Publications

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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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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