Life history theory (LHT) predicts a trade-off between reproductive effort and the pace of biological aging. Energy invested in reproduction is not available for tissue maintenance, thus having more offspring expected to lead accelerated senescence. Studies conducted variety non-human species are consistent with this LHT prediction. Here we investigate relationship number surviving children born woman telomere length (TL, marker cellular aging) over 13 years group 75 Kaqchikel Mayan women....

EVOLUTIONARY PHYSIOLOGISTS AND ecologists seek to understand the mechanisms that underlie trade-offs involving life-history traits. These arise when resources are limited, and allocation of certain traits limits amount available for other (Williams 1966, Stearns 1992). Recent studies have found maintaining or activating immune function can be resource-dependent (Tsiagbe et al. 1987; Saino 1997b, 2003; Alonso-Alvarez Tella 2001) metabolically costly (Demas 1997, Lochmiller Deerenberg 2000,...

Organisms theoretically manage their immune systems optimally across life spans to maximize fitness. However, we lack information on (1) how the system is managed life-history stages, (2) whether sexes immunity differentially, and (3) repeatable within an individual. We present a within-individual, repeated-measures experiment examining stage variation in inflammatory response zebra finch (Taeniopygia guttata). In juveniles, age-dependent differed sex- context-specific manner, resulting no...

Sexually reproducing organisms should mate with the highest quality individuals that they can. When female songbirds choose a mate, are thought to use several aspects of male song reflect his quality. Under resource-limited environmental conditions, Lincoln's sparrows (Melospiza lincolnii) vary among one another in quality, including length, complexity, and trill performance. In 2-pronged approach, we tested whether variation influences behavior females reproductive-like state. Over two...

SUMMARY Avian reproduction is generally timed to synchronize chick-rearing with periods of increased food abundance. Consequently, the energetically demanding period egg production may coincide lower availability,fluctuating temperature and more unstable weather. Little known about physiological mechanisms underlying temperature-induced variation in production. We therefore examined influence low ambient temperature(7°C vs 21°C) on reproductive output (e.g. mass, clutch size, laying...

Numerous studies indicate interspecies variation in the ontogeny of adrenocortical response birds; however, little is known about extent interindividual avian young. Toward this end, we examined and zebra finch (Taeniopygia guttata) nestlings. We measured baseline stress‐induced total (bound free) corticosterone, corticosteroid binding globulin capacity, resulting estimated free corticosterone levels nestlings four different ages (days 5, 10, 16, 21). In addition, investigated potential...

Abstract Interest in phenotypic flexibility has increased dramatically over the last decade, but during reproduction received relatively little attention from avian scientists, despite its possible impact on fitness. Because most species maintain atrophied reproductive organs when not active, birds requires major tissue remodeling preparation for breeding. Females undergo rapid (days) recrudescence and regression of their at each breeding attempt, while males grow ahead time a much slower...

A growing body of evidence suggests that gonadal steroids such as estradiol (E2) alter neural responses not only in brain regions associated with reproductive behavior but also sensory areas. Because catecholamine systems are involved processing and selective attention, because they sensitive to E2 many species, may mediate the effects Here, we tested on catecholaminergic innervation, synthesis activity auditory system white-throated sparrows, a seasonally breeding songbird which promotes...

Abstract Mate choice is among the most consequential decisions a sexually reproducing organism can make. In many songbird species, females make mate‐choice based, in part, on variation between males songs that reflect their quality. Importantly, may adjust relative to prevalence of high quality songs. European starlings ( Sturnus vulgaris ), prefer primarily sing long over those short songs, and sensitivity auditory telencephalon song length depends environment. Several lines evidence...

Because no organism lives in an unchanging environment, sensory processes must remain plastic so that any context, they emphasize the most relevant signals. As behavioral relevance of sociosexual signals changes along with reproductive state, perception those is altered by hormones such as estradiol (E2). We showed previously white-throated sparrows, immediate early gene responses auditory pathway females are selective for conspecific male song only when plasma E2 elevated to...

Maternal physiologic stress during gestation has been reported to be associated with negative developmental outcomes, including intra-uterine growth restriction and reduced birth weight, which can impact postnatal development, behavior health. The human fetus is partially protected from elevated cortisol exposure by placental 11 β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), oxidizes bioactive into bio-inactive cortisone. Importantly, despite the critical protective role hypothesized for...

Daily variation in circulating levels of the avian yolk precursor, vitellogenin (VTG), throughout laying cycle was investigated female zebra finches Taeniopygia guttata and compared with predicted ovarian follicle demand (based on a model follicular development for this species). In general, pattern plasma VTG matched from developing hierarchy. Plasma non‐detectable non‐breeders, but increased rapidly onset development, remaining high (1.43–1.82 μg/ml, zinc) through to 3‐egg stage. then...

Little is known about the energy costs of egg production in birds. We showed previous papers that, during production, European starlings (Sturnus vulgaris) undergo a 22% increase resting metabolic rate (RMR) and that maintenance activity oviduct are responsible for 18% variation elevated laying RMR. Therefore, other energy-consuming physiological mechanisms must be remaining unexplained Yolk precursor [vitellogenin (VTG) very-low-density lipoprotein (VLDL)] likely to costly because it...

SUMMARY During avian egg production, oestrogen mediates marked increases in hepatic lipid production and changes the diameter of assembled very-low density lipoprotein (VLDL). A nearly complete shift from generic VLDL (∼70 nm diameter), which transports lipids to peripheral tissues, yolk-targeted (VLDLy) (∼30 nm), supplies yolk with energy-rich lipid, has been observed plasma laying domestic fowl. We validated an established dynamic laser scattering technique for a passerine songbird...

Abstract Abstract: Measuring multiple hormones simultaneously in a single assay saves sample volume, labor, time, reagents, money, and consumables. Thus, multiplex arrays represent faster, more economically ecologically sound alternative to singleton assays. Objectives: To validate new, commercially available female array produced by Quansys Biosciences against individual immunoassays for the quantification of six urine samples from women different reproductive stages. Methods: Urine were...

Recent studies have shown that the metabolic cost of avian egg production involves a 16-27% increase in rate (MR) above non-reproductive basal or resting values (BMR and RMR, respectively). To determine how interacted with costs other essential processes (such as cold acclimation active heat production), we measured MR non-breeding egg-producing zebra finches (Taeniopygia guttata) while (a) warm-acclimated (to 19-21 degrees C) within their thermoneutral zone (at 35 C), (b) cold-acclimated 7...

Abstract Cortisol is one of the most frequently used stress biomarkers in humans. Urine and saliva are matrices choice to longitudinally monitor cortisol levels. Salivary urinary often discussed as though they provide similar information. However, relationship between “free” levels urine (nonconjugated) (non‐protein‐bound) has yet be properly evaluated using naturalistic designs. Objectives To investigate longitudinal salivary ( SC ) first morning FMUC ), compare advantages disadvantages...