The main aim of this thesis is to understand the extent to which intraspecific variation in developmental event timing might provide the raw material from which heterochronies may originate. To this end I studied the timing of a suite of both morphological and physiological events in the embryonic development of Radix balthica, a species of aquatic snail known to exhibit event timing variation during the embryonic period (Tills et al. 2010; Rundle et al. 2011) and that sits within an evolutionary clade, in which extensive heterochrony has been documented (Smirthwaite et al. 2007). I found that variation in embryonic developmental event timing within R. balthica is pervasive (Chapters 2 - 5) and distributed primarily at low (inter-individual and egg mass), rather than high (population) biological levels (Chapter 3). This variation also appears to have a genetic basis (Chapter 2) and to be heritable (Chapters 4 and 5). Examination of the development of function in the cardiovascular (CV) system in Chapter 5 also revealed extensive variation, including differences between egg masses in the timing of aspects of this development, and differences between populations in the rates of change in heart rate during different phases of ontogeny. Variation in CV development also had effects on life history, which suggest that altered embryonic development might have implications for Darwinian fitness (Chapter 5). This thesis demonstrates that intraspecific variation in developmental event timing represents a fundamental link between ontogeny and phylogeny and that study of altered timing at the inter-individual level provides the opportunity to address questions concerning its evolvability and implications.

No description available.

Over the past 10 years, multiple executable modelling formalisms for molecular biology have been developed in order to address the growing need for a system-level understanding of complex biological phenomena. An important class of these formalisms are biology-inspired process algebras, which offer-among other desirable properties - an almost complete separation of model specification (syntax) from model dynamics (semantics). In this thesis, the similarity between this separation and the genotype-phenotype duality in evolutionary biology is exploited to develop a process-algebraic approach to the study of evolution of biochemical systems. The main technical contribution of this thesis is the continuous π-calculus (cπ), a novel process algebra based on the classical π-calculus of Milner et. al. Its two defining characteristics are: continuous, compositional, computationally inexpensive semantics, and a exible interaction structure of processes (molecules). Both these features are conductive to evolutionary analysis of biochemical systems by, respectively, enabling many variants of a given model to be evaluated, and facilitating in silico evolution of new functional connections. A further major contribution is a collection of variation operators, syntactic model transformation schemes corresponding to common evolutionary events. When applied to a cπ model of a biochemical system, variation operators produce its evolutionary neighbours, yielding insights into the local fitness landscape and neutral neighbourhood. Two well-known biochemical systems are modelled in this dissertation to validate the developed theory. One is the KaiABC circadian clock in the cyanobacterium S. elongatus, the other is a mitogen-activated protein kinase cascade. In each case we study the system itself as well as its predicted evolutionary variants. Simpler examples, particularly that of a generic enzymatic reaction, are used throughout the thesis to illustrate important concepts as they are introduced.

Tal i bråkform är ett svårt område inom matematiken, vilket har visats i forskning och i diskussioner med verksamma lärare. Syftet med uppsatsen är att ta reda på hur lärarna synliggör aspekter av tal i bråkform för elever med hjälp av ett varierat arbetssätt och hur eleverna upplever momentet tal i bråkform. Undersökningen genomfördes i två klasser i årskurs 5 där klasserna observerades, lärarna intervjuades och eleverna svarade på ett formulär. I resultatet har tal i bråkform visat sig vara svårt för både lärare och elever. Trots detta har resultatet även visat att variation i undervisningen är betydelsefull för elevernas förståelse och vidareutveckling inom ämnet. Aspekter av lärandeobjektet har kunnat urskiljas av eleverna genom de variationsmönster som lärare skapat. Vidare har det framkommit att det är angeläget att som lärare utgå från elevernas förkunskaper för att främja lärandet och genom ett tillfredsställande samspel skapa förutsättningar som gynnar elevgruppen. Slutsatsen är att variation i undervisningen är nödvändig för att lärandet ska gynna alla elever.

I denna studie gör jag en analys av evolutionskapitlet i tre läroböcker som är utformade för gymnasiekursen Biologi 1. Fokus för analysen är hur läroböcker lyfter och kommenterar olika typar av alternativa uppfattningar. Dessutom intresserar jag mig för hur man beskriver uppkomsten av variation samt hur stort utrymme som ges för detta. Detta då jag menar att en svag förståelse för variation ligger till grund för flera av de alternativa uppfattningar forskningen har pekat på. De fyra alternativa uppfattningar som behandlas i studien är teleologiska resonemang, antropomorfa förklaringar, Lamarckistiska förklaringar samt att naturlig selektion beskrivs som den enda mekanismen för evolution. Studien visar att selektion ges ett större utrymme i läroböckerna samt att ingen av böckerna ger en grundlig förklaring av mutationer som uppkomst till variation. Detta menar jag kan bidra till att elever får en svag förståelse för variationens betydelse för evolution. Vidare visade analysen att alternativa uppfattningar sällan beskriv men i viss mån bemöts i enskilda meningar i kapitlet. Främst påpekar man bara att ett påstående är felaktigt och säger hur det faktiskt är. En beskrivning av varför påståendet är felaktig uteblir. Jag uppmanar lärare att komplettera läroboken med läsning av refutational texts för att stödja elevernas inlärning.

This study was initiated after finding two chromosomal types of Peromyscus maniculatus north and south of the Red River in Texas and Oklahoma. The problem was to explain the chromosomal variations and their implications to the systematics of the grassland subspecies of P. maniculatus in this region.

Draws a comparison between the piano variation techniques of Beethoven and Copland with reference only to the two works discussed herein, Thirty-Two Variations and Piano Variations, with the intent of gaining from these isolated examples knowledge of the changes in variation writing from Beethoven's time to the present.

The primary purpose of this investigation was to study the diurnal variation of cosmic-ray intensity.

Le présent travail consiste à proposer un modèle de représentation des notions théoriques et pratiques de la terminologie et de leurs relations sous forme de thésaurus. Selon la norme ISO 25964-1, 2011, « un thésaurus est un vocabulaire contrôlé et structuré dans lequel les concepts sont représentés par des termes, ayant été organisés afin de rendre explicites les relations entre les concepts (…) ». Notre objectif est de créer un outil pédagogique à la suite d’une réflexion théorique englobant différentes perspectives notionnelles au sein de cette discipline. Les enjeux soulevés par la classification des concepts de certains champs de savoir (notamment ceux donnant lieu à différentes perspectives) n’ont pas été approfondis suffisamment dans la littérature de la terminologie, ni dans celle portant sur les thésaurus. Comment décrire des concepts qui sont sujets à des dissensions théoriques entre les différentes écoles de pensée? Comment classer les différentes relations entretenues par les concepts théoriques et les applications pratiques d’une discipline? À ces questions s’ajoute celle de la prise en compte de ces difficultés dans un thésaurus. Nous commençons par délimiter et organiser les concepts saillants du domaine. Ensuite, à l’aide d’un corpus comprenant des publications associées à différentes approches de la terminologie, nous étudions les réalisations linguistiques de ces concepts et leurs relations en contexte, dans le but de les décrire, de les classer et de les définir. Puis, nous faisons l’encodage de ces données à l’aide d’un logiciel de gestion de thésaurus, en respectant les normes ISO applicables. La dernière étape consiste à définir la visualisation de ces données afin de la rendre conviviale et compréhensible. Enfin, nous présentons les caractéristiques fondamentales du Thésaurus de la terminologie. Nous avons analysé et représenté un échantillon de 45 concepts et leurs termes reliés. Les différents phénomènes associés à ces descripteurs comme la multidimensionalité, la variation conceptuelle et la variation dénominative sont aussi représentés dans notre thésaurus. / This thesis proposes a model to represent theoretical and practical concepts of terminology as well as their terminological relationships in the form of a thesaurus. According to the ISO 25964-1:2011 standard, “a thesaurus is a controlled and structured vocabulary in which concepts are represented by terms that have been previously arranged in order to show explicitly the relations among concepts (…)”. Our objective is to create a pedagogical tool that is grounded in a theoretical reflection about different theoretical perspectives within this discipline. The issues associated with the classification of concepts in certain fields of knowledge (especially those with different perspectives) require further study in the field of terminology and information science, and in the literature relating to thesauri. Indeed, how does one describe concepts that are subject to theoretical dissent and different schools of thought? How can the different relationships between theoretical concepts and practical applications of a discipline be classified? To these questions is added the additional challenge of reflecting these difficulties in a thesaurus. Our first step consists in delimiting and organizing the main concepts of the field. Then, by means of a corpus containing different publications associated with different approaches in terminology, we study the linguistic realizations of those concepts and their relationships in context, with the objective of describing, classifying and defining them. We then encode this data using thesaurus management software that respects the relevant ISO standards. Finally, we produce visualizations of this data to make it more user friendly and understandable. To conclude, we present the fundamental characteristics of the Thésaurus de la terminologie. We have analyzed and presented a sample of 45 concepts and their related terms. Different phenomena related to these descriptors, such as multidimensionality, conceptual variation and denominative variation, are also represented in our thesaurus.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.