1 |
Latitudinální trend v rychlosti růstu per a koncentrace steroidních hormonů v peří ptáků / Latitudinal trend in feather growth rates and steroid hormone concentrations in avian feathersBrzobohatá, Tereza January 2018 (has links)
Avian life histories range along the axis from slow to fast, with slow life histories being characterized by greater investments in future reproduction, and fast by greater investments in current reproduction. The concept of pace-of-life syndromes refers to the coevolution of life strategies and related physiological, immunological and behavioral traits. Avian species from tropical areas are characterised by slower life histories (longer parental care, later maturation, smaller clutches, reduced metabolic rate) when compared to temperate zone species. Within this latitudinal gradient, investments in the total amount (weight) of body feathers have also been shown to be reduced in tropical birds. It remains unclear, however, whether feather growth itself follows this latitudinal pattern, and is slower in tropical species. Tropical birds have lower basal levels of corticosterone and testosterone, however available studies are based mainly on analyzes of hormone concentrations from plasma. The first aim of this diploma thesis was to evaluate differences between tropical (Cameroon) and temperate zone (the Czech Republic) passerine species in investments in tail feather growth by using methods of comparative ptilochronology. The second aim of the diploma thesis was to analyze concentrations of steroid...
|
2 |
Linking individual behaviour and life history: bioenergetic mechanisms, eco-evolutionary outcomes and management implications / Vinculació del comportament individual amb la història de vida: mecanismes bioenergètics, implicacions eco-evolutives i de gestióCampos-Candela, Andrea 08 January 2019 (has links)
Animal behaviour is a state variable of the individual that deserves special attention given its determinant role in eco-evolutionary processes (Wolf et al. 2007 in Nature). The decomposition of the behavioural variation in between- and within-individual variability has revealed the existence of consistent between-individual differences referred to as personality or behavioural types (Dall et al. 2004 in Ecology Letters). Five axes of personality are usually recognized (exploration, aggressiveness, activity, sociability and boldness), and individual specificities along them tend to be correlated leading to what is known as behavioural syndromes. Recently, these patterns of covariation have been enlarged to accommodate movement behaviour within a personality-dependent spatial ecology theory (Spiegel et al. 2017 in Ecology Letters). Most animals tend to forage, reproduce and develop any activity within specific bounded space, which leads to the formation of home range (HR) areas (i.e., HR behaviour, Börger et al. 2008 in Ecology Letters). The increasing development of animal tracking technology is providing a huge amount of movement data revealing that HR behaviour is widespread among taxa and shows a large consistent variability, both at within- and between-individual level, which allows to define the existence of well-contrasted spatial behavioural types (SBTs). SBTs, as other personality traits, play an important role in selective processes as those impelled by harvesting activities. The Pace-of-Life-Syndrome (POLS) theory (Réale et al. 2010 in Philos. Trans. R. Soc. B Biol. Sci), hypothesises on how personality traits are expected to be correlated with life history (LH) traits along the fast-slow continuum (Stearns 1992 in Oxford Univ. Press) in the broadest sense. Accordingly, patterns of covariation between specific SBTs, physiology-related features and LHs would be expected to exist whenever they maximize the animal performance in a given environment. However, the way in which behavioural variation at the within-species level is translated to the wide range of LH traits remains a fundamental yet unresolved question, mainly due to the lack of a proper theoretical framework (Mathot & Frankenhuis, March 2018 in Behavioral Ecology and Sociobiology). Thus, unrevealing the mechanisms behind is certainly scientifically very exciting but also socially relevant. In such a context, this PhD thesis aimed to address from conceptual, empirical and theoretical perspectives cornerstone questions in behavioural ecology: what are the feasible mechanisms underpinning the establishment of HR areas and within-species variation, what are their consequences for animal functioning and performance (i.e., in. LH traits) at the individual and eco-evolutionary levels, or what are the implications for the assessment and conservation of wildlife of the existence of SBTs. The PhD thesis focusses in a fish heavily exploited by recreational fishers but it aims to provide general reasoning applicable to a wide range of wild animals. First, the PhD thesis proposes a mechanistic theory of personality-dependent movement behaviour based on dynamic energy budget models (i.e., a behavioural-bioenergetics theoretical model). Second, integrated in the field of animal personality (i.e., decomposition of behavioural variability into within- and between-individual’s components), it addresses empirically the study of behavioural variability in the main axis of personality for a marine fish species and looked for evidences of whether personality-mediated differences in energy acquisition may exist. Aiming to support empirically the possible connections between personality traits and space-use behaviour, the thesis provides some insights on the application of a novel-tracking algorithm to analyse the movement of individual fish submitted to different experimental conditions. Third, it provides two examples of how applying HR-related theoretical concepts may improve the management of natural resources: attending the properties of HR may facilitate the assessment of wildlife using fixed monitoring sampling stations, and considering SBTs may influence the assessment of the status of wild fish stocks. Finally, the adaptive value of the proposed behavioural-bioenergetics theory is explored by means of dynamic optimization to understand the eco-evolutionary consequences related with HR variability. In summary, this PhD thesis makes an important contribution to behavioural ecology by developing a unifying theory to test the generality and adaptive value of POLS based on dynamic energy budgets. This behavioural-bioenergetics model connects (1) personality traits (2) HR behaviour, (3) physiology and (4) LH traits through an interwoven of mass/energy fluxes, within which they interact and feedback with the ecological context. Overall, from an eco-evolutionary perspective, the proposed framework constitutes a powerful tool for exploring the ecological role of HR behaviour and predicting what combination of behavioural traits would be evolutionally favoured in a given ecological context. Moving forward to including managerial scenarios, this unifying theory provides scientifically founded knowledge that would promote to improve natural resource management by attending the behavioural component of animal populations.
|
3 |
Ecological consequences of personality in sharksDhellemmes, Félicie 13 December 2021 (has links)
In der Verhaltensökologie hat das Interesse an der Persönlichkeit von Tieren in den letzten zwei Jahrzehnten zugenommen und man geht davon aus, dass verschiedene Verhaltenstypen wichtige ökologische und evolutionäre Konsequenzen haben. Diese Konsequenzen sind besonders ausgeprägt, wenn eine konstante Verhaltensweise mit anderen Verhaltensweisen (sog. Verhaltenssyndrome) oder mit Life-History-Merkmalen (sog. Pace-of-life-Syndrome) korreliert. Bisher haben Studien zu Verhaltens- und Pace-of-life-Syndromen zu keinen schlüssigen Ergebnissen geführt – manche Hypothesen wurden bestätigt, andere jedoch nicht. Man nimmt an, dass Kovariation zwischen Merkmalen von der Umwelt geprägt ist. Da jedoch Tiere in Gefangenschaft in diesen Studien überrepräsentiert sind, kann dies ein möglicher Grund für die recht uneindeutigen Ergebnisse sein.
Um diese Wissenslücke zu schließen, erforschte ich die Entstehung von Verhaltens- und Pace-of-life-Syndromen in einer Wildpopulation juveniler Haie, die relevanten ökologischen Bedingungen ausgesetzt waren. Ich untersuchte (1) ob ein Syndrom zwischen zwei konstanten Verhaltensweisen besteht und ob das Auftreten des Syndroms kontextabhängig ist, (2) ob ein Trade-off zwischen Wachstum und Mortalität durch Explorationsverhalten vermittelt wird, und (3) ob Persönlichkeit das Nahrungshabitat der Haie vorhersagen kann und ob dieser Zusammenhang kontextabhängig ist.
Ich dokumentierte ein Verhaltenssyndrom das über Jahre und Standorte hinweg inkonsistent war und von inter-individueller Konkurrenz abhing. Ein Zusammenhang zwischen Explorationsverhalten und einem Wachstums-Mortalitäts-Trade-off war nur bei geringem Prädationsrisiko zu beobachten. Zudem sagte das Explorationsverhalten Nahrungshabitate nur bei geringem Prädationsrisiko vorher.
Zusammengenommen deuten diese Ergebnisse darauf hin, dass die ökologischen Bedingungen eine entscheidende Rolle bei der Entstehung und Ausprägung von Persönlichkeits- und Pace-of-life-Syndromen spielen. / In behavioural ecology, interest in the study of animal personality (i.e. consistent individual differences in behaviour across time and/or context) has increased in the last two decades as it is believed to have important ecological and evolutionary consequences. These consequences are especially pronounced when a behaviour that is consistent covaries with other consistent behaviours (i.e. behavioural syndrome) or with life-history traits (i.e. pace-of-life syndrome). So far, studies of behavioural and pace-of-life-syndromes have produced ambiguous outcomes (e.g. hypotheses are sometimes verified and others not), and the prominence of studies on captive animals (i.e. as opposed to wild animals) in the literature may be a reason for inconclusive results as trait covariation has been hypothesized to be environmentally driven.
To address this knowledge gap, I investigated the emergence of behavioural and pace-of-life-syndromes in a wild population of juvenile sharks subject to relevant ecological pressures (e.g. predation risk, inter-individual competition). I explored (1) whether a behavioural syndrome existed between two consistent traits (exploration and sociability) and whether the appearance of the syndrome was context dependent, (2) whether a growth-mortality trade-off was mediated by exploration personality and (3) whether personality could predict the foraging habitat of sharks and whether this link was context-dependent.
First, I observed a behavioural syndrome between sociability and exploration personality which was inconsistent across years and locations and was dependent on inter-individual competition. Then, I found the association between exploration personality and a growth-mortality trade-off to only be observable in low predation risk. Similarly, I found that exploration personality only predicted wild foraging habitat when predation risk was low.
Overall, these results suggest that ecological conditions play a crucial role in the emergence and the shaping of personality and trait association. This thesis offers a possible explanation for the ambiguous results of previous studies and highlights the importance of increasing the focus on wild study systems that are subject to relevant ecological pressures in future animal personality research.
|
Page generated in 0.0706 seconds