A merluza, Merluccius hubbsi Marini, 1933, é uma espécie demerso-pelágica típica da região Sudeste-Sul do Brasil, presente entre 21°S e 34°S. Capturada em pequenas quantidades pelas frotas de arrasto, a partir de 2001 tornou-se alvo de pescarias na plataforma externa e talude superior e, desde então, tem apresentado claros sinais de sobrepesca. Estudos sobre o crescimento, a mortalidade e a reprodução apontavam a necessidade de identificar os estoques de merluza na região Sudeste-Sul, visando o adequado ordenamento de sua pescaria, sendo este o objetivo do presente estudo. Com esta finalidade, exemplares da coleção do Museu de Zoologia da USP, otólitos de exemplares juvenis da coleção do Laboratório de Ictiofauna do Instituto Oceanográfico e exemplares coletados em 2004, junto às frotas pesqueiras no Rio de Janeiro, em Santos, em Itajaí e em Rio Grande, no verão e no inverno, foram utilizados para procurando identificar variações geográficas. Foram analisados dados sobre caracteres morfométricos e merísticos, sobre o crescimento de juvenis e de adultos e sobre a reprodução. Os caracteres morfométricos não variaram; os caracteres merísticos apresentaram maiores valores ao sul de 33°S; o crescimento de juvenis e adultos é diferencial entre as regiões, associado à diferentes épocas de desova, com pico no verão na região Sudeste e, no inverno na região Sul. Foram identificados dois estoques: um no sudeste, entre 21°S e 29°S, e outro no sul, entre 29°S e 34°S, este último compartilhado com o Uruguai e a Argentina. Para a gestão imediata da pescaria de M. hubbsi, sugere-se para os dois estoques, restringir a pesca de arrasto durante quatro meses, sendo nos dois primeiros entre 250 e 500 m e nos dois últimos entre 100 e 250 m. Para o estoque sudeste esta restrição deve ser aplicada, para a área entre 21°S e 25°S, de outubro a janeiro e, para a área entre 25°S e 29°S, de novembro a fevereiro. Para o estoque sul a restrição deve abranger a área entre 29°S e 34°S, e vigorar entre abril e julho. / The Argentine hake, Merluccius hubbsi Marini, 1933, is a demersal-pelagic fish inhabiting the South and the Southeast Brazilian area, between 21°S and 34°S. Since 2001, this species has been strongly targeted by trawlers operating at the external continental shelf and the slope. Previous studies about growth, mortality and reproduction pointed the necessity to identify stocks of this species which is the objective of this paper. Samples from the Museu de Zoologia USP collection, otoliths from juveniles fishes from the Ictiofauna Laboratory - IOUSP collection, and specimens collected during Summer and Winter of 2004 from fishing boats operanting in Rio de Janeiro, Santos, Itajaí and Rio Grande were used to analyze geographic variations. Morphometric and meristic data, juveniles and adults growth and reproduction characteristics were analysed. The morphometric characters did not present any variation, instead meristic counts tended to be larger in direction to south of 33°S. Juveniles and adults growth are different between the south and the southeast regions, and associated to different spawning periods, which is in the Summer and in the Winter, respectively. Two stocks were identified: one in the Southeast, between 21°S and 29°S, the other one in the south between 29°S and 34°S, the last one shared with Uruguay and Argentina. In order to manage these stocks, it is suggested the prohibition of the fishery activity during four months, the first two at depth between 250 and 500 m and the last two between 100 and 250 m. For the Southeast stock this restriction would be applied between 21°S and 25°S from October to January and between 25°S and 29°S from November to February. For the south stock the prohibition would be adopted in the area between 29°S and 34°S from April to July.

Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-08-24T17:57:59Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertaçãosuper_final_(1).pdf: 1088878 bytes, checksum: f1d95f7419b99281751c7ea750e47cf8 (MD5) / Made available in DSpace on 2016-08-24T17:57:59Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertaçãosuper_final_(1).pdf: 1088878 bytes, checksum: f1d95f7419b99281751c7ea750e47cf8 (MD5) Previous issue date: 2011-08-31 / CAPES / Nesta dissertação é apresentada uma solução estacionária para um modelo de dinâmica populacional de uma única espécie, considerando a dispersão da população num espaço heterogêneo e um crescimento logístico da população. No primeiro capítulo, para dar ao leitor alguma intimidade com os conceitos apresentados estudamos alguns modelos de dinâmica populacional de uma única espécie. Referimo-nos a uma única população para dizer que não analisamos aqui a interação entre diversas espécies. No segundo capítulo concentra-se a parte substancial do nosso trabalho. Na seção 1 apresentamos o modelo, na seção 2 apresentamos a solução estacionária para o problema e na seção 3 fazemos uma discussão sobre efeitos de isolamento para uma população. / This thesis presents a stationary solution to a model of population dynamics of a single species, considering the dispersion of biological population in a heterogeneous space and a logistic population growth. In the rst chapter, to give the reader some familiarity with the concepts presented study some models of population dynamics of a single species. We refer to a single population to say we do not analyze the interaction between di erent species. The second chapter focuses on the substantial part of our work. In Section 1 presents the problem and the model, section 2 presents the stationary solution to the problem and in Section 3 we make a discussion about isolation e ects on a population

O possível envolvimento de afídeos na transmissão de vírus associados à morte súbita dos citros (MSC) indica a necessidade de monitoramento desses insetos para melhor compreender sua dinâmica populacional e a epidemiologia da doença. Esta pesquisa teve como principal objetivo a determinação das principais espécies de afídeos que colonizam pomares de laranja doce [Citrus sinensis (L.) Osbeck] de um município afetado pela MSC, no Norte do Estado de São Paulo, bem como o estudo da dinâmica populacional destes insetos. Preliminarmente, padronizou-se uma metodologia de amostragem de afídeos, baseando-se em uma análise da distribuição espacial destes insetos na copa de árvores cítricas, em dois pomares de laranja doce, localizados em Comendador Gomes-MG e Santa Cruz do Rio Pardo-SP. Em cada pomar, delimitou-se um talhão com 960 plantas numeradas, no qual 100 plantas foram selecionadas ao acaso, para as avaliações. Cada árvore foi dividida em três estratos: i) inferior (0 - 1,0 m); ii) médio (1,0 - 1,8 m); e iii) superior (>1,8 m). Os estratos foram divididos em quadrantes (Leste, Oeste, Norte e Sul), amostrando-se uma brotação por quadrante, totalizando 12 brotações por planta. Através de análise de variância, observou-se efeito de planta e de estrato na densidade populacional dos afídeos, havendo menor número de afídeos no terço inferior em relação aos terços médio e superior da planta. Não houve efeito significativo de quadrantes nem da interação estrato x quadrante na estimativa populacional de afídeos. Definiu-se que a avaliação de uma brotação de cada quadrante do terço médio da copa, em 150 plantas, seria o procedimento mais adequado para o monitoramento de afídeos, visando-se ao estudo de dinâmica populacional. Utilizando-se este método de amostragem, iniciaram-se avaliações quinzenais de afídeos em dois talhões de laranja doce (‘Valência’ enxertada sobre limão ‘Cravo’) com idades diferentes (4 e 10 anos), no município de Nova Granada-SP, no período de abril/2003 a abril/2005. Simultaneamente, foram realizadas avaliações de brotações nas árvores cítricas, obtendo-se valores médios do número de brotações por m2 e do comprimento das brotações para cada talhão. Através de análises de regressão linear múltipla, os dados populacionais dos afídeos foram correlacionados com variáveis climáticas (temperaturas média, mínima e máxima; umidade relativa do ar e precipitação pluviométrica) registradas 30 dias antes da amostragem dos afídeos, e com variáveis fenológicas (comprimento das brotações e número de brotações/m²) registradas no dia da amostragem. Foram coletados afídeos das espécies Aphis gossypii Glover, A. spiraecola Patch e Toxoptera citricida Kirkaldy, com predominância de colônias de A. gossypii e A. spiraecola no pomar com 4 anos, e de colônias de T. citricida no pomar com 10 anos. A ocorrência desses afídeos em árvores cítricas coincide com períodos de brotações nos pomares, tanto em épocas de estiagem como em épocas de maior precipitação pluviométrica. O número de brotações cítricas/m², o comprimento das brotações e a temperatura são os fatores mais freqüentemente associados ao desenvolvimento das colônias de afídeos em árvores cítricas. A. gossypii, A. spiraecola e T. citricida mostram maiores picos de incidência de formas aladas em ramos cítricos nos meses de inverno (julho a setembro). As espécies T. citricida, A. gossypii e A. spiraecola diferem na capacidade de distorcer folhas e brotações cítricas, sendo que a última é a principal responsável por este tipo de dano direto. / Because aphids are possibly involved in the spread of viruses associated with a new and destructive disease, citrus sudden death (CSD), it is important to know their population dynamics in order to understand disease epidemiology. The goal of this research was to determine the main aphid species that colonize citrus groves [Citrus sinensis (L.) Osbeck] in CSD-affected areas of northern State of São Paulo, as well as to study their population dynamics. In order to establish procedures for sampling aphids that colonize citrus, a preliminary study of spatial distribution of these insects on the canopy of citrus trees was carried out in two sweet orange groves in Comendador Gomes-MG and Santa Cruz do Rio Pardo-SP. In each grove, 100 trees were randomly sampled in an experimental plot with 960 numbered plants. Each tree canopy was divided in three strata: i) lower (0 - 1,0 m); ii) medium (1,0 - 1,8 m); and iii) upper (>1,8 m). The canopy strata were subdivided in quadrants (E, W, N, S). Twelve young branches were sampled from each tree (1 per quadrant; 4 per stratum). By using analysis of variance, significant effects of plant and canopy stratum on aphid population were observed, with lower numbers of nymphs and adults found on the lower stratum than on the medium and upper strata. Aphid population was not influenced by quadrant or stratum x quadrant interaction. It was determined that sampling of 4 young branches (1 per quadrant) of the medium stratum from 150 citrus trees would be an adequate procedure for monitoring aphids on citrus trees, in order to obtain accurate population estimates for the population dynamics study. By using this sampling method, aphid surveys were carried out fortnightly in two sweet orange groves (‘Valência’ grafted on rangpur lime), 4 and 10 years old, in Nova Granada County, from April/2003 to April/2005. Simultaneous observations of mean number of young shoots/m2 of citrus canopy and mean shoot length were also conducted. By using multiple linear regression analysis, aphid numbers were correlated with local climatic variables (minimum, medium and maximum temperatures; relative humidity and rainfall) recorded 30 days before aphid sampling, as well as with phenological variables (mean number of young shoots/m2 and mean shoot length) recorded on the sampling date. Aphis gossypii Glover, A. spiraecola Patch, Toxoptera citricida Kirkaldy were the main aphid species sampled. A. gossypii and A. spiraecola were the prevalent species in the 4-year old grove, whereas T. citricida prevailed in the 10-year old grove. Aphid colonies were detected on citrus trees during periods of young shoot production, in different seasons, with either low (winter) or high (summer) rainfall. Mean number of young shoots/m2, mean shoot length and temperature were the main factors associated with aphid colony development on citrus trees. Peaks of A. gossypii, A. spiraecola and T. citricida alatae on citrus branches occurred during the winter months (July through September). A. spiraecola, A. gossypii and T. citricida differed in the ability to cause severe leaf deformation in the young shoots; this type of direct damage was mostly associated with colonies of the first species.

Thesis (MPA.) -- University of Limpopo, 2017 / The purpose of this qualitative research was to investigate the effects of migration on municipal planning using the case of the Greater Tubatse Local Municipality in the Limpopo Province. The research derives its origin from the notion that municipal planning, which does not consider population dynamics, is incomplete. Municipalities in South Africa are mandated to provide services to community members within their jurisdiction with limited available resources. To achieve this municipalities are expected to develop plans, referred to as Integrated Development Plans (IDPs). The IDPs are informed by various aspects for their completeness, namely: alignment with the national development perspective and consideration of population dynamics. The research was designed to explore the experience and understanding of municipal officials who are responsible for planning activities in the Greater Tubatse Local Municipality and the manner in which migration affects such municipal planning. This qualitative research employed a phenomenological method as the most appropriate to capture the perspective, understanding and experiences of individuals who were differently involved in migration and municipal planning processes. The research revealed how migration affects planning within municipal invironment in South Africa by using the experiences of municipal officials who are involved in planning activities in the Greater Tubatse Local Municipality. Among others,the research revealed the following findings, namely; (1) Migration in the Greater Tubatse Local Municipality is caused by several factors such job opportunities in the mines, better services in towns and townships among others,(2) the Greater Tubatse Local Municipality does not consider migration during community consultation processes, needs prioritisation and resource allocation, (3) the Greater Tubatse Local Municipality does not have effectivemigration data management system, (4) there is a lack of co-operation between the Greater Tubatse Local Municipality with otherspheres of government which are responsible for migration management, (5) Powers and functions delegated to the Greater Tubatse Local Municipality inhibit migration management and municipal planning and (6)there is sufficient legislative framework regulating migration management and inter-governmental relations in South Africa, however there is no implementation of such legislative framework by government officials. iii The overall experience of participants with regard to migration and municipal planning generally confirms findings of previous researches (Blase & Landau, 2014; Hofisi, 2014; Netswera & Phago, 2011) who for example, argue that migration is not taken into consideration during municipal decision making processes, need prioritisation and resource allocation. However, unlike the findings in previous researches (Friedementle & Misago, 2014; Mpehle, 2014) which highlight that municipal officials have negative attitudes towards migration this research revealed that municipal officials in the Greater Tubatse Local Municipality appreciate migrants. Municipal officials interviewed in this research appreciate migration and the challenges it poses to the municipality. Furthermore, contrary to what some reports highlight, participants in this research did not experience xenophobic attacks in the area despite the high prevalence of migration. Participants recommended that more powers and functions such as provision of water, electricity, migration management and others should be devolved to local municipalities as the sphere closest to the people. Participants further recommended that a dedicated research unit be institutionalised within municipalities to collect data which will supplement those of Statistics South Africa, and that other spheres of government should co-operate and capacitate local municipalities. This qualitative research is significant because the data gathered were analysed to develop themes which provide insight into how migration affects municipal planning, which planners in municipal environment can learn from and apply. It also contributes to a growing body of scholarly work and provides a conduit for future studies concerning the central phenomena - migration and municipal planning. This is vital, given the increasing pressure exerted by migration on municipalities and their limited resources.

Le changement climatique en cours modifie les conditions environnementales et les espèces doivent s'adapter à ces nouvelles conditions, en restant sur place ou en se déplaçant conduisant alors à de nouvelles distributions. Ce repositionnement revêt deux dimensions principales : (i) l'adaptabilité des espèces aux nouvelles conditions (changement de traits d'histoire de vie) liée à la résilience des populations et (ii) leur capacité à explorer de nouveaux habitats favorables. Cette étude avait pour objectif l’élaboration d’un modèle dynamique mécaniste intégrant ces deux dimensions de manière à pouvoir évaluer, comprendre et prédire les possibilités de repositionnement des poissons migrateurs amphihalins européens face au changement climatique.Pour accomplir leurs cycles de vie, les espèces migratrices amphihalines utilisent nécessairement des écosystèmes dulçaquicoles, estuariens et marins. Ces cycles de vie particuliers leur confèrent un plus grand potentiel de repositionnement que les espèces dulçaquicoles. Une base de données sur les traits de vie de ces espèces intégrant notamment ceux pouvant potentiellement être influencés par le changement climatique et ceux pouvant jouer un rôle dans le potentiel de dispersion des espèces a été construite pour l’ensemble des espèces amphihalines européens. Une méthode d’analyse multicritère hiérarchique a été proposée pour définir un indice basé sur les traits de vies visant à caractériser le potentiel de repositionnement des espèces migratrices amphihalines.Le modèle GR3D (Global Repositioning Dynamics for Diadromous fish Distribution) a ensuite été développé pour étudier de façon dynamique le repositionnement potentiel de ces espèces, à large échelle, dans un contexte scénarisé de changement climatique. Il s’agit d’un modèle de simulation stochastique, individus centré, intégrant les principaux processus de dynamique de population d’un poisson migrateur amphihalin (reproduction, mortalité, croissance, migration de montaison avec dispersion, migration de dévalaison).Un premier cas d’étude exploratoire simulant le repositionnement d’une population virtuelle de grande alose (Alosa alosa) de son bassin versant d’origine à un bassin versant voisin inhabité dans un contexte d’augmentation de la température a permis de réaliser une analyse de sensibilité globale du modèle GR3D à la fois aux paramètres incertains de dynamique de population et aux paramètres reliés à la structure de l’environnement. Il a été mis en évidence une sensibilité particulière du modèle aux paramètres liés à la durée de vie et à la mortalité en mer ainsi qu’à la distance entre les deux bassins versants de l’environnement pour déterminer le succès de colonisation.Enfin, l’utilisation du modèle GR3D sur un cas d’application réel a permis de commencer à évaluer l’évolution de la persistance de la grande alose à l’échelle de son aire de répartition (i.e. la façade atlantique) dans un contexte de changement climatique.Les simulations du modèle GR3D devraient ainsi trouver à terme des applications pour la gestion et la conservation des espèces migratrices amphihalines. / The ongoing climate change is modifying the environmental conditions and species have to adapt to these new constraints, either on the same site or migrating in new suitable sites leading to a modification of distribution area. This repositioning has two main dimensions: (i) the species capacity to adapt to the new conditions (modification of life history traits) which is linked to the species resilience and (ii) the species capacity to explore new suitable habitats. The objective of this study was to build a mechanistic model incorporating these two dimensions in order to evaluate, understand and predict the repositioning possibilities of European diadromous fish facing climate change.In their life cycles, diadromous fish species have to use freshwater, estuarine and marine ecosystems. These specific life history strategies represent a great repositioning potential in comparison to freshwater fish species. A database of diadromous fish life history traits, incorporating those that could be influenced by climate change and those that could have an importance in the species repositioning potential, has been built. An Analytic Hierarchy Process has been suggested to develop a composite score based on life traits aiming at assessing the diadromous species repositioning potential.Then, the GR3D model (Global Repositioning Dynamics for Diadromous fish Distribution) has been developed in order to study with a dynamic approach the repositioning potential of diadromous fish, at a large scale, in a context of climate change. This model is a simulation, stochastic and individual-based model incorporating the main population dynamics processes of a diadromous fish (reproduction, mortality, growth, upstream migration with dispersal and downstream migration).A first exploratory application case simulating the repositioning of a virtual allis shad (Alosa alosa) population between two river catchments under a scenario of temperature increase has been carried out and the associated global sensitivity analysis has been performed in order to determine the influence of uncertain population dynamics parameters and of parameters defining the landscape stucture. The results showed that dispersal distance and parameters related to sea lifespan and to survival at sea were crucial to determine the success of colonization.Finally, the use of GR3D in a real application case allowed improving the understanding of allis shad persistence at the scale of its distribution area (i.e. the Atlantic coast) in a context of climate change.Over time, simulation results of GR3D should be relevant and useful in management and conservation of diadromous fish species.

The White-bellied Sea-Eagle Haliaeetus leucogaster is widespread in Australia, but has been the subject of conservation concern due to suggested localised declines and extinctions. Regionalised monitoring programmes have addressed some aspects of local concern, however a broader approach is needed to gain an understanding of large-scale processes affecting long-term persistence at scales equivalent to the species Australian range. Ultimately, the ability to predict change in population size over time accurately depends on the scale of analysis. By necessity, ecological studies using direct sampling techniques are often made across spatial scales smaller than a species geographic range and across relatively short time frames. This seems counter-intuitive considering that long-term species persistence is often dependent on large-scale processes. The principal aim of this thesis was to identify historical and contemporary forces responsible for the current pattern of population structure in H. leucogaster. This required a multi-scale approach, and the resulting research uses genetic, distributional and morphometric data. Haliaeetus leucogaster is a large territorial raptor that historically has been associated with coastal regions, lakes and perennial river systems. It has an extensive worldwide distribution from the western coast of India throughout the Indomalaysian region, Papua New Guinea and Australia. By virtue of the species' large-scale distribution, in Australia it is fairly cosmopolitan in its use of habitat and prey types. Haliaeetus leucogaster is monomorphic for adult plumage colouration, but in body size displays reversed sexual dimorphism with female birds significantly larger. A discriminant function based on 10 morphometric characters was 100% effective in discriminating between 19 males and 18 females that had been sexed using molecular genetic methods. Re-classification using a jackknife procedure correctly identified 92% of individuals. The discriminant function should be a viable alternative to genetic sexing or laparoscopy for a large proportion of individuals within the Australo-Papuan range of this species; and can also be used to identify a small proportion of "ambiguous" individuals for which reliable sexing will require those other techniques. I used mitochondrial (mtDNA) control region sequence data to investigate the current distribution of genetic variation in this species at the continental level and within and between specified regional units. I was specifically interested in identifying breaks in genetic connectivity between the west and east of the continent and between Tasmania and the Australian mainland. Overall, genetic diversity was low and there was no significant level of genetic subdivision between regions. The observed genetic distribution suggests that the population expanded from a bottleneck approximately 160 000 years ago during the late Pleistocene, and spread throughout the continent through a contiguous range expansion. There is insufficient evidence to suggest division of the population into different units for conservation management purposes based on the theoretical definition of the 'evolutionary significant unit'. It is clear from the analysis that there are signatures of both historical and contemporary processes affecting the current distribution. Given the suggestion that population expansion has been relatively recent, additional sampling and confirmation of the perceived pattern of population structure using a nuclear marker is recommended to validate conservation monitoring and management at a continental scale. To determine the existence of perceived population declines across ecological time scales, I analysed the Australian Bird Atlas Data to identify the extent and pattern of change in range and density of the species between three Atlas Periods (1901-1976, 1977-1981 and 1998-2001) using a new standardised frequency measure, the Occupancy Index (OI) for 1° blocks (approx. 100km2) across the continent. At the continental scale, there was no significant difference in the spatial extent of occupancy between Atlas Periods. However, there were considerable changes in frequency and range extent between defined regions, and there were distinct differences in the pattern of change in OI between coastal and inland blocks over time. Coastal blocks showed much more change than inland blocks, with a clear increase in the use of coastal blocks, accompanied by a decrease in inland blocks, during the 1977-1981 Atlas Period, relative to both other Atlas Periods. The over-riding factor associated with distributional shifts and frequency changes was apparently climatic fluctuation (the 1977-1981 period showing the influence of El Nino associated drought). The impression of abundance was strongly dependent on both the temporal and spatial scale of analysis. To test for correspondence between geographic variation in morphology and geographic variation in mtDNA I analysed morphometric data from 95 individuals from Australia and Papua New Guinea. First, the degree of morphometric variation between specified regions was determined. This was then compared with the pattern of genetic differentiation. There was a strong latitudinal cline in body dimensions. However, there was no relationship between morphometric variation and patterns of genetic variation at least for mtDNA. Females showed a pattern of isolation by distance based on morphometric characters whereas males did not. Three hypotheses to explain the pattern of morphometric variation were considered: phenotypic plasticity, natural selection and secondary contact between previously isolated populations. I conclude that the pattern of morphometric variation is best explained by the suggestion that there is sufficient local recruitment for natural selection to maintain the observed pattern of morphometric variation. This implies that gene flow may not be as widespread as the mtDNA analysis suggested. In this instance either the relatively recent colonisation history of the species or the inability of the mtDNA marker to detect high mutation rates among traits responsible for maintaining morphometric variation may be overestimating the levels of mixing among regions. As might be expected given the physical scale over which this study was conducted, the pattern of genetic, morphometric and physical distribution varied dependent on the scale of analysis. Regional patterns of genetic variation, trends in occupancy and density and morphometric variation did not reflect continental patterns, reinforcing the contention that extrapolation of data from local or regional levels is often inappropriate. The combined indirect methodologies applied in this study circumvent the restrictions imposed by direct ecological sampling, because they allow survey across large geographic and temporal scales effectively covering the entire Australian range of H. leucogaster. They also allow exploration of the evolutionary factors underpinning the species' current distribution.

The sand lizard (Lacerta agilis) reaches the northern periphery of its distribution in south-central Sweden, where small, isolated relict populations occur in pine heath forests on sandy sediments. Modern forestry and fire suppression have reduced the amount of suitable open habitat for the species in this area and seem to be important for its decline. Main objectives of this thesis were to evaluate the efficiency of different management strategies, and if the sand lizard can function as an umbrella species for biodiversity conservation. Over a 16-year period, the estimated annual numbers of adult females in each of two study populations fluctuated between 23 and 3. Simulations of stochastic future population growth showed that the risk of extinction was highly dependent on population growth rate, which in turn was strongly affected by juvenile survival as indicated by elasticity analysis. Simulations of population growth for 50 years showed that the quasi-extinction risk (threshold ≤ 10 females) was > 56% for patches ≤ 1 ha; which is the observed average size of suitable habitat for inhabited patches during a 10-year period. In managed metapopulation networks with highly co-fluctuating local populations, among-population dispersal was not important to reduce extinction risks over a 50-year horizon. In the field the preferred microhabitat of sand lizards was successfully restored using tree felling and patch-soil scarification. The lizards gradually colonized the restored patches, and 16 years after restoration, sand lizards where mainly found there. Pine-heath area, and patch area within individual pine heaths, were of major importance for long-term population persistence at regional and landscape scales, respectively. Analyses of nested species subsets and an umbrella index suggest that the sand lizard can be a useful cross-taxonomic umbrella species on both scales for other red-listed species.

Este trabajo de tesis doctoral pretende contribuir a mejorar el conocimiento de la biología y la ecología del erizo de mar Paracentrotus lividus desde la perspectiva de su explotación como recurso marisquero. Con este fin se han analizado dos aspectos de la biología de este invertebrado de interés para su explotación sostenible: el ciclo gonadal y la dinámica poblacional de la especie. Para abordar el estudio del ciclo gonadal se realizó un muestreo mensual en tres localidades situadas a lo largo del litoral de Cantabria. En cada localidad se muestreó en dos hábitats contrastados: charcos de marea y fondos infralitorales durante dos épocas de puesta, desde mayo de 2004 hasta septiembre de 2005. Además de muestrear erizos, se tomaron datos de temperatura y de concentración de clorofila para estudiar la relación de la reproducción con los factores ambientales. El ciclo gonadal de P. lividus en Cantabria comienza en el mes de marzo y se extiende hasta el mes de septiembre, con entre uno y dos periodos de puesta a principios de primavera y en verano, en función del año y la población. Las diferencias entre las distintas localidades muestreadas fueron más importantes a las observadas entre los distintos hábitats, si bien en líneas generales todas las poblaciones mostraron un ciclo gonadal similar. El fotoperiodo parece mostrar un importante papel en el control de la vitelogénesis, que se inicia en los meses con menos horas de luz y termina en los meses estivales, con duraciones máximas del día. Otras variables como temperatura y estado nutricional también pueden tener un efecto significativo sobre este ciclo y probablemente son las responsables de algunas de las variaciones del ciclo más importantes observadas en las distintas poblaciones.El estudio de la dinámica poblacional de la especie se realizó en la cala de La Soledad, en la localidad cántabra de Laredo. Durante 40 meses (desde julio de 2004 hasta octubre de 2007) se realizó un muestreo mensual en una zona de esta cala que albergaba una población de P. lividus con más de 16.000 erizos distribuidos en un área aproximada de 1.200 metros cuadrados. La zona de estudio se dividió en 15 cuadrículas imaginarias. En cada cuadrícula se lanzaba cinco veces un cuadrado de área conocida de 0,25 m2, para un total de 75 veces por muestreo. Todos los erizos encontrados dentro del cuadrado de área conocida eran medidos y la densidad anotada. De esta forma se obtenía una distribución de la frecuencia de tallas para la población analizada, así como datos de densidad para cada cuadrícula muestreada.Una vez obtenidas la distribución de frecuencias para todos los meses muestreados, se calculo un modelo de crecimiento para la especie mediante el seguimiento de cohortes. Además, se estudió el reclutamiento de la especie en la zona de estudio, se analizaron los desplazamientos de la especie mediante análisis de densidad en las distintas cuadrículas y se estimó la tasa de mortalidad para algunas de las cohortes estudiadas. El crecimiento de P. lividus en la localidad se ajustó a la curva de Von Bertalanffy, más concretamente a su adaptación estacional, pues presentaba importantes diferencias de crecimiento entre el verano y el invierno. Se obtuvieron dos modelos de crecimiento, muy similares entre sí en el valor de sus parámetros, que fueron unidos en un solo modelo con un valor de K de 0,245 ± 0,03 y un valor de L∞ de 69 ± 4 mm. El reclutamiento no mostró diferencias significativas entre los distintos años estudiados, observándose un doble periodo de asentamiento que coincide con lo observado en el estudio del ciclo gonadal. Además, se observó una relación significativa entre la densidad de juveniles y la densidad de adultos, que permite pensar en la existencia de un reclutamiento denso-dependiente. No se observaron migraciones para el conjunto de la población dentro de la zona de estudio, no obstante se observaron desplazamientos durante el desarrollo del erizo desde zonas de asentamiento hasta zonas de crecimiento, siendo estos especialmente intensos a partir de cierta talla. La mortalidad Z presenta un valor medio para el conjunto de cohortes analizadas de 0,256 para erizos con una edad comprendida entre los ocho y los veintisiete meses. En este periodo, la mortalidad no permanece constante, sino que desciende a medida que los erizos aumentan de talla. / The main objective of this work was to improve the understanding of the biology and ecology of the sea urchin Paracentrotus lividus, from a fishery perspective. With this purpose, two interesting topics in the sustainable fisheries of this invertebrate were analyzed: gonad cycle and populations dynamics. The gonad cycle was studied in three localities along the Cantabrian littoral. In each locality, two habitats were sampled monthly: intertidal rock pools and infralitoral hard bottoms, from May 2004 to September 2005. In each sample, at least 15 sea urchins were collected for each habitat and locality. Moreover, temperature was measured and water samples were collected in plastic bottles to estimate chlorophyll concentration. The reproductive cycle of P. lividus starts in March and lasts until September, with one or two main spawning periods per year (depending on year and population) at the beginning of Spring and during the Summer. The differences between sea urchins from different localities but the same habitat were more important than between urchins of the same locality but different habitat, however all the urchins studied shown a similar reproductive cycle. The photoperiod shows an important role in the vitellogenesis control. This process starts in the months with the lowest photoperiod values and finishes in the highest. Other environmental variables as temperature or nutrional state are important too, causing some of the most important differences observed in the gonad cycle of the analyzed populations. The population dynamics were studied in the cove of La Soledad, in the cantabrian locality of Laredo. Along 40 months (from July 2004 to October 2007) the cove was sampled monthly in an area of 1.200 m2 with more than 16,000 urchins. This area was divided in a grid of 15 squares. In each of them, 5 randomly placed 0.25 m2 quadrats were sampled. All the urchins found in the quadrats were measured and its density counted, getting a frequency distribution of the population analyzed and density values of each square. A growth model for P. lividus was calculated knowing the monthly size-frequency distribution. Moreover, recruitment, migrations and mortality in the studied area were studied.P. lividus growth showed a good fit to the Von Bertalanffy curve, especially to the seasonality model, since the growth showed significant differences between the summer and the winter. Two growth curves were calculated, both of them very similar in growth parameters. Finally, both curves were joined in one model with a K value of 0,245 ± 0,03 and a L∞ de 69 ± 4 mm.The recruitment did not show significant differences between the studied years. A double settlement period was observed, coinciding with the spawning period described in the gonad cycle study. Moreover, a significant relationship between recruits' density and adults' density was observed, suggesting a positive density-dependent factor in the recruitment. The population did not show migrations in the study area. However, during the development of the urchins, movements were observed from settlement areas to growth areas, being especially important from a certain size. The mortality (Z) presented a mean value of 0.256 for all the cohorts analyzed in urchins with an age range between 8 and 27 months. In this period, mortality decreases with the urchins growth.

L’étude qualitative et quantitative du mode de développement des plantes envahissantes est actuellement considérée comme une étape clef dans la compréhension des phénomènes d’invasion. L’objectif de ce travail est de préciser les relations qui existent entre la structure architecturale des buissons et leur caractère proliférant. Nous avons sélectionné cinq espèces buissonnantes (Cornus sericea L., Cornaceae ; Prunus virginiana L., Rosaceae ; Rhamnus cathartica L., Rhamnaceae ; Rhus typhina L., Anacardiaceae ; Zanthoxylum americanum Mill., Rutaceae) qui sont connues pour leur aptitude à bloquer la succession végétale sous certaines conditions au Sud du Québec (Canada). L’analyse architecturale a permis chez ces espèces de caractériser les unités structurelles et leurs modifications ontogéniques. Ces modifications ontogéniques doivent être prise en compte afin d’obtenir une description complète de la plasticité phénotypique chez ces espèces. L’analyse des différentes unités structurelles révèle qu’elles ne possèdent pas la même signification fonctionnelle : les niveaux d’organisation les plus grands sont responsables majoritairement des capacités de plasticité phénotypique de la plante et de sa compétition. Ces analyses ont abouti à la définition de trois stratégies architecturales correspondant à des comportements individuels et qui sont également pertinentes pour expliquer la prolifération des populations. / Qualitative and quantitative studies of the pattern of invasive plant development is now considered a key aspect in understanding invasiveness. This work was performed to determine relationships between shrub architectural plasticity and proliferating behaviour. We selected five shrub species (Cornus sericea L., Cornaceae ; Prunus virginiana L., Rosaceae ; Rhamnus cathartica L., Rhamnaceae ; Rhus typhina L., Anacardiaceae ; Zanthoxylum americanum Mill., Rutaceae) known to arrest plant succession under certain conditions in Southern Québec, Canada. Architectural analysis revealed species’ structural units and their ontogenic changes. These ontogenic changes need to be calibrated if a full description of phenotypic plasticity is to be obtained. Analysis of the plant structural units reveals that they are of different functional significance: the higher the level of organization, the greater the capacity for phenotypic plasticity and competition. We defined three architectural strategies related to individual behaviours and which can relevantly explain the population proliferation of shrubs. / Réalisé en cotutelle avec l'Université Montpellier II

Abstract The negative impact of invasive plant species on biodiversity and ecosystem functions, such as productivity and nutrient cycling has been deemed a global epidemic. To address this worldwide concern, information is needed on how the invasion process happens and how to control an existing invasion. The main aim of the research presented in this thesis was to develop a better understanding of the interacting role different mechanisms play in facilitating invasion and then link this understanding to the design of more effective control strategies. This aim is significant because traditional weed control strategies are not working. The estimated cost of controlling weeds in Australia is $1.4 billion per year in agricultural landscapes. Despite this substantial investment, invasive weed species are estimated to continue to cost the agricultural industry $2.2 billion per year in loss of yield. Current control strategies tend to focus on killing or removing an invasive plant species directly with the application of herbicides and/or mechanical removal. These strategies have proven ineffectual because the plant communities that assemble after management often remain dominated by the same invader or another. In this thesis, I use a combination of empirical and modelling techniques to investigate how disturbance regimes and competitive interactions between invasive plants and native plants can be manipulated to improve the efficacy of restoration efforts. To do this, I use the model scenario of the invasion of Eragrostis curvula (African lovegrass), an invasive grass species introduced into Australia in the early 1900s from South Africa. This species has now spread into every Australian state and territory (chapter 2). I specifically focus on two mechanisms: (1) disturbance, i.e. cattle grazing, and (2) competitive interactions. In chapter 3, I examine connections between dominance and competitive differences among African lovegrass and several functionally similar native grass species in a pasture community. To test the displacement hypothesis, I used a glasshouse competition trial to investigate interactions between African lovegrass and two non-persisting native grass species (Themeda australis and Bothriochloa decipiens) with manipulations of resources, neighbour density, and establishment order. To test the partitioning hypothesis, I compared in situ water use patterns among African lovegrass and two coexisting native grass species (Aristida calycina and Aristida personata) based on the assumption that water is the most limiting resource in this system. The key finding of this chapter is that competition can have important, but contingent, impacts on dominance. Competitive differences appear to partially contribute to abundance patterns after establishment, but may be relatively unimportant during the establishment phase where disturbance appears more critical. In chapter 4, I provide evidence that the identification of mechanisms that led to an invasion, while crucial for the development of effective preventative measures and understanding the invasion process, may not be necessary for the design of more effective control strategies. To examine the effects of different control strategies on African lovegrass and the resultant community, I established a large factorial field-trial with a split-plot design. I manipulated grazing, soil nutrient levels and the presence of the invader. The most common control strategy (removing the causal disturbance and killing the invasive grass), based implicitly on traditional equilibrium models, was not an effective option for restoring a desirable native community. Instead, this strategy led to the dominance of a secondary invader. The most effective control strategy was based on alternative stable states models and involved maintaining grazing, and increasing the palatability of the invader with fertilizers. The key finding of this chapter is that novel approaches for control, which consider the dynamics of the invader-dominated system, are needed. In chapter 5, I investigate the benefits of explicitly incorporating actions that manipulate disturbance (natural or imposed) into control efforts. To do this, I first developed a process model that described the dynamics of an invader whose establishment is preferentially favoured by disturbance. I then couched this model in a decision theory framework, a stochastic dynamic program, and applied a case-study of another invasive plant species, Mimosa pigra (a perennial legume shrub and pan-tropical weed). The key finding of this chapter is that strategies should not only focus on existing invader-dominated sites, but should also protect sites occupied by native species from disturbances that facilitate invasion. The research discussed in this thesis makes three key contributions to a better understanding of the invasion process and the design of more effective control strategies: 1) the search for one key mechanism is not sufficient because multiple mechanisms can interact or shift in importance to facilitate different stages of invasion, 2) a novel approach is needed to restore a more desirable native community because the dynamics of the invader-dominated system can differ from the historical native community, and 3) control efforts should be broadened in focus to include protection of the integrity of native communities from disturbances that facilitate invasion.