Causes and consequences of natural hybridisation among coral reef butterflyfishes (Chaetodon: Chaetodontidae)

Natural hybridisation is the successful interbreeding of individuals from different populations, distinguishable through one or more heritable characters, and is a widespread phenomenon in the plant and animal kingdoms. The development of hybridisation theories has largely been based on studies in terrestrial and freshwater ecosystems. Hybridisation was traditionally considered rare and unimportant in marine systems and therefore received little attention. Recently however, there has been a surge of reported marine hybrids, particularly in corals and reef fishes. The ecological promoters and evolutionary and adaptive consequences of reef fish hybridisation are yet to be thoroughly evaluated. Butterflyfishes (f. Chaetodontidae) form a disproportionate number of hybrids and therefore represent an appropriate model group to investigate hybridisation in reef fishes. This thesis examines the causes and consequences of hybridisation in reef fishes and focuses on butterflyfishes (genus Chaetodon) at Christmas Island (Indian Ocean), a global hotspot for reef fish hybridisation. The aims of this thesis were to i) review the incidence and ecological/behavioural precursors of hybridisation in reef fishes, while providing a tentative framework for conducting studies within hybrid zones; ii) develop a microsatellite toolkit for species of the Chaetodon genus; iii) compare the ecology, behaviour and population genetics of hybridising sister species of butterflyfishes in order to, not only provide a snapshot of the evolutionary consequences of hybridisation in this group, but also determine which processes are likely to promote it; iv) use a comparative life history approach to determine the fitness of butterflyfish hybrids relative to their parental species. Chapter 1 reviews the current knowledge of hybridisation with a focus on marine fishes. Hybridisation was found to be highly prevalent in marine fish, despite previous assertions of rarity, and showed a taxonomic as well as latitudinal bias. Further, the current marine fish hybridisation literature was found to be largely lacking ecological and behavioural data, in contrast with freshwater counterparts, therefore highlighting the need for a framework to fill the data gap in order to better accompany the wealth of genetic data produced in the assessment of hybridisation. The development of a molecular toolkit, necessary for the rest of our investigations, is presented in Chapter 2. Twenty microsatellite loci were developed using 454 sequencing, to apply to the population genetic analysis of the Chaetodon guttatissimus × C. punctatofasciatus complex. This was done to facilitate direct comparison of the genetic underpinnings of hybridisation in this group to those of another previously studied group (C. trifasciatus and C. lunulatus), for which species-specific microsatellite loci had been designed and used. Chapter 3 uses the molecular toolkit and experimental framework outlined in the previous chapters to examine hybridisation between two butterflyfish sister species, Chaetodon guttatissimus and C. punctatofasciatus. The largely overlapping spatial and dietary ecologies of these species favour heterospecific encounters. Lack of assortative mating and local rarity of C. punctatofasciatus promote the formation of heterospecific breeding pairs. Analyses of mtDNA and microsatellite DNA were consistent with the hybrid status of the intermediately coloured hybrids. Maternal contribution to hybridisation in this complex was bidirectional, and introgression by C. punctatofasciatus mtDNA was detected in C. guttatissimus individuals within and beyond the hybrid zone (almost 1000 km to the west), potentially indicating a Pacific invasion of an Indian Ocean species genome. The comparisons drawn with previous work on hybrdising Chaetodon trifasciatus and C. lunulatus showed that, despite being driven by similar factors, hybridisation in reef fishes can have varying evolutionary consequences, possibly due to the magnitude of the genetic distance between hybridising species. Chapter 4 evaluates hybrid fitness in both Chaetodon hybridising groups presented in the previous study. Histology confirmed the reproductive viability of hybrids, and liver lipid analyses showed that hybrid condition was not different from parental species. Further, otolith data highlighted no difference in growth rate and maximum length between hybrids and parents. According to the fitness-related traits measured here, Chaetodon hybrids are as fit as their parents, and unlikely to promote the formation of a hybrid swarm. However, sufficient fitness and rapid transfer of genetic material between species allow persistence of hybrids within the suture zone, where they positively contribute to genetic diversity. The cases of hybridisation studied here appear to be initiated by similar ecological and behavioural settings, albeit showing different genetic consequences. Determining this was possible through the use of a comprehensive approach, which combined molecular analyses and extensive field observations. Further, the apparent lack of differences in fitness between hybrids and parental species points at the persistence of hybrid individuals within the Indo- Pacific suture zone, where they may continue to contribute positively to genetic diversity. The role of hybridisation in evolution and adaptability had been appreciated in terrestrial and freshwater systems, and this thesis shows that hybridisation can have a role in maintaining reef fish diversity. The studies presented here constitute a comprehensive overview of the relevance of hybridisation for reef fishes and may be a stepping stone toward ascertaining its role in the evolution and adaptation of new species in such a diverse group

Visual salience of the stop signal affects the neuronal dynamics of controlled inhibition

The voluntary control of movement is often tested by using the countermanding, or stop-signal task that sporadically requires the suppression of a movement in response to an incoming stop-signal. Neurophysiological recordings in monkeys engaged in the countermanding task have shown that dorsal premotor cortex (PMd) is implicated in movement control. An open question is whether and how the perceptual demands inherent the stop-signal affects inhibitory performance and their underlying neuronal correlates. To this aim we recorded multi-unit activity (MUA) from the PMd of two male monkeys performing a countermanding task in which the salience of the stop-signals was modulated. Consistently to what has been observed in humans, we found that less salient stimuli worsened the inhibitory performance. At the neuronal level, these behavioral results were subtended by the following modulations: when the stop-signal was not noticeable compared to the salient condition the preparatory neuronal activity in PMd started to be affected later and with a less sharp dynamic. This neuronal pattern is probably the consequence of a less efficient inhibitory command useful to interrupt the neural dynamic that supports movement generation in PMd

Semiring-based constraint logic programming

We extend the Constraint Logic Programming (CLP) formalism in order to handle semiring-based constraints. This allows us to perform in the same language both constraint solving and optimization. In fact, constraints based on semirings are able to model both classical constraint solving and more sophisticated features like uncertainty, probability, fuzziness, and optimization. We then provide this class of languages with three equivalent semantics: model-theoretic, fix-point, and proof-theoretic, in the style of classical CLP programs

The moderating effect of economic reputation on middle-status conformity: a study on the Italian film industry

The relationship between an actor’s status and his/her decision to conform to extant social norms of behavior or to deviate from them is a common theme in the managerial and sociological research. Drawing on previous studies that have highlighted the presence of a U- shaped relationship between status and nonconformity, whereby low-status and high-status actors are more likely to deviate from accepted norms of behavior, this paper aims at investigating how reputation moderates the relationship between status and nonconformity. By relying on a sample of more than 1,500 films introduced from 1990 to 2011 by 730 Italian film producing companies, we hypothesize and find that an organization’s economic reputation negatively moderates the curvilinear U-shaped relationship between its status and nonconformity in a way that, for high reputation, the high propensity of a high-status organization to non-conform is mitigated

Reactive Synthesis from Extended Bounded Response LTL Specifications

Reactive synthesis is a key technique for the design of correct-by-construction systems and has been thoroughly investigated in the last decades. It consists in the synthesis of a controller that reacts to environment's inputs satisfying a given temporal logic specification. Common approaches are based on the explicit construction of automata and on their determinization, which limit their scalability. In this paper, we introduce a new fragment of Linear Temporal Logic, called Extended Bounded Response LTL (\LTLEBR), that allows one to combine bounded and universal unbounded temporal operators (thus covering a large set of practical cases), and we show that reactive synthesis from \LTLEBR specifications can be reduced to solving a safety game over a deterministic symbolic automaton built directly from the specification. We prove the correctness of the proposed approach and we successfully evaluate it on various benchmarks.Comment: Extended Versio

A first-order logic characterization of safety and co-safety languages

Linear Temporal Logic (LTL) is one of the most popular temporal logics, that comes into play in a variety of branches of computer science. Among the various reasons of its widespread use there are its strong foundational properties: LTL is equivalent to counter-free omega-automata, to star-free omega-regular expressions, and (by Kamp's theorem) to the first-order theory of one successor (S1S[FO]). Safety and co-safety languages, where a finite prefix suffices to establish whether a word does not belong or belongs to the language, respectively, play a crucial role in lowering the complexity of problems like model checking and reactive synthesis for LTL. SafetyLTL (resp., coSafetyLTL) is a fragment of LTL where only universal (resp., existential) temporal modalities are allowed, that recognises safety (resp., co-safety) languages only. The main contribution of this paper is the introduction of a fragment of S1S[FO], called SafetyFO, and of its dual coSafetyFO, which are expressively complete with respect to the LTL-definable safety and co-safety languages. We prove that they exactly characterize SafetyLTL and coSafetyLTL, respectively, a result that joins Kamp's theorem, and provides a clearer view of the characterization of (fragments of) LTL in terms of first-order languages. In addition, it gives a direct, compact, and self-contained proof that any safety language definable in LTL is definable in SafetyLTL as well. As a by-product, we obtain some interesting results on the expressive power of the weak tomorrow operator of SafetyLTL, interpreted over finite and infinite words. Moreover, we prove that, when interpreted over finite words, SafetyLTL (resp. coSafetyLTL) devoid of the tomorrow (resp., weak tomorrow) operator captures the safety (resp., co-safety) fragment of LTL over finite words

Mindfulness-based stress reduction in patients with interstitial lung diseases: a pilot, single-centre observational study on safety and efficacy

open11siBackground Chronic, progressive respiratory symptoms are associated with great psychological and emotional impact in patients suffering from interstitial lung disease (ILD). This single-centre pilot study evaluated for the first time the safety, feasibility and efficacy of a Mindfulness Based Stress Reduction Program (MBSR) in a group of patients with ILD. Methods Prospective observational study set in a university hospital ILD outpatient clinic. Nineteen patients with different ILDs were recruited 2 months prior to the start of the 8-week MBSR program and followed up for 12 months. Primary outcomes were program safety and feasibility, while secondary outcomes were changes in moods and stress (assessed by Profile Of Mood State (POMS) and Perceived Stress Scale (PSS) questionnaires), symptoms (Shortness Of Breath (SOB) and Cough And Sputum Assessment (CASA-Q) questionnaires), lung function and exercise tolerance at 12 months. Results Two patients (10.5%) dropped out in the observational period before the start of the MBSR intervention because of non-respiratory causes. All 17 patients who entered the 8-week MBSR program managed to complete it with an adherence average of eight sessions of nine. No adverse events related to the mindfulness training were reported. Statistically significant improvements in the POMS total score and in several individual items of POMS and PSS were observed throughout the study. However, respiratory questionnaire scores, lung function and exercise tolerance did not show a significant difference over time. Conclusions An MBSR program appears to be safe and feasible in patients with ILD, and might affect perceived moods and stress producing a positive and lasting improvement in several stress-related negative domains. These findings pave the way to larger (possibly multicentre), randomised, controlled confirmatory trials.openSgalla, Giacomo; Cerri, Stefania; Ferrari, Roberto; Ricchieri, Maria Pia; Poletti, Stefano; Ori, Margherita; Garuti, Martina; Montanari, Gloria; Luppi, Fabrizio; Petropulacos, Kyriakoula; Richeldi, LucaSgalla, Giacomo; Cerri, Stefania; Ferrari, Roberto; Ricchieri, Maria Pia; Poletti, Stefano; Ori, Margherita; Garuti, Martina; Montanari, Gloria; Luppi, Fabrizio; Petropulacos, Kyriakoula; Richeldi, Luc