Male-biased sex allocation in ageing parents; a longitudinal study in a long-lived seabird.
Ontology highlight
ABSTRACT:
SUBMITTER: Vedder O
PROVIDER: S-EPMC5014021 | biostudies-literature | 2016 Aug
REPOSITORIES: biostudies-literature
Publications
Male-biased sex allocation in ageing parents; a longitudinal study in a long-lived seabird.
Vedder Oscar O Bouwhuis Sandra S Benito María M MM Becker Peter H PH
Biology letters 20160801 8
Optimal sex allocation is frequency-dependent, but senescence may cause behaviour at old age to be suboptimal. We investigated whether sex allocation changes with parental age, using 16 years of data comprising more than 2500 molecularly sexed offspring of more than 600 known-age parents in common terns (Sterna hirundo), slightly sexually size-dimorphic seabirds. We decomposed parental age effects into within-individual change and sex allocation-associated selective (dis)appearance. Individual p ...[more]
Similar Datasets
Project description:We developed a Hidden Markov mark-recapture model (R package marked) to examine sex-specific demography in Magellanic Penguins (Spheniscus magellanicus). Our model was based on 33 yr of resightings at Punta Tombo, Argentina, where we banded ~44,000 chicks from 1983 to 2010. Because we sexed only 57% of individuals over their lifetime, we treated sex as an uncertain state in our model. Our goals were to provide insight into the population dynamics of this declining colony, to inform conservation of this species, and to highlight the importance of considering sex-specific vital rates in demographic seabird studies. Like many other seabirds, Magellanic Penguins are long-lived, serially monogamous, and exhibit obligate biparental care. We found that the non-breeding-season survival of females was lower than that of males and that the magnitude of this bias was highest for juveniles. Biases in survival accumulated as cohorts aged, leading to increasingly skewed sex ratios. The survival bias was greatest in years when overall survival was low, that is, females fared disproportionality worse when conditions were unfavorable. Our model-estimated survival patterns are consistent with independent data on carcasses from the species' non-breeding grounds, showing that mortality is higher for juveniles than for adults and higher for females than for males. Juveniles may be less efficient foragers than adults are and, because of their smaller size, females may show less resilience to food scarcity than males. We used perturbation analysis of a population matrix model to determine the impact of sex-biased survival on adult sex ratio and population growth rate at Punta Tombo. We found that adult sex ratio and population growth rate have the greatest proportional response, that is, elasticity, to female pre-breeder and adult survival. Sex bias in juvenile survival (i.e., lower survival of females) made the greatest contribution to population declines from 1990 to 2009. Because starvation is a leading cause of morality in juveniles and adults, precautionary fisheries and spatial management in the region could help to slow population decline. Our data add to growing evidence that knowledge of sex-specific demography and sex ratios are necessary for accurate assessment of seabird population trends.
| S-EPMC6849821 | biostudies-literature
Project description:While personality differences in animals are defined as consistent behavioural variation between individuals, the widely studied field of foraging specialisation in marine vertebrates has rarely been addressed within this framework. However there is much overlap between the two fields, both aiming to measure the causes and consequences of consistent individual behaviour. Here for the first time we use both a classic measure of personality, the response to a novel object, and an estimate of foraging strategy, derived from GPS data, to examine individual personality differences in black browed albatross and their consequences for fitness. First, we examine the repeatability of personality scores and link these to variation in foraging habitat. Bolder individuals forage nearer the colony, in shallower regions, whereas shyer birds travel further from the colony, and fed in deeper oceanic waters. Interestingly, neither personality score predicted a bird's overlap with fisheries. Second, we show that both personality scores are correlated with fitness consequences, dependent on sex and year quality. Our data suggest that shyer males and bolder females have higher fitness, but the strength of this relationship depends on year quality. Females who forage further from the colony have higher breeding success in poor quality years, whereas males foraging close to the colony always have higher fitness. Together these results highlight the potential importance of personality variation in seabirds and that the fitness consequences of boldness and foraging strategy may be highly sex dependent.
| S-EPMC3913606 | biostudies-literature
Project description:Life-history theory predicts that suboptimal developmental conditions may lead to faster life histories (younger age at recruitment and higher reproductive investment), but experimental testing of this prediction is still scarce in long-lived species. We report the effects of an experimental manipulation of food availability during early development and at recruitment on the onset of reproduction and reproductive performance (productivity at first breeding) in a long-lived seabird, the black-legged kittiwake Rissa tridactyla, breeding on Middleton Island, Alaska. Birds were born and raised in nests with supplemented food ('fed') or unsupplemented control nests ('unfed'), and later recruited into either fed or unfed nests. Fed chicks grew faster than unfed chicks, and males grew faster than females. Birds were more likely to reproduce at younger ages when recruiting into fed nests. Faster growth during development tended to increase age at recruitment in all individuals. Social rank of individuals also affected age at recruitment: B-chicks recruited earlier than A-chicks and singletons recruited later than A- and B-chicks. Productivity increased with the age at recruitment and growth rate as chick, but much of the variability remained unexplained. We conclude that results of this study at least partially support predictions of life-history theory: younger age at first breeding for kittiwakes that experienced suboptimal natal conditions, as well as greater productivity of early recruiting kittiwakes that grew in control nests compared with those that grew in food-supplemented nests.
| S-EPMC3652464 | biostudies-literature
Project description:Studies of model animals like mice and rats have led to great advances in our understanding of the process of tumorigenesis, but this line of study has less to offer for understanding the mechanisms of cancer resistance. Increasing the diversity of nonmodel species from the perspective of molecular mechanisms of natural cancer resistance can lead to new insights into the evolution of protective mechanisms against neoplastic processes and to a wider understanding of natural cancer defense mechanisms. Such knowledge could then eventually be harnessed for the development of human cancer therapies. We suggest here that seabirds are promising, albeit currently completely ignored candidates for studying cancer defense mechanisms, as they have a longer maximum life span than expected from their body size and rates of energy metabolism and may have thus evolved mechanisms to limit neoplasia progression, especially at older ages. We here apply a novel, intraspecific approach of comparing old and young seabirds for improving our understanding of aging and neoplastic processes in natural settings. We used the long-lived common gulls (Larus canus) for studying the age-related pattern of expression of cancer-related genes, based on transcriptome analysis and databases of orthologues of human cancer genes. The analysis of differently expressed cancer-related genes between young and old gulls indicated that similarly to humans, age is potentially affecting cancer risk in this species. Out of eleven differentially expressed cancer-related genes between the groups, three were likely artifactually linked to cancer. The remaining eight were downregulated in old gulls compared to young ones. The downregulation of five of them could be interpreted as a mechanism suppressing neoplasia risk and three as increasing the risk. Based on these results, we suggest that old gulls differ from young ones both from the aspect of cancer susceptibility and tumor suppression at the genetic level.
| S-EPMC7428815 | biostudies-literature
Project description:Although population studies have long assumed that all individuals of a given sex and age are identical, ignoring among-individual differences may strongly bias our perception of eco-evolutionary processes. Individual heterogeneity, often referred to as individual quality, has received increasing research attention in the last decades. However, there are still substantial gaps in our current knowledge. For example, there is little information on how individual heterogeneity influences various life-history traits simultaneously, and studies describing individual heterogeneity in wild populations are generally not able to jointly identify possible sources of this variation. Here, based on a mark-recapture data set of 9,685 known-aged Wandering Albatrosses (Diomedea exulans), we investigated the existence of individual quality over the entire life cycle of this species, from early life to senescence. Using finite mixture models, we investigated the expression of individual heterogeneity in various demographic traits, and examined the origin of these among-individual differences by considering the natal environmental conditions. We found that some individuals consistently outperformed others during most of their life. In old age, however, the senescence rate was stronger in males that showed high demographic performance at younger ages. Variation in individual quality seemed strongly affected by extrinsic factors experienced during the ontogenetic period. We found that individuals born in years with high population density tended to have lower performances during their lifespan, suggesting delayed density dependence effects through individual quality. Our study showed that among-individual differences could be important in structuring individual life history trajectories, with substantial consequences at higher ecological levels such as population dynamics.
| S-EPMC6084314 | biostudies-literature
Project description:Long-lived microtubules endow the eukaryotic cell with long-range transport abilities. While long-lived microtubules are acetylated on Lys40 of α-tubulin (αK40), acetylation takes place after stabilization and does not protect against depolymerization. Instead, αK40 acetylation has been proposed to mechanically stabilize microtubules. Yet how modification of αK40, a residue exposed to the microtubule lumen and inaccessible to microtubule-associated proteins and motors, could affect microtubule mechanics remains an open question. Here we develop FRET-based assays that report on the lateral interactions between protofilaments and find that αK40 acetylation directly weakens inter-protofilament interactions. Congruently, αK40 acetylation affects two processes largely governed by inter-protofilament interactions, reducing the nucleation frequency and accelerating the shrinkage rate. Most relevant to the biological function of acetylation, microfluidics manipulations demonstrate that αK40 acetylation enhances flexibility and confers resilience against repeated mechanical stresses. Thus, unlike deacetylated microtubules that accumulate damage when subjected to repeated stresses, long-lived microtubules are protected from mechanical ageing through their acquisition of αK40 acetylation. In contrast to other tubulin post-translational modifications that act through microtubule-associated proteins, motors and severing enzymes, intraluminal acetylation directly tunes the compliance and resilience of microtubules.
| S-EPMC5376231 | biostudies-literature
Project description:BackgroundThe origin of functional innovation is among the key questions in biology. Recently, it has been shown that new genes could arise from non-coding DNA and that such novel genes are often involved in male reproduction.ResultsWith the aim of identifying novel genes, we used the technique "generation of longer cDNA fragments from serial analysis of gene expression (SAGE) tags for gene identification (GLGI)" to extend 84 sex-biased 3'end SAGE tags that previously could not be mapped to the D. pseudoobscura transcriptome. Eleven male-biased and 33 female-biased GLGI fragments were obtained, of which 5 male-biased and 3 female-biased tags corresponded to putatively novel genes. This excess of novel genes with a male-biased gene expression pattern is consistent with previous results, which found novel genes to be primarily expressed in male reproductive tissues. 5' RACE analysis indicated that these novel transcripts are very short in length and could contain introns. Interspecies comparisons revealed that most novel transcripts show evidence for purifying selection.ConclusionOverall, our data indicate that among sex-biased genes a considerable number of novel genes (approximately 2-4%) exist in D. pseudoobscura, which could not be predicted based on D. melanogaster gene models.
| S-EPMC2443716 | biostudies-literature
Project description:Although the reproductive success of most organisms depends on factors acting at several spatial scales, little is known about how organisms are able to synthesize multi-scale information to optimize reproduction. Using longitudinal data from a long-lived seabird, Monteiro's storm-petrel, we show that average breeding success is strongly related to oceanic conditions at the population level, and we postulate that (i) individuals use proximal information (their own reproduction outcome in year t) to assess the qualities of their mate and nest and to decide to retain them or not in year t + 1; (ii) the intensity of these responses depends on the quality of the oceanic environment in year t, which affects the predictability of reproduction outcome in year t + 1. Our results confirm that mate and nest fidelities are higher following successful reproduction and that the relationship between the success of a given pair and subsequent nest fidelity is stronger in years with unfavourable oceanic conditions, suggesting that individuals rely on distant information to modulate their use of proximal information and adjust their breeding strategy.
| S-EPMC4173691 | biostudies-literature
Project description:Many generalist species are composed of individuals varying in the size of their realized niches within a population. To understand the underlying causes and implications of this phenomenon, repeated samplings on the same individuals subjected to different environmental conditions are needed. Here, we studied individual specialization of feeding strategies in breeding and non-breeding grounds of Cory's shearwaters (Calonectris borealis) for 2-8 years, and its relationship with fitness. Individuals were relatively flexible in non-breeding destinations, but specialized in diet, habitat use and daily activity across years. Daily activity was also consistent throughout the year for the same individual, suggesting that it is driven by individual constraints, whereas individual diet and habitat use changed between breeding and non-breeding grounds, indicating that these specializations may be learned at each area. Moreover, individuals that were intermediate specialized in their diet tended to show higher breeding success than those with weakly and highly specialized diets, suggesting stabilizing selection. Overall, this study suggests that the development of individual specialization is more flexible than previously thought, i.e. it emerges under specific environmental conditions and can develop differently when environmental conditions vary. However, once established, individual specialization may compromise the ability of individuals to cope with environmental stochasticity.
| S-EPMC6694139 | biostudies-literature
Project description:Understanding the environmental mechanisms that govern population change is a fundamental objective in ecology. Although the determination of how top-down and bottom-up drivers affect demography is important, it is often equally critical to understand the extent to which, environmental conditions that underpin these drivers fluctuate across time. For example, associations between climate and both food availability and predation risk may suggest the presence of trophic interactions that may influence inferences made from patterns in ecological data. Analytical tools have been developed to account for these correlations, while providing opportunities to ask novel questions regarding how populations change across space and time. Here, we combine two modeling disciplines-path analysis and mark-recapture-recovery models-to explore whether shifts in sea-surface temperatures (SSTs) influenced top-down (entanglement in fishing equipment) or bottom-up (forage fish production) population constraints over 60 years, and the extent to which these covarying processes shaped the survival of a long-lived seabird, the Royal tern. We found that hemispheric trends in SST were associated with variation in the amount of fish harvested along the Atlantic coast of North America and in the Caribbean, whereas reductions in forage fish production were mostly driven by shifts in the amount of fish harvested by commercial fisheries throughout the North Atlantic the year prior. Although the indirect (i.e., stock depletion) and direct (i.e., entanglement) impacts of commercial fishing on Royal tern mortality has declined over the last 60 years, increased SSTs during this time period has resulted in a comparable increase in mortality risk, which disproportionately impacted the survival of the youngest age-classes of Royal terns. Given climate projections for the North Atlantic, our results indicate that threats to Royal tern population persistence in the Mid-Atlantic will most likely be driven by failures to recruit juveniles into the breeding population.
| S-EPMC10092490 | biostudies-literature