| carotenoids in bird plumage: the complement of red pigments in the plumage of wild and captive bullfinch (pyrrhula pyrrhula). | we have studied the carotenoid pigments in the red plumage of male bullfinch (pyrrhula pyrrhula) immediately following capture and after the completion of the moult in captivity under dietary control. astaxanthin, adonirubin, and alpha-doradexanthin, as well as papilioeritrinone and canthaxanthin (in lower amounts) are in every case the dominant carotenoids in the plumage pigment of wild individuals. alpha-doradexanthin is responsible for the reddish-rose colour, which captive individuals adopt ... | 2001 | 11250548 |
| the influence of a competitor on the geographic mosaic of coevolution between crossbills and lodgepole pine. | the geographic mosaic theory of coevolution posits that the form of selection between interacting species varies across a landscape with coevolution important and active in some locations (i.e., coevolutionary hotspots) but not in others (i.e., coevolutionary coldspots). we tested the hypothesis that the presence of red squirrels (tamiasciurus hudsonicus) affects the occurrence of coevolution between red crossbills (loxia curvirostra complex) and rocky mountain lodgepole pine (pinus contorta ssp ... | 2001 | 11308086 |
| diversifying coevolution between crossbills and black spruce on newfoundland. | coevolution is increasingly recognized as an important process structuring geographic variation in the form of selection for many populations. here we consider the importance of a geographic mosaic of coevolution to patterns of crossbill (loxia) diversity in the northern boreal forests of north america. we examine the relationships between geographic variation in cone morphology, bill morphology, and feeding performance to test the hypothesis that, in the absence of red squirrels (tamiasciurus h ... | 2002 | 12353759 |
| complete development of three species of haemoproteus (haemosporida, haemoproteidae) in the biting midge culicoides impunctatus (diptera, ceratopogonidae). | development of haemoproteus balmorali, h. dolniki, and h. tartakovskyi was followed in experimentally infected biting midges culicoides impunctatus on the curonian spit in the baltic sea. wild-caught flies were allowed to take blood meals on naturally infected spotted flycatchers muscicapa striata, chaffinches fringilla coelebs, or crossbills loxia curvirostra harboring mature gametocytes of these parasites. the engorged biting midges were collected, held at 14-18 c, and dissected daily. mature ... | 2002 | 12435121 |
| reciprocal selection causes a coevolutionary arms race between crossbills and lodgepole pine. | few studies have shown both reciprocal selection and reciprocal adaptations for a coevolving system in the wild. the goal of our study was to determine whether the patterns of selection on rocky mountain lodgepole pine (pinus contorta spp. latifolia) and red crossbills (loxia curvirostra complex) were concordant with earlier published evidence of reciprocal adaptations in lodgepole pine and crossbills on isolated mountain ranges in the absence of red squirrels (tamiasciurus hudsonicus). we found ... | 2003 | 12858263 |
| interactions among moths, crossbills, squirrels, and lodgepole pine in a geographic selection mosaic. | repeated patterns among biological communities suggest similar evolutionary and ecological forces are acting on the communities. conversely, the lack of such patterns suggests that similar forces are absent or additional ones are present. coevolution between a seed predator, the red crossbill (loxia curvirostra complex), and lodgepole pine (pinus contorta var. latifolia) exemplifies the ecological and evolutionary predictions for coevolving systems. in the absence of another seed predator and pr ... | 2004 | 15058722 |
| the geographic selection mosaic for squirrels, crossbills and aleppo pine. | the interactions between many species are structured in a geographic mosaic of populations among which selection is divergent. here we tested the hypothesis that such a geographic selection mosaic arises for common crossbills (loxia curvirostra) feeding on seeds in the cones of aleppo pine (pinus halepensis) because of geographic variation in the occurrence of european red squirrels (sciurus vulgaris). on the iberian peninsula, sciurus exerted directional selection favouring larger cones with la ... | 2005 | 15715841 |
| a role for habitat area in the geographic mosaic of coevolution between red crossbills and lodgepole pine. | understanding how resource abundance limits adaptive evolution and influences species interactions is an important step towards developing insight into the role of microevolutionary processes in establishing macroevolutionary patterns. we examined how variation in resource abundance (forest area of lodgepole pine pinus contorta ssp. latifolia) influenced patterns of co-adaptation and coevolution between red crossbill (loxia curvirostra complex) and lodgepole pine populations. first, we found tha ... | 2005 | 16033577 |
| can selection by an ectoparasite drive a population of red crossbills from its adaptive peak? | the bill structures of different call types of red crossbills (loxia curvirostra complex) in western north america usually approximate the predicted optima for foraging on single species of conifers. one clear exception is the call type in the south hills, idaho, that is coevolving in an evolutionary arms race with rocky mountain lodgepole pine (pinus contorta ssp. latifolia). although south hills crossbills forage only on the cones of these lodgepole pines, their average bill depth is smaller t ... | 2005 | 16261739 |
| patterns of genetic variation in the adaptive radiation of new world crossbills (aves: loxia). | incipient species groups or young adaptive radiations such as crossbills (aves: loxia) present the opportunity to investigate directly the processes occurring during speciation. new world crossbills include white-winged crossbills (loxia leucoptera), hispaniolan crossbills (loxia megaplaga), and red crossbills (loxia curvirostra complex), the last of which is comprised of at least nine morphologically and vocally differentiated forms ('call types') where divergent natural selection for specializ ... | 2006 | 16689904 |
| replicated population divergence caused by localized coevolution? a test of three hypotheses in the red crossbill-lodgepole pine system. | several lines of evidence support the hypothesis that local populations of red crossbills (loxia curvirostra complex) enter into a predator-prey arms race with lodgepole pine (pinus contorta latifolia) in the absence of competing pine squirrels (tamiasciurus hudsonicus). nevertheless, the alternative hypotheses that neutral evolution or factors other than squirrels have caused crossbill population differentiation have not been thoroughly tested. we compared crossbill and pine cone morphology bet ... | 2006 | 16910994 |
| a coevolutionary arms race causes ecological speciation in crossbills. | we examined three ecological factors potentially causing premating reproductive isolation to determine whether divergent selection as a result of coevolution between south hills crossbills (loxia curvirostra complex) and rocky mountain lodgepole pine (pinus contorta latifolia) promotes ecological speciation. one factor was habitat isolation arising because of enhanced seed defenses of lodgepole pine in the south hills. this caused the crossbill call types (morphologically and vocally differentia ... | 2007 | 17273981 |
| plasmodium relictum (lineage p-sgs1): effects on experimentally infected passerine birds. | we evaluated the effects of plasmodium relictum (lineage p-sgs1), which is a host generalist, to five species of passerine birds. light infection of p. relictum was isolated from a naturally infected adult reed warbler acrocephalus scirpaceus. the parasites were inoculated to naive juveniles of the chaffinch fringilla coelebs, common crossbill loxia curvirostra, house sparrow passer domesticus, siskin spinus spinus and starling sturnus vulgaris. susceptibility of these birds to the infection of ... | 2008 | 18809402 |
| under a neighbour's influence: public information affects stress hormones and behaviour of a songbird. | socially acquired information improves the accuracy and efficiency of environmental assessments and can increase fitness. public information may be especially useful during unpredictable food conditions, or for species that depend on resources made less predictable by human disturbance. however, the physiological mechanisms by which direct foraging assessments and public information are integrated to affect behaviour remain largely unknown. we tested for potential effects of public information o ... | 2010 | 20356895 |
| habitat area and structure affect the impact of seed predators and the potential for coevolutionary arms races. | both habitat patch size and structure affect the abundance and occurrence of species and thereby can affect the ecology and evolution of species interactions. here we contrast the level of seed predation and selection exerted by common crossbills (loxia curvirostra complex) and red squirrels (sciurus vulgaris) in the extensive mountain pine (pinus uncinata) forests in the pyrenees with their level of seed predation in two small, isolated forests. crossbills consumed 5.1 times more seeds in the p ... | 2010 | 20426338 |
| plasmodium relictum (lineage sgs1) and plasmodium ashfordi (lineage grw2): the effects of the co-infection on experimentally infected passerine birds. | the effects of avian malaria parasites of the genus plasmodium on their hosts are insufficiently understood. this is particularly true for malarial co-infections, which predominant in many bird populations. we investigated effects of primary co-infection of plasmodium relictum (lineage sgs1) and plasmodium ashfordi (grw2) on experimentally infected naive juveniles of siskin spinus spinus, crossbill loxia curvirostra and starling sturnus vulgaris. all siskins and crossbills were susceptible but s ... | 2010 | 21050849 |
| does avian malaria infection affect feather stable isotope signatures? | it is widely accepted that stable isotope ratios in inert tissues such as feather keratin reflect the dietary isotopic signature at the time of the tissue synthesis. however, some elements such as stable nitrogen isotopes can be affected by individual physiological state and nutritional stress. using malaria infection experiment protocols, we estimated the possible effect of malaria parasite infections on feather carbon (+¦(13)c) and nitrogen (+¦(15)n) isotope signatures in juvenile common cross ... | 2011 | 21671039 |
| survival and population size of a resident bird species are declining as temperature increases. | 1. a large number of migratory bird species appear to be declining as the result of climate change, but whether resident bird species have or will be adversely affected by climate change is less clear. we focus on the south hills crossbill (loxia curvirostra complex), which is endemic to about 70 km(2) of rocky mountain lodgepole pine (pinus contorta latifolia) forest in southern idaho, usa. 2. our results indicate that the south hills crossbill has declined by over 60% between 2003 and 2008, a ... | 2011 | 22010811 |
| consistency and variation in phenotypic selection exerted by a community of seed predators. | phenotypic selection that is sustained over time underlies both anagenesis and cladogenesis, but the conditions that lead to such selection and what causes variation in selection are not well known. we measured the selection exerted by three species of predispersal seed predators of lodgepole pine (pinus contorta latifolia) in the south hills, idaho, and found that net selection on different cone and seed traits exerted by red crossbills (loxia curvirostra) and cone borer moths (eucosma recissor ... | 2012 | 23289569 |
| mortality and pathology in birds due to plasmodium (giovannolaia) homocircumflexum infection, with emphasis on the exoerythrocytic development of avian malaria parasites. | species of avian malaria parasites (plasmodium) are widespread, but their virulence has been insufficiently investigated, particularly in wild birds. during avian malaria, several cycles of tissue merogony occur, and many plasmodium spp. produce secondary exoerythrocytic meronts (phanerozoites), which are induced by merozoites developing in erythrocytic meronts. phanerozoites markedly damage organs, but remain insufficiently investigated in the majority of described plasmodium spp. avian malaria ... | 2016 | 27146519 |
| genomic resources notes accepted 1 june 2013-31 july 2013. | this article documents the public availability of (i) raw transcriptome sequence data, assembled contigs and uniprot blast hits from common crossbill (loxia curvirostra) and plasmodium relictum (lineage sgs1) obtained from a controlled infection experiment; and (ii) raw transcriptome sequence data and 66 596 snps for the white-tailed deer (odocoileus virginianus). | 2014 | 24330193 |
| plasmodium relictum (lineages psgs1 and pgrw11): complete synchronous sporogony in mosquitoes culex pipiens pipiens. | plasmodium relictum is a widespread invasive agent of avian malaria, responsible for acute, chronic and debilitating diseases in many species of birds. recent pcr-based studies revealed astonishing genetic diversity of avian malaria parasites (genus plasmodium), with numerous genetic lineages deposited in genbank. many studies addressed distribution and evolutionary relationships of avian plasmodium lineages, but information about patterns of development of different lineages in mosquito vectors ... | 2013 | 23337824 |
| separation and identification of carotenoids in bird's plumage by high-performance liquid chromatography--diode-array detection. | the coloured feathers of carduelis spinus (siskin), c. flammea (redpoll), serinus serinus (serin), loxia curvirostra (crossbill), pinicola enucleator (grossbeak), carpodacus roseus (pallas rosefinch) and pyrrhula pyrrhula (bullfinch) have been extracted with a new procedure using mild conditions (a few minutes at room temperature). after the separation of melanines and proteins, the extracts were analyzed by hplc-ms and hplc-uv-vis. the main components of the pigments were identified in all the ... | 1995 | 8548026 |
| description of the first cryptic avian malaria parasite, plasmodium homocircumflexum n. sp., with experimental data on its virulence and development in avian hosts and mosquitoes. | for over 100 years studies on avian haemosporidian parasite species have relied on similarities in their morphology to establish a species concept. some exceptional cases have also included information about the life cycle and sporogonic development. more than 50 avian plasmodium spp. have now been described. however, pcr-based studies show a much broader diversity of haemosporidian parasites, indicating the possible existence of a diverse group of cryptic species. in the present study, using bo ... | 2015 | 25449950 |
| two new feather mites of the genus proctophyllodes robin, 1868 (acari: proctophyllodidae) from european passerines (aves: passeriformes). | two new species of the feather mite genus proctophyllodes robin, 1868 (analgoidea: proctophyllodidae) are described from two passerine birds (passeriformes) in europe: proctophyllodes markovetsi n. sp. from the tawny pipit anthus campestris (l.) (motacillidae) and p. loxiae n. sp. from the red crossbill loxia curvirostra (l.) (fringillidae). males of p. markovetsi are most clearly distinguished from the closely related p. tchagrae atyeo & braasch, 1966 by having greater terminal lamellae (30-40 ... | 2017 | 28130674 |
| new records and new species of mites of the subfamily harpirhynchinae (acariformes: harpirhynchidae) infesting birds in manitoba, canada. | five new species and one new genus of the subfamily harpirhynchinae (acariformes: harpirhynchidae) are described from birds in canada: harpyrhynchoides heatherae sp. nov. from junco hyemalis (passeriformes: emberizidae), h. botaurus sp. nov. from botaurus lentiginosus (pelecaniformes: ardeidae), h. phalaropus sp. nov. from phalaropus lobatus (charadriiformes: scolopacidae), neharpyrhynchus loxia sp. nov. from loxia curvirostra (passeriformes: fringillidae), and fainharpirhynchus contopus gen. no ... | 2013 | 24338301 |
| [method of calculating the distance between the classes of the structural components of the forebrain birds]. | the method of calculating the distance between the classes of the structural components of the brain of birds. compared interclass distances of glia, neurons and neuroglial complexes in the forebrain hooded crow (corvus cornix) (a bird with a highly rational activity) and common crossbill (loxia curvirostra) (birds with a medium level of rational activity). | 2016 | 27263281 |
| a review of the zumpti species group of the genus harpyrhynchoides (acariformes: harpirhynchidae)--ectoparasites of passerines. | the zumpti species group of the genus harpyrhynchoides (harpirhynchidae), parasites of passerines, is revised. a key to the species of this group is provided and data on host associations and geographic distribution of its constituent species are summarized. this group includes six previously recognized species: harpyrhynchoides alaudinus bochkov, 2000, h. brevis (ewing, 1911) comb. nov., h. heatherae bochkov and galloway, 2013, h. rubeculinus (cherny and sixl, 1971), h. vulgaris bochkov and gal ... | 2014 | 25543798 |
| tests of absolute photorefractoriness in four species of cardueline finch that differ in reproductive schedule. | species with different reproductive schedules may differ in how they respond to the annual change in photoperiod (the adaptive specialization hypothesis). seasonally breeding species are predicted to use photorefractoriness to terminate reproduction prior to inclement conditions in autumn and winter, whereas opportunistically breeding species may not exhibit photorefractoriness. we tested for absolute photorefractoriness in four species of cardueline finch that differ in their reproductive sched ... | 2006 | 16985195 |
| the evidence for rapid gametocyte viability changes in the course of parasitemia in haemoproteus parasites. | avian haemosporidian parasites of the genus haemoproteus (haemoproteidae, haemosporida) are widespread, and some species cause diseases both in vertebrate hosts and blood-sucking insects. parasitemia of haemoproteus species usually is long-lasting, with gametocytes present in the circulation for several months. however, the viability of gametocytes and their ability to produce sexual cells have been insufficiently understood in the course of parasitemia. we initiated the sexual development in vi ... | 2015 | 25944737 |
| molecular phylogeny of carduelinae (aves, passeriformes, fringillidae) proves polyphyletic origin of the genera serinus and carduelis and suggests redefined generic limits. | relationships of the 133 species of the subfamily carduelinae (fringillidae) are poorly resolved. for a more robust phylogenetic resolution, we sequenced two mitochondrial protein-coding genes (atpase 6 and nd3), two nuclear introns (myoglobin intron 2 and transforming growth factor-beta2 intron 5) and one nuclear protein-coding gene (c-mos) from 50 cardueline taxa representing especially the large genera serinus and carduelis. a total of 2934bp obtained was subjected to maximum likelihood and b ... | 2009 | 19027082 |
| coevolution, local adaptation and ecological speciation. | coevolution is one of the major processes organizing the earth's biodiversity, but it remains unclear when and how it may generate species diversity. the study by parchman et al. () in this issue of molecular ecology provides the clearest evidence to date that divergent local adaptation in a coevolving interaction may lead to speciation on one side of an interaction but not necessarily on the other side. red crossbills in north america have diversified into ecotypes that specialize on different ... | 2016 | 27870263 |
| genome divergence and diversification within a geographic mosaic of coevolution. | despite substantial interest in coevolution's role in diversification, examples of coevolution contributing to speciation have been elusive. here, we build upon past studies that have shown both coevolution between south hills crossbills and lodgepole pine (pinus contorta), and high levels of reproductive isolation between south hills crossbills and other ecotypes in the north american red crossbill (loxia curvirostra) complex. we used genotyping by sequencing to generate population genomic data ... | 2016 | 27682183 |
| phenotypic selection exerted by a seed predator is replicated in space and time and among prey species. | although consistent phenotypic selection arising from biotic interactions is thought to be the primary cause of adaptive diversification, studies documenting such selection are relatively few. here we analyze 12 episodes of phenotypic selection exerted by a predispersal seed predator, the red crossbill (loxia curvirostra complex), on five species of pines (pinus). we find that even though the intensity of selection for some traits increased with the strength of the interaction (i.e., proportion ... | 2015 | 26655781 |
| causes of variation in biotic interaction strength and phenotypic selection along an altitudinal gradient. | understanding the causes of variation in biotic interaction strength and phenotypic selection remains one of the outstanding goals of evolutionary ecology. here we examine the variation in strength of interactions between two seed predators, common crossbills (loxia curvirostra) and european red squirrels (sciurus vulgaris), and mountain pine (pinus uncinata) at and below tree limit in the pyrenees, and how this translates into phenotypic selection. seed predation by crossbills increased whereas ... | 2014 | 24593660 |
| assessing the role of reproduction and stress in the spring emergence of haematozoan parasites in birds. | a spring emergence of avian haemosporidian infections is nearly universal among temperate zone birds and is often described as a cost of reproductive effort. we take advantage of the opportunistic (i.e. aseasonal) breeding schedule of the red crossbill (loxia curvirostra) to determine the relative contributions of season versus host physiology to the timing and intensity of haemoproteus infections in the temperate zone. despite breeding activity in both the winter and summer, haemoproteus infect ... | 2014 | 24265426 |
| when directional selection reduces geographic variation in traits mediating species interactions. | although we often focus on the causes of geographic variation, understanding processes that act to reduce geographic variation is also important. here, we consider a process whereby adaptive foraging across the landscape and directional selection exerted by a conifer seed predator, the common crossbill (loxia curvirostra), potentially act to homogenize geographic variation in the defensive traits of its prey. we measured seed predation and phenotypic selection exerted by crossbills on black pine ... | 2013 | 23610637 |
| assortative flocking in crossbills and implications for ecological speciation. | how reproductive isolation is related to divergent natural selection is a central question in speciation. here, we focus on several ecologically specialized taxa or 'call types' of red crossbills (loxia curvirostra complex), one of the few groups of birds providing much evidence for ecological speciation. call types differ in bill sizes and feeding capabilities, and also differ in vocalizations, such that contact calls provide information on crossbill phenotype. we found that two call types of r ... | 2012 | 22915674 |
| coping with the extremes: stress physiology varies between winter and summer in breeding opportunists. | seasonal changes in stress steroid hormone secretions are thought to reflect investment in self-maintenance versus reproduction. the capricious conditions hypothesis (cch) posits that reduced corticosterone (cort) secretion during stress coincident with parental phases of breeding is necessary in harsh environments because a full response would otherwise trigger repeated nest abandonments. to test this hypothesis, we measured seasonal changes in stress physiology in free-living red crossbills (l ... | 2012 | 22012950 |
| physiological trade-offs in self-maintenance: plumage molt and stress physiology in birds. | trade-offs between self-maintenance processes can affect life-history evolution. integument replacement and the stress response both promote self-maintenance and affect survival in vertebrates. relationships between the two processes have been studied most extensively in birds, where hormonal stress suppression is down regulated during molt in seasonal species, suggesting a resource-based trade-off between the two processes. the only species found to differ are the rock dove and eurasian tree sp ... | 2011 | 21795575 |
| crossbills (loxia curvirostra) are able to form the "larger than" concept. | an original method for studying cognitive abilities in largely wild passerine birds was developed. studies of five crossbills (loxia curvirostra) showed that this approach could be used to assess their ability to form concepts. all five crossbills learned selection rules for the "larger number" feature over the range "1-10." the birds successfully transferred this to stimuli significantly different from those used in training, which were not comparable in terms of all quantitative properties, bu ... | 2010 | 20544392 |
| [crossbills (loxia curvirostra) are able to form concept "larger than"]. | a new original method to investigate some cognitive abilities of wild passerine birds was developed. in the course of experiments with five crossbills (loxia curvirostra), it was shown that the method can be used to evaluate the ability of birds to form concepts. crossbills were presented with pairs of stimuli each consisting of 1 to 10 equal elements. all the five crossbills learned to choose, within a pair, a stimulus with a larger array of elements. the birds successfully transferred this per ... | 2009 | 19591398 |
| the liver but not the skin is the site for conversion of a red carotenoid in a passerine bird. | carotenoids may provide numerous health benefits and are also responsible for the integumentary coloration of many bird species. despite their importance, many aspects of their metabolism are still poorly known, and even basic issues such as the anatomical sites of conversion remain controversial. recent studies suggest that the transformation of carotenoid pigments takes place directly in the follicles during feather growth, even though the liver has been previously recognised as a storing orga ... | 2009 | 19357818 |
| mate choice based on a key ecological performance trait. | mate preference for well-adapted individuals may strengthen divergent selection and thereby facilitate adaptive divergence. we performed mate choice experiments in which we manipulated male red crossbill (loxia curvirostra complex) feeding rates. using association time as a proxy for preference, we found that females preferred faster foragers, which reinforces natural selection because poorly adapted males would be less likely to obtain a mate as well as less likely to survive. although theoreti ... | 2009 | 19320795 |
| the role of marker traits in the assortative mating within red crossbills, loxia curvirostra complex. | we conducted mate choice experiments to determine whether differences in calls or bill morphology might influence assortative mating between call types of red crossbills (loxia curvirostra complex) that have diverged in bill structure to specialize on different species of conifers. females preferred males that gave calls that matched their own type, but did not prefer males that more closely approximated the average or optimal bill size of the female's call type. these results were consistent wi ... | 2007 | 17714309 |
| divergent selection drives the adaptive radiation of crossbills. | knowledge of how phenotype influences fitness is necessary if we are to understand the basis of natural selection and how natural selection contributes to adaptive radiations. here i quantify selection on a wild population of red crossbills (loxia curvirostra complex) in the south hills, idaho. bill depth is the target of selection and selection on bill depth is stabilizing. i then show how fitness is related to both bill depth and performance. i use these and previously published relationships ... | 2003 | 12836833 |
| phylogeographical evidence of gene flow among common crossbill (loxia curvirostra, aves, fringillidae) populations at the continental level | common crossbill subspecies have been described according to morphological traits, vocalizations and geographical distribution. in this study, we have tried to determine whether the subspecies correspond to clear-cut mitochondrial dna lineages, by sequencing 717 bp of the control region from individuals taken at several sampling locations in north america and the western palaearctic. we find 22 haplotypes from the 37 sampled individuals with a mean divergence of 0.0118 +/- 0.0069 (mean +/- sd). ... | 1999 | 10469208 |
| morphological evolution in response to fluctuating selection. | | 1996 | 28565688 |
| the selection mosaic and diversifying coevolution between crossbills and lodgepole pine. | asymmetrical competition determines which of two seed predators drives the evolution of lodgepole pine (pinus contorta ssp. latifolia) cones. red squirrels (tamiasciurus hudsonicus) are effective preemptive competitors in lodgepole pine forests so that red crossbills (loxia curvirostra) are uncommon and selection from tamiasciurus drives cone evolution. when tamiasciurus are absent, crossbills increase in abundance and coevolve in an evolutionary arms race with pine. similarly, tamiasciurus alte ... | 1999 | 29578779 |
| the experimental study on susceptibility of common european songbirds to plasmodium elongatum (lineage pgrw6), a widespread avian malaria parasite. | plasmodium elongatum (cytochrome b lineage pgrw6) is a widespread avian malaria parasite, often causing severe disease in non-adapted hosts. this parasite lineage is of global distribution however, its virulence remains insufficiently understood, particularly in wild birds. surprisingly, this infection has never been reported in common starlings sturnus vulgaris and common crossbills loxia curvirostra, common european songbirds which were extensively sampled across europe. a hypothesis was propo ... | 2019 | 31455375 |
| patterns of plasmodium homocircumflexum virulence in experimentally infected passerine birds. | avian malaria parasites (genus plasmodium) are cosmopolitan and some species cause severe pathologies or even mortality in birds, yet their virulence remains fragmentally investigated. understanding mechanisms and patterns of virulence during avian plasmodium infections is crucial as these pathogens can severely affect bird populations in the wild and cause mortality in captive individuals. the goal of this study was to investigate the pathologies caused by the recently discovered malaria parasi ... | 2019 | 31113429 |
| recovery of hematocrit and fat deposits varies by cage size in food-restricted captive red crossbills (loxia curvirostra). | hematocrit-or the percent volume of red blood cells in whole blood-is thought to fluctuate adaptively in response to changing oxygen demands that occur during different life activities and in different environments. because red blood cells are made from materials that can be limiting, however, it is thought that hematocrit may also reflect general body condition and access to resources. we tested the effect of hydration state, resource restriction (i.e., time available to forage), and activity ( ... | 2020 | 33026714 |
| testing the shared-pathway hypothesis in the carotenoid-based coloration of red crossbills. | the mechanisms involved in the production of red carotenoid-based ornaments of vertebrates are still poorly understood. these colorations often depend on enzymatic transformations (ketolation) of dietary yellow carotenoids, which could occur in the inner mitochondrial membrane (imm). thus, carotenoid ketolation and cell respiration could share biochemical pathways, favoring the evolution of ketocarotenoid-based ornaments as reliable indices of individual quality under sexual selection. captive m ... | 2020 | 32749066 |
| patterns of annual and seasonal immune investment in a temporal reproductive opportunist. | historically, investigations of how organismal investments in immunity fluctuate in response to environmental and physiological changes have focused on seasonally breeding organisms that confine reproduction to seasons with relatively unchallenging environmental conditions and abundant resources. the red crossbill, loxia curvirostra, is a songbird that can breed opportunistically if conifer seeds are abundant, on both short, cold, and long, warm days, providing an ideal system to investigate env ... | 2020 | 32576107 |
| character displacement of a learned behaviour and its implications for ecological speciation. | cultural evolution may accelerate population divergence and speciation, though most support for this hypothesis is restricted to scenarios of allopatric speciation driven by random cultural drift. by contrast, the role of cultural evolution in non-allopatric speciation (i.e. speciation with gene flow) has received much less attention. one clade in which cultural evolution may have figured prominently in speciation with gene flow includes the conifer-seed-eating finches in the red crossbill (loxi ... | 2019 | 31362636 |
| resource stability and geographic isolation are associated with genome divergence in western palearctic crossbills. | while many conifers produce annually variable seed crops, serotinous species (which hold seeds in cones for multiple years) represent unusually stable food resources for seed predators. such stability is conducive to residency and potentially population divergence of consumers as exemplified by the cassia crossbill (loxia sinesciuris) in north america. we used genotyping by sequencing (gbs) to test whether three mediterranean subspecies of common crossbills (l. curvirostra) associated with the s ... | 2018 | 30125437 |
| innate immunity and environmental correlates of haemoproteus prevalence and intensity in an opportunistic breeder. | while parasite infection can have substantial fitness consequences in organisms, the predictors of parasite prevalence and intensity are often complex and vary depending on the host species. here, we examined correlates of haemoproteus (a common malaria parasite) prevalence and intensity in an opportunistically breeding songbird, the red crossbill (loxia curvirostra). specifically, we quantified haemoproteus prevalence and intensity in crossbills caught in the grand teton national park from 2010 ... | 2018 | 29463323 |
| social information changes stress hormone receptor expression in the songbird brain. | social information is used by many vertebrate taxa to inform decision-making, including resource-mediated movements, yet the mechanisms whereby social information is integrated physiologically to affect such decisions remain unknown. social information is known to influence the physiological response to food reduction in captive songbirds. red crossbills (loxia curvirostra) that were food reduced for several days showed significant elevations in circulating corticosterone (a "stress" hormone oft ... | 2018 | 29030109 |
| early learning of discrete call variants in red crossbills: implications for reliable signaling. | the identification of appropriate companions and mates is essential to both speciation and the maintenance of species through prezygotic isolation. in many birds, social assortment is mediated by vocalizations learned through imitation. when imitative vocal learning occurs throughout life, emergent shared signals reflect current social associations. however, when vocal and genetic variation arises among populations, shared learned signal variants have a potential to reflect cultural or genetic o ... | 2011 | 30337770 |
| matching habitat choice in nomadic crossbills appears most pronounced when food is most limiting. | of the various forms of nonrandom dispersal, matching habitat choice, whereby individuals preferentially reside in habitats where they are best adapted, has relatively little empirical support. here, i use mark-recapture data to test for matching habitat choice in two nomadic ecotypes of north american red crossbills (loxia curvirostra complex) that exist in the lodgepole pine (pinus contorta) forests in the south hills, idaho, every summer. crossbills are adapted for foraging on seeds in conife ... | 2017 | 27925171 |
| photoperiod but not food restriction modulates innate immunity in an opportunistic breeder, loxia curvirostra. | an organism's investment in immune function often varies seasonally but understanding of how fluctuations in environmental conditions directly modulate investment remains limited. this experiment investigated how changes in photoperiod and food availability affect investment in constitutive innate immunity and the acute phase response induced by lipopolysaccharide (lps) injections in captive red crossbills (loxia curvirostra). crossbills are reproductively flexible songbirds that specialize on a ... | 2017 | 27956484 |
| the natural history of the south hills crossbill in relation to its impending extinction. | increasingly, the species that we discover will be uncommon, area restricted, and vulnerable to extinction. i describe the natural history of a newly discovered seed-eating finch from the rocky mountain region, the south hills crossbill (loxia curvirostra complex). it relies on seeds in the closed cones of the fire-adapted rocky mountain lodgepole pine (pinus contorta latifolia) and is found only in the higher elevations of two small mountain ranges in southern idaho. here crossbills and pine ar ... | 2016 | 27860509 |