Les premières civilisations péruviennes se sont épanouies pendant la période dite « formative » entre 2500 av. J.-C. et le début de notre ère. Les connaissances actuelles sur le Formatif et les cultures Cupisnique ou Chavín ont été largement influencées par les théories évolutionnistes et diffusionnistes héritées du XIXe siècle. Ce travail de recherche répond à la nécessité d’opérer une synthèse réactualisée de cette période mal connue et de redéfinir le premier horizon culturel communément appelé Chavín. D’une part, cette étude propose un cadre chronologique fondé sur la réévaluation systématique des séquences chrono-culturelles de l’ensemble des sites archéologiques occupés à cette époque. Elle établit une périodisation du Formatif et détermine les principaux groupes culturels qui caractérisent ses différentes étapes. D’autre part, ce travail apporte une réflexion épistémologique sur les concepts Cupisnique et Chavín. L’Horizon Chavín, traditionnellement défini comme le résultat de la diffusion stylistique de l’art religieux de Chavín de Huántar, est ici réinterprété au regard des données récentes de la recherche archéologique et d’une analyse approfondie des données chronologiques et culturelles des centres cérémoniels les plus importants. Cette étude précise enfin le rôle majeur que les sites de tradition culturelle Cupisnique et le temple de Chavín de Huántar ont joué dans l’élaboration et la mise en place de concepts religieux communs transcrits dans une écriture iconographique codifiée. / Early Peruvian civilisations were flourishing during the period called « Formative » between 2500 BC and the beginning of our era. The current knowledge of Formative and Cupisnique or Chavín cultures has been considerably influenced by evolutionist and diffusionist theories inherited from the nineteenth century. This research attempts to meet the necessity of realising an updated synthesis of this almost unknown period and to redefine the first cultural horizon usually called Chavín. On the one hand, this study proposes a chronological frame based on systematic revaluation of the chrono-cultural sequences of all the archaeological sites of this period. It sets out a chronology of the Formative cultures and determines the main cultural groups which characterise its different stages.On the other hand, this work offers an epistemological thought on Cupisnique and Chavín cultures. Chavín Horizon, traditionally defined as the result of the stylistic diffusion of Chavín de Huántar religious art is re-interpreted in the light of recent archaeological data collected in the main ceremonial centers. Finally, this dissertation makes clear the major role that Cupisnique sites and Chavín de Huántar temple have had in the creation and the development of shared religious concepts transcribed in a codified iconographic writing.

Peregrines Falco peregrinus and Gyrfalcons F. rusticolus were studied in Low and High Arctic Greenland, comparing populations within and between areas. Analyses of weather data from northwest Greenland (1979–2005) revealed a general warming trend, resulting in a lengthened breeding window for many bird species. Both falcon species depend on cliffs for nesting, and take a similar range of bird species as prey. However, Gyrfalcons lay six weeks earlier than Peregrines in Kangerlussuaq and one month earlier than Peregrines in Thule, and occupy more sheltered nest-sites. Being larger than Peregrines, Gyrfalcons also take some larger prey species. In addition, both species move to lower latitudes for the winter, but while most Gyrfalcons migrate relatively short distances, Peregrines are complete long-distance migrants to Central and South America. One Peregrine, satellite-tracked from its breeding site at 76.5° N, travelled ~12,500 km and >100° in latitude, one of the longest migrations ever documented for a raptor. Around Thule in northwest Greenland (at 76.5° N), scientists had historically documented no breeding Peregrines, but six occupied sites were discovered during this study, comprising what is probably the most northern nesting population in the world. Over the same period, breeding Gyrfalcons have apparently disappeared from southern Greenland, and may have declined in central-west Greenland (67° N). The ultimate cause of this retraction may be climate warming, but the proximate cause is probably competition from an increasing Peregrine population. Gyrfalcons tagged with satellite-received transmitters showed characteristics associated with both obligate and facultative migration. Their winter ranges varied greatly in size, with the largest, ~172,000 km2, being the biggest ever documented for a raptor. Many individuals made long movements within a winter, and some spent up to a month at sea. They may have rested on ice and fed upon seabirds. Carbon dating of stratified faecal accumulation from Gyrfalcon nests in central-west and northwest Greenland showed use of sites for up to ~2,500 and ~650 years, respectively. The age of nest sites correlated significantly with the current distance to the Greenland Ice Sheet, and probably reflects colonization patterns following glacial retreat. In central-west Greenland the ratio of Peregrine to Gyrfalcon pairs changed from 1:1 in the early 1970s to nearly 14:1 in 2005. Over this period, competition for nest sites and prey is likely to have intensified. The crucial prey for Gyrfalcons when they start nesting in early spring are resident ptarmigan, whose numbers are probably depleted by Peregrines during the months they are present. If recent trends in climate change continue, Peregrines may continue to increase in Greenland, and spread north into areas previously occupied only by Gyrfalcons. At the same time, Gyrfalcons may retreat north from many currently-occupied areas.

A highly structured tissue is formed from an unstructured accumulation of cells during morphogenesis. The pioneering works by Thompson, Turing and Meinhardt introduced physical principles allowing the breaking of symmetry, i.e. the emergence of patterns. This started an ongoing effort to understand the physics behind morphogenesis. In this thesis I will analyze spatial and temporal aspects of morphogenesis for different biological systems in separate parts. The planarian is an ideal model animal to understand mechanisms of spatial body axis formation. This is due to the possibility to measure its body orientation field which utilizes the orientation of the cilia of the planarian’s ventral tissue. Moreover, their astonishing regeneration capabilities allow extensive perturbation experiments. I propose a minimal model which demonstrates the emergence of the wild type body orientation as well as the development of dual-head body orientation due to beta-Catenin RNAi treatment. The topological defects of the body orientation field are calculated on a lattice for simulations and lattice-free for experimental data. These topological defects are a robust way to analyze and compare experiments with simulations. My minimal model reveals sufficient components and mechanisms for robust body axis regeneration. The second important aspect of morphogenesis is the growth regulation of tissues which is often driven by cell proliferation. The regulation of growth is not only important during growth, but also to maintain homeostasis. As fast renewing tissues are very dynamic they may have more pathways of morphogenesis active than non-renewing tissues which points to mechanisms of morphogenesis. The in vivo measurement of this proliferation rate is a challenging task. In this thesis the analysis of DNA labelling assays and the carbon 14 dating method are extended. The carbon 14 dating method can be used to determine cell renewal rates on time scales as long as the lifetime of organism last. Moreover, this method can be applied for tissues in any terrestrial organism because it utilizes the change of carbon 14 in the atmosphere due to atmospheric nuclear bomb tests in the 1960s. The method is extended to gain a better understanding of the tissue dynamics of liver, muscles and amygdala. On the other hand, the DNA labelling assays are used to estimate cell cycle parameters for fast cycling cells. The measurements are fatal to the samples and involve plenty of labor resulting in few sampled data for a time series. The deterministic Nowakowski model is extended to a stochastic model accounting for cell-to-cell and sample-to-sample variability to fully exploit the information contained even in the fluctuations of the data points. A comprehensive parameter recovery study with synthetic ground truth data is performed to evaluate the models. The new stochastic model shows no bias, a good accuracy and scales well with the number of measurements in contrast to the deterministic text-book method. I conclude with proposed applications of my new models and methods that can advance our understanding of growth and pattern formation during morphogenesis. All python software developed in this thesis is shared as open source and a website makes the stochastic analysis of DNA labelling assays available to experimentalists in a user-friendly way.

This research investigated carbon dynamics, water dynamics and peat formation at Wellington Plain peatland in the Victorian Alps. The properties of bog peat and dried peat were measured, and the ensuing results are outlined below. The carbon chemistries of both bog peat and dried peat displayed changes with depth consistent with an increase in the extent of decomposition of the organic material. Representative changes in the alkyl:O-alkyl ratio down the profile were 0.14 to 0.96 for bog peat and 0.28 to 1.07 for dried peat. Laboratory incubations on the influence of chemistry, particle size, water content and sample preparation indicated that, in the absence of confounding factors, peat chemistry was the most important factor in determining the size of the mineralisable carbon pool. Water content was the most important factor in determining the rate of carbon mineralization. In the field, both bog peat and dried peat emitted an average of 2 g CO2/m2/d from the surface. Carbon mineralisation was related to both soil temperature and soil water content, and this relationship was used to model peat mineralisation under a range of possible future climate scenarios. Below the surface, however, I measured lower rates of decomposition in the dried peat than in the bog peat. The water-holding capacity of peat was measured in the laboratory, as was the rate of water movement through peat. Specific yield decreased down the profile in both bog peat (0.88 to 0.45 cm3/cm3) and dried peat (0.36 to 0.11 cm3/cm3). Hydraulic conductivity also decreased down the profile in both peats: 5.1x10-4 to 3.0x10-6 m/s in bog peat, and 1.0x10-4 to 7.0x10-6 m/s in dried peat. Relationships between the hydrologic properties of peat and its physical and chemical properties were identified. In the field, fluctuations in the watertable were monitored in concert with rainfall. These laboratory and field measurements enabled me to develop models of the hydrology of bog peat and dried peat. Radioisotope dating indicated that both bog peat and dried peat began forming around 3300 years ago. The bog peat appeared to have drained to form dried peat between 131 and 139 years ago. Since that time, erosion appeared to have contributed more to the loss of organic material from dried peat than carbon mineralisation had.

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CO2 is a greenhouse gas which is significantly emitted by agricultural soils through the decomposition of plant residue and soil organic carbon. Carbon isotopes can be used in determining the source of the CO2, origin of the carbon, and the age of the CO2 emissions. This study investigates the transport of CO2 gas through agricultural soils using carbon isotopes 14C and 13C to complement concentration and production rate measurements in two comparative agricultural settings in Eastern Ontario, one of which has been modified by clearing and dredging of the adjacent riparian zone and one left undredged. Traditional radiocarbon dating measures time through loss by decay, while recent dating is based on matching measurements with the atmospheric 14CO2 signal (F14C) generated by nuclear bomb testing in the 1950s and 1960s. CO2 emissions were analyzed from soil core sections together with soil-probe gas samples and surface flux chamber samples collected from the study area. Soil cores were collected from 0- 90 cm at 7.5 cm increments and placed into IsoJar® microcosms for a period of one month. CO2 in-growth was monitored to provide production rates and samples for 14C and 13C analysis. The radiocarbon data for the microcosms showed that values increase with depth from the current fraction modern value of 1.00 F14C at the surface to an attenuated peak of 1.04 F14C at a depth of 30 to 40 cm and then decrease to values below 1.00 F14C. The data collected from the soil-probe gas showed a significant depletion in comparison to the microcosms and the surface chambers. The soil cores were subsequently analyzed by a selective leach oxidation protocol to sample decreasingly labile solid organic carbon. This involved placing the weighed soil samples into MilliQ water for 24 hours, before being passed through two sieves, 63 microns and 0.45 microns. The DOC leachate was collected and analyzed for 14C and 13C. The two solid soil fractions were then dried, treated with HCl to remove carbonate and then oxidized under vacuum with 5% H2O2 yielding CO2 and residual soil carbon for 14C and 13C. The radiocarbon analysis of these variously labile fractions, together with the microcosm and soil probe measurements, demonstrate that surface emissions at both sites are greatly dominated by CO2 from recently-sequestered labile organic carbon from the upper 30 cm with minor contribution from earlier, bomb-pulse carbon or from deeper pre-bomb carbon. No significant difference in age of emissions between the dredged and undredged sites was found.