation in actuarial senescence. in this species, genetically determined morphs display discrete mating strategies and disassortative pairing, providing an e ...201830518574
haplotype-based genomic sequencing of a chromosomal polymorphism in the white-throated sparrow (zonotrichia albicollis).inversion polymorphisms have been linked to a variety of fundamental biological and evolutionary processes. yet few studies have used large-scale genomic sequencing to directly compare the haplotypes associated with the standard and inverted chromosome arrangements. here we describe the targeted genomic sequencing and comparison of haplotypes representing alternative arrangements of a common inversion polymorphism linked to a suite of phenotypes in the white-throated sparrow (zonotrichia albicol ...201721613376
uncoupling basal and summit metabolic rates in white-throated sparrows: digestive demand drives maintenance costs, but changes in muscle mass are not needed to improve thermogenic capacity.avian basal metabolic rate (bmr) and summit metabolic rate (msum) vary in parallel during cold acclimation and acclimatization, which implies a functional link between these variables. however, evidence suggests that these parameters may reflect different physiological systems acting independently. we tested this hypothesis in white-throated sparrows (zonotrichia albicollis) acclimated to two temperatures (-8° and 28°c) and two diets (0% and 30% cellulose). we expected to find an uncoupling of m ...201728277963
experienced migratory songbirds do not display goal-ward orientation after release following a cross-continental displacement: an automated telemetry study.the ability to navigate implies that animals have the capability to compensate for geographical displacement and return to their initial goal or target. although some species are capable of adjusting their direction after displacement, the environmental cues used to achieve this remain elusive. two possible cues are geomagnetic parameters (magnetic map hypothesis) or atmospheric odour-forming gradients (olfactory map hypothesis). in this study, we examined both of these hypotheses by surgically ...201627876843
divergence and functional degradation of a sex chromosome-like supergene.a major challenge in biology is to understand the genetic basis of adaptation. one compelling idea is that groups of tightly linked genes (i.e., "supergenes" [1, 2]) facilitate adaptation in suites of traits that determine fitness. despite their likely importance, little is known about how alternate supergene alleles arise and become differentiated, nor their ultimate fate within species. herein we address these questions by investigating the evolutionary history of a supergene in white-throated ...201626804558
basal and maximal metabolic rates differ in their response to rapid temperature change among avian species.in birds, acclimation and acclimatization to temperature are associated with changes in basal (bmr), summit (msum) and maximal (mmr) metabolic rates but little is known about the rate at which species adjust their phenotype to short-term temperature variations. our aims were (1) to determine the pattern of metabolic adjustments following a rapid temperature change, (2) to determine whether performance varies at similar rates during exposure to warm or cold environments, and (3) to determine if b ...201627233918
new records of ixodes affinis (acari: ixodidae) parasitizing avian hosts in southeastern virginia.ixodes affinis neumann (acari: ixodidae) is a hard-bodied tick species distributed throughout much of the southeastern united states. although i. affinis does not parasitize humans, it is a competent vector of borrelia burgdorferi sensu stricto, the causative-agent of lyme disease, and thus contributes to the enzootic maintenance of this pathogen. this study presents evidence of i. affinis parasitizing five new host passerine species. during 2012-2014, 1,888 birds were captured and examined for ...201626586535
genes located in a chromosomal inversion are correlated with territorial song in white-throated sparrows.the genome of the white-throated sparrow (zonotrichia albicollis) contains an inversion polymorphism on chromosome 2 that is linked to predictable variation in a suite of phenotypic traits including plumage color, aggression and parental behavior. differences in gene expression between the two color morphs, which represent the two common inversion genotypes (zal2/zal2 and zal2/zal2(m) ), may therefore advance our understanding of the molecular underpinnings of these phenotypes. to identify genes ...201526463687
estrogen receptor alpha as a mediator of life-history trade-offs.trade-offs between competitive and parental strategies often are mediated by sex steroids. the mechanisms underlying steroid signaling and metabolism may therefore serve as targets of disruptive selection that leads to alternative behavioral phenotypes. white-throated sparrows exhibit two color morphs that differ in both competitive and parental behavior; white-striped (ws) birds engage in more territorial singing, whereas tan-striped (ts) birds provision nestlings more often. although ws birds ...201525855477
timing of feather molt related to date of spring migration in male white-throated sparrows, zonotrichia albicollis.in migratory birds, the ability to depart wintering grounds at the appropriate time is an important determinant of fitness. understanding the regulation of this timing will be essential for predicting whether timing of bird migration keeps up with global climate change. we examined whether the timing of the late-winter molt, in which white-throated sparrows (zonotrichia albicollis) replace head and body feathers in advance of mating, may constrain the timing of northward migratory departure. in ...201425287905
variation in preen oil composition pertaining to season, sex, and genotype in the polymorphic white-throated sparrow.evidence for the the ability of birds to detect olfactory signals is now well documented, yet it remains unclear whether birds secrete chemicals that can be used as social cues. a potential source of chemical cues in birds is the secretion from the uropygial gland, or preen gland, which is thought to waterproof, maintain, and protect feathers from ectoparasites. however, it is possible that preen oil also may be used for individual recognition, mate choice, and signalling social/sexual status. i ...201425236380
new insights into the hormonal and behavioural correlates of polymorphism in white-throated sparrows, zonotrichia albicollis.the white-throated sparrow is a promising model for behavioural neuroendocrinology and genetics because behaviour and endocrine function may be linked to a chromosomal rearrangement that determines plumage colour. the notion that the two colour morphs, tan-striped (ts) and white-striped (ws), differ predictably in aggression and parenting has been widely accepted, despite conflicting evidence. it is also hypothesized that morph-typic behaviour is hormone mediated, yet no field study has measured ...201425045171
sex steroid-independent effects of photostimulation on the song-control system of white-throated sparrows (zonotrichia albicollis).brain nuclei within the song-control system of songbirds are seasonally plastic during adulthood. these nuclei are larger in birds exposed to long, spring-like days than short, winter-like days. there is overwhelming evidence that this effect is mediated by testosterone (t). however, castration studies have also demonstrated that photostimulation has gonad-independent effects on song-control system plasticity, but these studies rarely control for extra-gonadal sources of t. in this study, we use ...201424818971
white-throated sparrows alter songs differentially in response to chorusing anurans and other background noise.animals can use acoustic signals to attract mates and defend territories. as a consequence, background noise that interferes with signal transmission has the potential to reduce fitness, especially in birds that rely on song. while much research on bird song has investigated vocal flexibility in response to urban noise, weather and other birds, the possibility of inter-class acoustic competition from anurans has not been previously studied. using sound recordings from central ontario wetlands, w ...201424607392
estrogen receptor α polymorphism in a species with alternative behavioral phenotypes.the evolution of behavior relies on changes at the level of the genome; yet the ability to attribute a behavioral change to a specific, naturally occurring genetic change is rare in vertebrates. in the white-throated sparrow (zonotrichia albicollis), a chromosomal polymorphism (zal2/2(m)) is known to segregate with a behavioral phenotype. individuals with the zal2(m) haplotype engage in more territorial aggression and less parental behavior than individuals without it. these behaviors are though ...201424474771
hormonal regulation of vasotocin receptor mrna in a seasonally breeding songbird.behaviors associated with breeding are seasonally modulated in a variety of species. these changes in behavior are mediated by sex steroids, levels of which likewise vary with season. the effects of androgens on behaviors associated with breeding may in turn be partly mediated by the nonapeptides vasopressin (vp) and oxytocin (ot) in mammals, and vasotocin (vt) in birds. the effects of testosterone (t) on production of these neuropeptides have been well-studied; however, the regulation of vt rec ...201424333848
evaluation of reference genes for quantitative real-time pcr in the brain, pituitary, and gonads of songbirds.quantitative real-time pcr (qpcr) is becoming a popular tool for the quantification of gene expression in the brain and endocrine tissues of songbirds. accurate analysis of qpcr data relies on the selection of appropriate reference genes for normalization, yet few papers on songbirds contain evidence of reference gene validation. here, we evaluated the expression of ten potential reference genes (18s, actb, gapdh, hmbs, hprt, ppia, rpl4, rpl32, tfrc, and ubc) in brain, pituitary, ovary, and test ...201424780145
brain transcriptome sequencing and assembly of three songbird model systems for the study of social behavior.emberizid sparrows (emberizidae) have played a prominent role in the study of avian vocal communication and social behavior. we present here brain transcriptomes for three emberizid model systems, song sparrow melospiza melodia, white-throated sparrow zonotrichia albicollis, and gambel's white-crowned sparrow zonotrichia leucophrys gambelii. each of the assemblies covered fully or in part, over 89% of the previously annotated protein coding genes in the zebra finch taeniopygia guttata, with 16,8 ...201424883256
spatial, temporal, molecular, and intraspecific differences of haemoparasite infection and relevant selected physiological parameters of wild birds in georgia, usa.the prevalence of five avian haemoparasite groups was examined for effects on health and associations with extrinsic factors. overall, 786 samples were examined from six sites in two georgia (usa) watersheds, during breeding and non-breeding periods in 2010 and 2011. among the four most commonly infected species, haemoproteus prevalence was significantly higher in northern cardinals (cardinalis cardinalis) compared to indigo buntings (passerina cyanea) and tufted titmice (baeolophus bicolor) whi ...201324533333
plasma testosterone correlates with morph type across breeding substages in male white-throated sparrows.white-throated sparrows (zonotrichia albicollis) exhibit a genetic polymorphism that affects plumage and behavior in both sexes. white-striped morphs are more territorially aggressive, whereas tan-striped morphs provision nestlings at a higher rate. we investigated testosterone physiology in this species in an effort to understand hormonal mechanisms for the observed differences in aggression and parental care between the morphs. we found a small but significant difference in plasma testosterone ...201319637970
differential regulation of adipokines may influence migratory behavior in the white-throated sparrow (zonotrichia albicollis).white-throated sparrows increase fat deposits during pre-migratory periods and rely on these fat stores to fuel migration. adipose tissue produces hormones and signaling factors in a rhythmic fashion and may be controlled by a clock in adipose tissue or driven by a master clock in the brain. the master clock may convey photoperiodic information from the environment to adipose tissue to facilitate pre-migratory fattening, and adipose tissue may, in turn, release adipokines to indicate the extent ...201323785393
testosterone alters genomic responses to song and monoaminergic innervation of auditory areas in a seasonally breeding songbird.behavioral responses to social stimuli often vary according to endocrine state. our previous work has suggested that such changes in behavior may be due in part to hormone-dependent sensory processing. in the auditory forebrain of female white-throated sparrows, expression of the immediate early gene zenk (egr-1) is higher in response to conspecific song than to a control sound only when plasma estradiol reaches breeding-typical levels. estradiol also increases the number of detectable noradrene ...201323362219
oxidative stress, circulating antioxidants, and dietary preferences in songbirds.oxidative stress is an unavoidable consequence of metabolism and increases during intensive exercise. this is especially problematic for migratory birds that metabolize fat to fuel long-distance flight. birds can mitigate damage by increasing endogenous antioxidants (e.g. uric acid) or by consuming dietary antioxidants (e.g. tocopherol). during flight, birds may increase protein catabolism of lean tissue which may increase circulating uric acid and many birds also consume an antioxidant-rich fru ...201323270695
behavioral characterization of a white-throated sparrow homozygous for the zal2(m) chromosomal rearrangement.the white-throated sparrow is rapidly becoming an important model in the genetics of social behavior because of a chromosomal rearrangement that segregates with a behavioral phenotype. within a population, 50 % of individuals are heterozygous for a rearranged chromosome 2 (zal2(m)). these birds sing more and are more aggressive than the other 50 %, who lack the rearrangement. a disassortative mating system, in which heterozygotes almost never interbreed, ensures that zal2(m)/2(m) homozygotes are ...201323264208
birdsong: is it music to their ears?since the time of darwin, biologists have wondered whether birdsong and music may serve similar purposes or have the same evolutionary precursors. most attempts to compare song with music have focused on the qualities of the sounds themselves, such as melody and rhythm. song is a signal, however, and as such its meaning is tied inextricably to the response of the receiver. imaging studies in humans have revealed that hearing music induces neural responses in the mesolimbic reward pathway. in thi ...201223226128
morph matters: aggression bias in a polymorphic sparrow.in species with discrete morphs exhibiting alternative behavioral strategies, individuals may vary their aggressive behavior in competitive encounters according to the phenotype of their opponent. such aggression bias has been documented in multiple polymorphic species evolving under negative frequency-dependent selection, but it has not been well-studied under other selection regimes. we investigated this phenomenon in white-throated sparrows (zonotrichia albicollis), a passerine with plumage p ...201223119092
rapid effects of hearing song on catecholaminergic activity in the songbird auditory pathway.catecholaminergic (ca) neurons innervate sensory areas and affect the processing of sensory signals. for example, in birds, ca fibers innervate the auditory pathway at each level, including the midbrain, thalamus, and forebrain. we have shown previously that in female european starlings, ca activity in the auditory forebrain can be enhanced by exposure to attractive male song for one week. it is not known, however, whether hearing song can initiate that activity more rapidly. here, we exposed es ...201222724011
estradiol-dependent modulation of serotonergic markers in auditory areas of a seasonally breeding songbird.because no organism lives in an unchanging environment, sensory processes must remain plastic so that in any context, they emphasize the most relevant signals. as the behavioral relevance of sociosexual signals changes along with reproductive state, the perception of those signals is altered by reproductive hormones such as estradiol (e2). we showed previously that in white-throated sparrows, immediate early gene responses in the auditory pathway of females are selective for conspecific male son ...201221942431
behavioral and physiological effects of photoperiod-induced migratory state and leptin on a migratory bird, zonotrichia albicollis: i. anorectic effects of leptin administration.the hormone leptin is involved in the regulation of energy balance in mammals, mainly by reducing food intake and body adiposity and increasing energy expenditure. during energetically demanding periods, leptin's action is often altered to facilitate fat deposition and maintain high rates of food intake. despite the present controversy over the existence of an avian leptin, there is evidence that a leptin receptor exists in birds and its activation influences energy intake and metabolism. howeve ...201121925179
behavioral and physiological effects of photoperiod-induced migratory state and leptin on zonotrichia albicollis: ii. effects on fatty acid metabolism.the migratory flights of birds are fuelled largely by fatty acids. fatty acid transporters, including fat/cd36, fabppm and h-fabp, and enzymes involved in fatty acid oxidation (cpt, cs, hoad) are seasonally up-regulated in flight muscle to meet the demands of this intense aerobic exercise. the mechanisms that control these biochemical changes in response to migration are mostly unknown. we studied the effects of a photoperiod-induced migratory state and a 7 day treatment with murine leptin (1 μg ...201121925178
combining stable-isotope (deltad) and band recovery data to improve probabilistic assignment of migratory birds to origin.the recent application of stable-isotope analyses, particularly the use of stable-hydrogen-isotope (deltad) measurements of animal tissues, has greatly improved our ability to infer geographic origins of migratory animals. however, many individual sources of error contribute to the overall error in assignment; thus likelihood-based assignments incorporating estimates of error are now favored. in addition, globally, the nature of the underlying precipitation-based deltad isoscapes is such that lo ...201121774434
estradiol-dependent catecholaminergic innervation of auditory areas in a seasonally breeding songbird.a growing body of evidence suggests that gonadal steroids such as estradiol (e2) alter neural responses not only in brain regions associated with reproductive behavior but also in sensory areas. because catecholamine systems are involved in sensory processing and selective attention, and because they are sensitive to e2 in many species, they may mediate the neural effects of e2 in sensory areas. here, we tested the effects of e2 on catecholaminergic innervation, synthesis and activity in the aud ...201121714815
neural distribution of vasotocin receptor mrna in two species of songbird.the neurohypophyseal hormones vasopressin and oxytocin are produced and released within the mammalian brain, where they act via multiple receptor subtypes. the neural distributions of these receptors, for example, v1a and oxytocin receptors, have been well described in many mammals. in birds, the distribution of binding sites for the homologous neuropeptides, vasotocin (vt) and mesotocin, has been studied in several species by using synthetic radioligands designed to bind to mammalian receptors. ...201122067316
migration- and exercise-induced changes to flight muscle size in migratory birds and association with igf1 and myostatin mrna expression.seasonal adjustments to muscle size in migratory birds may result from preparatory physiological changes or responses to changed workloads. the mechanisms controlling these changes in size are poorly understood. we investigated some potential mediators of flight muscle size (myostatin and insulin-like growth factor, igf1) in pectoralis muscles of wild wintering or migrating white-throated sparrows (zonotrichia albicollis), captive white-throated sparrows that were photoperiod manipulated to be i ...201121832125
carnitine palmitoyl transferase activity and whole muscle oxidation rates vary with fatty acid substrate in avian flight muscles.birds primarily fuel migratory flights with fat, and the composition of that fat has the potential to affect overall lipid oxidation rates. we measured the whole muscle lipid oxidation rates in extensor digitorum communis muscles from white-throated sparrows (zonotrichia albicollis gmelin) incubated for 20 min at 20°c with radiolabeled stearate (18:0), oleate (18:1ω9), or linoleate (18:2ω6). lipid oxidation rates were ~40% higher with linoleate than oleate (oleate: 36 ± 8.54 μmol co(2) g(-1) h(- ...201121153644
quantitative magnetic resonance analysis and a morphometric predictive model reveal lean body mass changes in migrating nearctic-neotropical passerines.most studies of lean mass dynamics in free-living passerine birds have focused on old world species at geographical barriers where they are challenged to make the longest non-stop flight of their migration. we examined lean mass variation in new world passerines in an area where the distribution of stopover habitat does not require flights to exceed more than a few hours and most migrants stop flying well before fat stores near exhaustion. we used either quantitative magnetic resonance (qmr) ana ...201121079970
comparative bac-based mapping in the white-throated sparrow, a novel behavioral genomics model, using interspecies overgo hybridization.abstract:201121693052
Widespread dispersal of Borrelia burgdorferi-infected ticks collected from songbirds across Canada.Abstract Millions of Lyme disease vector ticks are dispersed annually by songbirds across Canada, but often overlooked as the source of infection. For clarity on vector distribution, we sampled 481 ticks (12 species and 3 undetermined ticks) from 211 songbirds (42 species/subspecies) nationwide. Using PCR, 52 (29.5%) of 176 Ixodes ticks tested were positive for the Lyme disease spirochete, Borrelia burgdorferi s.l. Immature blacklegged ticks, Ixodes scapularis, collected from infested songbird ...201121864130
a w-linked palindrome and gene conversion in new world sparrows and blackbirds.a hallmark feature of the male-specific region of the human y chromosome is the presence of large and near-identical palindromes. these palindromes are maintained in a state of near identity via gene conversion between the arms of the palindrome, and both neutral and selection-based theories have been proposed to explain their enrichment on the human y and x chromosomes. while those proposed theories would be applicable to sex chromosomes in other species, it has not been established whether nea ...201020535633
evolution of a bitter taste receptor gene cluster in a new world sparrow.bitter taste perception likely evolved as a protective mechanism against the ingestion of harmful compounds in food. the evolution of the taste receptor type 2 (tas2r) gene family, which encodes the chemoreceptors that are directly responsible for the detection of bitter compounds, has therefore been of considerable interest. though tas2r repertoires have been characterized for a number of species, to date the complement of tas2rs from just one bird, the chicken, which had a notably small number ...201020624740
chromosome-wide linkage disequilibrium caused by an inversion polymorphism in the white-throated sparrow (zonotrichia albicollis).chromosomal inversions have been of long-standing interest to geneticists because they are capable of suppressing recombination and facilitating the formation of adaptive gene complexes. an exceptional inversion polymorphism (zal2(m)) in the white-throated sparrow (zonotrichia albicollis) is linked to variation in plumage, social behavior and mate choice, and is maintained in the population by negative assortative mating. the zal2(m) polymorphism is a complex inversion spanning > 100 mb and has ...201020571514
gonadotrophin-releasing hormone neurons in a photoperiodic songbird express fos and egr-1 protein after a single long day.birds use a variety of environmental cues, such as day length, temperature and social interactions, to time reproductive efforts. for most seasonally breeding birds, day length is the most important cue and takes precedence over all others. experimental manipulation of day length has shown that, in a number of galliformes and passeriformes, exposure to a single long day induces a rise in plasma luteinising hormone (lh). the mechanisms underlying this response are only beginning to be understood. ...201020070482
topography of estradiol-modulated genomic responses in the songbird auditory forebrain.sex steroids facilitate dramatic changes in behavioral responses to sociosexual signals and are increasingly implicated in the sensory processing of those signals. our previous work demonstrated that in female white-throated sparrows, which are seasonal breeders, genomic responses in the auditory forebrain are selective for conspecific song over frequency-matched tones only when plasma estradiol (e2) reaches breeding levels. here, we sought to map this e2-dependent selectivity in the best-studie ...201019885833
contrasting population genetic patterns within the white-throated sparrow genome (zonotrichia albicollis).the level of nucleotide diversity observed across the genome is positively correlated with the local rate of recombination. avian karyotypes are typified by large variation in chromosome size and the rate of recombination in birds has been shown to be negatively correlated with chromosome size. it has thus been predicted that nucleotide diversity is negatively correlated with chromosome size in aves. however, there is limited empirical evidence to support this prediction.201021029465
fatty acid composition of pectoralis muscle membrane, intramuscular fat stores and adipose tissue of migrant and wintering white-throated sparrows (zonotrichia albicollis).the fatty acid composition of muscle membrane phospholipids and fat stores may affect migration performance in birds. the purpose of this study was to investigate seasonal changes in the fatty acid composition of (1) pectoralis muscle phospholipids, (2) intramuscular triglyceride stores and (3) adipose tissue triglycerides in free-living white-throated sparrows (zonotrichia albicollis). during migratory seasons there was an increase in the n-6:n-3 ratio of muscle membrane phospholipid fatty acid ...200919915129
white-throated sparrows calibrate their magnetic compass by polarized light cues during both autumn and spring migration.the interaction and hierarchy of celestial and magnetic compass cues used by migratory songbirds for orientation has long been the topic of an intense debate. we have previously shown that migratory savannah sparrows, passerculus sandwichensis, use polarized light cues near the horizon at sunrise and sunset to recalibrate their magnetic compass. birds exposed to a +/-90 deg. shifted artificial polarization pattern at sunrise or sunset recalibrated their magnetic compass, but only when given full ...200919837888
examining the social landscapes of alternative reproductive strategies.social environments are inherently dynamic, often changing depending on the frequency and outcomes of conspecific interactions - they can be simultaneously the targets and agents of selection. understanding how organisms settle in heterogeneous social environments and the effects this has on reproductive success is vital to our understanding of the selective forces at work in wild populations. from an intensive behavioural and ecological study of territoriality in the polymorphic white-throated ...200919878503
corticosterone manipulations alter morph-specific nestling provisioning behavior in male white-throated sparrows, zonotrichia albicollis.in the polymorphic white-throated sparrow (zonotrichia albicollis), tan-striped males provision nestlings at higher rates than do white-striped males. in a previous study, we found that tan-striped males had lower baseline corticosterone levels than white-striped males during the nestling stage. to determine if this variation in corticosterone influences morph-specific differences in nestling provisioning behavior, we used intraperitoneal osmotic pumps to increase baseline corticosterone levels ...200919751738
seasonal upregulation of fatty acid transporters in flight muscles of migratory white-throated sparrows (zonotrichia albicollis).endurance flights of birds, some known to last several days, can only be sustained by high rates of fatty acid uptake by flight muscles. previous research in migratory shorebirds indicates that this is made possible in part by very high concentrations of cytosolic heart-type fatty acid binding protein (h-fabp), which is substantially upregulated during migratory seasons. we investigated if h-fabp and other components of muscle fatty acid transport also increase during these seasons in a passerin ...200919717675
neural distribution of nonapeptide binding sites in two species of songbird.vasotocin (vt) and its mammalian homologue, vasopressin (vp), modulate many social behaviors in a variety of vertebrate species. in songbirds, the effects of centrally administered vt vary according to species, which may reflect species-specific distributions of vt binding sites. different radioligands used to map receptors in previous autoradiographical studies have revealed nonoverlapping distributions of vt binding, suggesting a heterogeneous population of more than one type of vt receptor. f ...200919132730
the effect of muscle phospholipid fatty acid composition on exercise performance: a direct test in the migratory white-throated sparrow (zonotrichia albicollis).dietary polyunsaturated fatty acids (pufa) can have various effects on animal physiology through their roles as energy, structural, regulatory, and signaling molecules. of recent interest has been the incorporation of dietary pufa into muscle membranes as phospholipids, thereby potentially affecting exercise performance by mechanisms such as altered mitochondrial proton leak and membrane-bound protein activity. we first studied the effects of a high-omega6 pufa diet vs. a high-omega3 pufa diet o ...200919587112
dietary macronutrients affect lipid metabolites and body composition of a migratory passerine, the white-throated sparrow (zonotrichia albicollis).plasma lipid metabolites can provide information about fat metabolism and storage in migrating birds, yet little is known about the influence of diet and nutrition or how they relate to intraindividual differences in body composition of songbirds. we investigated how dietary macronutrient composition affects plasma lipid concentrations and subsequent changes in fat accumulation in white-throated sparrows (zonotrichia albicollis). birds fed a low-protein diet with more glucose had higher plasma t ...200919331582
behavioral phenotypes persist after gonadal steroid manipulation in white-throated sparrows.white-throated sparrows (zonotrichia albicollis) exhibit a behavioral polymorphism that segregates with a plumage marker. individuals with a white stripe (ws) on the crown engage in an aggressive strategy that involves more singing, whereas individuals with a tan stripe (ts) sing less and engage in more parental care. previous work has shown that plasma levels of gonadal steroids differ between the morphs in both sexes, suggesting a hormonal mechanism for the polymorphic behavior in this species ...200918848562
the value of avian genomics to the conservation of wildlife.genomic studies in non-domestic avian models, such as the california condor and white-throated sparrow, can lead to more comprehensive conservation plans and provide clues for understanding mechanisms affecting genetic variation, adaptation and evolution.developing genomic tools and resources including genomic libraries and a genetic map of the california condor is a prerequisite for identification of candidate loci for a heritable embryonic lethal condition. the white-throated sparrow exhibits ...200919607652
vocal tract motor patterns and resonance during constant frequency song: the white-throated sparrow.bird song is a complex behavior that requires the coordination of several motor systems. sound is produced in the syrinx and then modified by the upper vocal tract. movements of the hyoid skeleton have been shown in the northern cardinal (cardinalis cardinalis) to be extensively involved in forming an oropharyngeal-esophageal cavity (oec), which contributes a major resonance to the vocal tract transfer function. here we report that a similar relationship exists between the volume of the oec and ...200919082607
the chromosomal polymorphism linked to variation in social behavior in the white-throated sparrow (zonotrichia albicollis) is a complex rearrangement and suppressor of recombination.variation in social behavior and plumage in the white-throated sparrow (zonotrichia albicollis) is linked to an inversion polymorphism on chromosome 2. here we report the results of our comparative cytogenetic mapping efforts and population genetics studies focused on the genomic characterization of this balanced chromosomal polymorphism. comparative chromosome painting and cytogenetic mapping of 15 zebra finch bac clones to the standard (zal2) and alternative (zal2(m)) arrangements revealed tha ...200818562641
impacts of chronic anthropogenic noise from energy-sector activity on abundance of songbirds in the boreal forest.the effects of human activities in forests are often examined in the context of habitat conversion. changes in habitat structure and composition are also associated with increases in the activity of people with vehicles and equipment, which results in increases in anthropogenic noise. anthropogenic noise may reduce habitat quality for many species, particularly those that rely on acoustic signals for communication. we compared the density and occupancy rate of forest passerines close to versus f ...200818616740
estradiol modulates neural responses to song in a seasonal songbird.social behaviors such as courtship, parenting, and aggression depend primarily on two factors: a social signal to trigger the behavior, and a hormonal milieu that facilitates or permits it. gonadal steroids may alter the valence or perceived context of the signal so that the same pheromone, vocalization, or visual display may elicit very different responses depending on the receiver's plasma hormone level. the neural processes underlying this phenomenon, however, are not well understood. here, w ...200818770869
interaction of testosterone, corticosterone and corticosterone binding globulin in the white-throated sparrow (zonotrichia albicollis).plasma binding globulins bind steroid hormones and are thought to regulate hormone access to tissues. mammals have both sex steroid binding globulin (ssbg) and corticosteroid binding globulin (cbg). birds, however, have no detectable ssbg, leading to the early conclusion that birds have no plasma regulation of sex steroids. cbg, however, can bind androgens with relatively high affinity. in birds, therefore, the control of androgenic effects may be tightly regulated by glucocorticoid physiology b ...200818644248
endocrine and genomic architecture of life history trade-offs in an avian model of social behavior.life history trade-offs can drive the evolution of alternative phenotypes, the expression of which is usually under hormonal control. here, i review the endocrine and genetic bases of a trade-off between parental and competitive behavior in an increasingly popular model of social behavior, the white-throated sparrow (zonotrichia albicollis). within a population, approximately half of the individuals of this species exhibit a tan stripe (ts) on the crown and adopt a parental strategy, whereas the ...200818495122
activity of the hypothalamic-pituitary-gonadal axis differs between behavioral phenotypes in female white-throated sparrows (zonotrichia albicollis).the white-throated sparrow (zonotrichia albicollis) lends itself particularly well to investigations of neuroendocrine mechanisms of social behavior because of a behavioral polymorphism that correlates with a plumage phenotype. roughly half of the individuals of this species exhibit a white stripe (ws) on the crown and engage in a more aggressive strategy, whereas the other half exhibit a tan stripe (ts) and assume a more parental strategy. these behavioral differences are mirrored by hormonal a ...200818275963
rapid neuroendocrine responses to auditory courtship signals.in many species, courtship signals enhance reproductive function in the receiver. how these social signals are processed by the brain, particularly how they induce an endocrine response, is not well understood. songbirds provide an ideal model in which to study this phenomenon because of the large existing literature on both their auditory neurobiology and the control of their reproductive physiology by environmental cues. to date, all of the relevant studies on songbirds have involved measuring ...200717823268
estradiol modulates brainstem catecholaminergic cell groups and projections to the auditory forebrain in a female songbird.in songbirds, hearing conspecific song induces robust expression of the immediate early gene zenk in the auditory forebrain. this genomic response to song is well characterized in males and females of many species, and is highly selective for behaviorally relevant song. in white-throated sparrows, the selectivity of the zenk response requires breeding levels of estradiol; we previously showed that in non-breeding females with low levels of plasma estradiol, the zenk response to hearing song is n ...200717764666
intraperitoneal delivery of exogenous corticosterone via osmotic pump in a passerine bird.selecting the most reliable method to deliver exogenous steroids remains a problem for researchers, particularly when designing experiments on small birds. we used intraperitoneal (ip) osmotic pumps to deliver exogenous corticosterone (cort) and ru486 in captive white-throated sparrows. males received implants containing either a low (ld) or moderate dose (md) of cort, ru486 (ru), or polyethylene glycol vehicle only (v). this method provided sustained elevations in baseline cort in both ld and m ...200717428484
west nile virus surveillance in east baton rouge parish, louisiana.west nile virus (wnv) was detected for the first time in louisiana in the fall of 2001. surveillance data collected from east baton rouge parish in 2002 were examined to establish baseline data on wnv activity, to support the current design of disease surveillance programs, and to target vector control efforts in the parish. the first indications of wnv activity were from a dead northern cardinal collected in february and from a live male cardinal sampled on 14 march. in mosquito pools, wnv was ...200717536365
long-term effects of group-selection timber harvesting on abundance of forest birds.relatively few studies have examined the ecological effects of group-selection timber harvesting, and nearly all have been short-term and have lacked experimental manipulations that allow pre- and posttreatment comparisons. we have been documenting the effects of a group-selection timber harvest on bird abundance in a maine forest for 24 years (preharvest, 1983-1987; postharvest, 1988-2006). here we characterized the trends in bird abundance over the first 20 years of the study in the managed an ...200717883487
endocrine correlates of alternative phenotypes in the white-throated sparrow (zonotrichia albicollis).many vertebrate species exhibit alternative phenotypes (or morphs), in which one sex displays phenotypic variation equal to or greater than the variation between the sexes. males in such species typically display differences in reproductive strategies and morphology. steroid hormones such as testosterone are known modulators of reproductive behavior and morphology and therefore are obvious candidates for the mediation of phenotypic differences between morphs. we conducted a year-round study in t ...200616919277
estrogen-dependent selectivity of genomic responses to birdsong.behavioral responses to sociosexual signals often depend on gonadal steroid hormones, which are thought to modulate behavior by acting on motivational systems in the brain. there is mounting evidence that sex steroids may also modulate perception of sociosexual signals by affecting sensory processing. in seasonally breeding songbirds such as the white-throated sparrow (zonotrichia albicollis), the female's behavioral response to hearing male song depends on her plasma levels of estradiol (e2). h ...200616553615
diet quality and food limitation affect the dynamics of body composition and digestive organs in a migratory songbird (zonotrichia albicollis).migrating songbirds interrupt their feeding to fly between stopover sites that may vary appreciably in diet quality. we studied the effects of fasting and food restriction on body composition and digestive organs in a migratory songbird and how these effects interacted with diet quality to influence the rate of recovery of nutrient reserves. food limitation caused white-throated sparrows to reduce both lean and fat reserves, with about 20% of the decline in lean mass represented by a decline in ...200615286920
neuroendocrine correlates of behavioral polymorphism in white-throated sparrows.interspecific differences in the neuropeptide systems of the lateral septum (ls) often parallel differences in social behavior. in rodents, some closely related species that differ in aggressive behavior also differ according to the level of vasopressin (vp) innervation of the ls. in songbirds, the neuropeptides vasotocin (vt) and vasoactive intestinal peptide (vip) affect aggression when administered directly to the ls. here, we tested whether the density of vt or vip innervation of the ls refl ...200515878570
stable isotope and band-encounter analyses delineate migratory patterns and catchment areas of white-throated sparrows at a migration monitoring station.the canadian migration monitoring network consists of several fixed migration monitoring stations (mms) that apply constant-effort protocols to track changes in the abundance of migratory birds. such monitoring will be important for tracking long-term population trends of songbirds, especially for species breeding in remote areas such as the north american boreal forest. the geographical catchment sampled by individual mms, however, remains largely unknown. here, we used hydrogen isotope measure ...200515800746
a field validation of plasma metabolite profiling to assess refueling performance of migratory birds.plasma metabolite profiling offers a potential means to assess stopover refueling performance of migratory birds from a single capture. however, this method has not previously been validated where site quality has been determined independently using analysis of capture data. we captured and blood sampled six passerine bird species refueling at known high-quality (base) and low-quality (tip) sites at long point, ontario, canada. plasma triglyceride, an indicator of fat deposition, was higher at t ...200515702470
mercury concentrations in bicknell's thrush and other insectivorous passerines in montane forests of northeastern north america.anthropogenic input of mercury (hg) into the environment has elevated risk to fish and wildlife, particularly in northeastern north america. investigations into the transfer and fate of hg have focused on inhabitants of freshwater aquatic ecosystems, as these are the habitats at greatest risk for methylmercury (mehg) biomagnification. deviating from such an approach, we documented mehg availability in a terrestrial montane ecosystem using a suite of insectivorous passerines. intensive and extens ...200515931968
stable isotopes in breath, blood, feces and feathers can indicate intra-individual changes in the diet of migratory songbirds.we used stable isotopes of c in breath, blood, feces and feathers to identify intra-individual changes in diet and the timescale of diet changes in free-living songbirds at a stopover site. because accurate interpretation of differences between the delta13c of breath, plasma, and red blood cells (rbcs) relative to diet requires knowing the turnover rate of c within them, we determined the rate of change of c in breath, plasma and rbcs for yellow-rumped warblers (dendroica coronata). half-lives o ...200515586297
a behavior analysis of absolute pitch: sex, experience, and species.absolute pitch (ap) perception refers to the ability to identify, classify, and memorize pitches without use of an external reference pitch. in tests of ap, several species were trained to sort contiguous tones into three or eight frequency ranges, based on correlations between responding to tones in each frequency range and reinforcement. two songbird species, zebra finches and white-throated sparrows, and a parrot species, budgerigars had highly accurate ap, they discriminated both three and e ...200415157978
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