Publications

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immunological change in a parasite-impoverished environment: divergent signals from four island taxa.dramatic declines of native hawaiian avifauna due to the human-mediated emergence of avian malaria and pox prompted an examination of whether island taxa share a common altered immunological signature, potentially driven by reduced genetic diversity and reduced exposure to parasites. we tested this hypothesis by characterizing parasite prevalence, genetic diversity and three measures of immune response in two recently-introduced species (neochmia temporalis and zosterops lateralis) and two islan ...200717878931
invasive rats and recent colonist birds partially compensate for the loss of endemic new zealand pollinators.reported declines of pollinator populations around the world have led to increasing concerns about the consequences for pollination as a critical ecosystem function and service. pollination could be maintained through compensation if remaining pollinators increase their contribution or if novel species are recruited as pollinators, but empirical evidence of this compensation is so far lacking. using a natural experiment in new zealand where endemic vertebrate pollinators still occur on one offsh ...201122090388
mosquito communities and avian malaria prevalence in silvereyes (zosterops lateralis) within forest edge and interior habitats in a new zealand regional park.forest fragmentation and agricultural development are important anthropogenic landscape alterations affecting the disease dynamics of malarial parasites (plasmodium spp.), largely through their effects on vector communities. we compared vector abundance and species composition at two forest edge sites abutting pastureland and two forest interior sites in new zealand, while simultaneously assessing avian malaria prevalence in silvereyes (zosterops lateralis). twenty-two of 240 (9.2%) individual s ...201526065670
sugar preferences of avian nectarivores are correlated with intestinal sucrase activity.nectar-feeding birds generally demonstrate preference for hexose solutions at low sugar concentrations, switching to sucrose/no preference at higher concentrations. species vary in the concentration at which the switch from hexose preference occurs; this could reflect physiological constraints that would also influence nectar selection when foraging. we recorded concentration-dependent sugar type preferences in three opportunistic/generalist australian nectarivorous species: dicaeum hirundinaceu ...201323995481
night-migratory songbirds possess a magnetic compass in both eyes.previous studies on european robins, erithacus rubecula, and australian silvereyes, zosterops lateralis, had suggested that magnetic compass information is being processed only in the right eye and left brain hemisphere of migratory birds. however, recently it was demonstrated that both garden warblers, sylvia borin, and european robins have a magnetic compass in both eyes. these results raise the question if the strong lateralization effect observed in earlier experiments might have arisen from ...201222984416
light-dependent magnetoreception: quantum catches and opponency mechanisms of possible photosensitive molecules.dozens of experiments on magnetosensitive, migratory birds have shown that their magnetic orientation behavior depends on the spectrum of light under which they are tested. however, it is not certain whether this is due to a direct effect on the magnetoreceptive system and which photosensitive molecules may be involved. we examined 62 experiments of light-dependent magnetoreception in three crepuscular and nocturnal migrants (48 for the european robin erithacus rubecula, ten for the silvereye zo ...200717766294
effects of introducing threatened falcons into vineyards on abundance of passeriformes and bird damage to grapes.agricultural landscapes are becoming an important focus of animal conservation, although initiatives to conserve predators to date have rarely provided economic benefits to agricultural producers. we examined whether introduction to vineyards of the new zealand falcon (falco novaeseelandiae), a species listed as threatened by the new zealand department of conservation, affected the abundance of 4 species of passeriformes that are considered vineyard pests or affected the amount of economic loss ...201222010952
isolation and characterization of avipoxviruses from wild birds in western australia.avipoxviruses were isolated from wart-like lesions in an australian magpie (gymnorhina tibicen) and a silvereye (zosterops lateralis), and the poxvirus aetiology of wart-like lesions in a magpie-lark (grallina cyanoleuca) was confirmed. the three viruses produced typical pock lesions on the chorioallantoic membrane of embryonated eggs and were able to replicate in trypsin-dispersed chick embryo fibroblast cultures but not confluent monolayer cultures. pock neutralization and immunodiffusion stud ...19836307227
histomorphology of the proventriculus of three species of australian passerines: lichmera indistincta, zosterops lateralis and poephila guttata.histomorphology of the proventriculi of nectarivorous, granivorous and omnivorous passerines was studied. the proventriculus consisted of mucosal, submucosal, muscularis and serosal layers. proventricular wall was thickest in omnivore, thinnest in granivore and intermediate in nectarivore. the openings of mucosal glands had a single spiral-like fold of mucosa in the omnivorous silvereye, 2-3 spirals in the granivorous zebra finch and 4-5 spirals in the nectarivorous brown honeyeater. the mucosal ...200919476450
coccidia species in endemic and native new zealand passerines.new zealand native passerines are hosts to a large variety of gastrointestinal parasites, including coccidia. coccidian parasites are generally host-specific, obligate intracellular protozoan parasites. in passerine birds, members of the genus isospora are most common. under natural conditions, these parasites seldom pose a threat, but stressors such as quarantine for translocation, overcrowding, or habitat changes may cause an infection outbreak that can severely affect wild populations. althou ...201323468142
the influence of climatic variation and density on the survival of an insular passerine zosterops lateralis.understanding the influence of environmental factors on population dynamics is fundamental to many areas in biology. survival is a key factor of population biology, as it is thought to be the predominant driver of growth in long-lived passerines, which can be influenced by both biotic and abiotic environmental conditions. we used mark-recapture methods and generalized linear mixed models to test the influence of density and climatic variation, measured at a regional and local scale (southern osc ...201728453564
individual heterogeneity and senescence in silvereyes on heron island.individual heterogeneity and correlations between life history traits play a fundamental role in life history evolution and population dynamics. unobserved individual heterogeneity in survival can be a nuisance for estimation of age effects at the individual level by causing bias due to mortality selection. we jointly analyze survival and breeding output from successful breeding attempts in an island population of silvereyes (zosterops lateralis chlorocephalus) by fitting models that incorporate ...201121661544
4000 years of phenotypic change in an island bird: heterogeneity of selection over three microevolutionary timescales.pronounced phenotypic shifts in island populations are typically attributed to natural selection, but reconstructing heterogeneity in long-term selective regimes remains a challenge. we examined a scenario of divergence proposed for species colonizing a new environment, involving directional selection with a rapid shift to a new optimum and subsequent stabilization. we provide some of the first empirical evidence for this model of evolution using morphological data from three timescales in an is ...200818540948
large body size in an island-dwelling bird: a microevolutionary analysis.island races of passerine birds display repeated evolution towards larger body size compared with their continental ancestors. the capricorn silvereye (zosterops lateralis chlorocephalus) has become up to six phenotypic standard deviations bigger in several morphological measures since colonization of an island approximately 4000 years ago. we estimated the genetic variance-covariance (g) matrix using full-sib and 'animal model' analyses, and selection gradients, for six morphological traits und ...200717305830
large size in an island-dwelling bird: intraspecific competition and the dominance hypothesis.differences between island- and mainland-dwelling forms provide several classic ecological puzzles. why, for instance, are island-dwelling passerine birds consistently larger than their mainland counterparts? we examine the 'dominance hypothesis', based on intraspecific competition, which states that large size in island passerines evolves through selection for success in agonistic encounters. we use the heron island population of capricorn silvereyes (zosterops lateralis chlorocephalus), a larg ...200314640402
the genome of the "great speciator" provides insights into bird diversification.among birds, white-eyes (genus zosterops) have diversified so extensively that jared diamond and ernst mayr referred to them as the "great speciator." the zosterops lineage exhibits some of the fastest rates of species diversification among vertebrates, and its members are the most prolific passerine island colonizers. we present a high-quality genome assembly for the silvereye (zosterops lateralis), a white-eye species consisting of several subspecies distributed across multiple islands. we inv ...201526338191
the relative roles of cultural drift and acoustic adaptation in shaping syllable repertoires of island bird populations change with time since colonization.in birds, song divergence often precedes and facilitates divergence of other traits. we assessed the relative roles of cultural drift, innovation, and acoustic adaptation in divergence of island bird dialects, using silvereyes (zosterops lateralis). in recently colonized populations, syllable diversity was not significantly lower than source populations, shared syllables between populations decreased with increasing number of founder events, and dialect variation displayed contributions from bot ...201525496402
song convergence in multiple urban populations of silvereyes (zosterops lateralis).recent studies have revealed differences between urban and rural vocalizations of numerous bird species. these differences include frequency shifts, amplitude shifts, altered song speed, and selective meme use. if particular memes sung by urban populations are adapted to the urban soundscape, "urban-typical" calls, memes, or repertoires should be consistently used in multiple urban populations of the same species, regardless of geographic location. we tested whether songs or contact calls of sil ...201222957198
geographically pervasive effects of urban noise on frequency and syllable rate of songs and calls in silvereyes (zosterops lateralis).recent studies in the northern hemisphere have shown that songbirds living in noisy urban environments sing at higher frequencies than their rural counterparts. however, several aspects of this phenomenon remain poorly understood. these include the geographical scale over which such patterns occur (most studies have compared local populations), and whether they involve phenotypic plasticity or microevolutionary change. we conducted a field study of silvereye (zosterops lateralis) vocalizations o ...201121208948
bird navigation: what type of information does the magnetite-based receptor provide?previous experiments have shown that a short, strong magnetic pulse caused migratory birds to change their headings from their normal migratory direction to an easterly direction in both spring and autumn. in order to analyse the nature of this pulse effect, we subjected migratory australian silvereyes, zosterops lateralis, to a magnetic pulse and tested their subsequent response under different magnetic conditions. in the local geomagnetic field, the birds preferred easterly headings as before, ...200617015316
magnetic orientation in birds: non-compass responses under monochromatic light of increased intensity.migratory australian silvereyes (zosterops lateralis) were tested under monochromatic light at wavelengths of 424 nm blue and 565 nm green. at a low light level of 7 x 10(15) quanta m(-2) s(-1) in the local geomagnetic field, the birds preferred their seasonally appropriate southern migratory direction under both wavelengths. their reversal of headings when the vertical component of the magnetic field was inverted indicated normal use of the avian inclination compass. a higher light intensity of ...200314561276
bayesian inferences on the recent island colonization history by the bird zosterops lateralis lateralis.the founding of new populations by small numbers of colonists has been considered a potentially important mechanism promoting evolutionary change in island populations. colonizing species, such as members of the avian species complex zosterops lateralis, have been used to support this idea. a large amount of background information on recent colonization history is available for one zosterops subspecies, z. lateralis lateralis, providing the opportunity to reconstruct the population dynamics of i ...200312675822
microevolution in island forms: the roles of drift and directional selection in morphological divergence of a passerine bird.theory predicts that in small isolated populations random genetic drift can lead to phenotypic divergence; however this prediction has rarely been tested quantitatively in natural populations. here we utilize natural repeated island colonization events by members of the avian species complex, zosterops lateralis, to assess whether or not genetic drift alone is an adequate explanation for the observed patterns of microevolutionary divergence in morphology. morphological and molecular genetic char ...200212449495
genetic consequences of sequential founder events by an island-colonizing bird.the importance of founder events in promoting evolutionary changes on islands has been a subject of long-running controversy. resolution of this debate has been hindered by a lack of empirical evidence from naturally founded island populations. here we undertake a genetic analysis of a series of historically documented, natural colonization events by the silvereye species-complex (zosterops lateralis), a group used to illustrate the process of island colonization in the original founder effect m ...200212034870
genetic variability and population differentiation inferred from dna fingerprinting in silvereyes (aves: zosteropidae).this study evaluated dna fingerprinting as a tool for estimating population genetic diversity and differentiation by comparing minisatellite variation in island and mainland populations of silvereyes (aves: zosterops lateralis). three populations with different recent histories were compared: (1) heron island and neighboring islands, colonized 3000 to 4000 yr ago; (2) lady elliot island, colonized within the past two decades; and (3) an adjacent mainland population, which presumably has existed ...199328564288
a poxvirus isolated from silvereyes (zosterops lateralis) from lower hutt, new zealand. 19734349597
responses of new zealand forest birds to management of introduced mammals.over the past 1000 years new zealand has lost 40-50% of its bird species, and over half of these extinctions are attributable to predation by introduced mammals. populations of many extant forest bird species continue to be depredated by mammals, especially rats, possums, and mustelids. the management history of new zealand's forests over the past 50 years presents a unique opportunity because a varied program of mammalian predator control has created a replicated management experiment. we condu ...202031893568
morphological and molecular characterisation of isospora butcherae n. sp. in a silvereye (zosterops lateralis) (latham, 1801).a new isospora (apicomplexa:eimeriidae) species is described from a silvereye (zosterops lateralis) in western australia. sporulated oocysts of this species are spherical, 24.2 (23.1-25.2) × 23.3 (22.8-23.9) μm, with a shape index (length/width) of 1.02, and with a smooth bi-layered oocyst wall, 1.2 μm thick (outer layer 0.9 μm, inner 0.3 μm). a polar granule is present, but the oocyst residuum and a micropyle are absent. the ovoid-shaped sporocysts are 16.1 (15.7-17.3) × 10.5 (15.7-17.3) μm and ...201829527641
the genomic landscape of divergence across the speciation continuum in island-colonising silvereyes (zosterops lateralis).inferring the evolutionary dynamics at play during the process of speciation by analyzing the genomic landscape of divergence is a major pursuit in population genomics. however, empirical assessments of genomic landscapes under varying evolutionary scenarios that are known a priori are few, thereby limiting our ability to achieve this goal. here we combine rad-sequencing and individual-based simulations to evaluate the genomic landscape of divergence in the silvereye (zosterops lateralis). using ...202032660974
rapid morphological divergence following a human-mediated introduction: the role of drift and directional selection.theory predicts that when populations are established by few individuals, random founder effects can facilitate rapid phenotypic divergence even in the absence of selective processes. however, empirical evidence from historically documented colonisations suggest that, in most cases, drift alone is not sufficient to explain the rate of morphological divergence. here, using the human-mediated introduction of the silvereye (zosterops lateralis) to french polynesia, which represents a potentially ex ...202032080374
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