Many male birds use carotenoid pigments to acquire brilliant colors that advertise their health and condition prospective mates. The direct means by which the most colorful males achieve superior has been debated, however. One hypothesis, based on studies of carotenoids as antioxidants in humans other animals, is directly boost immune system birds. We studied relationship between pigments, function, sexual coloration zebra finches (Taeniopygia guttata), a species incorporate into beak...

1. Life-history theory predicts that immune responses have evolved in the context of costs and benefits. However, our understanding mounting an response is limited. 2. Using four species insects, we tested for metabolic immunity by inducing a short-term and/or wounding measuring CO2 production. Inducing encapsulation raised resting rate up to 28% with strong positive correlation between individual Tenebrio molitor, Acheta domesticus, Cotinis nitida Periplaneta americana. Interestingly, found...

Nest microclimate can have strong effects that carry over to later life-history stages. We experimentally cooled the nests of tree swallows ( Tachycineta bicolor ). Females incubating in reduced incubation time and allowed egg temperatures drop, leading extended periods. partially cross-fostered nestlings test carry-over cooling during on nestling innate constitutive immunity, assessed through bacteria killing ability (BKA) blood. Nestlings had been as eggs showed a lower kill than control...

ABSTRACT Orientation of nests can influence nest microclimate, particularly temperature. However, few investigators have examined orientation preference and microclimate simultaneously. We the possible correlation between entrance artificial boxes used by Tree Swallows (Tachycineta bicolor) internal temperature boxes. showed a for east- south-facing boxes, but only during first half breeding season (before 1 June). During second (after June), selected based on availability. found that were...

1. Life-history decisions are strongly affected by environmental conditions. In birds, incubation is energetically expensive and significantly ambient temperature. We reduced energetic constraints for female tree swallows (Tachycineta bicolor) experimentally heating nests during an average of 6.9 degrees C to test changes in behaviour. 2. Females heated boxes (hereafter 'heated females') increased time spent incubating maintained higher on-bout off-bout egg temperatures. This indicates that...

There has been a recent call for an Extended Synthesis in evolutionary biology (Pigliucci 2007). The Modern Synthesis, which united Mendelian and Darwinian ideas about genes natural selection, the cornerstone of last 60 years However, many important elements were left out that synthesis, particularly mechanisms whereby genetic variation is transduced into phenotypic variation. Such 'black boxes' still pervade biology, biological fields such as immunology, these black boxes are explicit...

Abstract Individuals often vary markedly in their ability to cope with stressors, but the drivers of this variation remain poorly understood. Many studies have tested relationships among individual glucocorticoid levels and response challenges—often finding inconsistent patterns; however, few addressed whether capacity terminate stress through negative feedback is associated resilience. While conceptual models predict that interactions different components hypothalamic–pituitary–adrenal...

Latitudinal differences in life histories are believed to be underlain by dif- ferences trade-offs between current and future reproduction. I report trade- offs parent offspring across the range of a widespread avian species, Tree Swallow (Tachycineta bicolor). manipulated parental effort found that Alaska, where yearly adult return rates low, breeding females increase their reproductive in- vestment maintain quality, whereas Tennessee, high, either unable or unwilling investment and,...

Carotenoid pigments are responsible for many examples of sexually attractive red, orange, and yellow coloration in animals play an important role antioxidant immune defenses. Because vertebrates cannot synthesize carotenoids, limited dietary availability may impose a trade-off between maintaining ornamental health. We used experimental approach to test the carotenoid hypothesis fighting fish Betta splendens, by examining whether allocation strategies differ among conspecifics that exhibit...

Summary Lipids are a major source of energy storage in vertebrates. A cross‐fostering brood manipulation was conducted to assess the role rearing environment vs common origin on lipid stores. Rearing conditions, especially nest temperatures, explained more variation levels than did origin. As temperatures increased, nestlings also increased. Larger individuals, reflected both wet and lean dry mass, tended store lipids. There no trade‐off between structural growth However, body mass linked...

Summary Individual variation in the trade‐off between self‐maintenance and offspring quality was assessed tree swallows, Tachycineta bicolor , by manipulating reproductive effort while simultaneously immunochallenging breeding females. An experimental manipulation of parental conducted creating broods of, on average, three, five eight nestlings. Breeding females were immunochallenged to mount a humoral immune response sheep red blood cells (SRBC) cell‐mediated phytohaemagglutinin (PHA). The...

Summary 1. Life history theory predicts that immunity should be plastic and reflect environmental contexts. However, individual variation in immune investment may arise not just because of adjustment, but developmental, physiological, genetic or immunological constraints which lead to non‐adaptive responses by limiting eliminating flexibility investment. Constraints can organisms are single integrated units with interconnected interacting components, physiological control mechanisms limit...

Individual variation in life-history trade-offs can be caused by differences quality and age. We tested for individual parental investment incubating tree swallows (Tacyhcineta bicolor) subjected to a feather-clipping manipulation. influenced how females were affected feather clipping; lower clipped showed greater reduction incubation loss of body condition than higher compared with controls. Most importantly, responses during nestling traits; females, particularly those losing the most...

Investment in one life-history stage can have delayed effects on subsequent stages within a single reproductive bout. We experimentally heated tree swallow ( Tachycineta bicolor ) nests during incubation to test for parental and nestling conditions. Females incubating boxes maintained higher body condition fed nestlings at rates. cross-fostered found that young (4–7 days old) incubated had mass, regardless of treatment status their rearing parent. However, older which were by females mass...

The nest environment can have important influences on incubation behavior and nestling development in birds. Nest thermal properties, particularly composition size, a major influence heat loss. To examine the role of size insulation clutch cooling rates, we collected tree swallow Tachycineta bicolor nests measured rate eggs controlled environment. We also examined benefits feathers by comparing rates with without feathers. Nests more feather heavier, deeper cupped cooled at slower rates. In...

Animal body temperature (Tbody) varies over daily and annual cycles, affecting multiple aspects of biological performance in both endothermic ectothermic animals. Yet a comprehensive comparison thermal among animals varying Tbody (mean variance) heat production is lacking. Thus, we examined the sensitivity immune function (a crucial fitness determinant) Vertebrata, group encompassing species biology. Specifically, investigated temperature-related variation two innate metrics,...

Abstract A central assumption in ecological immunology is that immune responses are costly, with costs manifesting directly (e.g., increases metabolic rate and increased amino acid usage) or as tradeoffs other life processes reduced growth reproductive success). Across taxa, host longevity, timing of maturity, effort affect the organization systems. It reasonable, therefore, to expect these related factors should also activation costs. Specifically, species spread their breeding efforts over...

We examined whether strategies of reproductive allocation may reduce long-term immunocompetence through the effects manipulated effort on secondary or acquired immunity. tested increased leads to reduced immune function and survival by manipulating brood size in tree swallows (Tachycineta bicolor) exposing breeding females a primary exposure sheep red blood cells elicit humoral response. Females raising enlarged broods produced fewer antibodies than did control broods. Most importantly,...

Variation in egg size and composition can have important consequences for the quality of offspring. We investigated factors influencing yolk mass tree swallows breeding Ithaca, NY. Using a nondestructive technique to estimate via standardized digital‐candler photographs, we compared Tachycineta bicolor response variation food availability individual quality. Insect one three days prior laying, but not four six days, predicted mass, while insect two laying total mass. This suggests that, eggs...

1. In wild birds, incubation period shortens and the general pace of life quickens with distance from equator. Temperature various biotic factors, including adult behaviours, cannot fully account for longer periods equatorial birds only explain some variation between tropical temperate histories. Here we consider role differences in light driving period. poultry, can be experimentally shortened by exposing eggs to light. The positive influence on embryonic growth, called photoacceleration,...

Acutely stressful experiences can have profound and persistent effects on phenotype. Across taxa, individuals differ remarkably in their susceptibility to stress. However, the mechanistic causes of enduring stress effects, individual differences susceptibility, are poorly understood. Here, we tested whether brief, acute increases glucocorticoid hormones phenotype, according magnitude or duration elevation. We used a novel method non-invasively manipulate hormone levels short time scales:...

The vibrant colors of many birds’ eggs, particularly those that are blue to blue-green, extraordinary in they striking traits present hundreds species have nevertheless eluded evolutionary functional explanation. We propose egg pigmentation mediates a trade-off between two routes by which solar radiation can harm bird embryos: transmittance through the eggshell and overheating absorbance. quantitatively test four components this hypothesis on variably colored eggs village weaverbird (Ploceus...