87 research outputs found
Coordination in parental effort decreases with age in a longâlived seabird
Biparental care is widespread in avian species. Individuals may match the contribution of their partner, resulting in equal parental effort, or may exploit their partner, to minimise their own investment. These two hypotheses have received much theoretical and empirical attention in shortâlived species, that change mates between seasons. However, in species with persistent pair bonds, where divorce is rare and costly, selective pressures are different, as partners share the value of future reproduction. In such species, coordination has been suggested to be adaptive and to increase early in life, as a consequence of the importance of mate familiarity. However, as birds age, an increase in reâpairing probability occurs in parallel to a decline in their survival probability. At the point when partners no longer share future reproductive success, exploitation of a partner could become adaptive, reducing selection for coordinated effort. As such, we suggest that coordination in parental effort will decline with age in longâlived species. Using incubation bout duration data, estimated from saltâwater immersion bioâloggers, deployed on blackâbrowed albatrosses Thalassarche melanophris, we examined the correlation in incubation bout durations for sequential bouts, as a measure of coordination. Our results show that coordination is highest in inexperienced pairs (early in reproductive life) and declines throughout the lifetime of birds. This suggests that both cooperation, indicated by coordinated effort, and conflict over care occurs in this species. We find no change in individual bout duration with increasing breeding experience, and hence no support for the hypothesis that aging leads to changes in individual incubation behaviour. This is, to our knowledge, the first study to demonstrate strong coordination in parental care when pairs share future reproductive success, but a decline in coordination with age, as sexual conflict increases
Flight Initiation Distance and Starting Distance: Biological Effect or Mathematical Artefact?
In many studies, flight initiation distance (FID, the distance at which a prey starts to flee at the approach of a walker) is positively related to starting distance (SD, the distance at which the walker begins to approach) and alert distance (AD, the distance at which the focal individual becomes alert to the threat). In spite of the fundamental differences between SD, a covariate that may not have any biological effect, and AD, a measure related to the behaviour of the animal, it is common to use SD as a proxy for AD when AD is hard to measure (e.g. in species that do not exhibit distinguishable alert postures). However, the relationship between SD and AD or FID may not have any biological reasons, but may instead simply result from a mathematical artefact because of the constraints SD = AD = FID. Under such constrains, the homoscedasticity assumption is violated, and thus, the classical null hypothesis of linear regression (slope = 0) is invalid. In this study, we first show that using SD as a proxy for AD can strongly affect the results on FID. Using data from FID tests on alpine marmots (Marmota marmota), a linear mixed model with AD as a covariate, suggested that the interaction between previous activity and AD had an effect on FID, while this effect was not detected when SD replaced AD as the covariate in the analysis. We then propose that the actual statistical test of the relationship between SD, AD and FID should be based on a null hypothesis that incorporates the constraint SD = AD = FID = 0 and generate 95% CI of simulated slopes obtained from random values under this constraint. This null hypothesis can be rejected if the observed slope of the relationship between two of these variables is outside the 95% CI. We demonstrated that, for alpine marmots, the observed slope of the relationship between AD and SD was within the 95% CI of the simulated slopes. The absence of a statistically significant biological effect in the relationship between SD and AD raises important questions on the outcome of relationship between SD and FID. In Alpine marmot flight, decision should be studied separating the effect of SD on AD and the effect of AD on FID
Personalities influence spatial responses to environmental fluctuations in wild fish
Although growing evidence supports the idea that animal personality can explain plasticity in response to changes in the social environment, it remains to be tested whether it can explain spatial responses of individuals in the face of natural environmental fluctuations. This is a major challenge in ecology and evolution as spatial dynamics link individualâ and populationâlevel processes.
In this study, we investigated the potential of individual personalities to predict differences in fish behaviour in the wild. Specifically, our goal was to answer if individual differences in plasticity of space use to sea surface temperature could be explained by differences in personality along the reactiveâproactive axis.
To address this question, we first conducted repeated standard laboratory assays (i.e., openâfield test, novel object test and mirror stimulation test) to assess the personality type of 76 wildâcaught Atlantic cod (Gadus morhua). Next, we released the fish back into the sea and monitored their spatial behaviour over large temporal (16 months) and spatial (a whole fjord) scales, using highâresolution acoustic tracking.
We demonstrate that (a) cod personality traits are structured into a proactiveâreactive syndrome (proactive fish being more bold, exploratory and aggressive), (b) mean depth use of individuals is mainly driven by sea temperature and (c) personality is a significant predictor of home range changes in the wild, where reactive, but not proactive, individuals reduced their home range as sea temperature increased.
These findings expand our understanding of the ecological consequences of animal personality and the mechanisms shaping spatial dynamics of animals in nature.publishedVersio
A global meta-analysis reveals higher variation in breeding phenology in urban birds than in their non-urban neighbours
Cities pose a major ecological challenge for wildlife worldwide. Phenotypic variation, which can result from underlying genetic variation or plasticity, is an important metric to understand eco-evolutionary responses to environmental change. Recent work suggests that urban populations might have higher levels of phenotypic variation than non-urban counterparts. This prediction, however, has never been tested across species nor over a broad geographical range. Here, we conducted a meta-analysis of the avian literature to compare urban versus non-urban means and variation in phenology (i.e. lay date) and reproductive effort (i.e. clutch size, number of fledglings). First, we show that urban populations reproduce earlier and have smaller broods than non-urban conspecifics. Second, we show that urban populations have higher phenotypic variation in laying date than non-urban populations. This result arises from differences between populations within breeding seasons, conceivably due to higher landscape heterogeneity in urban habitats. These findings reveal a novel effect of urbanisation on animal life histories with potential implications for species adaptation to urban environments (which will require further investigation). The higher variation in phenology in birds subjected to urban disturbance could result from plastic responses to a heterogeneous environment, or from higher genetic variation in phenology, possibly linked to higher evolutionary potential
Archiving primary data: solutions for long-term studies
The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes towards sharing data with the agreement or involvement of the PI, and 93% of PIs have historically shared data. Only 8% were in favor of uncontrolled, open access to primary data while 63% expressed serious concern. We present here their viewpoint on an issue that can have non-trivial scientific consequences. We discuss potential costs of public data archiving and provide possible solutions to meet the needs of journals and researchers
Ressources trophiques et reproduction chez les mammifĂšres et les oiseaux
Problems raised by relationships between food resources and reproduction in mammals and birds are various and imply many theoretical and empirical aspects of biological fields such as physiology, ecology, ethology, population biology and genetics. The study of these relationships reveals ecological or evolutionary consequences of spatial and temporal variation in abundance and quality of trophic resources on reproduction. This paper first reviews and clarifies the main concepts of life history theory and sociobiology/behavioural ecology, generally used in that literature, followed by several recommandations upon their use. Afterwards, several currently developed aspects of birds and mammals reproduction in function of food resources availability are reviewed. Reproductive capacities and fecundity, adjustment in the number of young before or after birth or hatching, sex-ratio adjustment in the progeny and sex-biased investment, parental care, parental expenditure, parental investment and parent-offspring conflict in function of availability in food resources are analysed in details. The consequences of lowering trophic resources on some aspects of the offspringâs ontogeny are also developed.Les problĂšmes soulevĂ©s par les relations entre les ressources trophiques et la reproduction des mammifĂšres et des oiseaux sont variĂ©s et font appel Ă des thĂ©ories couvrant de nombreux champs de la biologie tels que la physiologie, lâĂ©cologie, la biologie ou la gĂ©nĂ©tique des populations. LâĂ©tude de ces relations la mise en Ă©vidence des consĂ©quences, Ă©volutives ou immĂ©diates, des variations spatiales et temporelles de lâabondance et de la qualitĂ© des ressources alimentaires sur la reproduction. Cette synthĂšse prĂ©sente, tout dâabord, les deux approches thĂ©oriques des histoires de vie et sociobiologique/Ă©tho-Ă©cologique, couramment utilisĂ©es pour lâĂ©tude des relations entre ressources et reproduction. Suit une mise au point des concepts employĂ©s frĂ©quemment dans la littĂ©rature sur le sujet, de mĂȘme que quelques recommandations quant Ă leur utilisation. Dans un deuxiĂšme temps, un inventaire de certains aspects dĂ©veloppĂ©s rĂ©cemment sur la question, chez les oiseaux et les mammifĂšres, est dressĂ©. Les capacitĂ©s de reproduction et la fĂ©conditĂ©, lâajustement du nombre de jeunes avant ou aprĂšs la naissance, lâajustement de la sex-ratio de la progĂ©niture et lâinvestissement diffĂ©rentiel en fonction du sexe du jeune, les soins parentaux, les dĂ©penses parentales, lâinvestissement parental et le conflit parent-jeune, sont analysĂ©s plus en dĂ©tails. Les consĂ©quences dâune diminution des ressources sur quelques aspects de lâontogĂ©nĂšse des jeunes sont Ă©galement dĂ©veloppĂ©es.RĂ©ale Denis. Ressources trophiques et reproduction chez les mammifĂšres et les oiseaux. In: Revue d'Ăcologie (La Terre et La Vie), tome 52, n°4, 1997. pp. 369-410
Interactions agonistiques en fonction de la densité et de la structure dans une population insulaire de mouflons (Ovis musimon)
The Haute island (Kerguelen subantarctic archipelago) population of Corsican Mouflon (Ovis musimon) is characterized by a demographic cycle, with periodic die-offs every three to five years. The frequency of displacement from feeding sites between a period of peak population density (1992) and a period of relative low density that followed a winter crash (1993) were compared. Agonistic interactions that occurred in other situations than feeding competition were also investigated. During both years, mouflons did not interact at random, but mainly selected individuals of their own age-sex class. The frequency of displacements decreased for females and lambs between the two years but remained stable for males. Nevertheless, displacements from feeding sites were very infrequent, even at peak population density. This result suggests a low direct competition for food in this population. In contrast, the frequency of agonistic interactions decreased for all the age-sex classes except the adult males. At peak population density, the frequency of agonistic behaviours was much higher among subadult males than among the other classes. This was due to their frequent involvement in huddles (simultaneous interactions of three individuals or more). The high frequency of subadult male aggressive interactions, with associated high energy expenditure and risk of wounding, could reduce their winter survival probability at peak population density.La population de mouflons (Ovis musimon, Pallas, 1 802) introduits sur lâĂźle Haute, dans lâarchipel de Kerguelen (TAAF), est caractĂ©risĂ©e par un cycle dĂ©mographique marquĂ©, des Ă©pisodes de forte mortalitĂ© hivernale survenant tous les trois Ă cinq ans. Les frĂ©quences de dĂ©placements dâindividus par un congĂ©nĂšre de sites dâalimentation et les taux dâinteractions agonistiques ont Ă©tĂ© comparĂ©s entre une pĂ©riode de forte densitĂ© et sex-ratio Ă©quilibrĂ©e (Ă©tĂ© 1992) et une pĂ©riode de relative faible densitĂ© et forte proportion de femelles succĂ©dant Ă un crash hivernal (Ă©tĂ© 1993). Les deux annĂ©es, les animaux des diffĂ©rentes classes dâĂąge et de sexe ont interagi prĂ©fĂ©rentiellement avec des congĂ©nĂšres de leur propre classe. Avec la rĂ©duction de densitĂ©, la frĂ©quence de dĂ©placements dâun site dâalimentation a diminuĂ© pour les femelles et les agneaux, mais est restĂ©e stable pour les mĂąles. Ces interactions sont nĂ©anmoins trĂšs rares et suggĂšrent une faible compĂ©tition alimentaire directe dans cette population. Dâautre part, la frĂ©quence des interactions agonistiques a chutĂ© pour toutes les classes, Ă lâexception des mĂąles adultes. A forte densitĂ©, les mĂąles subadultes ont interagi beaucoup plus que les autres classes. La plupart de leurs interactions agonistiques sont survenues Ă lâoccasion de mĂȘlĂ©es, interactions impliquant simultanĂ©ment plus de deux individus. La frĂ©quence des mĂȘlĂ©es a fortement chutĂ© Ă faible densitĂ©. Lâimportante participation des mĂąles Ă des interactions agressives, impliquant des coĂ»ts Ă©nergĂ©tiques importants et des risques de blessures, pourrait contribuer Ă rĂ©duire leur probabilitĂ© de survie hivernale.RĂ©ale Denis, BoussĂšs Patrick. Interactions agonistiques en fonction de la densitĂ© et de la structure dans une population insulaire de mouflons (Ovis musimon). In: Revue d'Ăcologie (La Terre et La Vie), tome 50, n°1, 1995. pp. 49-67
Reconsidering acquisition and allocation in animal nutrition models to better understand efficiency
Reconsidering acquisition and allocation in animal nutrition models to better understand efficiency. 66. Annual Meeting of the European Federation of Animal Science (EAAP
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