Population Of Song Sparrows Research Articles

Cultural shifts after punctuated environmental stress: a study of song distributions in Dark-eyed Junco and Song Sparrow populations

Cultural shifts after punctuated environmental stress: a study of song distributions in Dark-eyed Junco and Song Sparrow populations

Immune genotypes, immune responses, and survival in a wild bird population.

Individuals vary in their immune genotype, inbreeding coefficient f, immune responses, survival to adulthood, and adult longevity. However, whether immune genes predict survival or longevity, whether such relationships are mediated through immune responses, and how f affects immune genotype remain unclear. We use a wild song sparrow (Melospiza melodia) population in which survival to adulthood, adult longevity, and f were measured precisely, and in which immune responses have previously been assessed. We investigate four toll-like receptor (TLR) and the major histocompatibility complex (MHC) class IIB exon 2 genes. We test: a) whether immune genes predict fitness (survival to adulthood or adult longevity); b) whether immune genes predict immune response; c) whether immune response predicts fitness; and d) whether fitness, immune responses, or immune genotypes are correlated with f. We find that survival to adulthood is not associated with immune gene variation, but adult longevity is decreased by high MHC allele diversity (especially in birds that were relatively outbred), and by the presence of a specific MHC supertype. Immune responses were affected by specific immune genotypes. Survival to adulthood and adult longevity were not predicted by immune response, implying caution in the use of immune response as a predictor for fitness. We also found no relationship between f and immune genotype. This finding indicates that immune gene associations with longevity and immune response are not artefacts of f, and suggests that pathogen-mediated selection at functional loci can slow the loss of genetic variation arising from genetic drift and small population size.

Are immigrants outbred and unrelated? Testing standard assumptions in a wild metapopulation.

Immigration into small recipient populations is expected to alleviate inbreeding and increase genetic variation, and hence facilitate population persistence through genetic and/or evolutionary rescue. Such expectations depend on three standard assumptions: that immigrants are outbred, unrelated to existing natives at arrival, and unrelated to each other. These assumptions are rarely explicitly verified, including in key field systems in evolutionary ecology. Yet, they could be violated due to non-random or repeated immigration from adjacent small populations. We combined molecular genetic marker data for 150-160microsatellite loci with comprehensive pedigree data to test the three assumptions for a song sparrow (Melospiza melodia) population that is a model system for quantifying effects of inbreeding and immigration in the wild. Immigrants were less homozygous than existing natives on average, with mean homozygosity that closely resembled outbred natives. Immigrants can therefore be considered outbred on the focal population scale. Comparisons of homozygosity of real or hypothetical offspring of immigrant-native, native-native and immigrant-immigrant pairings implied that immigrants were typically unrelated to existing natives and to each other. Indeed, immigrants' offspring would be even less homozygous than outbred individuals on the focal population scale. The three standard assumptions of population genetic and evolutionary theory were consequently largely validated. Yet, our analyses revealed some deviations that should be accounted for in future analyses of heterosis and inbreeding depression, implying that the three assumptions should be verified in other systems to probe patterns of non-random or repeated dispersal and facilitate precise and unbiased estimation of key evolutionary parameters.

Territory establishment, song learning strategies and survival in song sparrows

AbstractIn most songbirds, the processes of song learning and territory establishment overlap in the early life and a young bird usually winds up with songs matching those of his territorial neighbors in his first breeding season. In the present study, we examined the relationships among the timing of territory establishment, the pattern of song learning and territorial success in a sedentary population of song sparrows (Melospiza melodia). Males in this population tend to learn their songs from their neighbors and consequently they show high song sharing with neighbors and use these shared songs preferentially in interactions with them. Males also show significant variation in the timing of territory establishment, ranging from their natal summer to the next spring. Using a three‐year dataset, we found that the timing of territory establishment did not systematically affect the composition of the song repertoire of the tutee: early establishers and late establishers learned equally as much from their primary tutors and had a similar number of tutors and similar repertoire sizes, nor did timing of territory establishment affect subsequent survival on territory. Therefore, the song‐learning program of song sparrows seems versatile enough to lead to high song sharing even for birds that establish territories relatively late.

The simulation extrapolation technique meets ecology and evolution: A general and intuitive method to account for measurement error

Abstract Measurement error and other forms of uncertainty are commonplace in ecology and evolution, and may bias estimates of parameters of interest. Although a variety of approaches to obtain unbiased estimators are available, these usually require the formulation of an explicit (parametric) model for the error‐prone variable and a latent model for the unobserved (latent) error‐free variable. In practice, this is often difficult. We propose to generalize the simulation extrapolation (SIMEX) technique, a heuristic approach to correct for measurement error, to situations where it is difficult to explicitly formulate an error model or latent model for a variable of interest. We illustrate the idea with the example of error in pedigrees. Pedigree error causes error in estimates of inbreeding coefficients and the relatedness matrix, thus biasing estimates of inbreeding depression or heritability. Instead of formulating error models for inbreeding coefficients or the relatedness matrix, we directly apply the SIMEX idea to the pedigree. The initially known error proportion in the pedigree is progressively increased, all models are refitted, and the observed trend in the quantities of interest is extrapolated back to a hypothetical error‐free pedigree to obtain bias‐corrected estimates. We tested this pedigree‐SIMEX (PSIMEX) method with simulated pedigrees and with data from a free‐living population of song sparrows. The simulation study indicates that the PSIMEX estimator is almost unbiased for inbreeding depression and heritability, and that it has a much lower mean squared error (MSE) than the naive estimator. In the application to the song sparrows, the error‐corrected results could be validated against the actual values thanks to the availability of both an error‐prone and an error‐free pedigree. The results indicate that bias and MSE are reduced by PSIMEX. For easy accessibility of the method, we provide the R‐package PSIMEX. By transferring the SIMEX philosophy to error in pedigrees, we have illustrated how this heuristic approach can be generalized to situations where explicit error models are difficult to formulate. Thanks to the simplicity of the idea, many other error problems in ecology and evolution might be amenable to SIMEX‐like error correction methods.

Constraints on song type matching in a songbird

In an eastern population of song sparrows (Melospiza melodia), song type matching occurs at above chance levels but does not signal aggressiveness. One explanation for the apparent ineffectiveness of matching as a signal is that the occurrence of matching is constrained by internal rules for ordering the production of song types. This constraint hypothesis is tested here in an experiment in which the singing of territorial male song sparrows is monitored in the field in real time, and subjects are confronted with playback of one of their song types either immediately after switching away from that type (short-delay) or after having cycled through much of their repertoire since last singing that type (long-delay). Matching was not significantly more likely in the long-delay treatment than in the short-delay treatment. The probability of matching did, however, depend significantly on prior bout length: the longer was a singer’s last bout of a song type, the less likely the singer was to match it. There was also a suggestive effect of frequency of usage: males were more likely to match a song type the more frequently they normally sang that type, though this result was not significant after correcting for multiple comparisons. Thus, internal rules on how songs are sequenced exert constraints on the occurrence of song type matching, and such constraints can help to explain the apparent ineffectiveness of matching as a signal in this study population. Research on song type matching in songbirds has largely focused on the signal function of matching, especially on the hypothesis that matching serves as an aggressive signal directed at the matched individual. In some songbirds, however, such as our study population of eastern song sparrows, predictions of the aggressive signaling hypothesis are not supported. Here, we show that the probability that song sparrows match song playback is strongly influenced by internal rules governing the sequencing of song type production. Specifically, the probability that song sparrows will match a particular song type is inversely related to the length of their prior bout of that song type. This result demonstrates how internal syntactical rules governing song type sequencing can constrain the signal function of song type matching.

Sex-specific additive genetic variances and correlations for fitness in a song sparrow (Melospiza melodia) population subject to natural immigration and inbreeding.

Quantifying sex-specific additive genetic variance (VA ) in fitness, and the cross-sex genetic correlation (rA ), is prerequisite to predicting evolutionary dynamics and the magnitude of sexual conflict. Further, quantifying VA and rA in underlying fitness components, and genetic consequences of immigration and resulting gene flow, is required to identify mechanisms that maintain VA in fitness. However, these key parameters have rarely been estimated in wild populations experiencing natural environmental variation and immigration. We used comprehensive pedigree and life-history data from song sparrows (Melospiza melodia) to estimate VA and rA in sex-specific fitness and underlying fitness components, and to estimate additive genetic effects of immigrants alongside inbreeding depression. We found evidence of substantial VA in female and male fitness, with a moderate positive cross-sex rA . There was also substantial VA in male but not female adult reproductive success, and moderate VA in juvenile survival but not adult annual survival. Immigrants introduced alleles with negative additive genetic effects on local fitness, potentially reducing population mean fitness through migration load, but alleviating expression of inbreeding depression. Our results show that VA for fitness can be maintained in the wild, and be broadly concordant between the sexes despite marked sex-specific VA in reproductive success.

Husbandry of wild-caught song sparrows (Melospiza melodia).

Conservation and research efforts occasionally rely upon bringing wild animals into human care to establish breeding programs and to understand their biology. Wild-caught birds may have husbandry requirements that differ from captive-reared animals due, in part, to their social development in the wild and potential exposure to novel pathogens. We developed husbandry techniques to minimize stress and monitor health in a population of wild-caught song sparrows (Melospiza melodia). We describe enclosure conditions, diet and enrichment, and best practices for stress reduction. In addition, we describe several health monitoring strategies, including assessing feces quality, body condition scores, and specific signs of infection. These techniques led to successful housing of song sparrows during formal behavioral and developmental studies. This information will be useful for guiding the husbandry of wild-caught passerine birds in the future.

Temporal variation in the effects of individual and environmental factors on nest success

ABSTRACT Factors that affect the survival of nestling birds can drive the dynamics of populations and the evolution of life histories. Such factors may include a variety of intrinsic, biotic, or abiotic factors that vary in magnitude or effect over ecological time scales. Consequently, estimates of the influence of such factors on nest success may differ when estimated from short- vs. long-term studies. We tested this possibility by estimating the influence of 2 intrinsic factors (female age and inbreeding coefficient), 2 abiotic factors (rainfall and temperature), and 3 biotic factors (breeding density, parasitism rate, and brood parasitism) previously found to predict success (≥1 fledged young) in a 39 yr study of a Song Sparrow (Melospiza melodia) population on Mandarte Island, British Columbia, Canada. We then compared those estimates to others obtained from parallel models based on the the first 13 yr, middle 13 yr, and last 13 yr of the study. Over the entire study, nest success increased in females...

Demographic consequences of invasion by a native, controphic competitor to an insular bird population.

Species invasions and range shifts can lead to novel competitive interactions between historically resident and colonizing species, but the demographic consequences of such interactions remain controversial. We present results from field experiments and 45 years of demographic monitoring to test the hypothesis that the colonization of Mandarte Is., BC, Canada, by fox sparrows (Passerella iliaca) caused the long-term decline of the resident population of song sparrows (Melospiza melodia). Several lines of evidence indicate that competition with fox sparrows for winter food reduced over-winter survival in juvenile song sparrows by 48% from 1960 to 2015, enforcing population decline despite an increase in annual reproductive rate in song sparrows over the same period. Preference for locally abundant seeds presented at experimental arenas suggested complete overlap in diet in song and fox sparrows, and observations at arenas baited with commercial seed showed that fox sparrows displaced song sparrows in 91-100% of interactions in two periods during winter. In contrast, we found no evidence of interspecific competition for resources during the breeding season. Our results indicate that in the absence of marked shifts in niche dimension, range expansions by dominant competitors have the potential to cause the extirpation of historically resident species when competitive interactions between them are strong and resources not equitably partitioned.

No evidence of inbreeding depression in sperm performance traits in wild song sparrows.

Inbreeding is widely hypothesized to shape mating systems and population persistence, but such effects will depend on which traits show inbreeding depression. Population and evolutionary consequences could be substantial if inbreeding decreases sperm performance and hence decreases male fertilization success and female fertility. However, the magnitude of inbreeding depression in sperm performance traits has rarely been estimated in wild populations experiencing natural variation in inbreeding. Further, the hypothesis that inbreeding could increase within‐ejaculate variation in sperm traits and thereby further affect male fertilization success has not been explicitly tested. We used a wild pedigreed song sparrow (Melospiza melodia) population, where frequent extrapair copulations likely create strong postcopulatory competition for fertilization success, to quantify effects of male coefficient of inbreeding (f) on key sperm performance traits. We found no evidence of inbreeding depression in sperm motility, longevity, or velocity, and the within‐ejaculate variance in sperm velocity did not increase with male f. Contrary to inferences from highly inbred captive and experimental populations, our results imply that moderate inbreeding will not necessarily constrain sperm performance in wild populations. Consequently, the widely observed individual‐level and population‐level inbreeding depression in male and female fitness may not stem from reduced sperm performance in inbred males.

Individual fitness and the effects of a changing climate on the cessation and length of the breeding period using a 34-year study of a temperate songbird.

Studies of the phenological responses of animals to climate change typically emphasize the initiation of breeding although climatic effects on the cessation and length of the breeding period may be as or more influential of fitness. We quantified links between climate, the cessation and length of the breeding period, and individual survival and reproduction using a 34-year study of a resident song sparrow (Melospiza melodia) population subject to dramatic variation in climate. We show that the cessation and length of the breeding period varied strongly across years, and predicted female annual fecundity but not survival. Breeding period length was more influential of fecundity than initiation or cessation of breeding alone. Warmer annual temperature and drier winters and summers predicted an earlier cessation of breeding. Population density, the date breeding was initiated, a female's history of breeding success, and the number of breeding attempts initiated previously also predicted the cessation of breeding annually, indicating that climatic, population, and individual factors may interact to affect breeding phenology. Linking climate projections to our model results suggests that females will both initiate and cease breeding earlier in the future; this will have opposite effects on individual reproductive rate because breeding earlier is expected to increase fecundity, whereas ceasing breeding earlier should reduce it. Identifying factors affecting the cessation and length of the breeding period in multiparous species may be essential to predicting individual fitness and population demography. Given a rich history of studies on the initiation of breeding in free-living species, re-visiting those data to estimate climatic effects on the cessation and length of breeding should improve our ability to predict the impacts of climate change on multiparous species.

Age and years to death disparately influence reproductive allocation in a short‐lived bird

Theory predicts that reproduction will change as individuals near the end of their lives by either increasing reproductive allocation (terminal allocation hypothesis) or decreasing allocation (senescence hypothesis) toward the end of life. Although senescence has received more support, few studies examine how both age and years to death influence late-life reproduction. We used a 37-yr study of Song Sparrows (Melospiza melodia) to ask how age and years to death influenced reproductive allocation late in life. We observed both senescence and terminal allocation, and that age and years to death interacted to influence individual variation in allocation tactics. In particular, we observed a decline in allocation in older individuals (senescence), but only when comparing individuals with the same number of years to death. Likewise, we observed terminal allocation, but only in young females. Reproductive tactics were most variable in young females, with many exerting high effort but living 1-2yr, and others exerting low effort annually and living longer. Our results suggest that late-life reproductive tactics are influenced by both chronological age and years to death, and that short- and long-lived females with differing reproductive tactics exist within this population of Song Sparrows.

Pedigree-based inbreeding coefficient explains more variation in fitness than heterozygosity at 160 microsatellites in a wild bird population.

Although the pedigree-based inbreeding coefficient F predicts the expected proportion of an individual's genome that is identical-by-descent (IBD), heterozygosity at genetic markers captures Mendelian sampling variation and thereby provides an estimate of realized IBD. Realized IBD should hence explain more variation in fitness than their pedigree-based expectations, but how many markers are required to achieve this in practice remains poorly understood. We use extensive pedigree and life-history data from an island population of song sparrows (Melospiza melodia) to show that the number of genetic markers and pedigree depth affected the explanatory power of heterozygosity and F, respectively, but that heterozygosity measured at 160 microsatellites did not explain more variation in fitness than F This is in contrast with other studies that found heterozygosity based on far fewer markers to explain more variation in fitness than F Thus, the relative performance of marker- and pedigree-based estimates of IBD depends on the quality of the pedigree, the number, variability and location of the markers employed, and the species-specific recombination landscape, and expectations based on detailed and deep pedigrees remain valuable until we can routinely afford genotyping hundreds of phenotyped wild individuals of genetic non-model species for thousands of genetic markers.

Correction to 'Agonistic urban birds: elevated territorial aggression of urban song sparrows is individually consistent within a breeding period'.

You have accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Davies Scott and Sewall Kendra B. 2016Correction to ‘Agonistic urban birds: elevated territorial aggression of urban song sparrows is individually consistent within a breeding period’Biol. Lett.122016090020160900http://doi.org/10.1098/rsbl.2016.0900SectionYou have accessCorrectionCorrection to ‘Agonistic urban birds: elevated territorial aggression of urban song sparrows is individually consistent within a breeding period’ Scott Davies Scott Davies Google Scholar Find this author on PubMed Search for more papers by this author and Kendra B. Sewall Kendra B. Sewall Google Scholar Find this author on PubMed Search for more papers by this author Scott Davies Scott Davies Google Scholar Find this author on PubMed Search for more papers by this author and Kendra B. Sewall Kendra B. Sewall Google Scholar Find this author on PubMed Search for more papers by this author Published:01 November 2016https://doi.org/10.1098/rsbl.2016.0900This article corrects the followingResearch ArticleAgonistic urban birds: elevated territorial aggression of urban song sparrows is individually consistent within a breeding periodhttps://doi.org/10.1098/rsbl.2016.0315 Scott Davies and Kendra B. Sewall volume 12issue 6Biology Letters01 June 2016Biol. Lett.12, 20160315. (Published online 21 June 2016). (doi:10.1098/rsbl.2016.0315)We have been made aware that the estimate of individual repeatability that we used in our study (i.e. the intraclass correlation coefficient) overestimates repeatability, and that calculating repeatability using the analysis of variance-based method, as described by Lessells & Boag [1]), is a more appropriate estimate. Consequently, we have recalculated repeatability using this more appropriate approach and describe these changes below.When pooling the behaviour of urban and rural birds, there was a non-significant trend towards low repeatability of territorial aggression score (r = 0.21, F52,105 = 1.54, p = 0.06). However, when considering each population alone there was a trend toward repeatability in rural, but not urban birds (urban: r = 0.02, F24,49 = 1.04, p = 0.46; rural: r = 0.28, F27,55 = 1.78, p = 0.07). Overall, when considering both populations simultaneously or each alone, territorial aggression score was not significantly repeatable within individuals.In our study, we considered ‘repeatability’ to be the proportion of variation that is reproducible among repeated measurements. By contrast, we use the term ‘consistency’ to refer to the consistent difference in population means when measuring the same individuals at multiple times. Although the territorial aggression of individual male song sparrows was not individually repeatable, urban male song sparrows were more territorially aggressive than their rural counterparts at both time points, making the difference in behaviour across habitat types consistent. Thus, our corrected results show consistency in population differences without individual repeatability of behavioural scores. Further, our title should read ‘…elevated territorial aggression of urban song sparrows is consistent within a breeding period’ in reference to the consistent difference in population means, not the proportion of variation that is reproducible among repeated measurements.Additional research is required to determine whether there is a habitat-related difference in the repeatability of territorial aggression in male song sparrows, which our re-analyses and prior work [2,3] suggest may be the case.Footnotes© 2016 The Author(s)Published by the Royal Society. All rights reserved.References1Lessells CM, Boag PT. 1987Unrepeatable repeatabilities: a common mistake. Auk 104, 116–121. (doi:10.2307/4087240) Crossref, ISI, Google Scholar2Scales J, Hyman J, Hughes M. 2011Behavioral syndromes break down in urban song sparrow populations. Ethology 117, 887–895. (doi:10.1111/j.1439-0310.2011.01943.x) Crossref, ISI, Google Scholar3Akçay Ç, Campbell SE, Beecher MD. 2014Individual differences affect honest signaling in a songbird. Proc. R. Soc. B 281, 20132496. (doi:10.1098/rspb.2013.2496) Link, ISI, Google Scholar Previous ArticleNext Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsRelated articlesAgonistic urban birds: elevated territorial aggression of urban song sparrows is individually consistent within a breeding period01 June 2016Biology Letters This IssueNovember 2016Volume 12Issue 11 Article InformationDOI:https://doi.org/10.1098/rsbl.2016.0900PubMed:27903781Published by:Royal SocietyOnline ISSN:1744-957XHistory: Published online01/11/2016Published in print30/11/2016 License:© 2016 The Author(s)Published by the Royal Society. All rights reserved. Citations and impact Subjectsbehaviourecology Large datasets are available through Biology Letters' partnership with Dryad

A test for repertoire matching in eastern song sparrows

Repertoire matching occurs when one songbird replies to another with a song type that the two birds share. Repertoire matching has previously been demonstrated to occur at well above chance levels in a western population of song sparrows, where it is hypothesized to serve as a low level threat in a hierarchy of aggressive signals. Here we test for repertoire matching in an eastern population of song sparrows. Previous work indicates that this eastern population differs from the western one in having lower levels of song sharing between neighboring males and in showing no association between song sharing and territory tenure. Here we confirm that males in this eastern population on average share few whole songs with their neighbors. The eastern males are familiar with their neighbors’ repertoires, as evidenced by a stronger singing response to stranger song than to neighbor song. Males in the eastern population did not repertoire match: when played an unshared song type from a specific neighbor, they did not reply with a song type shared with that neighbor more often than expected by chance or more often than in response to playback of a control song (an unshared stranger song). The results thus demonstrate a qualitative difference in vocal signaling strategies between two populations of the same species.

Genetic Divergence of an Avian Endemic on the Californian Channel Islands.

The Californian Channel Islands are near–shore islands with high levels of endemism, but extensive habitat loss has contributed to the decline or extinction of several endemic taxa. A key parameter for understanding patterns of endemism and demography in island populations is the magnitude of inter–island dispersal. This paper estimates the extent of migration and genetic differentiation in three extant and two extinct populations of Channel Island song sparrows (Melospiza melodia graminea). Inter–island differentiation was substantial (G''ST: 0.14–0.37), with San Miguel Island having the highest genetic divergence and lowest migration rates. Santa Rosa and Santa Cruz Island populations were less diverged with higher migration rates. Genetic signals of past population declines were detected in all of the extant populations. The Channel Island populations were significantly diverged from mainland populations of M. m. heermanni (G''ST: 0.30–0.64). Ten mtDNA haplotypes were recovered across the extant and extinct Channel Island population samples. Two of the ten haplotypes were shared between the Northern and Southern Channel Islands, with one of these haplotypes being detected on the Californian mainland. Our results suggest that there is little contemporary migration between islands, consistent with early explanations of avian biogeography in the Channel Islands, and that song sparrow populations on the northern Channel Islands are demographically independent.

Habitat preference facilitates successful early breeding in an open‐cup nesting songbird

Summary Selecting breeding habitats that ameliorate environmental limits on fitness and facilitate successful reproduction should benefit individual animals. This is particularly true in the temperate zone, where breeding early in a season presents a unique series of environmental challenges that can limit an individual's fitness. While many studies document links between habitat quality and reproductive success, few identify the cues used to assess habitat quality or the components of reproduction most influenced by occupying higher quality habitat, particularly during the early breeding season. We used detailed spatial maps and observations of all early season nesting attempts in an insular song sparrow (Melospiza melodia) population over 38 years to estimate the influence of nest‐site preference on reproductive success and to test whether relative microclimate or food availability may act as cues for early season site selection. Female sparrows in preferred early season nest sites had earlier laying dates, exhibited more energetically efficient incubation behaviour and produced more offspring that recruited to the population than those nesting in less‐preferred sites. Preference for potential nesting sites was positively related to leaf damage by Lepidopteran larvae, an indicator of food abundance, negatively related to early season microclimate, likely due to greater vegetation cover, and unrelated to site‐specific plant phenology. Our findings show that breeding in preferred, high‐quality habitat may offer females a fitness advantage by facilitating early laying and the production of offspring more likely to recruit to the population at a lower potential reproductive cost to the parent. We provide a clear demonstration of potential links between habitat preference and quality and their contributions to the ecology and life history of animals in seasonal environments.

A microsatellite-based linkage map for song sparrows (Melospiza melodia).

Although linkage maps are important tools in evolutionary biology, their availability for wild populations is limited. The population of song sparrows (Melospiza melodia) on Mandarte Island, Canada, is among the more intensively studied wild animal populations. Its long-term pedigree data, together with extensive genetic sampling, have allowed the study of a range of questions in evolutionary biology and ecology. However, the availability of genetic markers has been limited. We here describe 191 new microsatellite loci, including 160 high-quality polymorphic autosomal, 7 Z-linked and 1 W-linked markers. We used these markers to construct a linkage map for song sparrows with a total sex-averaged map length of 1731 cM and covering 35 linkage groups, and hence, these markers cover most of the 38-40 chromosomes. Female and male map lengths did not differ significantly. We then bioinformatically mapped these loci to the zebra finch (Taeniopygia guttata) genome and found that linkage groups were conserved between song sparrows and zebra finches. Compared to the zebra finch, marker order within small linkage groups was well conserved, whereas the larger linkage groups showed some intrachromosomal rearrangements. Finally, we show that as expected, recombination frequency between linked loci explained the majority of variation in gametic phase disequilibrium. Yet, there was substantial overlap in gametic phase disequilibrium between pairs of linked and unlinked loci. Given that the microsatellites described here lie on 35 of the 38-40 chromosomes, these markers will be useful for studies in this species, as well as for comparative genomics studies with other species.

Developmental stress, condition, and birdsong: a case study in song sparrows.

Sexual-selection theory posits that ornaments and displays can reflect a signaler's condition, which in turn is affected both by recent and developmental conditions. Moreover, developmental conditions can induce correlations between sexually selected and other traits if both types of traits exhibit developmental phenotypic plasticity in response to stressors. Thus, sexually selected traits may reflect recent and/or developmental characteristics of signalers. Here, we review data on the relationships between birdsong, a sexually selected trait, and developmental and current condition of birds from a long-term study of a population of song sparrows (Melospiza melodia). Field studies of free-living birds indicate that the complexity of a male's songs, a permanent trait, reflects the size of a song-control region of his brain (HVC), and is correlated with body size and several parameters of immunity, specifically investment in protective proteins. However, the performance of a male's songs, a dynamic trait, is not correlated to immune investment. Complexity of song is correlated with the glucocorticoid stress-response, and in some years response to stress predicts overwinter survival. Experimental manipulations have revealed that stressors in early life impair development of HVC, but that HVC recovers in size by adulthood. These manipulations result in impaired song-complexity and song-learning, but not song-performance. Experimental developmental stressors also affect growth, endocrine physiology, metabolism, and immune-function, often in a sex-specific manner. Combined, these studies suggest that song-complexity provides reliable information about early developmental experience, and about other traits that have critical developmental periods. Birdsong thus provides a multi-faceted sexually selected trait that may be an indicator both of developmental and recent conditions.