Egg rejection is an effective and widespread antiparasitic defense to eliminate foreign eggs from the nests of hosts of brood parasitic birds. Several lines of observational and critical experimental evidence support a role for learning by hosts in the recognition of parasitic versus own eggs; specifically, individual hosts that have had prior or current experience with brood parasitism are more likely to reject foreign eggs. Here we confirm experimentally the role of prior experience in altering subsequent egg-rejection decisions in the American robin , a free-living host species of an obligate brood parasite, the brown-headed cowbird .
View Article and Find Full Text PDFClimate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average offspring production has declined in recent decades, but considerable differences were found among species and populations.
View Article and Find Full Text PDFTo curb fitness costs associated with obligate avian brood parasitism, some hosts have evolved to reject foreign eggs in the nest. American robins (Turdus migratorius) are among the few hosts of the brown-headed cowbird (Molothrus ater) that mostly remove parasitic eggs from their nests. With the parasite's eggs looking nothing like their own, American robins likely rely most on visual cues when making rejection decisions.
View Article and Find Full Text PDFAvian obligate brood parasites lay their eggs in the nests of other species that may provide care for the foreign offspring. Brood parasitism often imparts substantial fitness losses upon host nestlings when they are raised alongside the typically more competitive, larger, and older parasitic chick(s). Whereas fitness costs due to reduced host offspring survival in parasitized broods have been studied in detail, the physiological changes in host nestlings caused by parasitic nestmate(s) are less well known.
View Article and Find Full Text PDFBrood parasitism is the introduction of unrelated progeny into the nest or colony of a host that then raises the foreign young. This reproductive strategy has evolved independently and repeatedly among diverse animal taxa, and brood parasite-host interactions have become models for understanding coevolutionary arms races. Yet brood parasites have remained largely overlooked in previous syntheses of natural enemy ecology.
View Article and Find Full Text PDFSome hosts of avian brood parasites reduce or eliminate the costs of parasitism by removing foreign eggs from the nest (rejecter hosts). In turn, even acceptor hosts typically remove most non-egg-shaped objects from the nest, including broken shells, fallen leaves and other detritus. In search for the evolutionary origins and sensory mechanisms of egg rejection, we assessed where the potential threshold between egg recognition and nest hygiene may lie when it comes to stimulus shape.
View Article and Find Full Text PDFBackground: To investigate how changes in sedentary behavior relate to health outcomes, it is important to establish the test-retest reliability of activity monitors in measuring habitual sedentary behavior in people with type 2 diabetes (T2D) as a prerequisite for interpreting this information. Thus, the authors' objective was to examine the test-retest reliability of a common activity monitor (activPAL™) in measuring sedentary behavior and physical activity in people with T2D.
Methods: Sedentary-time, standing-time, stepping-time, step-count, and sit-to-stand transitions were obtained from two 7-day assessment periods separated by at least 1 week.
Raising an obligate avian brood parasite is costly for host parents because it redirects valuable parental resources from one's own offspring to genetically unrelated young. The costs of raising a brood parasite may be mediated by physiological stressors for foster parents if it requires greater or biased parental effort compared to raising non-parasitized broods. For example, upregulating glucocorticoid hormones or reducing immune responses may mediate a trade-off between resource allocation to a current brood versus future reproductive opportunities, but published data on parasitized hosts' physiology are scarce.
View Article and Find Full Text PDFBackground And Aims: Stroke is a leading cause of death and disability worldwide. However, our knowledge of the incidence of stroke for Saudi Arabian population is not known. Thus, we aimed to determine the pooled annual incidence of stroke in Saudi Arabia.
View Article and Find Full Text PDFQuantifying arthropod vectors can be a time-consuming process. Here, we describe a technique to count large samples of small arthropods using ImageJ. ImageJ is an open source image processing software, produced by the National Institutes of Health, with a straightforward interface that has proven useful in quantifying small organisms (i.
View Article and Find Full Text PDFAims: Individuals with type 2 diabetes (T2DM) are advised to undertake diabetes self-care behavior (DSCB) in order to avoid complications of T2DM. However, comorbidities, such as insomnia symptoms which are commonly reported in people with T2DM, may limit the ability to engage in DSCB. Insomnia and the common sequelae accompanying insomnia such as pain, depression, and anxiety may negatively influence the performance of DSCB.
View Article and Find Full Text PDFBackground: Insomnia symptoms are a common form of sleep difficulty among people with type 2 diabetes (T2D) affecting sleep quality and health outcomes. Several interventional approaches have been used to improve sleep outcomes in people with T2D. Nonpharmacological approaches, such as cognitive behavioral therapy for insomnia (CBT-I), show promising results regarding safety and sustainability of improvements, although CBT-I has not been examined in people with T2D.
View Article and Find Full Text PDFFemales are expected to have evolved to be more discriminatory in mate choice than males as a result of greater reproductive investment into larger gametes (eggs vs. sperm). In turn, males are predicted to be more promiscuous than females, showing both a larger variance in the number of mates and a greater increase in reproductive success with more mates, yielding more intense sexual selection on males vs.
View Article and Find Full Text PDFAim: The aim of this study was to conduct a systematic review and meta-analysis for studies that have examined the prevalence and risk factors of falls in older adults living in the Gulf Cooperation Council countries (GCC).
Methods: A literature search was performed using PubMed, Web of Science, Physiotherapy Evidence Database; and SCOPUS up to October 2018 to identify studies that have examined prevalence, risk factors, or consequences of falls in older adults living in the GCC.
Results: A total of 6 studies met the inclusion criteria.
Introduction: Recruiting participants into research trials is essential for the advancement of scientific knowledge that depends on clinical research studies. For the field of exercise and physical activity, there is an added difficulty in recruiting participants because participants must be willing to participate in an intervention that requires a significant commitment of both time and physical effort. Therefore, we have planned a systematic review to analyse how methodological factors, intervention characteristics and participant demographics impact recruitment rates in specific populations.
View Article and Find Full Text PDFBackground: Cardiovascular disease is a common health problem resulting from many factors, including dyslipidemia. T'ai chi is one of the interventions assigned to improve lipid profiles and other physical outcomes. However, conflicting results might be attributed to different study designs and interventional approaches.
View Article and Find Full Text PDFAvian obligate brood parasites, which rely solely on hosts to raise their young, should choose the highest quality hosts to maximize reproductive output. Brown-headed cowbirds (Molothrus ater) are extreme host generalists, yet female cowbirds could use information based on past reproductive outcomes to make egg-laying decisions thus minimizing fitness costs associated with parasitizing low-quality hosts. We use a long-term (21 years) nest-box study of a single host, the prothonotary warbler (Protonotaria citrea), to show that local cowbird reproductive success, but not host reproductive success, was positively correlated with the probability of parasitism the following year.
View Article and Find Full Text PDFNeurturin (NRTN) is a neurotrophic factor required for the development of many parasympathetic neurons and normal cholinergic innervation of the heart, lacrimal glands and numerous other tissues. Previous studies with transgenic mouse models showed that NRTN is also essential for normal development and function of the retina (J. Neurosci.
View Article and Find Full Text PDFPACAP and VIP have prominent effects on cardiac function in several species, but little is known about their influence on the murine heart. Accordingly, we evaluated the expression of PACAP/VIP receptors in mouse heart and the response of isolated atria to peptide agonists. Quantitative PCR demonstrated that PAC₁, VPAC₁, and VPAC₂ receptor mRNAs are present throughout the mouse heart.
View Article and Find Full Text PDFAttempts to estimate and identify factors influencing first-year survival in passerines, survival between fledging and the first reproductive attempt (i.e. juvenile survival), have largely been confounded by natal dispersal, particularly in long-distance migratory passerines.
View Article and Find Full Text PDFBrood parasitic birds impose variable fitness costs upon their hosts by causing the partial or complete loss of the hosts' own brood. Growing evidence from multiple avian host-parasite taxa indicates that exposure of individual hosts to parasitism is not necessarily random and varies with habitat use, nest-site selection, age or other phenotypic attributes. For instance, nonrandom patterns of brood parasitism had similar evolutionary consequences to those of limited horizontal transmission of parasites and pathogens across space and time and altered the dynamics of both population productivity and co-evolutionary interactions of hosts and parasites.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
March 2007
Why do many hosts accept costly avian brood parasitism even when parasitic eggs and nestlings differ dramatically in appearance from their own? Scientists argue that evolutionary lag or equilibrium can explain this evolutionary enigma. Few, however, consider the potential of parasitic birds to enforce acceptance by destroying eggs or nestlings of hosts that eject parasitic eggs and thereby reject parasitism. This retaliatory "mafia" behavior has been reported in one species of parasitic cuckoo but never in parasitic cowbirds.
View Article and Find Full Text PDFInterspecific brood parasitism in birds presents a special problem for the host because the parasitic offspring exploit their foster parents, causing them to invest more energy in their current reproductive effort. Nestling brown-headed cowbirds (Molothrus ater) are a burden to relatively small hosts and may reduce fledgling quality and adult survival. We documented food-provisioning rates of one small host, the prothonotary warbler (Protonotaria citrea), at broods that were similar in age (containing nestlings 8-9 days old), but that varied in composition (number of warbler and cowbird nestlings) and mass, and measured the effect of brood parasitism on offspring recruitment and adult returns in the host.
View Article and Find Full Text PDFA highly automated RT-PCR-based approach has been established to validate novel human gene predictions with no prior experimental evidence of mRNA splicing (ab initio predictions). Ab initio gene predictions were selected for high-throughput validation using predicted protein classification, sequence similarity to other genomes, colocalization with an MPSS tag, or microarray expression. Initial microarray prioritization followed by RT-PCR validation was the most efficient combination, resulting in approximately 35% of the ab initio predictions being validated by RT-PCR.
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