Zebra Finches Taeniopygia Guttata Research Articles

Parentally biased favouritism in relation to offspring sex in zebra finches

Family conflicts over parental care result in offspring attempting to exert control using solicitation behaviours, whilst the parents are potentially able to retaliate through provisioning rules. However, the evolutionary interests of one parent may not necessarily support the evolutionary interests of the other parent, and such conflicts of interest may be expressed in how the two parents allocate the same form of parental care to individual offspring. Theory suggests that such parentally biased favouritism is a universally predicted outcome of evolutionary conflicts of interest, and empirical evidence suggests that parentally biased favouritism occurs in relation to offspring size and solicitation behaviours. However, unequivocal empirical evidence of parentally biased favouritism in relation to offspring sex is absent, due to being strongly confounded by sex differences in size and solicitation behaviours. Here, we present strong evidence for parentally biased favouritism in relation to offspring sex in zebra finches (Taeniopygia guttata), independent of the effects of chick size and begging intensity. Mothers preferentially provisioned sons over daughters, whilst fathers showed no bias, meaning that sons received more food than daughters. Parentally biased favouritism in relation to offspring sex facilitates parental control over evolutionary conflicts of interest and is probably more widespread than previously realised.

Male Traits and Female Choice in Java Sparrows: Preference for Large Body Size

Abstract Estrildine finches are important model species in experimental studies on female mating preferences, but research has focused on only two species from this family, namely, the Zebra Finch Taeniopygia guttata and the Bengalese Finch Lonchura striata var. domestica, and we know comparatively little about other closely related species. Therefore, we investigated sexual dimorphism and female choice in the Java Sparrow Padda oryzivora, which also belongs to the family Estrildidae, to open up the potential for comparative research and to better understand sexual selection in this family. First, we took measurements of eight morphological traits of six male and six female Java Sparrows: natural wing length, maximum wing length, tarsus length, tail length, exposed culmen length, bill width, bill depth and body mass. We quantitatively confirmed that Java Sparrows show sexual dimorphism in bill depth, with males having deeper bills than females. Second, we examined individual variation in male courtship so...

Characterization of a divergent chromosome region in the willow warbler Phylloscopus trochilus using avian genomic resources

Genome scans have made it possible to find outlier markers thought to have been influenced by divergent selection in almost any wild population. However, the lack of genomic information in nonmodel species often makes it difficult to associate these markers with certain genes or chromosome regions. Furthermore, the extent of linkage disequilibrium (LD) in the genome will determine the density of markers required to identify the genes under selection. In this study, we investigated a chromosome region in the willow warbler Phylloscopus trochilus surrounding a single marker previously identified in a genome scan. We first located the marker in the assembled genome of another species, the zebra finch Taeniopygia guttata, and amplified surrounding sequences in Fennoscandian willow warblers. Within an investigated chromosome region of 7.3 Mb as mapped to the zebra finch genome, we observed elevated genetic differentiation between a southern and a northern population across a 2.5-Mb interval comprising numerous coding genes. Within the southern and northern populations, higher values of LD were mostly found between SNPs within the same locus, but extended across distantly situated loci when the analyses were restricted to sampling sites showing intermediate allele frequencies of southern and northern alleles. Our study shows that cross-species genome information is a useful resource to obtain candidate sequences adjacent to outlier markers in nonmodel species.

Adverse effects of fipronil on avian reproduction and development: maternal transfer of fipronil to eggs in zebra finch Taeniopygia guttata and in ovo exposure in chickens Gallus domesticus

Two studies were carried out to examine the impact of maternal fipronil exposure on embryonic and offspring development. In the first study, breeding female zebra finches were orally dosed with single sublethal levels of fipronil (1, 5, and 10mg/kg body weight) to determine behavioural and developmental consequences on chicks following maternal pesticide exposure. Significant levels of fipronil and fipronil-sulfone residues were detected in eggs laid by females in all dosed groups, however, these were undetectable in eggs laid 13days after treatment. The level of sulfone detected in eggs was consistently higher than that of the parent fipronil compound. Of the seven eggs laid in the treatment groups, only one (14%) chick hatched and this was from the lowest dose group. This chick was severely underdeveloped at 10days of age in comparison to control chicks and fiproles were detected in brain, liver, and adipose tissues collected following euthanasia of this individual. In contrast, there was 100% hatchability of control group eggs and all chicks fledged nests on schedule. In the second study, domestic chicken eggs were injected with 5.5, 17.5, and 37.5mg/kg egg weight of fipronil directly into the yolk sac on day 12 of incubation. Treatment did not affect hatching success, however, behavioural and developmental abnormalities were observed in hatchlings from the highest dose group. These chicks also demonstrated reduced feeding rates, as indicated by reduced body mass at 48h period post hatch. Both fipronil and fipronil-sulfone residues were detected in brain and liver tissue of hatchlings at all pesticide dose levels tested.

Zebra finch nestlings beg more under better nutritional conditions

Abstract Providing parental care involves costs for the parents when investing resources such as food and time to raise their offspring. In many species, offspring communicate their need by begging signals which often are linked to their physiological condition but also may be affected by the expectation they may develop depending on previous parental behaviour. To test whether or not offspring begging is affected by the food quality to which parents have access, we experimentally manipulated the early nutritional conditions of zebra finch (Taeniopygia guttata) nestlings by providing the parents with either a low or a high quality diet. We expected that lower early nutritional conditions increase begging behaviour resulting from a presumed higher nestling need. Yet, the experiments revealed that broods of nestlings begged more intensely when they were raised on a high compared to a low quality diet. Nestlings raised under high quality food conditions may have a higher begging intensity due to their higher need associated with a fast growth trajectory. Likewise, lower begging intensity by nestlings raised on low quality food might result from a general delay in development, or nestlings adjusted their begging to behavioural adjustments made by parents as a response to the different diets. These findings highlight that begging signals can be affected by a complex set of factors and expands the classical view of signalling need. Begging call rates can increase with offspring condition and with their expectations about the quality of food that can be provided by the parents.

Memories of Richard Zann

Richard Zann was the authority on Zebra Finches (Taeniopygia guttata) and as such played a pivotal role in the careers of several others who, like myself, mainly studied domesticated Zebra Finches in captivity. I met Richard in 1988, we became friends and over the next 20 years we worked on several projects together. On that first visit, Richard told me how the recent forest fires that had claimed many lives, not far from where he lived, were still very fresh in his and his wife Eileen’s minds. On the evening of 6 February 2009, as I watched the television news, reports of the dreadful bushfires near Kinglake reminded me of their concern and I feared for their safety. Two days later, an email confirmed my worst fears: Richard, his wife and daughter had died on 7 February. His death, which cut short our relationship, deprives the ornithological community of an excellent researcher, and his friends and family of a charming, generous man. This brief account of how we met is a memorial to Richard and his family. I kept Zebra Finches in my bedroom and in an aviary in the garden when I was a teenager growing up outside Leeds in Yorkshire in the 1960s. Passionate about birds and bird watching, I had no qualms about keeping Zebra Finches in captivity since they seemed so content and because they allowed me such privileged access to their lives. Watching Zebra Finches at close range as they went through their entire life cycle, from courtship, nest-building, egg-laying and chick-rearing to their inevitable death, was an extraordinary experience and an important part of my ornithological education. My parents encouraged my interest in birds, although later, when I started missing lessons in order to go bird watching, they were less enthusiastic and warned me of the risks of ignoring my studies. Their admonishments had little effect until the day my father, frustrated by my lack of scholastic aptitude, told me very firmly that if I didn’t ‘pull my socks up’ I would end up working in one of the clothing factories that Leeds was then famous for. The thought filled me with absolute dread; it was the antithesis of what I loved and almost overnight I became more focussed. In 1976, I was fortunate to find myself a position as a university lecturer in another Yorkshire town, and I have been basedinSheffieldeversince.Duringthe first7yearsthere,Ispent each summer in the Arctic, continuing with the seabird studies that had constituted my Ph.D. research, but throughout this time, amidst the icebergs and polar bears I continued to think about using the Zebra Finch as a study species. As an undergraduate I had been inspired by the topic of sperm competition – a heady combination of evolutionary thinking and sex – and I wanted see if what had been discovered in insects was also true of birds. To some this didn’t seem very promising for everyone ‘knew’ that birds were monogamous. My Ph.D. studies on guillemots (Uriaaalge),however,convincedmethatspermcompetitionhad a lot going for it, so in the early 1980s with my wanderlust somewhatdepletedbyloomingpaternalresponsibilities,Ipicked up where I had left off as a teenager and began keeping Zebra Finches again. Grudgingly, I think, I was given space in a cellar-like part of the Zoology Department. Although the facilities were basic, the birds didn’t seem to mind and were wonderfully cooperative. With the enthusiastic help of a technician Jayne Pellatt, and an undergraduate, Fiona Hunter, we quantified and documented the behavioural aspects of sperm competition in our captive Zebra Finches. These were exciting times: behavioural ecology was new; studies of sexual selection and sperm competition, especially in birds, was also new and our results gratifyingly consistent with what theory predicted. Therewasjustoneproblem–asseveralofmycolleagueswere quick to point out: how did I know that what my domesticated ZebraFinchesweredoingincaptivitywaswhatZebraFinchesdid in the wild? I began writing to various ornithologists in Australia to see if there might be somewhere suitable I could study wild Zebra Finches. Most of the replies were disappointing as it was pointed out to me that Zebra Finches breed unpredictably more or less where and when they like, which was hardly compatible with persuading my head of department to give me study leave. I had almost given up when in late 1987 I received a letter from Richard Zann and suddenly everything seemed

Isolation, characterisation and predicted genome locations of Light-bellied Brent goose (Branta bernicla hrota) microsatellite loci (Anatidae, AVES)

We isolated 137 unique microsatellite loci from an enriched Light-bellied Brent goose (Branta bernicla hrota) genomic library. Thirty-seven polymorphic loci were characterised in 24 unrelated individuals sampled from a Light-bellied Brent goose population located at Ringneill quay in Strangford Lough, Northern Ireland. The 37 polymorphic loci displayed between 2 and 38 alleles. Sequence homology was used to assign a predicted chromosome location for 31 polymorphic loci (31 in the chicken (Gallus gallus) and 30 in the zebra finch (Taeniopygia guttata) assembled genome). Two polymorphic microsatellite loci were Z-linked based on the typing of known sex individuals (24 females and 25 females) and sequence homology.

Family-related differences in social foraging tactic use in the zebra finch (Taeniopygia guttata)

When animals forage in groups, they can search for food themselves (producer tactic), or they can search for opportunities to exploit the food discoveries of others (scrounger tactic). Both theoretical and empirical work have shown that group-level use of these alternative tactics is influenced by environmental conditions including group size and food distribution, and individual tactic use can be influenced by several measures of individual state, including body condition. Because body condition has been shown to be heritable for various species, social foraging tactics may also be heritable. We looked for evidence of heritability in social foraging tactic use in the zebra finch (Taeniopygia guttata) by testing whether: (1) natural variation in body condition correlates with tactic use, (2) there are family-related differences in body condition, and (3) there are family-related differences in observed tactic use. Tactic use in the zebra finch was significantly related to body condition; individuals with lower body condition scores had a significantly higher use of the scrounger tactic as predicted from variance-sensitive producer-scrounger models. Body-condition scores differed significantly between families, suggesting that this aspect of individual state may have a heritable component. Finally, we recorded significant family-related differences in the use of producer and scrounger alternatives. These results are consistent with heritability in observed tactic use resulting from an inheritance of individual state, in this case body condition, which itself influences tactic use. Understanding how and why individuals differ in their use of alternative tactics is fundamental as it may provide important insights into inter-individual variation in fitness.

Behavioural correlates of female zebra finch (Taeniopygia guttata) responses to multimodal species recognition cues

Successful sexual reproduction requires accurate mate selection, including correct species recognition. When studying multimodal species recognition cues, uncorrelated presentations of visual and acoustic traits can be valuable tools for investigating the relative importance of various sensory modalities in the recognition process. Using a model system for species recognition research, the zebra finch (Taeniopygia guttata), we investigated captive-bred females' behavioural responses to video and acoustic playbacks of male conspecific or phylogeographically relevant heterospecific cues. Females consistently spatially preferred conspecific cues when acoustic and visual cues were presented together or acoustic-only cues were played back. In contrast, females showed no discrimination when visual cues only were available and when the visual and acoustic cues of stimulus species were experimentally mismatched. Subjects showed significant individual variation in their attentiveness to playback stimulus types. The relevance of this behavioural individuality to mate choice was confirmed by a correlation between a female's attentiveness and whether it became pair bonded with an unfamiliar male in a free-flight aviary paradigm. These results are consistent with acoustic cues being more salient than visual cues presented through video playbacks and suggest that consistency in behavioural variation in female zebra finches across testing contexts may be relevant for appropriate mate selection decisions.

Individual recognition and potential recognition errors in parent–offspring communication

The recognition of food-provisioning parents is crucial for fledglings of many bird species. Vocalizations are the most commonly used cues in avian parent–offspring communication, and it has been shown in several species that fledglings respond specifically to their parents' contact calls. However, fledglings occasionally also react to unrelated adults. Such responses may reflect recognition errors or alternatively a strategy of fledglings to obtain food or other direct benefits from unrelated adult birds. In a playback experiment, we tested whether zebra finch Taeniopygia guttata fledglings perceive variation in adult call signatures to recognize their parents and whether the propensity to respond to unrelated individuals is related to the gender of adults and to signal properties of male and female calls. Male calls are learnt and show high intra-sexual variation, which may improve the accurate recognition of the father's individual signature. In contrast, calls of adult females are innate, show lower intra-sexual variation such that the mother's call is more likely to be confused with another female call. We demonstrate that fledglings are able to recognize their parents. In addition, fledglings reacted more strongly to unrelated females compared with unrelated males. Our findings suggest that responses to unrelated adults may reflect recognition errors and indicate the importance of variation in identity signals for individual recognition processes in parent–offspring communication.

New methods to identify conserved microsatellite loci and develop primer sets of high cross‐species utility – as demonstrated for birds

We have developed a new approach to create microsatellite primer sets that have high utility across a wide range of species. The success of this method was demonstrated using birds. We selected 35 avian EST microsatellite loci that had a high degree of sequence homology between the zebra finch Taeniopygia guttata and the chicken Gallus gallus and designed primer sets in which the primer bind sites were identical in both species. For 33 conserved primer sets, on average, 100% of loci amplified in each of 17 passerine species and 99% of loci in five non-passerine species. The genotyping of four individuals per species revealed that 24-76% (mean 48%) of loci were polymorphic in the passerines and 18-26% (mean 21%) in the non-passerines. When at least 17 individuals were genotyped per species for four Fringillidae finch species, 71-85% of loci were polymorphic, observed heterozygosity was above 0.50 for most loci and no locus deviated significantly from Hardy-Weinberg proportions. This new set of microsatellite markers is of higher cross-species utility than any set previously designed. The loci described are suitable for a range of applications that require polymorphic avian markers, including paternity and population studies. They will facilitate comparisons of bird genome organization, including genome mapping and studies of recombination, and allow comparisons of genetic variability between species whilst avoiding ascertainment bias. The costs and time to develop new loci can now be avoided for many applications in numerous species. Furthermore, our method can be readily used to develop microsatellite markers of high utility across other taxa.

Gene duplication and fragmentation in the zebra finch major histocompatibility complex.

BackgroundDue to its high polymorphism and importance for disease resistance, the major histocompatibility complex (MHC) has been an important focus of many vertebrate genome projects. Avian MHC organization is of particular interest because the chicken Gallus gallus, the avian species with the best characterized MHC, possesses a highly streamlined minimal essential MHC, which is linked to resistance against specific pathogens. It remains unclear the extent to which this organization describes the situation in other birds and whether it represents a derived or ancestral condition. The sequencing of the zebra finch Taeniopygia guttata genome, in combination with targeted bacterial artificial chromosome (BAC) sequencing, has allowed us to characterize an MHC from a highly divergent and diverse avian lineage, the passerines.ResultsThe zebra finch MHC exhibits a complex structure and history involving gene duplication and fragmentation. The zebra finch MHC includes multiple Class I and Class II genes, some of which appear to be pseudogenes, and spans a much more extensive genomic region than the chicken MHC, as evidenced by the presence of MHC genes on each of seven BACs spanning 739 kb. Cytogenetic (FISH) evidence and the genome assembly itself place core MHC genes on as many as four chromosomes with TAP and Class I genes mapping to different chromosomes. MHC Class II regions are further characterized by high endogenous retroviral content. Lastly, we find strong evidence of selection acting on sites within passerine MHC Class I and Class II genes.ConclusionThe zebra finch MHC differs markedly from that of the chicken, the only other bird species with a complete genome sequence. The apparent lack of synteny between TAP and the expressed MHC Class I locus is in fact reminiscent of a pattern seen in some mammalian lineages and may represent convergent evolution. Our analyses of the zebra finch MHC suggest a complex history involving chromosomal fission, gene duplication and translocation in the history of the MHC in birds, and highlight striking differences in MHC structure and organization among avian lineages.

Identifying Genes that Help One Sex but Harm the Other

Traits that help one sex can harm the other, resulting in conflicting evolutionary pressures on males and females. In zebra finches (Taeniopygia guttata), for instance, males with redder bills attract more mates but females with redder bills attract fewer mates. This battle of the sexes is thought to extend to the genetic level, with individual genes favoring one sex over the other. Some of the strongest evidence for these sexually antagonistic genes comes from studies showing that fruit fly lines with high reproductive success in one sex typically have low reproductive success in the other. Thus, if males in a particular line have many offspring, the females do not and vice versa. The genes underlying this sexual tug-of-war, however, have been difficult to find. Now, Paolo Innocenti and Edward Morrow reveal this conflict's genetic basis by linking the expression of sexually antagonistic genes in the fruit fly Drosophila melanogaster to the reproductive success of one sex at the expense of the other. The first step was identifying fruit fly lines where males and females had differential reproductive success or fitness. The researchers tested the fitness of males and females in 100 lines of fruit flies. For each line, test males and competitor males vied for mates. The test males had the normal red eyes, whereas the competitor males and females had brown eyes. Because red eyes are dominant, the proportion of red-eyed offspring yielded the relative fitness of males in each line. Similarly, females from each line and competitor females vied for food, with the number of offspring yielding the relative fitness of females in each line. As expected, lines with high-fitness males generally had low-fitness females, whereas lines with high-fitness females generally had low-fitness males. Next, Innocenti and Morrow compared gene expression in five lines with high male and low female fitness, five lines where the reverse held, and five lines where the fitness of the two sexes was average. RNA analysis of the males and females in these 15 lines revealed that although most gene expression was sex-biased, only a minority of transcripts were consistently associated with male or female fitness. While about 17,000 transcripts, or about 90% of the total, were expressed at higher levels in one sex or the other, only 867 were associated with male fitness and only 634 were associated with female fitness. To identify which genes were sexually antagonistic, the researchers determined which of these transcripts were associated with fitness in one sex at the expense of the other. They found that nearly 1,500 transcripts benefitted one sex over the other, with roughly half favoring males and half favoring females. These transcripts correspond to nearly 1,300 known genes, and these sexually antagonistic genes comprise the majority (about two-thirds) of the sex-specific fitness genes. This suggests that sexually antagonistic selection maintains genetic variation for fitness. The researchers were surprised that sexually antagonistic genes accounted for so few of the sex-biased transcripts, which were expressed at higher levels in one sex over the other, but were not necessarily associated with fitness. Sex-biased gene expression has been used as a proxy for sexual antagonism, based on the assumption that these differences in expression reflect conflict at the genetic level. However, this study questions that approach: sexually antagonistic genes accounted for a mere 8% of the total sex-biased transcripts. Innocenti and Morrow also tested—and confirmed—the key prediction that sexually antagonistic genes should accumulate on sex chromosomes. Because these chromosomes are inherited differently by males and females, this should help resolve the evolutionary conflict between the sexes. X chromosomes could have a recessive “male fitness” gene, for instance, which would benefit males with that gene on their single X chromosome. But this male benefit would not necessarily come at the expense of females: they would not be harmed if this recessive gene was on only one of their X chromosomes. As expected, the researchers found that sexually antagonistic genes were overwhelmingly concentrated on the X chromosome. Previous studies suggest that sexually antagonistic genes are widespread amongst animals, from insects to birds to mammals. By offering this initial glimpse of the genetic basis of such findings, Innocenti and Morrow lay the groundwork for pinpointing the locations and functions of these genes that pit males and females against each other. Innocenti P, Morrow EH (2010) The Sexually Antagonistic Genes of Drosophila melanogaster. doi:10.1371/journal.pbio.1000335 Males and females display the yin-yang duality represented in the Taijitu (above): opposing forces (sexually antagonistic selection) tend to drive them apart, but an ontogenic constraint—the shared genetic material—prevents their disjunction. ...

Exposure to cold but not exercise increases carbon turnover rates in specific tissues of a passerine

Carbon turnover differs between tissues within an animal, but the extent to which ecologically relevant increases in metabolism affect carbon turnover rates is largely unknown. We tested the energy expenditure and protein turnover hypotheses that predict increased carbon turnover, either in association with increased daily energy expenditure, or in concert with tissue-specific increased protein metabolism. We used stable-isotope-labeled diets to quantify the rate of carbon turnover in 12 different tissues for three groups of zebra finches (Taeniopygia guttata): cold-exposed birds kept at ambient temperatures below their thermoneutral zone, exercised birds that were flown for 2 h per day in a flight arena, and control birds that were kept at ambient temperatures within their thermoneutral zone and that were not exercised. We found that increases in metabolism associated with cold-exposure but not exercise produced measurable increases in carbon turnover rate of, on average, 2.4+/-0.3 days for pectoral muscle, gizzard, pancreas and heart, even though daily energy intake was similar for exercised and cold-exposed birds. This evidence does not support the energy expenditure hypothesis, and we invoke two physiological processes related to protein metabolism that can explain these treatment effects: organ mass increase and tissue-specific increase in activity. Such changes in carbon turnover rate associated with cold temperatures translate into substantial variation in the estimated time window for which resource use is estimated and this has important ecological relevance.

Female Zebra Finches (Taeniopygia guttata) Are Chronically but Not Cumulatively “Anemic” during Repeated Egg Laying in Response to Experimental Nest Predation

Recently it has been recognized that reproduction itself, or the regulatory processes controlling reproduction, might contribute to physiological costs of reproduction. Reproductive anemia, a decrease in hematocrit and hemoglobin concentration, might provide one such mechanism underlying the costs of egg production in birds. In this study, we investigated the effect of repeated cycles of egg production in response to experimental nest predation (egg removal) on hematological traits in female zebra finches (Taeniopygia guttata). We predicted that if the negative effect of egg production on hematocrit and hemoglobin concentration was cumulative, with anemia being proportional to reproductive effort, then females laying more clutches, or laying successive clutches without recovery during incubation, would show greater reproductive anemia. In contrast, if females maintain hematocrit and hemoglobin concentration at some minimum functional level independent of reproductive effort, then there should be no difference in hematological traits among females laying two or more successive clutches. Our results supported the second of these hypotheses: egg-laying females had reduced hematocrit (-7.5%) and hemoglobin concentrations (-10%), but the extent of reproductive anemia did not differ among females laying either two or three successive clutches, with or without recovery during incubation, or in females laying 7-21 eggs. Females maintained low hematocrit and hemoglobin for 20-35 d, and we suggest that prolonged periods of anemia might be common and functionally important in free-living birds, for example, where females produce multiple successive clutches in response to high levels of nest predation or where they initiate a second clutch while still rearing first brood chicks.

SPERM MORPHOLOGY AND VELOCITY ARE GENETICALLY CODETERMINED IN THE ZEBRA FINCH

Sperm morphology (size and shape) and sperm velocity are both positively associated with fertilization success, and are expected to be under strong selection. Until recently, evidence for a link between sperm morphology and velocity was lacking, but recent comparative studies have shown that species with high levels of sperm competition have evolved long and fast sperm. It is therefore surprising that evidence for a phenotypic or genetic relationship between length and velocity within species is equivocal, even though sperm competition is played out in the intraspecific arena. Here, we first show that sperm velocity is positively phenotypically correlated with measures of sperm length in the zebra finch Taeniopygia guttata. Second, by using the quantitative genetic "animal model" on a dataset from a multigenerational-pedigreed population, we show that sperm velocity is heritable, and positively genetically correlated to a number of heritable components of sperm length. Therefore, selection for faster sperm will simultaneously lead to the evolution of longer sperm (and vice versa). Our results provide, for the first time, a clear phenotypic and genetic link between sperm length and velocity, which has broad implications for understanding how recently described macroevolutionary patterns in sperm traits have evolved.

Real‐time quantitative PCR assay for measurement of avian telomeres

We present the application of a real‐time quantitative PCR assay, previously developed to measure relative telomere length in humans and mice, to two bird species, the zebra finchTaeniopygia guttataand the Alpine swiftApus melba. This technique is based on the PCR amplification of telomeric (TTAGGG)nsequences using specific oligonucleotide primers. Relative telomere length is expressed as the ratio (T/S) of telomere repeat copy number (T) to control single gene copy number (S). This method is particularly useful for comparisons of individuals within species, or where the same individuals are followed longitudinally. We used glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) as a single control gene. In both species, we validated our PCR measurements of relative telomere length against absolute measurements of telomere length determined by the conventional method of quantifying telomere terminal restriction fragment (TRF) lengths using both the traditional Southern blot analysis (Alpine swifts) and in gel hybridization (zebra finches). As found in humans and mice, telomere lengths in the same sample measured by TRF and PCR were well correlated in both the Alpine swift and the zebra finch.. Hence, this PCR assay for measurement of bird telomeres, which is fast and requires only small amounts of genomic DNA, should open new avenues in the study of environmental factors influencing variation in telomere length, and how this variation translates into variation in cellular and whole organism senescence.

Use of nest-boxes by the Zebra Finch (Taeniopygia guttata): implications for reproductive success and research

Nest-boxes have been used widely and for many decades in Europe and North America to increase avian reproductive success in species management and conservation programs and to increase the amenability and efficiency with which a species can be studied. Here we describe the establishment of a breeding population of Zebra Finches using nest- boxes in semi-arid, far-western New South Wales, over three breeding seasons (2005–07). The nest-boxes were used readily by Zebra Finches, with a total of 572 breeding attempts recorded in this study. After the introduction of nest-boxes, nearly all breeding attempts were made in these artificial cavities. Zebra Finches breeding in natural nests are prone to high levels of nest predation (>60% in previous studies), but such predation was almost completely eliminated with nest-boxes, with <2% of nests being depredated. Not surprisingly, the reproductive success of pairs breeding in nest-boxes (58% of nests successfully fledged at least one young) was significantly higher than in the natural nests monitored at the same sites in a previous year, and by comparison with previous studies of the same species in other localities across Australia. Our study of the Zebra Finch, a laboratory model used throughout the world, shows the effectiveness of artificial nest-boxes at decreasing levels of predation in the wild and increasing the capacity for research.

Expression of fragile X mental retardation protein within the vocal control system of developing and adult male zebra finches

Individuals with fragile X syndrome (FXS) are cognitively impaired and have marked speech delays and deficits. Our goal was to characterize expression of fragile X mental retardation protein (FMRP), encoded by Fmr1 fragile X mental retardation 1 gene or transcript (FMR1), in an animal model that learns to vocalize, namely the zebra finch Taeniopygia guttata (Tgu). We cloned and sequenced the zebra finch ortholog of FMR1 (TguFmr1) and developed an antibody that recognizes TguFmrp specifically. TguFmrp has structural features similar to its human ortholog FMRP. Because FXS patients exhibit sensorimotor deficits, we examined TguFmrp expression prior to, during, and after sensorimotor song learning in zebra finches. We found that TguFmrp is expressed throughout the brain and in four major song nuclei of the male zebra finch brain, primarily in neurons. Additionally, prior to sensorimotor learning, we observed elevated TguFmrp expression in the robust nucleus of the arcopallium (RA) of post-hatch day 30 males, compared with the surrounding telencephalon, suggesting a preparation for this stage of song learning. Finally, we observed variable TguFmrp expression in the RA of adolescent and adult males: in some males it was elevated and in others it was comparable to the surrounding telencephalon. In summary, we have characterized the zebra finch ortholog of FMRP and found elevated levels in the premotor nucleus RA at a key developmental stage for vocal learning.

Relationship between physical and genetic distances along the zebra finch Z chromosome

Nine bacterial artificial chromosomes containing genes linked to the Z chromosome of the zebra finch (Taeniopygia guttata) were localized using FISH on synaptonemal complex spreads. Their positions were correlated with those previously reported on the mitotic Z chromosome, showing a linear relationship between positions along the mitotic chromosome and its synaptonemal complex. Distances in cM between the genes were calculated using a cytological map of the crossing-over based on the distribution of MLH1 foci along the ZZ synaptonemal complex (MLH1-cM map). It is shown that physical and genetic distances lack a linear relationship along most of the chromosome length, due to clustering of crossover events around the telomeres. This relationship departs strongly from that observed in the chicken Z chromosome and reflects the existence of different recombination rates and patterns among birds in spite of wide genomic conservation.