ORCID Profile
0000-0001-8512-2805
Current Organisation
CSIRO
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Host-Parasite Interactions | Conservation and Biodiversity | Wildlife and Habitat Management | Environmental Science and Management | Vertebrate Biology | Evolutionary Biology
Disease Distribution and Transmission (incl. Surveillance and Response) | Control of Pests, Diseases and Exotic Species at Regional or Larger Scales | Flora, Fauna and Biodiversity of environments not elsewhere classified | Control of Pests, Diseases and Exotic Species not elsewhere classified | Flora, Fauna and Biodiversity at Regional or Larger Scales |
Publisher: Oxford University Press (OUP)
Date: 2011
Publisher: Springer Science and Business Media LLC
Date: 17-10-2017
DOI: 10.1038/S41598-017-13476-Z
Abstract: Genetic ersity at community, population and in idual levels is thought to influence the spread of infectious disease. At the in idual level, inbreeding and heterozygosity are associated with increased risk of infection and disease severity. Host genotype rarity may also reduce infection risk if pathogens are co-adapted to common or local hosts, but to date, no studies have investigated the relative importance of genotype rarity and heterozygosity for infection in a wild, sexually reproducing vertebrate. With beak and feather disease virus (BFDV) infection in a wild parrot ( Platycercus elegans ), we show that both heterozygosity and genotype rarity of in idual hosts predicted infection, but in contrasting ways. Heterozygosity was negatively associated with probability of infection, but not with infection load. In contrast, increased host genotype rarity was associated with lower viral load in infected in iduals, but did not predict infection probability. These effects were largely consistent across subspecies, but were not evident at the population level. Subspecies and age were also strongly associated with infection. Our study provides novel insights into infection dynamics by quantifying rarity and ersity simultaneously. We elucidate roles that host genetic ersity can play in infection dynamics, with implications for understanding population ergence, intraspecific ersity and conservation.
Publisher: Public Library of Science (PLoS)
Date: 05-12-2012
Publisher: Springer Science and Business Media LLC
Date: 12-05-2020
DOI: 10.1038/S41598-020-64631-Y
Abstract: Understanding patterns of pathogen emergence can help identify mechanisms involved in transmission dynamics. Beak and feather disease virus (BFDV) poses a major threat world-wide to wild and captive parrots. Yet data from wild birds on seasonal fluctuations in prevalence and infection intensity, and thereby the potential high-risk times for virus transmission, have been lacking. We screened wild Crimson Rosellas ( Platycercus elegans ) for BFDV in blood and cloacal swabs. Prevalence in blood s les and cloacal swabs, as well as viral load varied with Julian date and in blood, were highest after the breeding season. Breeding birds had lower viral load and lower BFDV prevalence in blood than non-breeding birds (10.1% prevalence in breeding vs. 43.2% in non-breeding birds). BFDV prevalence was much higher in younger ( years) than older (≥3 years) birds for both blood s les (42.9% vs. 4.5%) and cloacal swabs (56.4% vs. 12.3%). BFDV status in blood and cloacal s les was not correlated within in iduals. We show that, at least in P. elegans , BFDV infection seems to occur year-round, with seasonal changes in prevalence and load found in our s les. Our analyses suggest that the seasonal changes were associated primarily with the breeding season. We also discuss age and sex as important predictors of BFDV infection.
Publisher: Informa UK Limited
Date: 02-04-2018
Publisher: The Royal Society
Date: 22-08-1998
Publisher: Elsevier BV
Date: 10-2007
Publisher: Informa UK Limited
Date: 04-08-2019
Publisher: Wiley
Date: 27-03-2013
Publisher: Springer Science and Business Media LLC
Date: 24-11-2020
DOI: 10.1038/S41598-020-77405-3
Abstract: Senescence is widespread in nature, often resulting in diminishing survival or reproduction with age, but its role in age-dependent variation in sexual traits is often poorly understood. One reason is that few studies of sexual traits consider non-linear relationships with age, or only consider a narrow range of years relative to the life span of the species. Birdsong has evolved to allow assessment of conspecific quality in numerous bird species. Whilst theory and empirical work suggests that song may become more elaborate with age, there are a paucity of long-term studies testing whether song is associated with age or longevity. In particular, the occurrence of song senescence has rarely been demonstrated. Using an exceptional long-term dataset for the Seychelles warbler ( Acrocephalus sechellensis ), we analysed relationships between male song, age, survival, and longevity. This species is a long-lived songbird with early life increases, followed by senescent declines, in survival and reproduction. The study population (Cousin Island, Seychelles) is a closed population, with no depredation of adults, providing an excellent opportunity to study senescence in free-living animals. We tested whether song traits were related to age at recording, future survival, longevity, and territory quality. We found age-dependent changes in five song traits (duration, maximum frequency, peak frequency of songs, and duration and frequency bandwidth of trills). Relationships with age were quadratic, indicating reversal in the expression of song coinciding with the onset of senescence in reproduction and survival in this species. One song trait (trill bandwidth) had a quadratic relationship with future survival, but no song traits were related to longevity, suggesting age-related patterns were not the result of selective disappearance. Our study provides one of the first ex les of functional senescence in song, offering new insights into avian senescence. Late-life declines in avian song, and possibly other sexual traits, may be more common than currently known, and may play a fundamental role in age-dependent changes in reproductive success.
Publisher: University of Chicago Press
Date: 06-2015
DOI: 10.1086/681021
Abstract: The world in color presents a dazzling dimension of phenotypic variation. Biological interest in this variation has burgeoned, due to both increased means for quantifying spectral information and heightened appreciation for how animals view the world differently than humans. Effective study of color traits is challenged by how to best quantify visual perception in nonhuman species. This requires consideration of at least visual physiology but ultimately also the neural processes underlying perception. Our knowledge of color perception is founded largely on the principles gained from human psychophysics that have proven generalizable based on comparative studies in select animal models. Appreciation of these principles, their empirical foundation, and the reasonable limits to their applicability is crucial to reaching informed conclusions in color research. In this article, we seek a common intellectual basis for the study of color in nature. We first discuss the key perceptual principles, namely, retinal photoreception, sensory channels, opponent processing, color constancy, and receptor noise. We then draw on this basis to inform an analytical framework driven by the research question in relation to identifiable viewers and visual tasks of interest. Consideration of the limits to perceptual inference guides two primary decisions: first, whether a sensory-based approach is necessary and justified and, second, whether the visual task refers to perceptual distance or discriminability. We outline informed approaches in each situation and discuss key challenges for future progress, focusing particularly on how animals perceive color. Given that animal behavior serves as both the basic unit of psychophysics and the ultimate driver of color ecology/evolution, behavioral data are critical to reconciling knowledge across the schools of color research.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/ZO14052
Abstract: The detection of avian viruses in wild populations has considerable conservation implications. For DNA-based studies, feathers may be a convenient s le type for virus screening and are, therefore, an increasingly common technique. This is despite recent concerns about DNA quality, ethics, and a paucity of data comparing the reliability and sensitivity of feather s ling to other common s le types such as blood. Alternatively, skeletal muscle tissue may offer a convenient s le to collect from dead birds, which may reveal viraemia. Here, we describe a probe-based quantitative real-time PCR for the relative quantification of beak and feather disease virus (BFDV), a pathogen of serious conservation concern for parrots globally. We used this method to test for BFDV in wild crimson rosellas (Platycercus elegans), and compared three different s le types. We detected BFDV in s les from 29 out of 84 in iduals (34.5%). However, feather s les provided discordant results concerning virus presence when compared with muscle tissue and blood, and estimates of viral load varied somewhat between different s le types. This study provides evidence for widespread infection of BFDV in wild crimson rosellas, but highlights the importance of s le type when generating and interpreting qualitative and quantitative avian virus data.
Publisher: Springer Science and Business Media LLC
Date: 15-04-2021
DOI: 10.1038/S41598-021-88215-6
Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Publisher: Proceedings of the National Academy of Sciences
Date: 05-08-1997
Abstract: Avian plumage has long been used to test theories of sexual selection, with humans assessing the colors. However, many birds see in the ultraviolet ( nm), to which humans are blind. Consequently, it is important to know whether natural variation in UV reflectance from plumage functions in sexual signaling. We show that female starlings rank males differently when UV wavelengths are present or absent. Principal component analysis of ≈1300 reflectance spectra (300–700 nm) taken from sexually dimorphic plumage regions of males predicted preference under the UV+ treatment. Under UV− conditions, females ranked males in a different and nonrandom order, but plumage reflectance in the human visible spectrum did not predict choice. Natural variation in UV reflectance is thus important in avian mate assessment, and the prevailing light environment can have profound effects on observed mating preferences.
Publisher: The Royal Society
Date: 28-07-2010
Abstract: Long-term exposure to ultraviolet (UV) light generates substantial damage, and in mammals, visual sensitivity to UV is restricted to short-lived diurnal rodents and certain marsupials. In humans, the cornea and lens absorb all UV-A and most of the terrestrial UV-B radiation, preventing the reactive and damaging shorter wavelengths from reaching the retina. This is not the case in certain species of long-lived diurnal birds, which possess UV-sensitive (UVS) visual pigments, maximally sensitive below 400 nm. The Order Psittaciformes contains some of the longest lived bird species, and the two species examined so far have been shown to possess UVS pigments. The objective of this study was to investigate the prevalence of UVS pigments across long-lived parrots, macaws and cockatoos, and therefore assess whether they need to cope with the accumulated effects of exposure to UV-A and UV-B over a long period of time. Sequences from the SWS1 opsin gene revealed that all 14 species investigated possess a key substitution that has been shown to determine a UVS pigment. Furthermore, in vitro regeneration data, and lens transparency, corroborate the molecular findings of UV sensitivity. Our findings thus support the claim that the Psittaciformes are the only avian Order in which UVS pigments are ubiquitous, and indicate that these long-lived birds have UV sensitivity, despite the risks of photodamage.
Publisher: Springer Science and Business Media LLC
Date: 07-12-2018
DOI: 10.1038/S41598-018-35853-Y
Abstract: Sound is arguably the external cue most accessible to embryos of many species, and as such may constitute an unrivalled source of early information. Recent evidence shows that prenatal sounds, similarly to maternal effects, may shape developmental trajectories. Establishing whether parental vocalisations are signals directed at embryos, or parental cues on which embryos eavesdrop, can elucidate whether parents or embryos control developmental outcomes. Prenatal exposure to a characteristic heat-related parental call was recently shown to alter zebra finch growth and fitness. Here, we test the ecological context of this behaviour in the wild, and assess the information value and specificity of this vocalisation for an embryonic audience. We show that wild zebra finches also produce this characteristic call, only at high temperatures. In addition, in the lab, we demonstrate experimentally that calling is specifically triggered by high air temperatures, can occur without an embryonic audience, and importantly, is predicted by in iduals’ body mass. Overall, our findings reveal a specialised heat vocalisation that enables embryonic eavesdropping, by indicating high ambient temperatures, and parents’ capacity to cope with such conditions. This challenges the traditional view of embryos as passive agents of their development, and opens exciting research avenues on avian adaptation to extreme heat.
Publisher: Proceedings of the National Academy of Sciences
Date: 15-09-2014
Abstract: The roles of disease and species hybridization in maintaining bio ersity are of wide interest, yet are rarely studied simultaneously in wild populations. Using genomic analysis of beak and feather disease virus in an avian ring-species complex, Platycercus elegans , to our knowledge we find viral phylogenetic structure analogous to Mayr’s ring-species hypothesis for the first time in any pathogen. Across 8 y, the host’s viral prevalence and infection load was lower in hybrid birds and in phenotypically intermediate subspecies. Viral genetic variation did not explain host prevalence or infection load, supporting conclusions that the evolved host response is more important. We show how host–species complexes and viral genomic analyses can provide insight into maintenance of bio ersity.
Publisher: PeerJ
Date: 11-06-2020
DOI: 10.7717/PEERJ.9211
Abstract: Indirect transmission of pathogens can pose major risks to wildlife, yet the presence and persistence of wildlife pathogens in the environment has been little studied. Beak and feather disease virus (BFDV) is of global conservation concern: it can infect all members of the Psittaciformes, one of the most threatened bird orders, with infection often being lethal. Indirect transmission of BFDV through contaminated nest hollows has been proposed as a major infection source. However, data on whether and for how long nest sites in the wild remain contaminated have been absent. We determined the BFDV status of birds (parents and nestlings) for 82 nests of Crimson Rosellas, Platycercus elegans and Eastern Rosellas, Platycercus eximius . In 11 of these nests (13.4%, 95% confidence interval 6.9–22.7), we found an infected parent or nestling. Using nest swabs, we then compared BFDV presence at three points in time (before, during and after breeding) in three groups of nest boxes. These were nest boxes occupied by infected birds, and two control groups (nest boxes occupied by uninfected birds, and unoccupied nest boxes). Detection of BFDV on nest swabs was strongly associated with the infection status of parents in each nest box and with the timing of breeding. During breeding, boxes occupied by BFDV-positive birds were significantly more likely to have BFDV-positive nest swabs than boxes occupied by BFDV-negative birds nest swabs tested BFDV-positive in 80% (28.4–99.5) of nests with parental antigen excretion, 66.7% (9.4–99.2) of nests occupied by parents with BFDV-positive cloacal swabs and 66.7% (22.3–95.7) of nests occupied by parents with BFDV–positive blood. 0% (0–52.2) of nests with BFDV–positive nestlings had BFDV–positive nest swabs. Across all boxes occupied by BFDV-positive birds (parents or nestlings), no nest swabs were BFDV–positive before breeding, 36.4% (95% CI 10.9–69.2) were positive during breeding and 9.1% (0.2–41.3) remained positive after breeding. BFDV was present on nest swabs for up to 3.7 months. Our study provides novel insights into the potential role of nest cavities and other fomites in indirect transmission of BFDV, and possibly other pathogens, and offers a non-invasive method for surveillance of pathogens in wild bird populations.
Publisher: Springer Science and Business Media LLC
Date: 04-10-2023
Publisher: Wiley
Date: 19-09-2013
DOI: 10.1111/EVO.12261
Abstract: Birdsong is a classic ex le of a learned trait with cultural inheritance, with selection acting on trait expression. To understand how song responds to selection, it is vital to determine the extent to which variation in song learning and neuroanatomy is attributable to genetic variation, environmental conditions, or their interactions. Using a partial cross fostering design with an experimental stressor, we quantified the heritability of song structure and key brain nuclei in the song control system of the zebra finch and the genotype-by-environment (G × E) interactions. Neuroanatomy and song structure both showed low levels of heritability and are unlikely to be under selection as indicators of genetic quality. HVC, in particular, was almost entirely under environmental control. G × E interaction was important for brain development and may provide a mechanism by which additive genetic variation is maintained, which in turn may promote sexual selection through female choice. Our study suggests that selection may act on the genes determining vocal learning, rather than directly on the underlying neuroanatomy, and emphasizes the fundamental importance of environmental conditions for vocal learning and neural development in songbirds.
Publisher: The Royal Society
Date: 29-07-2008
Abstract: Speciation, despite ongoing gene flow can be studied directly in nature in ring species that comprise two reproductively isolated populations connected by a chain or ring of intergrading populations. We applied three tiers of spatio-temporal analysis (phylogeny/historical biogeography, phylogeography and landscape opulation genetics) to the data from mitochondrial and nuclear genomes of eastern Australian parrots of the Crimson Rosella Platycercus elegans complex to understand the history and present genetic structure of the ring they have long been considered to form. A ring speciation hypothesis does not explain the patterns we have observed in our data (e.g. multiple genetic discontinuities, discordance in genotypic and phenotypic assignments where terminal differentiates meet). However, we cannot reject that a continuous circular distribution has been involved in the group's history or indeed that one was formed through secondary contact at the ‘ring's’ east and west however, we reject a simple ring-species hypothesis as traditionally applied, with secondary contact only at its east. We discuss alternative models involving historical allopatry of populations. We suggest that population expansion shown by population genetics parameters in one of these isolates was accompanied by geographical range expansion, secondary contact and hybridization on the eastern and western sides of the ring. Pleistocene landscape and sea-level and habitat changes then established the birds' current distributions and range disjunctions. Populations now show idiosyncratic patterns of selection and drift. We suggest that selection and drift now drive evolution in different populations within what has been considered the ring.
Publisher: The Company of Biologists
Date: 12-2013
DOI: 10.1242/JEB.094136
Abstract: Intraspecific differences in retinal physiology have been demonstrated in several vertebrate taxa and are often subject to adaptive evolution. Nonetheless, such differences are currently unknown in birds, despite variations in habitat, behaviour and visual stimuli that might influence spectral sensitivity. The parrot Platycercus elegans is a species complex with extreme plumage colour differences between (and sometimes within) subspecies, making it an ideal candidate for intraspecific differences in spectral sensitivity. Here, the visual pigments of P. elegans were fully characterised through molecular sequencing of five visual opsin genes and measurement of their absorbance spectra using microspectrophotometry. Three of the genes, LWS, SW1 and SWS2, encode for proteins similar to those found in other birds however, both the RH1 and RH2 pigments had polypeptides with carboxyl termini of different lengths and unusual properties that are unknown previously for any vertebrate visual pigment. Specifically, multiple RH2 transcripts and protein variants (short, medium and long) were identified for the first time that are generated by alternative splicing of downstream coding and non-coding exons. Our work provides the first complete characterisation of the visual pigments of a parrot, perhaps the most colourful order of birds, and moreover suggests more variability in avian eyes than hitherto considered.
Publisher: Wiley
Date: 11-02-2019
DOI: 10.1111/JBI.13497
Publisher: MDPI AG
Date: 28-07-2021
Publisher: Wiley
Date: 2018
DOI: 10.1111/EMR.12292
Publisher: Hindawi Limited
Date: 14-07-2020
DOI: 10.1111/TBED.13703
Publisher: Elsevier BV
Date: 06-2010
Publisher: Springer Science and Business Media LLC
Date: 24-11-2020
DOI: 10.1038/S41598-020-77500-5
Abstract: Chlamydia psittaci (order: Chlamydiales ) is a globally distributed zoonotic bacterium that can cause potentially fatal disease in birds and humans. Parrots are a major host, yet prevalence and risk factors for infection in wild parrots are largely unknown. Additionally, recent research suggests there is a erse range of novel Chlamydiales circulating in wildlife. We therefore s led seven abundant parrot species in south-eastern Australia, taking cloacal swabs and serum from n = 132 wild adults. We determined C. psittaci and Chlamydiales prevalence and seroprevalence, and tested for host species, sex, geographical and seasonal differences, and temporal changes in in idual infection status. Across all species, Chlamydiales prevalence was 39.8% (95% CI 31.6, 48.7), C. psittaci prevalence was 9.8% (95% CI 5.7, 16.3) and C. gallinacea prevalence was 0.8% (95% CI 0.1, 4.5). Other Chlamydiales species were not identified to species level. We identified two C. psittaci strains within the 6BC clade, which is highly virulent in humans. Seroprevalence was 37.0% (95% CI 28.5, 46.4). Host species (including crimson rosellas, galahs, sulphur-crested cockatoos and blue-winged parrots) differed in seroprevalence and Chlamydiales prevalence. Galahs had both highest Chlamydiales prevalence (54.8%) and seroprevalence (74.1%). Seroprevalence differed between sites, with a larger difference in males (range 20–63%) than females (29–44%). We reveal a higher chlamydial prevalence than previously reported in many wild parrots, with implications for potential reservoirs, and transmission risks to humans and other avian hosts.
Publisher: Elsevier
Date: 2000
Publisher: Springer Science and Business Media LLC
Date: 27-01-2017
DOI: 10.1038/SREP41445
Abstract: Variation in wavelength sensitivity among subspecies is unknown among vertebrates. The parrot Platycercus elegans has extreme plumage variation between subspecies ranging from pale yellow to crimson which, with differences in background colour and light environment between subspecies, makes it a good candidate for the evolution of within-species differences in vision. We report differences in visual pigments between populations of P. elegans from two subspecies, providing the first known support for population and subspecies variation in visual pigments within a vertebrate species it is also the first instance of intraspecific variation in rod sensitivity within any vertebrate species. Differences in wavelength sensitivity of rods and cones corresponded to geographic differences in plumage colour. Between study populations, visual pigments varied but not oil droplets. Adaptive functions for the visual pigment differences are untested but they could cause ergence in behaviours associated with colour as well as in dim light, and provide insights into the role of senses in ergence and speciation.
Publisher: Elsevier BV
Date: 03-2009
Publisher: Informa UK Limited
Date: 02-10-2021
Publisher: Springer Science and Business Media LLC
Date: 19-11-1998
Abstract: There is a growing body of data on avian eyes, including measurements of visual pigment and oil droplet spectral absorption, and of receptor densities and their distributions across the retina. These data are sufficient to predict psychophysical colour discrimination thresholds for light-adapted eyes, and hence provide a basis for relating eye design to visual needs. We examine the advantages of coloured oil droplets, UV vision and tetrachromacy for discriminating a erse set of avian plumage spectra under natural illumination. Discriminability is enhanced both by tetrachromacy and coloured oil droplets. Oil droplets may also improve colour constancy. Comparison of the performance of a pigeon's eye, where the shortest wavelength receptor peak is at 410 nm, with that of the passerine Leiothrix, where the ultraviolet-sensitive peak is at 365 nm, generally shows a small advantage to the latter, but this advantage depends critically on the noise level in the sensitivity mechanism and on the set of spectra being viewed.
Publisher: Oxford University Press (OUP)
Date: 29-05-2018
Publisher: The Company of Biologists
Date: 09-2015
DOI: 10.1242/JEB.131854
Publisher: Informa UK Limited
Date: 09-2015
DOI: 10.1071/MU14081
Publisher: PeerJ
Date: 20-12-2021
DOI: 10.7717/PEERJ.12642
Abstract: Beak and feather disease virus (BFDV) is a circovirus that infects captive and wild psittacine birds, and is of conservation concern. The haemagglutination inhibition (HI) assay is used to determine antibody titres against BFDV, and the use of dried blood spots (DBS) on filter paper stored at room temperature has been suggested to be an equally valid technique to the use of frozen serum. However, research on other pathogens has found variable results when investigating the longevity of antibodies stored on DBS at room temperature. Consequently, we aimed to test the temporal stability of antibodies to BFDV in DBS s les stored long-term at room temperature. A further goal was to add to the current knowledge of antibody response to naturally acquired BFDV infection in crimson rosellas ( Platycercus elegans ). Blood was collected from wild P. elegans in Victoria, Australia, that had been live-trapped ( n = 9) or necropsied ( n = 11). BFDV virus load data were obtained from blood stored in ethanol by real-time quantitative PCR (qPCR) antibody titres were obtained by HI assay from either DBS or serum s les, which had been collected concurrently. All HI assays were performed commercially by the Veterinary Diagnostic Laboratory (VDL) in Charles Sturt University, Australia, who were blind to BFDV blood status. HI titres from DBS stored at room temperature declined significantly over time (~80 weeks). By contrast, frozen serum s les assayed after 80 weeks in storage all had high HI titres, only varying up to one dilution step from the initial HI titres obtained from DBS at 3–6 weeks after s ling. Weak HI titres from DBS s les all came back negative when the test was repeated only nine weeks later. Novel high HI titres were reported in P. elegans , and while most birds with high antibody titres had corresponding negative qPCR results, a single subadult presented with high HI titres and virus load simultaneously. Detection of antibodies on filter paper stored at room temperature decreases over time, increasing the chances of false negatives in these s les, and in repeated testing of s les with weak HI titres. Consequently, serum should be the preferred s le type to use for seroepidemiological studies on BFDV in parrots and other bird species. When not possible, it may help to store DBS on filter paper at −20 °C or lower. However, prompt testing of DBS s les ( e.g. , weeks in storage) is recommended pending further research on antibody temporal stability. We also show that P. elegans , especially adults, can produce high antibody titres against BFDV, which may help them resist infection.
Publisher: Wiley
Date: 16-07-2019
DOI: 10.1111/AVJ.12856
Abstract: Chlamydia gallinacea is a recently described bacterial species in a genus known to infect and cause disease in animals and humans. Our report describes the identification of C. gallinacea infection in free-range laying chickens (Gallus gallus) in Australia, and the identification of C. gallinacea infection in a parrot, a wild Australian galah (Eolophus roseicapillus). There is currently little knowledge of the effects of C. gallinacea infection on avian hosts, but it has been linked to respiratory disease in humans and could potentially cause similar disease in other species. Our report highlights the need for further study and surveillance of Chlamydia species in both wild and domestic hosts in Australia.
Publisher: Wiley
Date: 12-10-2017
DOI: 10.1111/ETH.12701
Publisher: Springer Science and Business Media LLC
Date: 14-12-2017
DOI: 10.1038/S41598-017-17859-0
Abstract: Understanding of avian nocturnal flight comes mainly from northern hemisphere species in seasonal temperate ecosystems where nocturnal flight is often precisely timed and entrained by annual photoperiod. Here we investigate patterns of nocturnal flight in waterbirds of Australian desert ecosystems that fly considerable distances to find temporary water bodies formed from rainfall which is highly unpredictable seasonally and spatially, and when there is sufficient water, they then breed. How they perform these feats of navigation and physiology remain poorly known. Using GPS tracking of 38 satellite tagged Pacific black ducks ( Anas superciliosa ) in two contrasting ecosystems, before and after heavy rainfall we revealed a key role for facultative nocturnal flight in the movement ecology of this species. After large rainfall events, birds rapidly increased nocturnal flight activity in the arid aseasonal ecosystem, but not in the mesic seasonal one. Nocturnal flights occurred throughout the night in both ecosystems. Long range flights ( km in 2 hours) occurred almost exclusively at night at night the distance flown was higher than during the day, birds visited more locations, and the locations were more widely dispersed. Our work reveals that heavy rainfall triggers increased nocturnal flight activity in desert populations of waterbirds.
Publisher: Informa UK Limited
Date: 12-2011
DOI: 10.1071/MU10080
Publisher: Springer Science and Business Media LLC
Date: 25-04-2000
Abstract: The spectral absorption characteristics of the retinal photoreceptors of the blue tit (Parus caeruleus) and blackbird (Turdus merula) were investigated using microspectrophotometry. The retinae of both species contained rods, double cones and four spectrally distinct types of single cone. Whilst the visual pigments and cone oil droplets in the other receptor types are very similar in both species, the wavelength of maximum sensitivity (lambda(max)) of long-wavelength-sensitive single and double cone visual pigment occurs at a shorter wavelength (557 nm) in the blackbird than in the blue tit (563 nm). Oil droplets located in the long-wavelength-sensitive-single cones of both species cut off wavelengths below 570-573 nm, theoretically shifting cone peak spectral sensitivity some 40 nm towards the long-wavelength end of the spectrum. This raises the possibility that the precise lambda(max) of the long-wavelength-sensitive visual pigment is optimised for the visual function of the double cones. The distribution of cone photoreceptors across the retina, determined using conventional light and fluorescence microscopy, also varies between the two species and may reflect differences in their visual ecology.
Publisher: IOP Publishing
Date: 04-2018
Publisher: The Company of Biologists
Date: 2015
DOI: 10.1242/JEB.119404
Abstract: Intraspecific differences in sensory perception are rarely reported but may occur when a species range extends across varying sensory environments, or there is coevolution between the sensory system and a varying signal. Ex les in colour vision and colour signals are rare in terrestrial systems. The tawny dragon lizard Ctenophorus decresii is a promising candidate for such intraspecific variation, because the species comprises two geographically and genetically distinct lineages in which throat colour (a social signal used in intra- and inter-specific interactions) is locally adapted to the habitat and differs between lineages. Male lizards from the southern lineage have UV-blue throats, whereas males from the northern lineage are polymorphic with four discrete throat colours that all show minimal UV reflectance. Here we determine the cone photoreceptor spectral sensitivities and opsin expression of the two lineages, to test whether they differ, particularly in the UV wavelengths. Using microspectrophotometry on retinal cone photoreceptors, we identified a long wavelength sensitive visual pigment, a ‘short’ and ‘long’ medium wavelength sensitive pigment and a short wavelength sensitive pigment, all of which did not differ in λmax between lineages. Through transcriptome analysis of opsin genes we found that both lineages express four cone opsin genes, including that SWS1 opsin with peak sensitivity in the UV range, and that amino acid sequences did not differ between lineages with the exception of a single leucine/valine substitution in the RH2 opsin. Counts of yellow and transparent oil droplets associated with LWS+MWS and SWS+UVS cones respectively showed no difference in relative cone proportions between lineages. Therefore, contrary to predictions, we find no evidence of differences between lineages in single cone photoreceptor spectral sensitivity or opsin expression however, we confirm the presence of four single cones classes and thus likely tetrachromacy in C. decresii, and provide the first evidence of UV sensitivity in agamid lizards.
Publisher: Elsevier BV
Date: 03-2012
Publisher: Elsevier BV
Date: 2012
Publisher: Springer Science and Business Media LLC
Date: 08-02-2019
Publisher: University of Chicago Press
Date: 02-1999
DOI: 10.1086/303160
Abstract: Assessment of color using human vision (or standards based thereon) is central to tests of many evolutionary hypotheses. Yet fundamental differences in color vision between humans and other animals call this approach into question. Here we use techniques for objectively assessing color patterns that avoid reliance on species-specific (e.g., human) perception. Reflectance spectra are the invariant features that we expect the animal's color cognition to have evolved to extract. We performed multivariate analyses on principal components derived from >2,600 reflectance spectra (300-720 nm) s led in a stratified random design from different body regions of male and female starlings in breeding plumage. Starlings possess spatially complex plumage patterns and extensive areas of iridescence. Our study revealed previously unnoticed sex differences in plumage coloration and the nature of iridescent and noniridescent sex differences. Sex differences occurred in some body regions but not others, were more pronounced at some wavelengths (both ultraviolet and human visible), and involved differences in mean reflectance and spectral shape. Discriminant analysis based on principal components were sufficient to sex correctly 100% of our s le. If hidden sexual dichromatism is widespread, then it has important implications for classifications of animals as mono- or dimorphic and for taxonomic and conservation purposes.
Publisher: Springer Science and Business Media LLC
Date: 28-04-1998
Publisher: Elsevier BV
Date: 05-2023
Publisher: Springer Science and Business Media LLC
Date: 04-1996
DOI: 10.1038/380433A0
Publisher: Informa UK Limited
Date: 03-2016
DOI: 10.1071/MU15061
Publisher: CSIRO Publishing
Date: 13-05-2022
DOI: 10.1071/AJ21130
Abstract: Interest in hydrogen (H2) energy has exploded in the last few years. Much of the interest comes from transitioning to a decarbonised energy future, through the use of renewables, to convert hydrogen-rich materials (methane, water) to pure hydrogen gas streams. Each of these methods have their own challenges, such as the need for carbon capture and storage to manage carbon emissions or perspectives on the use of fresh water. At the same time as this engineered approach to generating hydrogen, there has been a quiet but exponential upsurge in research surrounding the origins and fate of naturally occurring hydrogen. Sometimes referred to as ‘gold’ or ‘white’ hydrogen, geological forms of hydrogen have been recognised for thousands of years. While already present as H2, hydrogen may exist with other gases, such as methane, helium, hydrogen sulfide and/or nitrogen. But is it real? Is it volumetrically significant, discoverable, predictable or exploitable? Early work suggests that we can begin to characterise potential sources of hydrogen, the depth ranges they may be generated from, the migration mechanisms that are relevant, and how they might be retained or lost in relation to the discovery and exploitation of this gas. However, existing publicly available data is constrained by a lack of analysis and limited evidence. While there are increased reports of seeps containing hydrogen, there is an absence of evidence of more significant finds and a lack of major analogues and case studies to date. We explore these risks and uncertainties and provide a roadmap for reducing the evidence gap.
Publisher: Springer Science and Business Media LLC
Date: 10-06-2000
Abstract: A microspectrophotometric study was conducted on the retinal photoreceptors of four species of bird: cut-throat finches (Amadina fasciata), gouldian finches (Erythrura gouldiae), white-headed munias (Lonchura maja) and plum-headed finches (Neochmia modesta). Spectral characteristics of the photoreceptors in all four species were very similar. Rods contained a medium-wavelength-sensitive visual pigment with a wavelength of maximum absorbance at 502-504 nm. Four spectrally distinct types of single cone contained a visual pigment with wavelength of maximum absorbance at either 370-373 nm (ultraviolet-sensitive), 440-447 nm (short-wavelength-sensitive) 500 nm (medium-wavelength-sensitive) or 562-565 nm (long-wavelength-sensitive). Oil droplets in the ultraviolet-sensitive single cones showed no detectable absorption between 330 nm and 800 nm. Oil droplets in the short-, medium-, and long-wavelength-sensitive single cones had cut-off wavelengths at 415-423 nm, 510-520 nm and 567-575 nm, respectively. Double cones contained the visual pigment with wavelength of maximum absorbance at 562-565 nm observed in long-wavelength-sensitive single cones. Only the principal member of the double cone pair contained an oil droplet (P-type, cut-off wavelength at 414-489 nm depending on species and retinal location). Spectral transmittance of the intact ocular media of each species was measured along the optic axis. Wavelengths of 0.5 transmittance for all species were very similar (316-318 nm).
Publisher: Elsevier BV
Date: 09-2014
Publisher: Springer Science and Business Media LLC
Date: 09-2015
Publisher: The Royal Society
Date: 25-11-2009
Abstract: Avian vision is highly developed, with bird retinas containing rod and double-cone photoreceptors, plus four classes of single cones subserving tetrachromatic colour vision. Cones contain an oil droplet, rich in carotenoid pigments (except VS/ultraviolet-sensitive cones), that acts as a filter, substantially modifying light detected by the photoreceptor. Using dietary manipulations, we tested the effects of carotenoid availability on oil droplet absorbance properties in two species: Platycercus elegans and Taeniopygia guttata . Using microspectrophotometry, we determined whether manipulations affected oil droplet carotenoid concentration and whether changes would alter colour discrimination ability. In both species, increases in carotenoid concentration were found in carotenoid-supplemented birds, but only in the double cones. Magnitudes of effects of manipulations were often dependent on retinal location. The study provides, to our knowledge, the first experimental evidence of dietary intake over a short time period affecting carotenoid concentration of retinal oil droplets. Moreover, the allocation of carotenoids to the retina by both species is such that the change potentially preserves the spectral tuning of colour vision. Our study generates new insights into retinal regulation of carotenoid concentration of oil droplets, an area about which very little is known, with implications for our understanding of trade-offs in carotenoid allocation in birds.
Publisher: Springer Science and Business Media LLC
Date: 27-08-2020
Publisher: BirdLife Australia, Ltd.
Date: 2018
DOI: 10.20938/AFO35087090
Publisher: The Company of Biologists
Date: 15-12-2007
DOI: 10.1242/JEB.007104
Abstract: The effects of environmental stress on the physiology and behaviour of higher vertebrates has become an important avenue of research in recent years. Evidence from recent studies has suggested that the avian stress-related hormone corticosterone (CORT) may play a role in immunocompetence and sexual selection. We tested whether CORT is immunosuppressive by studying humoral and cell-mediated immune responses in populations of captive zebra finches selected for ergent peak levels of CORT. We also investigated whether selection for peak CORT has an effect on the quality of several sexually selected regions of the male zebra finch in addition we compared morphometric parameters and the dominance ranking in males from the different selection lines. We also tested whether different components of the immune system compete for limited resources. We found that selection for ergent levels of peak CORT had little effect on humoral immunity, male sexual signal quality or dominance ranking. However, contrary to expectations, we did find a positive relationship between CORT titre and cell-mediated immunity, as well as a greater cell-mediated response in the birds selected for high CORT titre than those selected for low CORT titre. Consistent with predictions, significant negative relationships were found between both testosterone and CORT titre on humoral immunity. Birds from the low CORT lines were significantly larger in terms of skeletal size than those from the high CORT lines. Overall, our results suggest that the cell-mediated immune response is associated with a reduction in the humoral response, but only in males, and that there is no simple relationship between peak CORT levels and immune function.
Location: Australia
Start Date: 02-2015
End Date: 02-2018
Amount: $315,138.00
Funder: Australian Research Council
View Funded ActivityStart Date: 06-2018
End Date: 12-2024
Amount: $309,762.00
Funder: Australian Research Council
View Funded Activity