Dans le contexte actuel de crise de la biodiversité et des risques associés de dégradation des services écosystémiques, les réseaux plantes-pollinisateurs sont parmi les réseaux mutualistes les plus étudiés. Sans pollinisateurs, de nombreuses plantes sauvages et cultivées ne pourraient pas se reproduire. Il est important de comprendre les réseaux plantes-pollinisateurs si nous souhaitons empêcher la destruction des interactions de pollinisation et des services écosystémiques connexes. Dans ces réseaux, les espèces doivent être présentes au même endroit et au même moment pour interagir. En France, l'abondance, la richesse des plantes et des pollinisateurs diffèrent le long du gradient latitudinal, qui correspond aux variations naturelles de la biodiversité. Ces variations pourraient potentiellement affecter la structure du réseau. En outre, les réseaux d'interactions sont souvent décrits sur la base de données agrégées dans le temps, mais en réalité les interactions varient dans le temps. Les grands ensembles de données sur les interactions plantes-pollinisateurs, couvrant toute la saison de floraison ou plusieurs années et permettant des comparaisons pertinentes entre les réseaux le long du gradient environnemental, sont rares. En raison de leur complexité et de leur variation interannuelle, la plupart des études sur les réseaux mutualistes se sont concentrées sur la comparaison des mesures classiques des réseaux qui sont toutes influencées par la taille des réseaux (le nombre d'espèces). De plus, la plupart de ces réseaux sont fondés sur des interactions observées sur le terrain, ce qui fait que certains liens ne sont pas observés. Ainsi, ces réseaux représentent un sous-échantillon d'interactions possibles, ce qui nécessite l'élaboration de nouvelles approches méthodologiques pour mieux explorer les processus écologiques qui déterminent les interactions entre les espèces. L'objectif général de cette étude est de comprendre et d'aider à prédire les effets des changements environnementaux sur les communautés de plantes et de pollinisateurs en étudiant les associations plantes-pollinisateurs selon un gradient environnemental. Je fournis et analyse ici une nouvelle base de données constituée de données géolocalisées caractérisant les associations plantes-pollinisateurs au niveau de l'espèce, la variation spatiale de la structure des communautés et l'assemblage des traits, en me concentrant sur six prairies calcaires le long d'un gradient latitudinal en France. J'ai d'abord comparé la variation de la diversité taxonomique dans l'espace (inter et intra-région) et dans le temps (tout au long de la saison). Ensuite, j'ai utilisé une nouvelle approche méthodologique pour comparer des réseaux de tailles différentes et pour étudier les conséquences des gradients environnementaux sur la probabilité d'interaction plante-pollinisateur. Pour comprendre à quel point notre vision des réseaux échantillonnés selon des méthodes classiques est déformée, j'ai construit des réseaux d'interaction plus complets en utilisant le pollen trouvé sur les insectes. Enfin, j'ai étudié le mécanisme de variation géographique des odeurs florales et les différences entre les populations liées à la variation de la communauté des pollinisateurs. En raison de la complexité et variabilité des interactions plantes-pollinisateurs, notre étude a souligné l'importance de tenir compte de toute la saison de floraison et de la période de vol des insectes, en utilisant des identifications au niveau de l'espèce, afin de démêler le rôle écologique des espèces et les variations du réseau. L'utilisation d'une nouvelle approche méthodologique nous a permis de faire des comparaisons de réseaux le long du gradient environnemental et de diversité en évitant des problèmes de circularité. La grande quantité de données fournies dans cette thèse a permis d'effectuer des comparaisons à différents niveaux, du réseau dans son ensemble aux variations entre populations d’une même espèce. / In the current context of biodiversity crisis and the associated risks of ecosystem service failure, plant-pollinator networks are among the most studied mutualistic networks. Without pollinators, many plants could not reproduce and set seed, and 70% of agricultural production directly depends on them. However, pollinating insects constitute some of the terrestrial taxa most affected by global changes. As such, understanding plant-pollinator networks is of particular relevance if we are to prevent catastrophic disruption of pollination interactions and associated ecosystem services. In plant-pollinator networks, species need to be present in the same site and at the same moment for interactions to occur. In France, plant and pollinator abundance, richness and presence differ along the latitudinal gradient, which correspond to natural variations in biodiversity, and these variations could potentially affect network structure. Moreover, interaction networks are often reported based on temporally aggregated data, but in truth pollination interactions are not static and vary in time, since different plant and pollinator species display different phenologies. Large datasets on plant-pollinator interactions which comprise the entire flowering season or multiple years and allow relevant comparisons among networks along environmental gradient are rare. Due to their complexity and variation among years, most studies of mutualistic networks have focused on predicting and comparing classic network metrics which are all influenced by network size, i.e. the number of plant and insect species. Furthermore, most of these networks are based on interactions observed in the field, and thus some existing links between species remain unobserved. As such, visit-based networks represent a subsample of possible interactions, which call for the development of new methodological approaches to better explore the ecological processes determining species interactions. The general aim of this study is to understand and help predict the effects of environmental changes on plant and pollinator communities by studying plant-pollinator associations along an environmental gradient. Here, I provide and analyse a new database made of geo-localized data characterizing plant-pollinator associations at the species level, spatial variation in community structure and trait assemblage, focusing on six different calcareous grasslands along a latitudinal gradient in France. I first compared the taxonomical diversity variation in space (between and within region) and time (along the season). Then, I used a new methodological approach to compare networks of different size and to study the consequences of environmental gradients on plant-pollinator interaction probability. To understand how much distorted is our vision of plant-pollinator networks sampled following classic methods, I built more complete interaction networks using the pollen found on insects. Finally, I studied the mechanism behind geographical variation of floral scents and among-populations differences linked to the variation in the pollinator community. Because of the complexity and variation of plant-pollinator interactions, our study highlighted the importance to consider the entire flowering season and insects flying period, using species-level identifications, to disentangle the ecological species' role and the network variations. The use of new methodological approach allowed us to make networks comparison along the environmental and diversity gradient avoiding data circularity. The high amount of data provided in this thesis permitted to make comparisons at different level, from the entire network to species-specific variation among-populations.

Orientador: Elza Guimarães / Resumo: A variação em atributos de proteção, principalmente os foliares, pode ter importante papel no desempenho das espécies ao longo de um gradiente de condições ambientais ou em hábitats heterogêneos. O domínio Cerrado está inserido em um gradiente climático e suas formações savânicas estão submetidas a queimadas recorrentes. Neste trabalho nós caracterizamos atributos de proteção às gemas em três espécies lenhosas, coocorrentes em fitofisionomias savânicas ao longo do gradiente latitudinal N-S do Cerrado e investigamos a ocorrência de fogo em uma escala espácio-temporal. Caracterizamos a posição das gemas nas plantas, morfologia e anatomia e indicadores de flamabilidade das mesmas. De modo geral, as plantas de diferentes localidades apresentaram diferenças quanto a altura das gemas na planta em relação ao nível do solo, sendo que plantas mais altas foram observadas nas latitudes menores e as mais baixas nas latitudes maiores, provavelmente devido a maior produtividade associada à proximidade da linha do Equador. Primórdios com maior área ocupada por idioblastos fenólicos foram observados nas duas localidades mais próximas à linha do Equador, possivelmente devido a alta intensidade de radiação. Além disso, registramos distintos regimes de queimada nas cinco localidades nos últimos 15 anos. Considerando a ampla distribuição geográfica das três espécies deste estudo, podemos concluir que suas gemas axilares toleram certa variação nos fatores climáticos como a amplitude de temperatur... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The variation in protection traits, especially the foliar ones, can play an important role in species performance along a gradient of environmental conditions or in heterogeneous habitats. The Cerrado domain is inserted in a climatic gradient and its savannah formations are under recurrent burning. In this study, we characterized bud protection traits of three woody species that co-ocurr in savannah phytophysiognomys along the Cerrado latitudinal gradient and we investigated fire occurrence in a spatio-temporal scale. We characterized bud position in each plant species, its morphology, anatomy and flammability indicators. In general, plants of different locations showed differences in bud height in relation to soil level. Taller plants were observed at lower latitudes and the smallest ones at higher latitudes, probably due to the higher productivity associated to the proximity to Equator line. Primordia with a larger area occupied by phenolic idioblasts were observed in the two locations nearest to the Equator line, possibly due to high radiation intensity. Besides that, we registered different fire regimes at the five locations in the last 15 years. Considering the wide distribution of the three species of this study, we can conclude that their axillary buds tolerate some variation in climatic factors like temperature, solar radiation and pluviosity amplitude. Besides that, this species are capable of persisting in environments under different fire frequency. Additionally, b... (Complete abstract click electronic access below) / Mestre

The legacy of historical biogeography impacts many organisms and results in a wide range of character variation over a latitudinal gradient. The pitcher-plant mosquito Wyeomyia smithii is one such organism that demonstrates a wide range of phenotypic and genotypic variation over the entirety of its range from the Gulf Coast to Canada. A geographic cline established by the presence and recession of the Laurentide Ice Sheet is manifest in the narrow range of thermal tolerance exhibited by different populations and also in the differing propensity of bloodfeeding by these mosquitoes. These contemporary clines were analyzed by a variety of experimental methods ranging from year-long fitness assays, scanning electron microscopy, and RNA-sequencing to determine the patterns underlying the resulting evolutionary differences among established populations. This dissertation includes both unpublished and co-authored material.

Global warming will affect every level of biological organization from the metabolism of individuals to the functioning of ecosystems. I explored the effects of warming on three rock-pool meioinvertebrate communities along a latitudinal gradient (temperate, tropical, and sub-Arctic regions) to determine effects on community and food-web structure and functioning. Warming affected regions differently, having a positive effect on sub-Arctic communities, a negative effect on temperate communities, and intermediate responses in tropical communities in terms of abundance, stability and extinction frequency. Differences in structural properties of the food webs supported the insurance hypothesis: that greater redundancy in webs results in greater stability, and helped to explain why the tropical community was more stable than the temperate community in warmed treatments. My study highlights the importance of considering differential response of species and communities from different latitudes and the importance of food web structure in predicting species response to global climate change.

Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-07-25Bitstream added on 2014-06-13T18:47:10Z : No. of bitstreams: 1 nardy_o_dr_rcla.pdf: 3226439 bytes, checksum: 5a6b6af0a77e36a028fdd67051607c4c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Foram realizadas meta análises com o Gradiente Latitudinal de Riqueza de espécies, a Regra de Rapoport e sua interação para vertebrados ao longo de todo o Globo. Com os resultados é possível concluir que ambos os padrões são generalizáveis e consistentes para todos os grupos de vertebrados, no entanto nenhuma variável moderadora associada à característica ecológicas, biológicas ou biogeográficas pode ser confirmada como principal condicionante destes padrões, não apresentando padrões constantes entre hemisférios, continentes, classes, número de províncias biogeográficas, tamanho corpóreo ou outra variável analisada. Foram utilizados como effect sizes a inclinação da reta de regressão ou o coeficiente angular da regressão linear (b) e o Coeficiente de Correlação de Spearman corrigido por Z-Fisher (r), entre estes dois, o segundo apresentou melhores resultados referentes as suas adequações e restrições associadas a meta análise, tais como normalidade dos dados e pressupostos de viés de publicações. As variáveis moderadoras associadas a características metodológicas como poder do teste, significância e tamanho amostral apresentaram maior poder explicativo do padrão do que as demais variáveis, sugerindo uma necessidade de se adotar um padrão mais rigoroso no delineamento de estudos que abordem este tema. Para a Regra de Rapoport o método utilizado na confecção do teste foi a variável moderadora mais evidente para a detecção de uma estrutura nos dados. / In the present work where made meta analysis with Latitudinal Gradient of Species richness, Rapoport Rule and their interaction for vertebrates along a global scale. With the results is possible to conclude that both patterns are general for vertebrates, nevertheless none of the ecological, biological or biogeographical moderators variables could be confirmed as the primary cause of the patterns, don’t showing any constant pattern between hemispheres, continents, classes, number of biogeographical provinces or other analyzed variable. It will be used as effect size the angular coefficient or the linear regression (b) and the Spearman Correlation Coefficient transformed by Z-Fisher (r), among these two effect size, the second presents best results associated with restrictions and fits inherent to meta analysis, such as normality and publication bias. The moderator’s variables associates with methodological issues, like statistical power, significance and sample size show higher explanation strength than the others variables, suggesting a necessity of more strength methods in the studies that claim these global patterns. For Rapoport Rule the method used to do the test was the moderator variable more evident to detect some data structure.

Os principais objetivos deste trabalho foram conhecer a distribuição da riqueza dos Hymenoptera parasitoides Diapriidae Belytinae ao longo de um gradiente latitudinal da Mata Atlântica e explicar as causas do padrão de riqueza encontrado por comparação com os padrões descritos para outros grupos. Os Belytinae exercem papel chave na regulação natural de populações de muitas espécies de Mycetophilidae e Sciaridae (Diptera) e o conhecimento sobre a diversidade desta subfamília no bioma Mata Atlântica é relativamente pequeno. O material utilizado neste estudo provém de coletas realizadas em 18 localidades regularmente espaçadas, da Paraíba à Santa Catarina, entre os anos de 2000 e 2002, no âmbito do projeto Riqueza e diversidade de Hymenoptera e Isoptera ao longo de um gradiente latitudinal na Mata Atlântica - a floresta pluvial do leste do Brasil (Biota/SP Fapesp). Através de um número padronizado de armadilhas Malaise e de Moericke, e varredura da vegetação foram obtidos 1241 exemplares separados em 115 morfoespécies e oito gêneros. Destes, Scorpioteleia é registrado pela primeira vez na região neotropical e sete (Aclista, Belyta, Cinetus, Odontopsilus, Scorpioteleia, Lyteba e Camptopsilus) são registrados pela primeira vez no Brasil. Foram feitos mapeamentos e diagnoses para todas as morfoespécies e gêneros; as morfoespécies foram todas ilustradas com pelo menos duas fotos. A maior parte das morfoespécies (86) está presente em apenas uma ou duas localidades. Nota-se uma tendência das localidades nas maiores latitudes de apresentarem riquezas de morfoespécies e gêneros significativamente maiores que as das localidades em latitudes menores, mesmo que estas apresentem quantidades de indivíduos significativamente maiores que as daquelas. Os resultados da análise da distribuição dos Belytinae indicam uma quantidade de morfoespécies exclusivas do sul do bioma (6 ou 8) ligeiramente maior que as exclusivas do norte (2), apesar das diferenças serem pouco significativas. A análise de similaridade indicou que a proximidade geográfica parece ser importante condicionante para o padrão de distribuição da fauna na maioria das localidades; os três agrupamentos principais formados nos dendogramas de índices de Sørensen e Jaccard sugerem a presença de dois sub-biomas (Sul + Sudeste e Nordeste). Indícios obtidos a partir das análises e dos dados do presente estudo combinados com informações da literatura ou de pesquisadores sobre a biologia, ecologia e distribuição da riqueza dos Belytinae, seus hospedeiros e fungos do solo, tornam plausível a ideia de que os Belytinae tenham a riqueza de espécies aumentada com o aumento da latitude, contrariamente ao padrão mais comum para a maioria dos grupos animais. / The main objectives of this work were to describe the distribution of Hymenoptera parasitoids Diapriidae Belytinae richness along a latitudinal gradient of Atlantic Forest and to explain the reasons for the pattern of richness found, by comparison with patterns described for other groups. The Belytinae play a key role in the natural regulation of populations of many species of Mycetophilidae and Sciaridae (Diptera) and the knowledge about the diversity of this subfamily in the Atlantic Forest biome is relatively poor. The material used in this study comes from collections in 18 regularly spaced locations, from Paraiba to Santa Catarina, between the years of 2000 and 2002, under the project \"Richness and Diversity of Hymenoptera and Isoptera along a latitudinal gradient in the Atlantic forest - the Eastern Brazilian Rain Forest\" (Biota/SP - FAPESP). Using a standardized number of Malaise and Moericke traps, and sweeping the vegetation a total of 1241 specimens separated in 115 morphospecies and eight genera were obtained. Of these, Scorpioteleia is recorded for the first time in the neotropical region and seven genera (Aclista, Belyta, Cinetus, Odontopsilus, Scorpioteleia, Lyteba and Camptopsilus) are recorded for the first time in Brazil. Mappings and diagnoses were made for all morphospecies and genera; all morphospecies were illustrated with at least two pictures. There is a tendency of localities in the highest latitudes to present similar or significantly greater richness of morphospecies and genera than those of localities in lowest latitudes, even if these present quantities of individuals significantly higher than the latter. The results of the analysis of the distribution of Belytinae indicate a quantity of exclusive morphospecies of the southern biome (6 or 8) slightly higher than the exclusive northern (2), although these differences are not highly significant. Most morphospecies (86) are present in only one or two locations. The similarity analysis indicated that the geographical proximity appears to be important to define the pattern of distribution of fauna in most localities; the three main groups formed in dendograms with indices of Sorensen and Jaccard suggest the presence of two sub-biomes (South + East and Northeast). Evidences obtained with the data and analyzes of the present study combined with information deducted from or obtained through literature or researchers about the biology, ecology and distribution of the richness of Belytinae, their hosts and soil fungi, make plausible the idea that the Belytinae have the species richness increased with the increase of latitude, unlike the most common pattern displayed by most animal groups.

Os principais objetivos deste trabalho foram conhecer a distribuição da riqueza dos Hymenoptera parasitoides Diapriidae Belytinae ao longo de um gradiente latitudinal da Mata Atlântica e explicar as causas do padrão de riqueza encontrado por comparação com os padrões descritos para outros grupos. Os Belytinae exercem papel chave na regulação natural de populações de muitas espécies de Mycetophilidae e Sciaridae (Diptera) e o conhecimento sobre a diversidade desta subfamília no bioma Mata Atlântica é relativamente pequeno. O material utilizado neste estudo provém de coletas realizadas em 18 localidades regularmente espaçadas, da Paraíba à Santa Catarina, entre os anos de 2000 e 2002, no âmbito do projeto Riqueza e diversidade de Hymenoptera e Isoptera ao longo de um gradiente latitudinal na Mata Atlântica - a floresta pluvial do leste do Brasil (Biota/SP Fapesp). Através de um número padronizado de armadilhas Malaise e de Moericke, e varredura da vegetação foram obtidos 1241 exemplares separados em 115 morfoespécies e oito gêneros. Destes, Scorpioteleia é registrado pela primeira vez na região neotropical e sete (Aclista, Belyta, Cinetus, Odontopsilus, Scorpioteleia, Lyteba e Camptopsilus) são registrados pela primeira vez no Brasil. Foram feitos mapeamentos e diagnoses para todas as morfoespécies e gêneros; as morfoespécies foram todas ilustradas com pelo menos duas fotos. A maior parte das morfoespécies (86) está presente em apenas uma ou duas localidades. Nota-se uma tendência das localidades nas maiores latitudes de apresentarem riquezas de morfoespécies e gêneros significativamente maiores que as das localidades em latitudes menores, mesmo que estas apresentem quantidades de indivíduos significativamente maiores que as daquelas. Os resultados da análise da distribuição dos Belytinae indicam uma quantidade de morfoespécies exclusivas do sul do bioma (6 ou 8) ligeiramente maior que as exclusivas do norte (2), apesar das diferenças serem pouco significativas. A análise de similaridade indicou que a proximidade geográfica parece ser importante condicionante para o padrão de distribuição da fauna na maioria das localidades; os três agrupamentos principais formados nos dendogramas de índices de Sørensen e Jaccard sugerem a presença de dois sub-biomas (Sul + Sudeste e Nordeste). Indícios obtidos a partir das análises e dos dados do presente estudo combinados com informações da literatura ou de pesquisadores sobre a biologia, ecologia e distribuição da riqueza dos Belytinae, seus hospedeiros e fungos do solo, tornam plausível a ideia de que os Belytinae tenham a riqueza de espécies aumentada com o aumento da latitude, contrariamente ao padrão mais comum para a maioria dos grupos animais. / The main objectives of this work were to describe the distribution of Hymenoptera parasitoids Diapriidae Belytinae richness along a latitudinal gradient of Atlantic Forest and to explain the reasons for the pattern of richness found, by comparison with patterns described for other groups. The Belytinae play a key role in the natural regulation of populations of many species of Mycetophilidae and Sciaridae (Diptera) and the knowledge about the diversity of this subfamily in the Atlantic Forest biome is relatively poor. The material used in this study comes from collections in 18 regularly spaced locations, from Paraiba to Santa Catarina, between the years of 2000 and 2002, under the project \"Richness and Diversity of Hymenoptera and Isoptera along a latitudinal gradient in the Atlantic forest - the Eastern Brazilian Rain Forest\" (Biota/SP - FAPESP). Using a standardized number of Malaise and Moericke traps, and sweeping the vegetation a total of 1241 specimens separated in 115 morphospecies and eight genera were obtained. Of these, Scorpioteleia is recorded for the first time in the neotropical region and seven genera (Aclista, Belyta, Cinetus, Odontopsilus, Scorpioteleia, Lyteba and Camptopsilus) are recorded for the first time in Brazil. Mappings and diagnoses were made for all morphospecies and genera; all morphospecies were illustrated with at least two pictures. There is a tendency of localities in the highest latitudes to present similar or significantly greater richness of morphospecies and genera than those of localities in lowest latitudes, even if these present quantities of individuals significantly higher than the latter. The results of the analysis of the distribution of Belytinae indicate a quantity of exclusive morphospecies of the southern biome (6 or 8) slightly higher than the exclusive northern (2), although these differences are not highly significant. Most morphospecies (86) are present in only one or two locations. The similarity analysis indicated that the geographical proximity appears to be important to define the pattern of distribution of fauna in most localities; the three main groups formed in dendograms with indices of Sorensen and Jaccard suggest the presence of two sub-biomes (South + East and Northeast). Evidences obtained with the data and analyzes of the present study combined with information deducted from or obtained through literature or researchers about the biology, ecology and distribution of the richness of Belytinae, their hosts and soil fungi, make plausible the idea that the Belytinae have the species richness increased with the increase of latitude, unlike the most common pattern displayed by most animal groups.

Traits provide an informative approach to examine species-environment interactions. Often, species-by-species approaches are inefficient to generate generalizable ecological relationships and do not predict species responses to environmental changes based on specific traits species possess. Multiple lines of inquiry and multi-scale approaches are best for assessing environment-trait responses. This thesis examines important questions not specifically addressed before in traits-based research. Chapter one explores biological and ecological trait associations incorporating ontogenetic diet shifts for New River fishes. Niche shift analysis as a chapter one sub-objective quantitatively support where species-specific diet shifts likely occur. Strong biological-ecological trait associations, some intuitive and others not so intuitive, were found that relate biological structure to ecological function. Improved understanding of trait associations, including what factors influence others, supports inference of ecology of fishes. Chapters two and three examine spatial and intraspecific trait variability. Chapter two specifically examines large-scale life history trait variability along latitudinal gradients for twelve widely distributed fish species, including directionality of trait variation, and hypothesizing how optimal traits change with large-scale environmental factors. Strong positive and negative patterns found include average total length of newly hatched larvae, average total length at maturation, average spawning temperature, average egg diameter, and maximum length. These five traits are correlated with other adaptive attributes (i.e. growth rate, reproductive output, and longevity/population turnover rate). In contrast to latitudinal scale, Chapter three examines trait variability of white sucker (Catostomus commersonii) and fantail darter (Etheostoma flabellare) as a function of small-watershed scale spatial factors and anthropogenic disturbance. Toms Creek and Chestnut Creek white sucker and fantail darter displayed positive response to disturbance, contrary to past studies. Lower resource competition, and / or competitive exclusion of fishes with similar niche requirements are possible mechanisms. All three objectives support understanding of trait association and variability as a useful foundation in ecological applications and for formulating plans for conservation and management of species. / Master of Science

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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.