The mechanisms and functions of shark grouping behaviour have received relatively little scientific attention to date. The current widespread use of social network analysis to study animal groups, in concert with rapid advances in animal tracking technology, now allows us to test specific hypotheses about how and why sharks form groups. This thesis uses replicated laboratory experiments to investigate some of the mechanisms underpinning aggregation in a model species of benthic, oviporous elasmobranch, the small spotted catshark (Scyliorhinus canicula L. 1758; Scyliorhinidae). Acoustic tracking of this species in the wild is also conducted to explore how network analyses can be adopted to study the localized movements, habitat connectivity and ranging behaviour of adult sharks. Groups of juvenile S. canicula were characterized by non-random social preferences, crucially, only when individuals were familiar with one another suggesting social recognition is important in young sharks of this species. Genetic analyses of parent and offspring DNA revealed very high levels of multiple paternity in this species, likely due to male sexual harassment and multiple mating, which leads to increased genetic diversity between juvenile sharks. Perhaps unsurprisingly, there was no evidence of kin relatedness structuring social interactions between conspecifics. Furthermore, testing the effects of environment on social behaviour provided evidence that these juveniles aggregated more in structurally complex environments than simple ones. However, at the individual level sharks showed consistency in their social network positions through time and across different habitat types. This result is indicative of personality traits in S. canicula. Using data gathered via passive acoustic telemetry of wild shark behaviour, network analysis provided a useful tool with which to quantify movement between receivers. One chapter has been dedicated to the application of these methods, highlighting a number of different analyses for predicting movement behaviour from such data. Finally, these methods were adopted to address ecological questions in this sexually segregated species. Persistent site fidelity to a localised inshore area by both male and female sharks suggested that segregation occurred at a relatively small spatial and temporal scale. Despite strong evidence of segregation, analyses of movement networks and individual co-occurrences revealed distinct periods of behavioural synchronicity during the months of March, April and May. In addition, habitat complexity appeared to be a significant driver of female behavioural strategy. Enhancing our knowledge of the social and environmental drivers of aggregation and movement in sharks is of great importance given the ecological threat facing many of our ocean’s top elasmobranch predators.

Determining the dynamic nature of animal movement has been an important component in a wider understanding of animal population ecology. Generally, this is because temporal change in the density of a population at a specific geographic location is not only a function of births and deaths but also of movements, including migration. The increased availability of remote telemetry and biologging systems in recent years has enabled many studies tracking marine predators, such as turtles, seabirds and marine mammals, but a general understanding of spatial dynamics in large sharks remains less well developed. This is in part due to few studies having achieved sufficiently long-term, multi-year tracks to detect changes in movement behaviour over time. Determining the timing, repeatability and potential motivations for movements of large sharks is necessary to understand the ecological and evolutionary role of such behaviour more generally in marine predators. Furthermore, given global concerns of declining shark populations, a detailed appreciation of shark movements can reveal the extent 6 of overlap with area-focused human activities (e.g. fishing), as well as inform assessments of population trends and spatial management options. In order to demonstrate how shark migratory behaviour and spatial dynamics can vary dramatically depending on the species and location, with subsequent contrasting conservation implications, the present work used longterm, remote telemetry to reveal detailed patterns in shark movement behaviour at two very different geographical scales: broad-scale movements of larger species that encompass ocean basins, versus fine-scale movements of reef-associated species at a remote atoll. First, using satellite telemetry, it was revealed for the tiger shark Galeocerdo cuvier, that adult males undertake annually repeated, roundtrip migrations of over 7,500 km in the northwest Atlantic. Second, acoustic telemetry was used to determine the fine-scale spatial dynamics of a multispecies shark assemblage at a small, remote atoll in the Seychelles, Indian Ocean, where a number of species displayed perennial residency. While the fine-scale movements of reef sharks in the Seychelles suggest an MPA of moderate size may be an effective management option, the long-distance migrations of the tiger sharks in the Atlantic reveal that conservation efforts targeting them must account for dynamic fisheries interactions over large geographical scales, potentially requiring time-area closures to be effective. Examining the long-term movement behaviour of different shark species over contrasting geographical scales has emphasised the importance of understanding spatial dynamics when informing management decisions, and has contributed to a wider understanding of the population ecology of these species.

Communication among animals often relies on visible signals and the ability to compatibly perceive them. Correct signal perception is especially important for animals with male sexual selection. In my master's thesis, I am addressing the issue of how does a male golden-ringed dragonfly (Cordulegaster boltonii) recognize a female of the same kind and therefore, what is the main trigger of copulation behavior. Dragonflies display a wide variety of colors and possess very big eyes. These characteristics already suggest that they are very liable on color vision (Futahashi, 2015). Their sight is perfectly developed within the insect class and plays the most important role in the imagines in comparison to other senses. The ability to orient themselves using sight is not just important for orientation in space, nonetheless it is important for reproduction. Since golden-ringed dragonflies do not demonstrate visible color dimorphism, previous as well as my research suggests that the key role for female reconnaissance is primarily their typical movement above water surface during oviposition. In my research, I presented variable types of lure - females to male golden-ringed dragonflies and I observed what is the foremost trigger of reproduction behavior in the males. Besides the above mentioned female...

Η εργασία αυτή αποσκοπούσε στη μελέτη της πληθυσμιακής και συμπεριφορικής οικολογίας σε δύο είδη τριτώνων που διαβιούν συμπάτρια σε ένα εποχικό τέλμα στο όρος Χελμός κατά την αναπαραγωγική τους περίοδο. Εφαρμόστηκε η μέθοδος της σύλληψης-επανασύλληψης ατόμων με τη χρήση παθητικών πομπών (PIT-tags). Χρησιμοποιήθηκε η μέθοδος εφαρμογής και επιλογής μοντέλων για την εκτίμηση του μεγέθους των πληθυσμών, της αναλογίας φύλων και των πιθανοτήτων επιβίωσης και επανασύλληψης των ατόμων, για την εξέταση του προτύπου μετανάστευσης των ατόμων προς το τέλμα, καθώς και για τη συσχέτιση των πιο πάνω παραμέτρων με περιβαλλοντικές μεταβλητές (θερμοκρασία νερου και εδάφους). Έγινε συγκριτική αξιολόγηση σωματικών μετρήσεων (μήκος και βάρος ατόμων) και διερευνήθηκε η μεταβολή στο χρόνο της κάθε μιας από τις πιο πάνω παραμέτρους ανά είδος και φύλο. Με γενετικές αναλύσεις με τη χρήση μικροδορυφορικών δεικτών προσπαθήσαμε να εκτιμήσουμε τη γενετική ποικιλομορφία (αριθμό αλληλομόρφων) των δύο πληθυσμών, να εξετάσουμε αν βρίσκονται σε ισορροπία Hardy-Weinberg και αν έχουν περάσει από φαινόμενα στενωπού. Η εκτίμηση για τον πληθυσμό του είδους I. alpestris είναι 1032 άτομα και του είδους L. vulgaris 306 άτομα. Οι αναλογίες αρσενικών:θηλυκών ατόμων είναι 1:1 και 2:7, αντίστοιχα. Λόγω ανεπάρκειας των δεδομένων, η εφαρμογή και επιλογή μοντέλων πραγματοποιήθηκε μόνο στο είδος I. alpestris. Η μέση ελάχιστη θερμοκρασία εδάφους είχε ισχυρή επίδραση στις πιθανότητες μετανάστευσης προς το τέλμα. Το ποσοστό ατόμων που εισέρχονταν στο τέλμα μεταβαλλόταν στο χρόνο, αλλά ήταν παρόμοιο για τα δύο φύλα. Η φαινομενική επιβίωση των αρσενικών ατόμων ήταν μικρότερη από την αντίστοιχη των θηλυκών, ενδεχομένως επειδή τα αρσενικά άτομα παραμένουν μέσα στο τέλμα για μικρότερο χρονικό διάστημα. Η σύγκριση του μέσου σωματικού μεγέθους και του μέσου σωματικού βάρους των ατόμων που συλλαμβάναμε σε κάθε δειγματοληψία έδειξε ότι στο είδος I. alpestris άτομα μεγαλύτερα σε μέγεθος και βάρος βρίσκονται στο τέλμα νωρίτερα στην αναπαραγωγική περίοδο. Προς το τέλος της αναπαραγωγικής περιόδου ο πληθυσμός αποτελούνταν από μικρότερα και ελαφρύτερα άτομα, ενώ το πρότυπο αυτό δεν παρατηρήθηκε στο είδος L. vulgaris. Οι γενετικές αναλύσεις αποκάλυψαν μειωμένα επίπεδα γενετικής ποικιλότητας, ειδικά στο είδος L. vulgaris, ο πληθυσμός του οποίου ενδεχομένως να έχει υποστεί φαινόμενα στενωπού, ενώ υποδεικνύουν την ανάγκη λήψης μέτρων προστασίας. / Our purpose was the study of the population and behavioural ecology of two syntopic newts at a temporary pond in Helmos mountain during their breeding period. We performed a capture-recapture experiment using Passive Integrated Transponders (PIT-tags). We fitted models to our data in order to estimate population sizes, sex ratios, apparent survival and probabilities of capture and to examine the patterns of migration into the pond. Water and ground temperature were used as covariates in the analyses in order to determine their effect on the above parameters. Measurements of length and weight were used to investigate for inter- and intra-population variability. Microsatellite DNA analyses were performed to assess the genetic structure of the two populations and to check for the occurrence of genetic bottlenecks. Population size estimates were 1032 individuals for I. alpestris and 306 individuals for L. vulgaris. Male: female ratios were 1:1 and 2:7 respectively. Due to sparseness of data, models were fitted to the I. alpestris data only. The probabilities of individuals entering the pond in each sampling interval were greatly affected by the mean minimum ground temperature for that interval. The percentage of individuals entering the pond varied with time, but was roughly the same for both sexes. Apparent survival of males was lower than that of females, probably due to the fact that males spent less time in the pond. Comparisons of mean body size and weight of individuals caught in each sampling occasion showed that in I. alpestris larger and heavier individuals entered the pond early in the breeding period. As the period drew to its end, smaller and lighter individuals comprised the sampled population. This was not observed in L. vulgaris. Genetic analyses revealed reduced levels of genetic variation relative to other conspecific populations, particularly for L. vulgaris, suggesting that genetic bottlenecks might have occurred, and call for specific conservation measures

Social intelligence is thought to have evolved as an adaptation to the complex situations group-living animals encounter in their daily lives. High levels of sociality provide individuals with opportunities to learn from one another. Social learning provides individuals with a relatively cheap and quick alternative to individual learning. This thesis investigated social learning in three corvid species: gregarious rooks (Corvus frugilegus) and jackdaws (Corvus monedula) and nongregarious, territorial Eurasian jays (Garrulus glandarius). In addition to that, the species' social structure was analysed and individual differences between members of each species were determined. Introducing the field of social learning research, I presented a new framework for investigating social learning, combining ecology, ethology and evolution. Experiments were conducted within that framework. I found that rooks and jackdaws develop social bonds and dominance hierarchies, whereas Eurasian jays do not. This is most likely related to their territoriality. In two experiments using two-action tasks, jackdaws learned socially. The underlying social learning mechanism was enhancement, which fits in with their feeding ecology. Rooks did not show social learning when presented with videos of conspecifics opening an apparatus. This might have been due to the difficulty of transferring information from videos or due to an ingrained 'affinity' to innovation and/or rapid trial-and-error learning overriding social learning processes. Individual differences along the bold/shy axis existed in all three species, but they were not stable across contexts. Thus, it seemed that the individuals perceived the two seemingly similar contexts that were designed to investigate neophobia and exploration (novel object in familiar environment; novel environment) as two different situations. The information may therefore have been processed by two distinct underlying mechanisms, which elicited different responses in each of the contexts. The implications of the findings of this thesis are discussed with regard to the new framework, integrating sociality, social learning and individual differences with the species' ecology.