Biology subjects

Briga, M.

Publications and source records attributed to Briga, M..

6 recordsLinked to original sources

bioRxiv2026

Carotenoid-based ornaments predict survival in male but not female birds: a meta-analysis

Many vertebrates exhibit colourful ornaments generated by carotenoid pigments that presumably evolve as signals under sexual selection. To function as sexual signals, carotenoid-based coloured ornaments should accurately reveal an individuals quality, commonly defined as fitness potential, which includes the ability to survive. We performed a meta-analysis for testing the association between the expression level of carotenoid-based ornaments and longevity estimates (annual survival or lifespan) in birds, the taxon with the largest body of evidence. We detected a significant positive correlation in males but not in females. This result contrasts with recent meta-analytic work showing a positive association between carotenoid-based coloured traits and avian fecundity in both sexes. The link to survival was consistent among colourations produced by enzymatically transformed pigments (mostly red ketocarotenoids) and those based on dietary yellow carotenoids. The latter suggests that the association with survival holds across the physiological mechanisms involved in the production of these ornaments. In summary, our study reveals sex-specific selection in the evolution of carotenoid-based ornaments.

evolutionary biology↗

bioRxiv2025

Long-term effects of early-life adversity on DNA methylation in zebra finches

Early-life experiences can have profound and long-lasting effects on adult phenotype and thereby Darwinian fitness, though the mechanisms driving these effects remain poorly understood. Epigenetic alterations, especially DNA methylation which affects gene expression, potentially mediate developmental condition effects on adult phenotype. We tested for such effects using captive zebra finches that were reared in either small or large broods, a manipulation that is known to have pleiotropic phenotypic effects. Analyzing whole genome DNA methylation patterns in erythrocytes from 50 individuals sampled in adulthood, we found 0.8% of all CpG sites after filtering to be differentially methylated after correction for multiple testing. We identified 149 non-transiently differentially methylated sites (DMSs) where the DNA methylation difference between treatments was larger than 25%. These DMSs were located in 19 autosomal chromosomes, in or near genes involved in critical biological processes such as cell growth, division, and differentiation, regulation of immune response, muscle contraction, and neuronal signaling. These findings suggest that epigenetic modifications such as DNA methylation potentially mediate long-term effects of early-life adversity via differential gene expression, but follow-up studies are needed to identify the extent to which the observed DMSs are functionally related to the previously observed phenotypic effects.

ecology↗

bioRxiv2025

Begging costs rather than food received cause brood size effect on growth in zebra finches

Altricial species rely on parental provisioning for early-life sustenance, and a larger brood size leads to higher levels of competition between siblings for parental resources. Early-life stress can have severe and lifelong effects on Darwinian fitness. Indeed, it is well established that being reared in a larger brood impairs growth and fitness prospects of birds, but the mechanistic underpinnings of this effect are still largely unknown. Specifically, it is not well known to what extent the reduced growth and fitness prospects of nestlings reared in large broods is due to increased resource allocation to competition versus a per capita reduction in parental provisioning rate, or a combination of the two. We cross-fostered zebra finch (Taeniopygia castanotis) chicks into small and large broods, and recorded their growth as well as the behavior of parents and offspring throughout the nestling period. As in previous experiments, growth rate was higher in small broods. In large broods, chicks begged more and parents invested more time feeding which more than compensated for the difference in brood size. We therefore conclude that the lower growth rate for nestlings raised in large broods must be atleast in part-attributed to increased energy expenditure on begging rather than a reduction in the amount of food received. These results suggest significant energetic costs associated with begging and raise the interesting possibility that brood size would not have negatively affected growth in large broods if chicks had not increased their begging effort due to increased levels of competition in nest.

animal behavior and cognition↗

bioRxiv2020

Sex-specific body mass ageing trajectories in adult Asian elephants

In species with marked sexual dimorphism and where one sex undergoes stronger intrasexual competition, that sex is expected to age earlier or quicker. Here, we utilise a unique, longitudinal dataset of a semi-captive population of Asian elephants (Elephas maximus), a species with marked male-biased intrasexual competition, with males being larger and living shorter, and test the hypothesis that males show earlier and/or faster body mass ageing than females. We show sex-specific body mass ageing trajectories: adult males gained weight up to the age of 48 years old, followed by a decrease in body mass until natural death. In contrast, adult females gained body mass with age until a body mass decline in the last year of life. Our study shows that sex-specific life-histories shape ageing patterns, consistent with the predictions of the classical theory of ageing.

evolutionary biology↗

bioRxiv2019

Mosaic metabolic ageing: Basal and standard metabolic rate age in opposite directions and independent of lifespan in a passerine

O_LICrucial to our understanding of the ageing process is identifying how traits change with age, which variables alter their ageing process and whether these traits associate with lifespan. C_LIO_LIWe here investigated metabolic ageing in zebra finches. We longitudinally monitored 407 individuals during six years and collected 3213 measurements of two independent mass-adjusted metabolic traits: basal metabolic rate (BMRm) at thermoneutral temperatures and standard metabolic rate (SMRm), which is the same as BMRm but at ambient temperatures below thermoneutrality. C_LIO_LIBMRm decreased linearly with age, consistent with earlier reports. In contrast, SMRm increased linearly with age. To the best of our knowledge, this is the first quantification of SMRm ageing, and thereby of the contrast between SMRm and BMRm ageing. C_LIO_LINeither metabolic rate nor metabolic ageing rate were associated with individual lifespan. Moreover, experimental manipulations of environmental quality that decreased BMRm and SMRm and shortened lifespan with 6 months (12%) did not affect the ageing of either metabolic trait. Females lived 2 months (4%) shorter than males, but none of the metabolic traits showed sex-specific differences at any age. C_LIO_LIOur finding that ageing patterns of metabolic rate vary depending on the ambient temperature illustrates the importance of studying ageing in an ecologically realistic setting. C_LIO_LIOur results add to the mounting evidence that within an organism ageing is an asynchronous process. C_LI

ecology↗

bioRxiv2018

Body mass aging trajectory is modulated by environmental conditions but independent of lifespan

How lifespan associates with aging trajectories of health and disease is an urgent question in societies with increasing lifespan. Body mass declines with age are associated with decreased organismal functioning in many species. We tested whether two factors that decreased lifespan in zebra finches, sex and manipulated environmental quality, accelerated the onset and/or rate of within-individual body mass declines. We subjected 597 birds for nine years to experimentally manipulated foraging costs (harsh = H, benign = B) during development and in adulthood in a 2x2 design. This yielded four treatment combinations (HH, HB, BH, BB). Harsh environments during development and in adulthood decreased average body mass additively. In males, the aging trajectory was quadratic, with a maximum between 3.5 and 4 years, and independent of the environment (HH=HB=BH=BB). In females, the shape of the aging trajectory differed between environments: a quadratic trajectory as in males in the benign adult environment (HB=BB), a linear decline when benign development was followed by harsh adulthood (BH) and a linear increase when in a lifelong harsh environment (HH). We found no evidence for an association between lifespan and body mass aging trajectories either between or within experimental groups. However, females lived shorter than males, and their body mass decline started earlier for most treatment combinations. Thus, we conclude that foraging conditions can affect the shape of body mass aging trajectories, but these are independent of lifespan.

ecology↗